原位生长VS_(2)微米球-rGO锂硫电池正极复合材料的制备及其电化学性能研究

Study on synthesis and electrochemical performance of vanadiumdisulfide microsphere/reduced graphene oxide cathode composite by in-situ growth for lithium sulfur batteries

片状VS_(2)对多硫化锂吸附性能优异,晶体结构层间距大,导电性优良,是一种理想的锂硫电池正极硫载体材料.但其片状容易堆叠且稳定性差导致电化学性能不佳.采用溶剂热法制备出纳米片自组装的VS_(2)微米球结构(MS-VS_(2)),有效改善了水热法制备的VS_(2)片易堆叠的问题.在此基础上,与石墨烯原位复合得到MS-VS_(2)/rGO复合材料,原位复合良好的结合强度和石墨烯优异的导电能力及机械稳定性提高了电极的导电性和稳定性.MS-VS_(2)/rGO正极材料锂硫电池在0.2C电流密度下首圈放电比容量为1160.9 mAh·g^(-1),循环100圈后放电比容量为825.3 mAh·g^(-1),容量保持率为71.1%,表现出良好的电化学性能.

Lamellar VS_(2)is an ideal positive sulfur carrier material for lithium-sulfur batteries due to its excellent adsorption performance,large interlayer spacing and excellent electrical conductivity.Despite its excellent properties,lamellar VS_(2)is susceptible to stacking and lacks stability,leading to poor electrochemical performance.VS_(2)microspheres with nanosheet self-assembly(MS-VS_(2))were obtained using the solvothermal method,efficiently mitigating the sheet stacking issue associated with VS_(2)by hydrothermal method.Following the above method,MS-VS_(2)/rGO composites were successfully fabricated by in-situ solvothermal synthesis.The resulting composite materials exhibits strong bonding between MS-VS_(2)and graphene.The graphene provides excellent electrical conductivity and mechanical stability,significantly enhancing the conductivity and stability of the electrodes.The MS-VS_(2)/rGO composite cathode delivers a high initial specific capacity of 1160.9 mAh·g-1 at 0.2 C,and the discharge capacity reaches 825.3 mAh·g-1 after 100 cycles with the capacity retention rate of 71.1%,indicating the good electrochemical performance of the composite.