Trisulfide-Bond Acenes for Organic Batteries

Carbon skeleton materials derived from rare earth phthalocyanines (MPcs) (M = Yb, La) used as high performance anode materials for lithium-ion batteries

In this work, novel carbon skeleton materials were prepared by high-temperature carbonization of rare earth phthalocyanines (MPcs) (M = Yb, La) under a nitrogen atmosphere. The resulting carbon materials of YbPc-900 (carbonisation temperature of 900 °C for 2 h) and LaPc-1000 (carbonization temperature of 1000 °C for 2 h) have a graphite-layered structure in predominantly ordered states, with a smaller particle size, a larger specific surface area and a higher degree of hard carbonization compared to those of the uncarbonized sample. As a result, the batteries using the YbPc-900 and LaPc-1000 carbon skeleton materials as electrodes display excellent energy storage behaviors. The initial capacities of the YbPc-900 and LaPc-1000 electrodes at 0.05 A g^-1 were 1100 and 850 mA h g^-1, respectively. After 245 cycles and 223 cycles, the capacities remain at 780 and 716 mA h g^-1 with retention ratios of 71% and 84%. At a high rate of 1.0 A g^-1, the initial capacities of the YbPc-900 and LaPc-1000 electrodes were 400 and 520 mA h g^-1, respectively, and after 300 cycles, the capacities can still remain at 526 and 587 mA h g^-1 with retention ratios of 131.5% and 112.8%, respectively, which were much higher than those of the pristine rare earth phthalocyanine (MPc) (M = Yb, La) electrodes. Moreover, better rate capabilities were also observed during the YbPc-900 and LaPc-1000 electrode tests. The capacities of the YbPc-900 electrode at 0.05, 0.1, 0.2, 0.5, 1 and 2C were 520, 450, 407, 350, 300 and 260 mA h g^-1 respectively, which were higher than those of the YbPc electrode (550, 450, 330, 150, 90 and 40 mA h g^-1). Similarly, the rate performance of the LaPc-1000 electrode at different rates was also significantly improved compared to that of the pristine LaPc electrode. In addition, the initial Coulomb efficiencies of the YbPc-900 and LaPc-1000 electrodes were also greatly improved compared to those of pristine YbPc and LaPc electrodes. After carbonization, the YbPc-900 and LaPc-1000 carbon skeleton materials derived from rare earth phthalocyanines (MPcs) (M = Yb, La) exhibit improved energy storage behaviors, which would provide new ideas for developing novel organic carbon skeleton negative materials for lithium ion batteries.

Organosulfur Materials for Rechargeable Batteries: Structure, Mechanism, and Application

Lithium-ion batteries have received significant attention over the last decades due to the wide application of portable electronics and increasing deployment of electric vehicles. In order to further enhance the performance of the batteries and overcome the capacity limitations of inorganic electrode materials, it is imperative to explore new cathode and functional materials for rechargeable lithium batteries. Organosulfur materials containing sulfur-sulfur bonds as a kind of promising organic electrode materials have the advantages of high capacities, abundant resources, tunable structures, and environmental benignity. In addition, organosulfur materials have been widely used in almost every aspect of rechargeable batteries because of their multiple functionalities. This review aims to provide a comprehensive overview on the development of organosulfur materials including the synthesis and application as cathode materials, electrolyte additives, electrolytes, binders, active materials in lithium redox flow batteries, and other metal battery systems. We also give an in-depth analysis of structure-property-performance relationship of organosulfur materials, and guidance for the future development of organosulfur materials for next generation rechargeable lithium batteries and beyond.

Covalent Organic Framework with Highly Accessible Carbonyls and π-Cation Effect for Advanced Potassium-Ion Batteries

Covalent organic frameworks (COF) possess a robust and porous crystalline structure, making them an appealing candidate for energy storage. Herein, we report an exfoliated polyimide COF composite (P-COF@SWCNT) prepared by an in situ condensation of anhydride and amine on the single-walled carbon nanotubes as advanced anode for potassium-ion batteries (PIBs). Numerous active sites exposed on the exfoliated frameworks and the various open pathways promote the highly efficient ion diffusion in the P-COF@SWCNT while preventing irreversible dissolution in the electrolyte. During the charging/discharging process, K⁺ is engaged in the carbonyls of imide group and naphthalene rings through the enolization and π-K⁺ effect, which is demonstrated by the DFT calculation and XPS, ex-situ FTIR, Raman. As a result, the prepared P-COF@SWCNT anode enables an incredibly high reversible specific capacity of 438 mA h g^-1 at 0.05 A g^-1 and extended stability. The structural advantage of P-COF@SWCNT enables more insights into the design and versatility of COF as an electrode.

Advances of Organosulfur Materials for Rechargeable Metal Batteries

Battery materials have become a hotspot in the academic research. Organosulfur compounds are considered as a promising class of cathode materials for rechargeable metal batteries. They have attracted increasing attention in recent years after a long-term stagnancy since 1980s. Recent studies have focused on the understanding of redox mechanism of linear organosulfur molecules R-Sn -R with defined structures. In addition, some new organosulfur compounds are developed. The reversible sulfursulfur (SS) bond breakage/formation of organosulfur in batteries makes them applicable as functional materials in batteries. In this review, new organosulfur materials including molecules, polymers, and composites are introduced. In the following, organosulfur-inorganic hybrid materials are discussed, which have shown unique redox process and enhanced battery performance. In the third part, organosulfur additives are used in Li-S batteries, which can improve the formation of solid-electrolyte interphase (SEI) and alter the redox pathways of sulfur cathodes. In the fourth part, organosulfur materials used in other metal batteries are introduced. Lastly, a summary and some perspectives are given. This review presents an overview of the recent advances of organosulfur materials in batteries and provides guidance for the future development of these materials.

