Quasi-Solid-State Rechargeable Lithium-Ion Batteries with a Calix[4]quinone Cathode and Gel Polymer Electrolyte

Finite Element Approach for Rheological Behavior in Colloidal Electrolytes in Lithium-Ion Battery Performance

The main implication of articulating electrolyte performance is studying the energy density, charging aspects, formation of precipitates, thermal fluctuations during charging-discharging, and safety of batteries against fire or spark. One of the most significant aspects is the ability to design colloidal electrolytes that can enhance the overall performance of batteries along with dealing with all internal problems within a battery system. Through this optimization progression, the general performance and efficiency of Li-ion batteries can be improved. This work is presented in the study of the boundary value problem for rheological properties of colloidal electrolytes as a fourth grade fluid for lithium ion (Li-ion) batteries down a vertical cylinder. They have exceptional characteristics, such as low volatility and high thermal stability. The practical usage of the exact flow is restricted, as it involves very complicated integrals. The nonlinear problem that arises is solved by Galerkin's finite element approach based on the weighted-residual formulation, which is used to find the approximate solutions of the fourth-grade problem. This approach utilizes a piecewise linear approximation using linear Lagrange polynomials. Convergence of the solutions, which briefly describes the flow characteristics, includes the effects of the emerging parameters. The results obtained after implementation are not restrictive to small values of the flow parameters. Numerical studies have shown the superior accuracy and lesser computational cost of this scheme in comparison to collocation, the homotopy analysis method, and the homotopy perturbation method. The impact of the relevant parameters is examined through graphical results after implementation of a number of iterations.

Carbonyl Chemistry for Advanced Electrochemical Energy Storage Systems

On the basis of the sustainable concept, organic compounds and carbon materials both mainly composed of light C element have been regarded as powerful candidates for advanced electrochemical energy storage (EES) systems, due to theie merits of low cost, eco-friendliness, renewability, and structural versatility. It is investigated that the carbonyl functionality as the most common constituent part serves a crucial role, which manifests respective different mechanisms in the various aspects of EES systems. Notably, a systematical review about the concept and progress for carbonyl chemistry is beneficial for ensuring in-depth comprehending of carbonyl functionality. Hence, a comprehensive review about carbonyl chemistry has been summarized based on state-of-the-art developments. Moreover, the working principles and fundamental properties of the carbonyl unit have been discussed, which has been generalized in three aspects, including redox activity, the interaction effect, and compensation characteristic. Meanwhile, the pivotal characterization technologies have also been illustrated for purposefully studying the related structure, redox mechanism, and electrochemical performance to profitably understand the carbonyl chemistry. Finally, the current challenges and promising directions are concluded, aiming to afford significant guidance for the optimal utilization of carbonyl moiety and propel practicality in EES systems.

A bipolar organic molecule towards the anion/cation-hosting cathode compatible with polymer electrolytes for quasi-solid-state dual-ion batteries

Ion concentration and mobility are tightly associated with the ionic conductance of polymer electrolytes in solid-state lithium batteries. However, the anions involved in the movement are irrelevant to energy generation and cause uncontrolled dendritic growth and concentration polarization. In the current study, we proposed the strategy of using a bipolar organic molecule as the anion/cation-hosting cathode to expand the active charge carriers of polymer electrolytes. As a proof-of-concept demonstration of the novel strategy, a bipolar phthalocyanine derivative (2,3,9,10,16,17,23,24-octamethoxyphthalocyaninato) Ni(II) (NiPc-(OH)8) that could successively store anions and cations was used as the cathode hosting material in quasi-solid-state dual-ion batteries (QSSDIBs). Interestingly, peripheral polyhydroxyl substituents could build a compatible interface with poly(vinylidene fluoride-hexafluoro propylene-based gel polymer electrolytes (PVDF-HFP). As expected, NiPc-(OH)8 displays a high specific capacity of 248.2 mAh/g (at 50 mA g-1) and improved cyclic stability compared with that in liquid electrolyte. This study provides a solution to the issue of anion migration and could open another way to build high-performance QSSDIBs.

A Review of Macrocycles Applied in Electrochemical Energy Storge and Conversion

Macrocycles composed of diverse aromatic or nonaromatic structures, such as cyclodextrins (CDs), calixarenes (CAs), cucurbiturils (CBs), and pillararenes (PAs), have garnered significant attention due to their inherent advantages of possessing cavity structures, unique functional groups, and facile modification. Due to these distinctive features enabling them to facilitate ion insertion and extraction, form crosslinked porous structures, offer multiple redox-active sites, and engage in host-guest interactions, macrocycles have made huge contributions to electrochemical energy storage and conversion (EES/EEC). Here, we have summarized the recent advancements and challenges in the utilization of CDs, CAs, CBs, and PAs as well as other novel macrocycles applied in EES/EEC devices. The molecular structure, properties, and modification strategies are discussed along with the corresponding energy density, specific capacity, and cycling life properties in detail. Finally, crucial limitations and future research directions pertaining to these macrocycles in electrochemical energy storage and conversion are addressed. It is hoped that this review is able to inspire interest and enthusiasm in researchers to investigate macrocycles and promote their applications in EES/EEC.

