碘-活化石墨烯复合正极材料的制备及电化学性能研究

Fabrication and the Electrochemical Performance of Iodine-Active Graphene Cathodes for Lithium-Iodine Batteries

为了抑制锂碘(Li-I2)电池充放电过程中碘单质的溶解穿梭效应和自放电效应,提高Li-I2电池的循环稳定性,以多孔活化石墨烯(AG)为载体,采用溶液吸附法制备了碘-活化石墨烯(I2-AG)复合材料。结构测试结果表明,AG为三维层状堆积的疏松多孔结构,具有较高的比表面积、丰富的纳米孔结构和大孔容,有利于活性物质碘的负载及充放电过程中离子的传输。电化学测试结果表明,I2-AG复合材料表现出了优良的电化学循环和倍率性能,具体表现为I2-AG复合材料在1、2、5和20 C倍率下的放电比容量分别为325.3、302、293.3和270.4 mA h g–1,循环500周后,其剩余放电比容量分别为220.6、209.9、234.7和274.3mA h g–1。整体而言,制备的I2-AG复合材料有效地抑制了碘单质的溶解穿梭效应和自放电效应。

In order to restrain the dissolving shuttle effect and self discharge effect of iodine during the charging and discharging processes and improve the cycle stability of lithium-iodine(Li-I2) batteries, I2-AG composite is prepared by solution adsorption method with porous active graphene as carrier. The microstructure and morphology of the I2-AG composite reveal that iodine is well dispersed in the nanopores of AG. The as-prepared I2-AG composite delivers high specific capacity of 325.3、302、293.3 and 270.4 mA h g–1 at the rate of 1、2、5 and 20 C, and retain 220.6、209.9、234.7 和 274.3 mA h g–1 after 500 cycles, exhibiting excellent cyclic performance and high rate performance. The results indicate that the soluble iodine can be well constrained in the nanopores of AG during charging and discharging processes, making Li-I2 battery a promising alternative energy storage device.