Recent Advances in Heterocyclic Nanographenes and Other Polycyclic Heteroaromatic Compounds

This review surveys recent progress in the chemistry of polycyclic heteroaromatic molecules with a focus on structural diversity and synthetic methodology. The article covers literature published during the period of 2016-2020, providing an update to our first review of this topic (Chem. Rev. 2017, 117 (4), 3479-3716).

Mesoporous Yolk-Shell Structured Organosulfur Nanotubes with Abundant Internal Joints for High-Performance Lithium-Sulfur Batteries by Kinetics Acceleration

Although organosulfur compounds can protect lithium anodes, participate in the redox reaction, and suppress the shuttle effect, the sluggish electrochemical dynamics of their bulk structure and the notorious shuttle effect of covalent long-chain sulfurs largely impede their actual applications. Herein, sulfurized carbon nanotube@aminophenol-formaldehyde (SC@A) with covalently linked short-chain sulfurs is firstly synthesized by in situ polymerization of aminophenol-formaldehyde (AF) on the surface of carbon nanotubes (CNTs) followed by acetone etching and inverse sulfurization processes, forming mesoporous yolk-shell organosulfur nanotubes with abundant internal joints between the yolk of CNTs and the shell of sulfurized AF for the first time. In situ Raman spectra, in situ XRD patterns, and ex situ XPS spectra verify that the covalent short-chain sulfurs bring about a reversible solid-solid conversion process of sulfur, thoroughly avoiding the shuttle effect. The mesoporous yolk-shell structure with abundant internal joints can effectively accommodate the volume change, fully expose active sites and efficiently improve the transport of electrons and lithium ions, thus highly promoting the solid-solid electrochemical reaction kinetics. Therefore, the SC@A cathode exhibits a superior specific capacity of 841 mAh g^-1 and a capacity decay of 0.06% per cycle within 500 cycles at a large current density of 5.0 C.

High Capacity and Energy Density Organic Lithium-Ion Battery Based on Buckypaper with Stable π-Radical

Owing to an increasing demand on high performance and rare-metal free energy storage systems, organic rechargeable battery has attracted much attention. To increase the capacity of the whole battery, we have fabricated coin-type buckypaper cells composed of a trioxotriangulene neutral radical derivative (H₃ TOT) and single-walled carbon nanotubes as a cathode and lithium metal plate as an anode without current collector. The cells exhibited a stable charge-discharge behavior even at a 90 wt % H₃ TOT content with a high-rate performance of 10 C originating from high electrical conductivity of H₃ TOT. Furthermore, based on the four-stage redox ability of H₃ TOT, the H₃ TOT 90 wt % cathode showed a high capacity of approximately 260 mAh g^-1 and a high energy density of 546 Wh g^-1 . In view of the simple fabrication of the cathode and excellent performance, TOT-based buckypaper will open a new strategy for the flexible cells for next-generation energy storages.

The Stoichiometry of TCNQ-Based Organic Charge-Transfer Cocrystals

Organic charge-transfer cocrystals (CTCs) have attracted significant research attention due to their wide range of potential applications in organic optoelectronic devices, organic magnetic devices, organic energy devices, pharmaceutical industry, etc. The physical properties of organic charge transfer cocrystals can be tuned not only by changing the donor and acceptor molecules, but also by varying the stoichiometry between the donor and the acceptor. However, the importance of the stoichiometry on tuning the properties of CTCs has still been underestimated. In this review, single-crystal growth methods of organic CTCs with different stoichiometries are first introduced, and their physical properties, including the degree of charge transfer, electrical conductivity, and field-effect mobility, are then discussed. Finally, a perspective of this research direction is provided to give the readers a general understanding of the concept.

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.

In Situ Coating Graphdiyne for High-Energy-Density and Stable Organic Cathodes

The preparation of organic small-molecule cathodes is simple and low-cost; however, their low conductivity and molecular dissolution are two key issues that mean their energy density and power performance are far lower than those of inorganic batteries, thus hindering their practical application. To develop an effective coating technology is the key to obtain high-performance organic batteries. A general method of in situ weaving all-carbon graphdiyne nanocoatings is demonstrated. The graphdiyne can be conformally weaved on organic particles under mild conditions so that the conductivity is increased and the dissolution is suppressed. After weaving graphdiyne nanocoat, the active mass of the small-molecule organic cathodes rise to 93%, thus delivering a higher energy density of 310 W h kg^-1 than previously reported, and the power performance and long-term stability are greatly improved. Additionally, this method shows great potential to become the crucial technology for fabricating organic batteries with energy density close to prevailing lithium-ion batteries.

Organic Electrode Materials for Metal Ion Batteries

Organic and polymer materials have been extensively investigated as electrode materials for rechargeable batteries because of the low cost, abundance, environmental benignity, and high sustainability. To date, organic electrode materials have been applied in a large variety of energy storage devices, including nonaqueous Li-ion, Na-ion, K-ion, dual-ion, multivalent-metal, aqueous, all-solid-state, and redox flow batteries, because of the universal properties of organic electrode materials. Moreover, some organic materials enable the batteries to be operated in the extreme conditions, such as a wide temperature range (-70 to 150 °C), a wide pH range, and in the presence of O₂. As a guidance for the research in organic batteries, this Review focuses on the reaction mechanisms and applications of organic electrode materials. Six categories of reaction mechanisms and the applications of organic and polymer materials in various rechargeable batteries are discussed to provide an overview of the state-of-the-art organic batteries.