Search for New Anode Materials for High Performance Li-Ion Batteries

Owing to an unmatched combination of power and energy density along with cyclic stability, the Li-ion battery has qualified itself to be the highest performing rechargeable battery. Taking both transportable and stationary energy storage requirements into consideration, Li-ion batteries indeed stand tall in comparison to any other existing rechargeable battery technologies. However, graphite, which is still one of the best performing Li-ion anodes, has specific drawbacks in fulfilling the ever-increasing energy and power density requirements of the modern world. Therefore, further research on alternative anode materials is absolutely essential. Equally important is the search for and enhanced use of right earth abundant materials for battery electrodes so as to bring down the costs of the battery systems. In this spotlight article, we discuss the current research progress in the area of alternative anode materials for Li-ion battery, putting our own research work over the past several years into perspective. Starting from conversion anode systems like oxides and sulfides, to insertion cum alloying systems like transition metal carbides, to molecularly engineered open framework systems like metal organic frameworks (MOFs), covalent organic frameworks (COFs), and organic-inorganic hybrid perovskites (OIHPs), this spotlight provides a complete essence of the recent developments in the area of alternative anodes. The possible and potential impact of these new anode materials is detailed and discussed here.

Effects of Annealing on Electrochemical Properties of Solvothermally Synthesized Cu2SnS3 Anode Nanomaterials

Cu₂SnS₃, as a modified material for high-capacity tin-based anodes, has great potential for lithium-ion battery applications. The solvothermal method is simple, convenient, cost-effective, and easy to scale up, and has thus been widely used for the preparation of nanocrystals. In this work, Cu₂SnS₃ nanoparticles were prepared by the solvothermal method. The effects of high-temperature annealing on the morphology, crystal structure, and electrochemical performance of a Cu₂SnS₃ nano-anode were studied. The experimental results indicate that high-temperature annealing improves the electrochemical performance of Cu₂SnS₃, resulting in higher initial coulombic efficiency and improved cycling and rate characteristics compared with those of the as-prepared sample.

Supercapacitive Performances of Ternary CuCo2S4 Sulfides

Currently, ternary CuCo₂S₄ sulfides are intensively investigated as electrode materials for electrochemical capacitors due to their low cost, high conductivity, and synergistic effect. The research of CuCo₂S₄ materials for energy storage has gradually grown from 2016. The supercapacitive performances of CuCo₂S₄ electrodes for electrochemical capacitors are briefly reviewed in this work. The structure, morphology, and particle size of CuCo₂S₄ are related to the synthesis conditions and electrochemical performances. The thin films of CuCo₂S₄ nanostructures deposited on conductive substrates and their composites both show better properties than single CuCo₂S₄. CuCo₂S₄ and its composites reveal large potential for asymmetric capacitors, delivering high energy densities. However, there is still much new space remaining for future research. The possible development directions, challenges, and opportunities for CuCo₂S₄ materials are also discussed.

Synthesis of single-phase CuCo2-xNixS4 for high-performance supercapacitors

Developing safe, efficient and environment-friendly energy storage systems continues to inspire researchers to synthesize new electrode materials. Doping or substituting host material by some guest elements has been regarded as an effective way to improve the performance of supercapacitors. In this work, single-phase CuCo_2-xNi_xS₄ materials were synthesized by a facile two-step hydrothermal method, where Co in CuCo₂S₄ was substituted by Ni. Cobalt could be easily substituted with Ni in a rational range to keep its constant phase. But, a high content of Ni resulted in a multi-phase composite. Among a series of CuCo_2-xNi_xS₄ materials with different Ni/Co mole ratios, CuCo_1.25Ni_0.75S₄ material presented a significantly high specific capacitance (647 F g^-1 or 272 C g^-1 at 1 A g^-1) and the best cycling stability (∼98% specific capacitance retention after 10,000 charge-discharge cycles), which was mainly due to the modified composition, specific single phase, higher electroconductivity, more electroactive sites and the synergistic effect between Ni and Co. Moreover, the assembled asymmetric capacitor using CuCo_1.25Ni_0.75S₄ as a positive electrode and activated carbon as a negative electrode delivered a high energy density of 31.8 Wh kg^-1 at the power density of 412.5 W kg^-1. These results demonstrated that ternary metal sulfides of CuCo_2-xNi_xS₄ are promising electrode materials for high-performance supercapacitors.