A Layered Organic Cathode for High-Energy, Fast-Charging, and Long-Lasting Li-Ion Batteries

Eliminating the use of critical metals in cathode materials can accelerate global adoption of rechargeable lithium-ion batteries. Organic cathode materials, derived entirely from earth-abundant elements, are in principle ideal alternatives but have not yet challenged inorganic cathodes due to poor conductivity, low practical storage capacity, or poor cyclability. Here, we describe a layered organic electrode material whose high electrical conductivity, high storage capacity, and complete insolubility enable reversible intercalation of Li+ ions, allowing it to compete at the electrode level, in all relevant metrics, with inorganic-based lithium-ion battery cathodes. Our optimized cathode stores 306 mAh g-1cathode, delivers an energy density of 765 Wh kg-1cathode, higher than most cobalt-based cathodes, and can charge-discharge in as little as 6 min. These results demonstrate the operational competitiveness of sustainable organic electrode materials in practical batteries.

Organic Cathodes, a Path toward Future Sustainable Batteries: Mirage or Realistic Future?

Organic active materials are seen as next-generation battery materials that could circumvent the sustainability and cost limitations connected with the current Li-ion battery technology while at the same time enabling novel battery functionalities like a bioderived feedstock, biodegradability, and mechanical flexibility. Many promising research results have recently been published. However, the reproducibility and comparison of the literature results are somehow limited due to highly variable electrode formulations and electrochemical testing conditions. In this Perspective, we provide a critical view of the organic cathode active materials and suggest future guidelines for electrochemical characterization, capacity evaluation, and mechanistic investigation to facilitate reproducibility and benchmarking of literature results, leading to the accelerated development of organic electrode active materials for practical applications.

Reliable Organic Carbonyl Electrode Materials Enabled by Electrolyte and Interfacial Chemistry Regulation

ConspectusLithium-ion batteries (LIBs) have achieved great success and dominated the market of portable electronics and electric vehicles owing to their high energy density and long-term cyclability. However, if applying LIBs for large-scale energy storage scenarios, such as regulating the output of electricity generated by sustainable energy in the future age of carbon neutrality, the current electrochemistry of LIBs based on Li-ion interaction/deinteraction between a transition-metal oxide cathode and graphite anode will suffer from problems of scarce natural resources (e.g., Li, Co, and Ni) and high energy consumption/CO2 emission involved in the production of electrodes. Similarly, other commercial batteries such as lead-acid batteries and nickel-metal hydride batteries are also plagued by these issues.In contrast, organic electrode materials, especially carbonyl materials, exhibit advantages of abundant resources, renewability, high capacity, environmental friendliness, and structural designability and have shown great promise for various rechargeable batteries in recent years. However, organic carbonyl electrode materials generally exhibit unsatisfactory cycling stability and rate performance, which are highly dependent on the electrolyte and interfacial chemistry. Appropriate electrolytes and a stable electrode/electrolyte interface would be beneficial for preventing the dissolution of organic carbonyl electrode materials and/or their redox intermediates in electrolytes and promoting fast ion transport between the electrode and electrolyte. In this regard, designing an appropriate electrolyte and constructing a stable electrode/electrolyte interface are the keys to enhancing the comprehensive performance of organic carbonyl electrode materials.In this Account, on the basis of our progress and related works from other groups in the past decade, we afford an overview of understanding the effects of electrolyte and interfacial chemistry on the electrochemical performance of organic carbonyl electrode materials. We will start by briefly introducing the basic properties, working mechanisms, and issues of organic carbonyl electrode materials. Then, the implications of electrolyte and electrode/electrolyte interfacial chemistry on electrochemical performance will be summarized and highlighted through discussing the performance of organic carbonyl electrodes in different types of electrolytes (organic liquid and aqueous and solid-state electrolytes). Meanwhile, the design principles of electrolytes and interfacial chemistry for organic carbonyl electrodes are also discussed. A representative example is that organic carbonyl electrode materials often exhibit better electrochemical performance in ether-based electrolytes than in ester-based electrolytes, which could be mainly attributed to the stable and robust solid electrolyte interphase (SEI) formed on carbonyl electrodes in the ether-based electrolyte. This example demonstrates the importance of investigating the electrode/electrolyte interfacial chemistry of organic carbonyl electrode materials. Finally, future perspectives on designing appropriate electrolytes and understanding electrode/electrolyte interfacial chemistry will also be discussed. It is meaningful to thoroughly reveal the dynamic evolution of the electrode/electrolyte interface during discharge/charge processes and evaluate the compatibility between electrolytes and organic carbonyl electrode materials under practical conditions using limited quantities of electrolytes and high areal-specific-capacity electrodes in the future. This Account could attract more attention to electrolytes and the electrode/electrolyte interfacial chemistry of organic carbonyl electrode materials and finally promote their future commercial applications.

High-Performance Poly(1-naphthylamine)/Mesoporous Carbon Cathode for Lithium-Ion Batteries with Ultralong Cycle Life of 45000 Cycles at -15 °C

Organic electrode materials for lithium-ion batteries have attracted significant attention in recent years. Polymer electrode materials, as compared to small-molecule electrode materials, have the advantage of poor solubility, which is beneficial for achieving high cycling stability. However, the severe entanglement of polymer chains often leads to difficulties in preparing nanostructured polymer electrodes, which is vital for achieving fast reaction kinetics and high utilization of active sites. This study demonstrates that these problems can be solved by the in situ electropolymerization of electrochemically active monomers in nanopores of ordered mesoporous carbon (CMK-3), combining the advantages of the nano-dispersion and nano-confinement effects of CMK-3 and the insolubility of the polymer materials. The as-prepared nanostructured poly(1-naphthylamine)/CMK-3 cathode exhibits a high active site utilization of 93.7%, ultrafast rate capability of 60 A g-1 (≈320 C), and an ultralong cycle life of 10000 cycles at room temperature and 45000 cycles at -15 °C. The study herein provides a facile and effective method that can simultaneously solve both the dissolution problem of small-molecule electrode materials and the inhomogeneous dispersion issue of polymer electrode materials.

