钠离子电池金属硫化物负极材料的研究进展

Recent Research Progress of Metal Sulfides as Anode Materials for Sodium Ion Batteries

由于全球有限的锂资源无法满足巨大的能源市场需求,而钠元素与锂元素处于同一主族,其性质相似,且钠具有资源丰富以及成本低等优势,使得钠离子电池有望成为极具发展前景的储能装置。但是,钠离子电池存在以下劣势:(1)钠元素的相对分子质量大于锂元素,致使其理论能量密度低于锂离子电池;(2)钠离子半径大于锂,充放电过程中钠离子脱嵌困难。因此,电极材料的合理设计与高效合成是提升钠离子电池性能和降低成本的关键。目前,钠离子电池的研究进展较快并取得了一定的成果,研究热点主要集中在钠离子嵌入机理、电池能量密度提升、循环性能改善等方面。金属硫化物种类丰富,具有相对较高的理论比容量和能量密度,适合用作储能钠离子电池负极材料。但金属硫化物自身存在导电性差、体积膨胀剧烈、首次库伦效率低、钠离子扩散缓慢等缺点,同时电池的性能又取决于电极材料的形貌、结构和颗粒尺寸等。因此,需对材料进行一系列结构调控以及相应机理研究来提高其电化学性能。本文主要从纳米形貌调控和材料复合两个方面对金属硫化物最新的研究进展进行综合概述,并对钠离子电池金属硫化物负极材料的未来发展方向进行了评述及展望。

The huge discrepancy between the worldwide supply-both existent and potential-and the tremendous energy market demand for sodium resources has been motivating the attempts of seeking substitutes for lithium-based electrochemical energy storage systems,in which sodium ion batteries are now expected to become one of the promising candidates.Belonging to the same main group in the periodic table,sodium element boasts excellent chemical properties similar to lithium element,and is even more competitive in reserves and cost.But,on the other side,sodium ion batteries also have its disadvantages:(1)higher ion weight which renders its theoretical energy density lower than that of lithium ion battery;(2)larger radius which makes sodium ions more difficult to be intercalated and deintercalated during the charge and discharge processes.Thus reasonable design and efficient synthesis of electrode materials are the key factors to increase the electrochemical performance and reduce the cost of sodium ion batteries.At present the global researches on sodium ion batteries are mainly concentrated on the mechanism of sodium ion insertion and the improvement in energy density as well as cycle performance.The large variety of metal sulfides have been proved to possess large theoretical capacity and high energy density and suitable to serve as anode material of sodium ion batteries,though they still have obvious deficiencies such as poor conductivity,severe volume expansion,low first coulomb efficiency,and slowly diffusion coefficient.Moreover,systematical works on the structural regulation and corresponding mechanisms are also necessary,because the performance of battery depends on,besides chemical composition,morphology,structure and particle size of the electrode material.This paper provides mainly a summary of the latest research progress on metal sulfides from the aspects of nano-structure regulation and material compounding,as well as a prospective discussion of the future development trends.