CHEN Dong, ZHAO Hao, ZHANG Yuhong, CHEN Jian, TU Jiangping
Hard carbon is considered the most promising commercial anode material for sodium-ion batteries(SIBs) due to its abundant resources, low cost, and low operating voltage platform. However, due to the high specific surface area and a large number of micropores, the initial coulomb efficiency(ICE) of conventional hard carbon materials is low, which affects their application in batteries. Therefore, this study focuses on using chemical vapor deposition(CVD) technology to modify the surface of hard carbon, with the aim of alleviating the negative impact of surface defects on ICE by filling or masking micropores. Specifically, biomass coconut shell was selected as the carbon source, and after acid washing and CVD coating treatment, the surface structure of the hard carbon was effectively improved, the specific surface area was reduced, and sodium storage active sites were increased, thereby significantly enhancing the ICE and platform sodium storage capacity of the hard carbon materials. The prepared high-performance hard carbon material exhibits a reversible capacity and ICE as high as 345 mAh/g and 88%, respectively, and the capacity retention rate still exceeds 93% after 50 cycles. The pouch cells assembled with commercialized layered oxide cathode materials also exhibit excellent low-temperature discharge and rate charge/discharge performance.