MOFs Containing Solid-State Electrolytes for Batteries

The use of metal-organic frameworks (MOFs) in solid-state electrolytes (SSEs) has been a very attractive research area that has received widespread attention in the modern world. SSEs can be divided into different types, some of which can be combined with MOFs to improve the electrochemical performance of the batteries by taking advantage of the high surface area and high porosity of MOFs. However, it also faces many serious problems and challenges. In this review, different types of SSEs are classified and the changes in these electrolytes after the addition of MOFs are described. Afterward, these SSEs with MOFs attached are introduced for different types of battery applications and the effects of these SSEs combined with MOFs on the electrochemical performance of the cells are described. Finally, some challenges faced by MOFs materials in batteries applications are presented, then some solutions to the problems and development expectations of MOFs are given.

Polynitrosoarene Radical as an Efficient Cathode Material for Lithium-Ion Batteries

Organic radical batteries (ORBs) with radical-branched polymers as cathode materials represent a valuable alternative to meet the continuously increasing demand on energy storage. However, the low theoretical capacities of current radical-contained compounds strongly hamper their practical applications. To address this issue, a chemically robust polynitrosoarene (tris(4-nitrosophenyl)amine) with a pronounced radical property is rationally designed as an efficient cathode for ORBs. Its unique multi-nitroso structure displays remarkably reversible charge/discharge capability and a superior capacity up to 300 mA h g-1 (93% theoretical capacity) after 100 cycles at 100 mA g-1 within a broad potential window of 1.3-4.3 V (vs Li+/Li). Moreover, the ultra-long cycle life is also achieved at 1000 mA g-1 with 85% preservation of the capacity after 1000 cycles, making it the best-reported organic radical cathode material for lithium-ion batteries.

Electrolytes in Organic Batteries

Organic batteries using redox-active polymers and small organic compounds have become promising candidates for next-generation energy storage devices due to the abundance, environmental benignity, and diverse nature of organic resources. To date, tremendous research efforts have been devoted to developing advanced organic electrode materials and understanding the material structure-performance correlation in organic batteries. In contrast, less attention was paid to the correlation between electrolyte structure and battery performance, despite the critical roles of electrolytes for the dissolution of organic electrode materials, the formation of the electrode-electrolyte interphase, and the solvation/desolvation of charge carriers. In this review, we discuss the prospects and challenges of organic batteries with an emphasis on electrolytes. The differences between organic and inorganic batteries in terms of electrolyte property requirements and charge storage mechanisms are elucidated. To provide a comprehensive and thorough overview of the electrolyte development in organic batteries, the electrolytes are divided into four categories including organic liquid electrolytes, aqueous electrolytes, inorganic solid electrolytes, and polymer-based electrolytes, to introduce different components, concentrations, additives, and applications in various organic batteries with different charge carriers, interphases, and separators. The perspectives and outlook for the future development of advanced electrolytes are also discussed to provide a guidance for the electrolyte design and optimization in organic batteries. We believe that this review will stimulate an in-depth study of electrolytes and accelerate the commercialization of organic batteries.

Trinitroaromatic Salts as High-Energy-Density Organic Cathode Materials for Li-Ion Batteries

Even though organic molecules with designed structures can be assembled into high-capacity electrode materials, only limited functional groups such as -C═O and -C═N- could be designed as high-voltage cathode materials with enough high capacity. Here, we propose a common chemical raw material, trinitroaromatic salt, to have promising potential to develop organic cathode materials with high discharge voltage and capacity through a strong delocalization effect between -NO₂ and aromatic ring. Our first-principles calculations show that electrochemical reactions of trinitroaromatic potassium salt C₆H₂(NO₂)₃OK are a 6-electron charge-transfer process, providing a high discharge capacity of 606 mAh g^-1 and two voltage plateaus of 2.40 and 1.97 V. Electronic structure analysis indicates that the discharge process from C₆H₂(NO₂)₃OK to C₆H₂(NO₂Li₂)₃OK stabilizes oxidized [C₆]ⁿ⁺ to achieve a stable conjugated structure through electron delocalization from -NO₂ to [C₆]ⁿ⁺. The ordered layer structure C₆H₂(NO₂)₃OK can provide large spatial pore channels for Li-ion transport, achieving a high ion diffusion coefficient of 3.41 × 10^-6 cm² s^-1.

