A Lithium-Organic Primary Battery

Modulation of Radical Intermediates in Rechargeable Organic Batteries

Organic materials have been considered as promising electrodes for next-generation rechargeable batteries in view of their sustainability, structural flexibility, and potential recyclability. The radical intermediates generated during the redox process of organic electrodes have profound effect on the reversible capacity, operation voltage, rate performance, and cycling stability. However, the radicals are highly reactive and have very short lifetime during the redox of organic materials. Great efforts have been devoted to capturing and investigating the radical intermediates in organic electrodes. Herein, this review summarizes the importance, history, structures, and working principles of organic radicals in rechargeable batteries. More importantly, challenges and strategies to track and regulate the radicals in organic batteries are highlighted. Finally, further perspectives of organic radicals are proposed for the development of next-generation high-performance rechargeable organic batteries.

Salen-based porous aromatic frameworks with multi-active sites as anode materials for lithium-ion batteries

Porous organic polymers are considered as excellent candidates for the electrode materials in rechargeable battery due to their desirable properties including porosity, customizable structure, and intrinsic chemical stability. Herein a Salen-based porous aromatic framework (Zn/Salen-PAF) is synthesized through a metal directed method and further used as efficient anode materialfor lithium-ion battery. Attributing to the stable functional skeleton, Zn/Salen-PAF delivers a reversible capacity of 631 mAh·g^-1 at 50 mA·g^-1, a high-rate capability of 157 mAh·g^-1 at 20.0 A·g^-1 and a long-term cycling capacity of 218 mAh·g^-1 at 5.0 A·g^-1 even after 2000 cycles. Compared to the Salen-PAF without metal ions, Zn/Salen-PAF possesses better electrical conductivity and more active sites. X-ray photoelectron spectroscopy (XPS) investigation indicates that the coordination of Zn²⁺ with N₂O₂ unit not only improves the conjugation of the framework but also contributes to the in situ cross-sectional oxidation of the ligand during reaction, which results in the electron redistribution of oxygen atom and the formation of CO bonds.

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.

Two-Dimensional Iron Phosphorus Trisulfide as a High-Capacity Cathode for Lithium Primary Battery

Metal phosphorus trichalcogenide (MPX₃) materials have aroused substantial curiosity in the evolution of electrochemical storage devices due to their environment-friendliness and advantageous X-P synergic effects. The interesting intercalation properties generated due to the presence of wide van der Waals gaps along with high theoretical specific capacity pose MPX₃ as a potential host electrode in lithium batteries. Herein, we synthesized two-dimensional iron thio-phosphate (FePS₃) nanoflakes via a salt-template synthesis method, using low-temperature time synthesis conditions in single step. The electrochemical application of FePS₃ has been explored through the construction of a high-capacity lithium primary battery (LPB) coin cell with FePS₃ nanoflakes as the cathode. The galvanostatic discharge studies on the assembled LPB exhibit a high specific capacity of ~1791 mAh g^-1 and high energy density of ~2500 Wh Kg^-1 along with a power density of ~5226 W Kg^-1, some of the highest reported values, indicating FePS₃'s potential in low-cost primary batteries. A mechanistic insight into the observed three-staged discharge mechanism of the FePS₃-based primary cell resulting in the high capacity is provided, and the findings are supported via post-mortem analyses at the electrode scale, using both electrochemical- as well as photoelectron spectroscopy-based studies.

