Design of Cobalt-Based Transitional Metal Chalcogenide Anodes for High-Performance Rechargeable Batteries

Abstract

Exploitation of high-performance anode materials is essential but challenging to the development of lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Among all the proposed anode materials, cobalt chalcogenides (oxides and sulfides) have been proved promising candidates due to their unique chemical and physical properties as well as high theoretical capacities (500-900 mAh g-1). The practical applications of cobalt chalcogenides in LIBs and SIBs, however, are still limited due to their large volume change, poor cycling stability and sluggish electrode kinetics. Moreover, cobalt species is somewhat toxic and expansive, further blocked the utilization of cobalt chalcogenides in large scale and long term. To overcome those issues, various approaches including controlling the size, structure and components of cobalt-based chalcogenides have been raised. By reducing the size of cobalt chalcogenides into nanostructures, easier accesses for Li/Na ions would be achieved owing to the higher surface area and shorter diffusion length. Moreover, engineering cobalt-based chalcogenides into hollow structures would greatly enhance the electrochemical properties as the internal void space of the hollow structures could effectively alleviate the stress-induced structure variation during long-term electrochemical reactions. To solve the problem of toxicity and relative high price of cobalt component, it’s an efficient way to introduce cheaper and more environmental-friendly elements into the cobalt-based chalcogenides system. Not only the content of cobalt would be reduced, higher electrical conductivity and a buffering effect would also be achieved by the hybrid system due to the relative low activation energy for electron transfer between cations. In this article, synthesis apporaches of hollow nanostructured cobalt-based chalcogenides materials and their electrochemical peformance as anode materials in LIBs and SIBs are reviewed. To lower down the price and toxicity of cobalt chalcogenides, eco-friendly and cheap component including vanadium and molybdenum was introduced to the cobalt-based chalcogenides by smart and facile strategies. To effectively accommodate the large volume expansion during charging/discharging process, rationally-designed hollow structures including hollow nanofibers and hollow nanocubes have been constructed through electrospining and template methods. Moreover, to further enhance the electronic conductivity of the materials, carbon was introduced to the cobalt-molybdenum chalcogenides system. Benefitting from the well-desigend hollow structures, smarted-chosen hybridation components and buffering effect provided by the cobalt-based transitional metal chalcogenides, excellent electrochemical properties including high specific capacity, rate capability, and ultra-long cycling performance in LIBs and SIBs were achieved. Those works demonstrate that constructing the well-designed hollow nanostructures of cobalt-based transitional metal chalcogenides would be a general design strategy for cobalt-based electrode materials for novel high-performance energy storage devices.