Synergy of an In Situ-Polymerized Electrolyte and a Li3N-LiF-Reinforced Interface Enables Long-Term Operation of Li-Metal Batteries

The long-term operation of a Li-metal anode remains a great challenge due to the severe dendrite growth in an organic liquid electrolyte. To protect a Li-anode surface from continuous corrosion by an electrolyte, a consistent and robust solid electrolyte interface (SEI) is an essential prerequisite. This work proposes a secure gel polymer electrolyte, which is in situ constructed via a facile polymerization process of vinylidene carbonate inside Li-metal batteries. The liquid components that are not involved in polymerization are well entrapped in the poly(vinyl carbonate) framework, leading to a high oxidative stability of up to 4.5 V (vs Li/Li+). A Li3N-LiF-reinforced SEI resulting from the reduction of fluoroethylene carbonate and lithium nitrate additives has a synergistic effect on the suppression of Li-dendrite growth. The densely packed Li deposition behavior is revealed by in situ/ex situ microscopic observations. Steady cycling of over 2500 h with a relatively low voltage hysteresis is achieved by the Li||Li symmetric cells. A Coulombic efficiency above 96% upon long-term cycling is available for the asymmetric Li||Cu cells. The smooth operation of batteries with commercial LiFePO4 cathodes further indicates that the SEI with homogeneity in composition and structure prompts Li deposition with alleviative dendrites.

Ethynyl and Furyl Functionalized Porphyrin Complexes as New Organic Cathodes Enabling High Power Density and Long-Term Cycling Stability

Organic cathode materials have recently attracted abundant attention due to their flexible structural tunability and recyclability. However, the low intrinsic electrical conductivity and high solubility in electrolytes of organic electrode materials have significantly limited their practical application. Herein, we present [5,15-bis(ethynyl)-10,20-difurylporphinato] copper(II) (CuDEOP) as a new cathode for rechargeable organic lithium batteries (ROLBs). The combination of both ethynyl and furyl groups of the CuDEOP cathode with a nanorod structure renders it with enhanced structural stability and an extended delocalized π-electron system to deliver excellent cycling stability (capacity retention of 76% after 6000 cycles) and a high power density (16 kW kg^-1). The furyl electroactive groups participate in charge storage contribution to achieve a reversible six-electron-transfer redox reaction in a specific voltage range. The mechanism characterizations indicate that the nitrogen atoms on the porphyrin ring act as active sites to alternatively store both PF₆^- anions and Li⁺ cations, and the charge storage process is a pseudocapacitive-dominated reaction. This observation will offer a new avenue for designing functionalized molecules for electrochemical energy-storage (EES) systems.

π-Conjugated Hexaazatrinaphthylene-Based Azo Polymer Cathode Material Synthesized by a Reductive Homocoupling Reaction for Organic Lithium-Ion Batteries

A novel hexaazatrinaphthylene-based (HATN) azo polymer (PAH) was synthesized from a newly designed tri-nitro compound trinitrodiquinoxalino[2,3-a:2',3'-c]phenazine (HATNTN) through a Zn-induced reductive homocoupling reaction and used as a cathode material for lithium-ion batteries (LIBs). The integration of redox-active HATN units and azo linkages can improve the specific capacity, rate performance, and cycling stability of the PAH cathode. The control LIBs were assembled from HATNTN, in which HATNTN can be electrochemically reduced to an HATN-based azo polymer. Compared with the HATNTN cathode, the PAH cathode delivers higher specific capacities with much-improved cycling stability (97 mA h g^-1 capacity retention after 1500 cycles at 500 mA g^-1, which is around 28 times that of the HATNTN cathode) and considerably better rate performance (118 mA h g^-1 at 2000 mA g^-1, which is around 90 times that of the HATNTN cathode), simultaneously. This work provides a chemical polymerization strategy to construct extended π-conjugated azo polymers with multiple redox centers from nitro compounds for developing high-performance LIBs.

Intermolecular Interactions Drive the Unusual Co-Crystallization of Different Calix[4]arene Conformations

Crystallization of 5,17-dibromo-11,27,23,25-tetraone-26,28-dipropoxycalix[4]arene results in the rare observation of two different calix[4]arene conformations (partial cone and 1,3-alternate) co-crystallized within the same single crystal X-ray structure. Analysis using 1H and 13C NMR spectroscopy revealed that only a single conformation (the cone) was present in solution, and in contrast to the structures of other reported calix[4]arenes and calix[4]quinones, both conformations of the compound present in this crystal structure have a “pinched” shape, drastically reducing Br-Br separation and associated cavity sizes.

A nitroaromatic cathode with an ultrahigh energy density based on six-electron reaction per nitro group for lithium batteries

Organic electrode materials have emerged as promising alternatives to conventional inorganic materials because of their structural diversity and environmental friendliness feature. However, their low energy densities, limited by the single-electron reaction per active group, have plagued the practical applications. Here, we report a nitroaromatic cathode that performs a six-electron reaction per nitro group, drastically improving the specific capacity and energy density compared with the organic electrodes based on single-electron reactions. Based on such a reaction mechanism, the organic cathode of 1,5-dinitronaphthalene demonstrates an ultrahigh specific capacity of 1,338 mAh⋅g-1 and energy density of 3,273 Wh⋅kg-1, which surpass all existing organic cathodes. The reaction path was verified as a conversion from nitro to amino groups. Our findings open up a pathway, in terms of battery chemistry, for ultrahigh-energy-density Li-organic batteries.