A Fast-Charging and High-Temperature All-Organic Rechargeable Potassium Battery

Developing fast-charging, high-temperature, and sustainable batteries is critical for the large-scale deployment of energy storage devices in electric vehicles, grid-scale electrical energy storage, and high temperature regions. Here, a transition metal-free all-organic rechargeable potassium battery (RPB) based on abundant and sustainable organic electrode materials (OEMs) and potassium resources for fast-charging and high-temperature applications is demonstrated. N-doped graphene and a 2.8 m potassium hexafluorophosphate (KPF6 ) in diethylene glycol dimethyl ether (DEGDME) electrolyte are employed to mitigate the dissolution of OEMs, enhance the electrode conductivity, accommodate large volume change, and form stable solid electrolyte interphase in the all-organic RPB. At room temperature, the RPB delivers a high specific capacity of 188.1 mAh g-1 at 50 mA g-1 and superior cycle life of 6000 and 50000 cycles at 1 and 5 A g-1 , respectively, demonstrating an ultra-stable and fast-charging all-organic battery. The impressive performance at room temperature is extended to high temperatures, where the high-mass-loading (6.5 mg cm-2 ) all-organic RPB exhibits high-rate capability up to 2 A g-1 and a long lifetime of 500 cycles at 70-100 °C, demonstrating a superb fast-charging and high-temperature battery. The cell configuration demonstrated in this work shows great promise for practical applications of sustainable batteries at extreme conditions.

Insights into Redox Processes and Correlated Performance of Organic Carbonyl Electrode Materials in Rechargeable Batteries

Organic carbonyl electrode materials have shown great prospects for rechargeable batteries in view of their high capacity, flexible designability, and sustainable production. However, organic carbonyl electrode materials still suffer from unsatisfactory electrochemical performance, which is highly relevant to their redox processes. Herein, an in-depth understanding on redox processes and the correlated electrochemical performance of organic carbonyl electrode materials is provided. The redox processes discussed mainly involve molecular structure evolution (intermediates), crystal structure evolution (phase transition), and charge storage mechanisms. The properties of intermediates can affect voltage, cycling stability, reversible capacity, and rate performance of batteries. Moreover, the reversible capacity/cycling stability and rate performance would be also influenced by phase transition and charge storage mechanisms (diffusion- or surface-controlled), respectively. To accelerate the practical applications of organic carbonyl electrode materials, future work should focus on developing more in situ or operando characterization techniques and further understanding the intrinsic relationships between redox processes and performance. It is hoped that the work discussed herein will stimulate more attention to the detailed redox processes and their correlations with the performance of organic carbonyl electrode materials in rechargeable batteries.

Advanced Lithium Primary Batteries: Key Materials, Research Progresses and Challenges

In recent years, with the vigorous development and gradual deployment of new energy vehicles, more attention has been paid to the research on lithium-ion batteries (LIBs). Compared with the booming LIBs, lithium primary batteries (LPBs) own superiority in specific energy and self-discharge rate and are usually applied in special fields such as medical implantation, aerospace, and military. Widespread application in special fields also means more stringent requirements for LPBs in terms of energy density, working temperature range and shelf life. Therefore, how to obtain LPBs with high energy density, wide operational temperature range and long storage life is of great importance in future development. In view of the above, this paper reviews the latest research on LPBs in cathode, anode and electrolyte over the years, and puts forward relevant insights for LPBs, along with the intention to explore avenues for the design of LPBs components in the coming decades and promote further development in this field.

Capacity Estimation Models of Primary Lithium Batteries during Whole Life Cycle of Underwater Vehicles

Storage and discharge conditions of primary lithium batteries are studied and the capacity estimation models during the whole life cycle of underwater vehicles is developed based on temperature. The storage experiments for 90 days at different temperatures and discharge experiments at different temperatures and current rates are conducted. At low temperatures, experimental results reveal that there is no significant capacity decay during storage. At high temperatures, the charge storage capacity attenuates with the increase of storage, and the attenuation rate is directly related to the temperature. In discharge experiments, maximum available capacity increases with temperature during 0 °C to 25 °C, whereas the given phenomenon is not significant at other temperatures. Moreover, the current rate is less important for the maximum available capacity. To establish capacity estimation models during the storage stage and working stage of underwater vehicles, we have developed a capacity decay model and a temperature calibration model. Moreover, the model accuracy is evaluated, and the errors in capacity decay model and temperature calibration model are less than 2% and 0.7%, respectively. Capacity estimation models provided in this research are not only accurate, but also relatively simple, which have high value for underwater vehicles in engineering applications.

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.