Soluble Organic Cathodes Enable Long Cycle Life, High Rate, and Wide-Temperature Lithium-Ion Batteries

Organic electrode materials free of rare transition metal elements are promising for sustainable, cost-effective, and environmentally benign battery chemistries. However, severe shuttling effect caused by the dissolution of active materials in liquid electrolytes results in fast capacity decay, limiting their practical applications. Here, using a gel polymer electrolyte (GPE) that is in situ formed on Nafion-coated separators, the shuttle reaction of organic electrodes is eliminated while maintaining the electrochemical performance. The synergy of physical confinement by GPE with tunable polymer structure and charge repulsion of the Nafion-coated separator substantially prevents the soluble organic electrode materials with different molecular sizes from shuttling. A soluble small-molecule organic electrode material of 1,3,5-tri(9,10-anthraquinonyl)benzene demonstrates exceptional electrochemical performance with an ultra-long cycle life of 10 000 cycles, excellent rate capability of 203 mAh g^-1 at 100 C, and a wide working temperature range from -70 to 100 °C based on the solid-liquid conversion chemistry, which outperforms all previously reported organic cathode materials. The shielding capability of GPE can be designed and tailored toward organic electrodes with different molecular sizes, thus providing a universal resolution to the shuttling effect that all soluble electrode materials suffer.

Probing Mechanistic Insights into Highly Efficient Lithium Storage of C60 Fullerene Enabled via Three-Electron-Redox Chemistry

Renewable organic cathodes with abundant elements show promise for sustainable rechargeable batteries. Herein, for the first time, utilizing C₆₀ fullerene as organic cathode for room-temperature lithium-ion battery is reported. The C₆₀  cathode shows robust electrochemical performance preferably in ether-based electrolyte. It delivers discharge capacity up to 120 mAh g^-1 and specific energy exceeding 200 Wh kg^-1 with high initial Coulombic efficiency of 91%. The as-fabricated battery holds a capacity of 90 mAh g^-1 after 50 cycles and showcases remarkable rate performance with 77 mAh g^-1 retained at 500 mA g^-1 . Noteworthily, three couples of unusual flat voltage plateaus recur at ≈2.4, 1.7, and 1.5 V, respectively. Diffusion-dominated three-electron-redox reactions are revealed by cyclic voltammogram and plateau capacities. Intriguingly, it is for the first time unveiled by in situ X-ray diffraction (XRD) that the C₆₀ cathode underwent three reversible phase transitions during lithiation/delithiation process, except for the initial discharge when irreversible polymerization in between C₆₀ nanoclusters existed as suggested by the characteristic irreversible peak shifts in both in situ XRD pattern and in situ Raman spectra. Cs-corrected transmission electron microscope corroborated these phase evolutions. Importantly, delithiation potentials derived from density-functional-theory simulation based on proposed phase structures qualitatively consists with experimental ones.

Naphthalene diimides: perspectives and promise

In this review, we describe the developments in the field of naphthalene diimides (NDIs) from 2016 to the presentday. NDIs are shown to be an increasingly interesting class of molecules due to their electronic properties, large electron deficient aromatic cores and tendency to self-assemble into functional structures. Almost all NDIs possess high electron affinity, good charge carrier mobility, and excellent thermal and oxidative stability, making them promising candidates for applications in organic electronics, photovoltaic devices, and flexible displays. NDIs have also been extensively studied due to their potential real-world uses across a wide variety of applications including supramolecular chemistry, sensing, host-guest complexes for molecular switching devices, such as catenanes and rotaxanes, ion-channels, catalysis, and medicine and as non-fullerene accepters in solar cells. In recent years, NDI research with respect to supramolecular assemblies and mechanoluminescent properties has also gained considerable traction. Thus, this review will assist a wide range of readers and researchers including chemists, physicists, biologists, medicinal chemists and materials scientists in understanding the scope for development and applicability of NDI dyes in their respective fields through a discussion of the main properties of NDI derivatives and of the status of emerging applications.

Lignin biopolymer: the material of choice for advanced lithium-based batteries

Lignin, an aromatic polymer, offers interesting electroactive redox properties and abundant active functional groups. Due to its quinone functionality, it fulfils the requirement of erratic electrical energy storage by only providing adequate charge density. Research on the use of lignin as a renewable material in energy storage applications has been published in the form of reviews and scientific articles. Lignin has been used as a binder, polymer electrolyte and an electrode material, i.e. organic composite electrodes/hybrid lignin-polymer combination in different battery systems depending on the principal charge of quinone and hydroquinone. Furthermore, lignin-derived carbons have gained much popularity. The aim of this review is to depict the meticulous follow-ups of the vital challenges and progress linked to lignin usage in different lithium-based conventional and next-generation batteries as a valuable, ecological and low-cost material. The key factor of this new finding is to open a new path towards sustainable and renewable future lithium-based batteries for practical/industrial applications.

Theoretical prediction on photoelectric and supramolecular properties of benzoquinone-tetrathiafulvalene macrocyclic molecules

Benzoquinone has the ability to serve as an electron acceptor, and tetrathiafulvalene has the ability to serve as an electron donor. Based on the facts above, this work creatively cycles the benzoquinone unit and the tetrathiafulvalene unit alternately into macrocyclic molecules, the cyclopolymers of benzoquinone-tetrafluorene (C[n]QTTF, n = 3~6). To explore their structure and properties, the M06-2X functional of density functional theory (DFT) with 6-311g(d) basis set was used to optimize the ground-state structures of C[n]QTTF. Based on the stable configurations of the ground states, the electronic structure property is analyzed systematically. The results show that these macrocyclic molecules have excellent electron transport capability and electrochemical activity. Then, the electron absorption spectra of each system are carried out by using time-dependent density functional theory (TD-DFT) at the M062X/6-311+G(d) level. It turns out that their maximum absorption wavelengths are all in the visible range. Further calculation suggests that C[n]QTTF can also be characterized with one-dimensional self-assembly, double-walled assembly, and the host-guest inclusion performance, based on which it gains a variety of supramolecular structures. In summary, the benzoquinone-tetrafluorofurene macrocyclic molecules predicted by DFT calculations may be of assistance to the potential applications in organic electronics and supramolecular chemistry.

The Progress and Prospect of Tunable Organic Molecules for Organic Lithium-Ion Batteries

Compared to inorganic electrodes, organic materials are regarded as promising electrodes for lithium-ion batteries (LIBs) due to the attractive advantages of light elements, molecular-level structural design, fast electron/ion transferring, favorable environmental impacts, and flexible feature, etc. Not only specific capacities but also working potentials of organic electrodes are reasonably tuned by polymerization, electron-donating/withdrawing groups, and multifunctional groups as well as conductive additives, which have attracted intensive attention. However, organic LIBs (OLIBs) are also facing challenges on capacity loss, side reactions, electrode dissolution, low electronic conductivity, and short cycle life, etc. Many strategies have been applied to tackle those challenges, and many inspiring results have been achieved in the last few decades. In this review, we have introduced the basic concepts of LIBs and OLIBs, followed by the typical cathode and anode materials with various physicochemical properties, redox reaction mechanisms, and evolutions of functional groups. Typical charge-discharge behaviors and molecular structures of organic electrodes are displayed. Moreover, effective strategies on addressing problems of organic electrodes are summarized to give some guidance on the synthesis of optimized organic electrodes for practical applications of OLIBs.

Permselective metal-organic framework gel membrane enables long-life cycling of rechargeable organic batteries

Rechargeable organic batteries show great potential as a low-cost, sustainable and mass-producible alternatives to current transition-metal-based cells; however, serious electrode dissolution issues and solubilization of organic redox intermediates (shuttle effect) have plagued the capacity retention and cyclability of these cells. Here we report on the use of a metal-organic framework (MOF) gel membrane as a separator for organic batteries. The homogeneous micropores, intrinsic of the MOF-gel separator, act as permselective channels for targeted organic intermediates, thereby mitigating the shuttling problem without sacrificing power. A battery using a MOF-gel separator and 5,5'-dimethyl-2,2'-bis-p-benzoquinone (Me₂BBQ) as the electrode displays high cycle stability with capacity retention of 82.9% after 2,000 cycles, corresponding to a capacity decay of ~0.008% per cycle, with a discharge capacity of ~171 mA h g^-1 at a current density of 300 mA g^-1. The molecular and ionic sieving capabilities of MOF-gel separators promise general applicability, as pore size can be tuned to specific organic electrode materials. The use of MOF-gel separators to prevent side reactions of soluble organic redox intermediates could lead to the development of rechargeable organic batteries with high energy density and long cycling life.

Revealing better organic sodium battery performance in ionic liquid electrolytes

Ionic liquid (IL) electrolyte conduced to better sodium storage performance for organic electrode materials.

Revealing practical specific capacity and carbonyl utilization of multi-carbonyl compounds for organic cathode materials

Organic carbonyl compounds are regarded as promising candidates for next-generation rechargeable batteries due to their low cost, environmentally benign nature, and high capacity. The carbonyl utilization is a key issue that limits the practical specific capacity of multi-carbonyl compounds. In this work, a combination of thermodynamic computation and electronic structure analysis is carried out to study the influence of carbonyl type and carbonyl number on the electrochemical performance of a series of multi-carbonyl compounds by using density functional theory (DFT) calculations. By comparing discharge profiles of six tetraone compounds with different carbonyl sites, it is demonstrated that pentacene-5,7,12,14-tetraone (PT) with para-dicarbonyl and pyrene-4,5,9,10-tetraone (PTO) with ortho-dicarbonyl undergo four-lithium transfer while the other four compounds with meta-dicarbonyl fragments show only two-lithium transfer during the discharge process. By further increasing the carbonyl number, the electrochemical performance of molecules with similar para-dicarbonyl sites to PT can not be strongly improved. Among all the studied multi-carbonyl compounds, triphenylene-2,3,6,7,10,11-hexaone (TPHA) and tribenzo[f,k,m]tetraphen-2,3,6,7,11,12,15,16-octaone (TTOA) with similar ortho-dicarbonyl sites to PTO exhibit the best electrochemical performance due to simultaneous high specific capacity and high discharge voltage. Our results offer evidence that conjugated multiple-carbonyl molecules with ortho-dicarbonyl sites are promising in developing high energy-density organic rechargeable batteries.