MXene/Organics Heterostructures Enable Ultrastable and High-Rate Lithium/Sodium Batteries

Organic electrode materials have shown potential for rechargeable batteries because they are environmentally friendly, earth-abundant sources, recyclable, high sustainable, designable, flexible, and lightweight. However, low electrical conductivity and dissolution in organic liquid electrolytes hinder their further development. Herein, MXene/organics heterostructures are designed to address the problems of organic electrodes via a scalable and simple electrostatic self-assembly strategy. Under the effect of the electrostatic interaction, organic cathode material, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), is tightly attached to MXene nanosheets. Owing to the high electronic conductivity and special two-dimensional (2D) structure of MXene nanosheets, the issues of PTCDA cathode are effectively relieved. When applied in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), the MXene@PTCDA heterostructure exhibits significantly enhanced rate capability and cycling performance than bare PTCDA. The heterostructures proposed here can be applied to other (K, Zn, Al, Mg, Ca, etc.) battery systems. In addition to energy storage and conversion, the heterostructures can be also extended to many fields such as catalysis, sensors, electronics, optics, membranes, semiconductors, biomedicines, etc.

FEC Additive for Improved SEI Film and Electrochemical Performance of the Lithium Primary Battery

The solid electrolyte interphase (SEI) film plays a significant role in the capacity and storage performance of lithium primary batteries. The electrolyte additives are essential in controlling the morphology, composition and structure of the SEI film. Herein, fluoroethylene carbonate (FEC) is chosen as the additive, its effects on the lithium primary battery performance are investigated, and the relevant formation mechanism of SEI film is analyzed. By comparing the electrochemical performance of the Li/AlF3 primary batteries and the microstructure of the Li anode surface under different conditions, the evolution model of the SEI film is established. The FEC additive can decrease the electrolyte decomposition and protect the lithium metal anode effectively. When an optimal 5% FEC is added, the discharge specific capacity of the Li/AlF3 primary battery is 212.8 mAh g−1, and the discharge specific capacities are respectively 205.7 and 122.3 mAh g−1 after storage for 7 days at room temperature and 55 °C. Compared to primary electrolytes, the charge transfer resistance of the Li/AlF3 batteries with FEC additive decreases, indicating that FEC is a promising electrolyte additive to effectively improve the SEI film, increase discharge-specific capacities and promote charge transfer of the lithium primary batteries.

A poorly soluble organic electrode material for high energy density lithium primary batteries based on a multi-electron reduction

Here we report an organic cathode material with poor solubility for lithium primary batteries, i.e. indeno[3,2-b]fluorene-6,12-dione. Each carbonyl group experiences a four-electron reduction to a methylene group, resulting in a high energy density of 1392 W h kg^-1, which is among the best results for organic electrode materials.

Insight into the reversible conversion-(de)incorporation of redox-active dopants within a polymer-based electrode

We combined a microporous polymer backbone with an organic redox-active dopant to construct a reversible electrode system based on the conversion-(de)incorporation behaviour of the dopant. The correspondence between the reversible conversion-(de)incorporation mechanism of the dopant and the electrochemical performance of the designed electrode system was established by electrochemical quartz crystal microbalance and in situ Fourier transform infrared spectroscopy.

Accordion-Like Fluorinated Graphite Nanosheets with High Power and Energy Densities for Wide-Temperature, Long Shelf-Life Sodium/Potassium Primary Batteries

Sodium and potassium are considered to be the most promising anode candidates due to their easy availability, low-cost and similar chemical properties to lithium. Here, novel 3D accordion-like fluorinated graphite nanosheets (FGNSs) are reported as cathodes for sodium primary batteries (SPBs) and potassium primary batteries (PPBs). The FGNSs-x cathode exhibits unprecedented power and energy density due to the impressive 3D structure, high F/C ratio (1.0), and more surface CC bonds (7.14%). The FGNSs-1.0 exhibits very high specific capacities of 831.3 and 834.1 mAh g^-1 for SPBs and PPBs, respectively, close to the theoretical capacity. Besides, the maximum energy density of FGNSs-1.0 in SPBs and PPBs are 1960.5 and 2144.6 Wh kg^-1 , respectively. The maximum power density for Na/CFx and K/CFx batteries could reach up to 7076.8 and 6227.4 W kg^-1 , respectively. The electrochemical performance of FGNSs-1.0 at extreme temperatures (-30 to 100 °C), long storage time (60 days), high mass loading (3.6 mg cm^-2 ), and pouch-type cell is also evaluated for the first time. Surprisingly, FGNSs-1.0 has outstanding performance in these projects. Therefore, the new-type Na/CF_x and K/CF_x primary battery systems developed here have broad application prospects in high-energy applications that require high-power, low-cost, and normal use under extreme conditions.