Conductive Polyacrylic Acid-Polyaniline as a Multifunctional Binder for Stable Organic Quinone Electrodes of Lithium-Ion Batteries

High solubility in aprotic organic electrolytes and poor electrical conductivity are the main restrictions of organic electrodes in practical application. Conductive binder contributes to the high-performance electrodes as it enables both mechanical and electronic integrity of the electrode, which have been scarcely explored for organic electrodes. Herein, a conductive interpenetrating polymeric network is synthesized through in situ polymerization of polyaniline with poly(acrylic acid) (denoted PAA-PANi), which served as a novel conductive binder for organic 2-aminoanthraquinone (AAQ) materials. The conductive PANi component enhances the electrical conductivity of the electrode. Meanwhile, the PAA component serves as the binding matrix to condense with the amino groups (-NH₂) of AAQ, which therefore effectively inhibits their dissolution and maintains electrode integrity during cycling. As expected, the conductive binder exhibits both excellent electrical conductivity (10^-3 S cm^-1) and strong mechanical adhesion. The AAQ/reduced graphene oxide (AAQ@rGO) composite electrode prepared with the as-synthesized PAA-PANi binder delivers a high specific capacity of 126.1 mAh g^-1 at 0.1 A g^-1, superior rate capability (71.3 mAh g ^-1 at 3 A g^-1), and outstanding cycling stability (2000 cycles at 1 A g^-1), which greatly rivals polyvinylidene fluoride and PAA binder-based electrodes. Such a strategy points the way for the design and synthesis of conductive polymeric binders for organic electrodes, whose electrical conductivity and dissolution are massive issues.

Overview of the Synthesis and Structure of Calix[n]quinones (n=4, 6, 8)

Calix[n]quinones, a class of cyclic oligomers composed of p-benzoquinone structures connected by methylene, have multi-conjugated carbonyl structures and adjustable cavities, which make their synthesis extremely attractive. In this minireview, synthetic methods of calix[n]quinones and recent synthetic experience of our group are summarized. The merits and demerits of various synthetic methods are briefly reviewed as well. When synthesizing calix[n]quinone (n≥6) with a larger ring, the reduction-oxidation method is considered to be the most recommended.

Introducing a cell moisturizer: organogel nano-beads with rapid response to electrolytes for Prussian white analogue based non-aqueous potassium ion battery

Prussian white analogue nanoparticles were connected internally by a composite consisting of poly(butyl methacrylate) (PBMA) nano-gel and a conducting polymer layer via a one-step route. The powder falling problems have been mitigated by the intrinsic good binding strength of PBMA organogel; meanwhile, the conducting polymer provides extra transfer paths for electrons.

Nitrogen-Doped Hierarchical Porous Carbon-Promoted Adsorption of Anthraquinone for Long-Life Organic Batteries

Organic quinone molecules are attractive electrochemical energy storage devices because of their high abundance, multielectron reactions, and structural diversity compared with transition metal-oxide electrode materials. However, they have problems like poor cycle stability and low rate performance on account of the inherent low conductivity and high solubility in the electrolyte. Solving these two key problems at the same time can be challenging. Herein, we demonstrate that using a nitrogen-doped hierarchical porous carbon (NC) with mixed microporous/low-range mesoporous can greatly alleviate the shuttle effect caused by the dissolution of organic molecules in the electrolyte through physical binding and chemisorption, thereby improving the electrochemical performances. Lithium-ion batteries based on the anthraquinone (AQ) electrode exhibit dramatic capacity decay (5.7% capacity retention at 0.2 C after 1000 cycles) and poor rate performance (14.2 mA h g^-1 at 2 C). However, the lithium-ion battery based on the NC@AQ cathode shows excellent cycle stability (60.5% capacity retention at 0.2 C after 1000 cycles, 82.8% capacity retention at 0.5 C after 1000 cycles), superior rate capability (152.9 mA h g^-1 at 2 C), and outstanding energy efficiency (98% at 0.2 C). Our work offers a new approach to realize the next-generation organic batteries for long life and high rate performance.

Maleamic Acid as an Organic Anode Material in Lithium-Ion Batteries

Low-molecular-weight carbonyl-containing compounds are considered beneficial energy storage materials in alkali metal-ion/alkaline earth metal-ion secondary batteries owing to the ease of their synthesis, low cost, rapid kinetics, and high theoretical energy density. This study aims to prepare a novel carbonyl compound containing a maleamic acid (MA) backbone as a material with carbon black to a new MA anode electrode for a lithium-ion battery. MA was subjected to attenuated total reflection-Fourier-transform infrared spectroscopy, and its morphology was assessed through scanning electron microscopy, followed by differential scanning calorimetry to determine its thermal stability. Thereafter, the electrochemical properties of MA were investigated in coin cells (2032-type) containing Li metal as a reference electrode. The MA anode electrode delivered a high reversible capacity of about 685 mAh g⁻¹ in the first cycle and a higher rate capability than that of the pristine carbon black electrode. Energy bandgap analysis, electrochemical impedance, and X-ray photoelectron spectroscopy revealed that MA significantly reduces cell impedance by reforming its chemical structure into new nitrogen-based highly ionic diffusion compounds. This combination of a new MA anode electrode with MA and carbon black can increase the performance of the lithium-ion battery, and MA majorly outweighs transitional carbon black.