Ultrafast Li/Fluorinated Graphene Primary Batteries with High Energy Density and Power Density

Lithium/fluorinated carbon (Li/CF_x) primary batteries have essential applications in consumer electronics and medical and high-power military devices. However, their application is limited due to the difficulty in achieving simultaneous high power density and high energy density in the CF_x cathode. The tradeoff between conductivity and fluorine content is the decisive factor. Herein, by rational design, 3D porous fluorinated graphene microspheres (FGS-x) with both high conductivity and a high F/C ratio are successfully synthesized for the first time. FGS-x possesses an F/C ratio as high as 1.03, a nanosheet structure with hierarchical pores, abundant C═C bonds, few inactive C-F₂ bonds, and electrochemically active C-F bonds. The beneficial features that can increase discharge capacity, shorten the diffusion length for both ions and electrons, enhance the Li⁺ intercalation kinetics, and accommodate the volume change are demonstrated. The Li/FGS-1.03 coin cell delivers an unprecedented power density of 71,180.9 W/kg at an ultrahigh rate of 50 C (43.25 A/g), coupled with a high energy density of 830.7 Wh/kg. Remarkably, the Li/FGS-1.03 pouch cell exhibits a record cell-level power density of 12,451.2 W/kg at 20 C. The in-depth investigation by the ex situ method on structural evolution at different discharge depths reveals that the excellent performance benefits from the structural stability and the uniform formation of LiF. The FGS-1.03 cathode also has excellent performance in extreme operating temperatures (0 to 100 °C) and high active material mass loading (4.3 mg/cm²). These results indicate that the engineered fluorinated graphene developed here has great potential in applications requiring both high power density and high energy density.

Recent advances of covalent organic frameworks in lithium ion batteries

This review divides the active sites of COFs into four categories: carbonyl, phenyl, imine bonds and other groups, and introduces their applications in LIBs.

Organic Electrode Materials for Non-aqueous K-Ion Batteries

The demands for high-performance and low-cost batteries make K-ion batteries (KIBs) considered as promising supplements or alternatives for Li-ion batteries (LIBs). Nevertheless, there are only a small amount of conventional inorganic electrode materials that can be used in KIBs, due to the large radius of K+ ions. Differently, organic electrode materials (OEMs) generally own sufficiently interstitial space and good structure flexibility, which can maintain superior performance in K-ion systems. Therefore, in recent years, more and more investigations have been focused on OEMs for KIBs. This review will comprehensively cover the researches on OEMs in KIBs in order to accelerate the research and development of KIBs. The reaction mechanism, electrochemical behavior, etc., of OEMs will all be summarized in detail and deeply. Emphasis is placed to overview the performance improvement strategies of OEMs and the characteristic superiority of OEMs in KIBs compared with LIBs and Na-ion batteries.

Progress of Organic Electrodes in Aqueous Electrolyte for Energy Storage and Conversion

Aqueous batteries using inorganic compounds as electrode materials are considered a promising solution for grid-scale energy storage, while wide application is limited by the short life and/or high cost of electrodes. Organics with carbonyl groups are being investigated as the alternative to inorganic electrode materials because they offer the advantages of tunable structures, renewability, and they are environmentally benign. Furthermore, the wide internal space of such organic materials enables flexible storage of various charged ions (for example, H⁺ , Li⁺ , Na⁺ , K⁺ , Zn²⁺ , Mg²⁺ , and Ca²⁺ , and so on). We offer a comprehensive overview of the progress of organics containing carbonyls for energy storage and conversion in aqueous electrolytes, including applications in aqueous batteries as solid-state electrodes, in flow batteries as soluble redox species, and in water electrolysis as redox buffer electrodes. The advantages of organic electrodes are summarized, with a discussion of the challenges remaining for their practical application.