All-Solid-State Lithium-Organic Batteries Comprising Single-Ion Polymer Nanoparticle Electrolytes

Advances in lithium battery technologies necessitate improved energy densities, long cycle lives, fast charging, safe operation, and environmentally friendly components. This study concerns lithium-organic batteries comprising bioinspired poly(4-vinyl catechol) (P4VC) cathode materials and single-ion conducting polymer nanoparticle electrolytes. The controlled synthesis of P4VC results in a two-step redox reaction with voltage plateaus at around 3.1 and 3.5 V, as well as a high initial specific capacity of 352 mAh g^-1 . The use of single-ion nanoparticle electrolytes enables high electrochemical stabilities up to 5.5 V, a high lithium transference number of 0.99, high ionic conductivities, ranging from 0.2×10^-3 to 10^-3  S cm^-1 , and stable storage moduli of >10 MPa at 25-90 °C. Lithium cells can deliver 165 mAh g^-1 at 39.7 mA g^-1 for 100 cycles and stable specific capacities of >100 mAh g^-1 at a high current density of 794 mA g^-1 for 500 cycles. As the first successful demonstration of solid-state single-ion polymer electrolytes in environmentally benign and cost-effective lithium-organic batteries, this work establishes a future research avenue for advancing lithium battery technologies.

An Insoluble Anthraquinone Dimer with Near-Plane Structure as a Cathode Material for Lithium-Ion Batteries

Conjugated carbonyl-based organic electrode materials for lithium-ion batteries have gained increasing interests owing to their many advantages such as resource abundance and sustainable development. However, serious dissolution in organic liquid electrolytes is often encountered, resulting in inferior electrochemical performance such as poor cycling stability. Herein, a new molecular design strategy was developed to address the dissolution issue of 9,10-anthraquinone (AQ). An AQ dimer with near-plane molecular structure, 1,4-bis(9,10-anthraquinonyl)benzene (BAQB), was facilely synthesized. The near-plane structure was proved by DFT calculations. It was found that the obtained BAQB was insoluble in ether electrolyte. Compared to AQ, BAQB displayed remarkably enhanced cycling stability. After 100 cycles at 0.2 C, a high capacity retention of 91.6 % was achieved (195 mAh g^-1 ). BAQB also exhibited excellent rate performance (138 mAh g^-1 at 10 C). The results demonstrate the effectiveness of the near-plane molecular design concept. This work provides a new idea for rational molecular design to inhibit the dissolution of conjugated carbonyl-based organic electrode materials.

A Self-Polymerized Nitro-Substituted Conjugated Carbonyl Compound as High-Performance Cathode for Lithium-Organic Batteries

Conjugated carbonyl compounds have received much attention as cathode materials for developing green lithium-ion batteries (LIBs). However, their high dissolution and poor electronic conductivity in organic electrolyte restrict their further application. Herein, a self-polymerized nitro-substituted conjugated carbonyl compound (2,7-dinitropyrene-4,5,9,10-tetraone, PT-2 NO₂ ) is applied as a high-performance cathode material for LIBs. PT-2 NO₂ exhibits a high reversible capacity of 153.9 mAh g^-1 at 50 mA g^-1 after 120 cycles, which is higher than that of other substituted compounds. Detailed characterization and theoretical calculations have testified that PT-2 NO₂ is transformed into an azo polymer through an irreversible reductive coupling reaction in the first discharge process, and then carbonyl and azo groups reversibly react with Li ions in subsequent cycles. In addition, this azo polymer is also synthesized and applied as the electrode material, which shows similar electrochemical performance to PT-2 NO₂ but with higher initial coulombic efficiency. Thus, this work provides a simple but effectively way to construct organic cathode materials with multiple redox sites for green and high-performance LIBs.

A Comparative Review of Electrolytes for Organic-Material-Based Energy-Storage Devices Employing Solid Electrodes and Redox Fluids

Electrolyte chemistry is critical for any energy-storage device. Low-cost and sustainable rechargeable batteries based on organic redox-active materials are of great interest to tackle resource and performance limitations of current batteries with metal-based active materials. Organic active materials can be used not only as solid electrodes in the classic lithium-ion battery (LIB) setup, but also as redox fluids in redox-flow batteries (RFBs). Accordingly, they have suitability for mobile and stationary applications, respectively. Herein, different types of electrolytes, recent advances for designing better performing electrolytes, and remaining scientific challenges are discussed and summarized. Due to different configurations and requirements between LIBs and RFBs, the similarities and differences for choosing suitable electrolytes are discussed. Both general and specific strategies for promoting the utilization of organic active materials are covered.

Composition Modulation and Structure Design of Inorganic-in-Polymer Composite Solid Electrolytes for Advanced Lithium Batteries

Owing to their safety, high energy density, and long cycling life, all-solid-state lithium batteries (ASSLBs) have been identified as promising systems to power portable electronic devices and electric vehicles. Developing high-performance solid-state electrolytes is vital for the successful commercialization of ASSLBs. In particular, polymer-based composite solid electrolytes (PCSEs), derived from the incorporation of inorganic fillers into polymer solid electrolytes, have emerged as one of the most promising electrolyte candidates for ASSLBs because they can synergistically integrate many merits from their components. The development of PCSEs is summarized. Their major components, including typical polymer matrices and diverse inorganic fillers, are reviewed in detail. The effects of fillers on their ionic conductivity, mechanical strength, thermal/interfacial stability and possible Li⁺ -conductive mechanisms are discussed. Recent progress in a number of rationally constructed PCSEs by compositional and structural modulation based on different design concepts is introduced. Successful applications of PCSEs in various lithium-battery systems including lithium-sulfur and lithium-gas batteries are evaluated. Finally, the challenges and future perspectives for developing high-performance PCSEs are proposed.