柔性自支撑PDDA-Si/G纳米复合薄膜的制备及储锂性能

摘要

Silicon is an active electrode material for future commercial lithium-ion batteries with extremely high theoretical specific capacity (4200 (mA · h) /g). However, the large volume change of silicon over charge-discharge cycles weakens its competitiveness in the capacity and cycle life. A flexible self-supporting polydiene dimethylammonium chloride-Si/graphene (PDDA-Si/G) nanocomposite film was successfully prepared by electrostatic self-assembly technique. The composite film can maintain the integrity of electrode structure without adding binder and conductive carbon black. Graphene provides complete conductive network and mechanical toughness. The electrochemical test results show that when the current density was 0.2 A/g, the specific capacity of PDDA-Si/G composite could reach 1439.9 (mA · h) /g and the Coulombic efficiency was above 98％. The specific capacity was 1209.3 (mA · h) /g after 80 cycles. The specific capacity still maintained 499.9 (mA · h) /g at a high current density (2 A/g).%通过静电自组装技术成功制备得到柔性自支撑聚二烯二甲基氯化铵-Si/石墨烯(PDDA-Si/G)纳米复合薄膜.该复合薄膜无添加黏结剂及导电炭黑且仍能保持电极结构的完整性,其中石墨烯提供完整的导电网络和机械韧性.电化学测试结果表明,当电流密度为0.2 A/g,复合材料的比容量可达1439.9(mA·h)/g,库仑效率保持98％以上.且在高电流密度(2 A/g)下,复合材料的比容量仍可维持在499.9(mA·h)/g,远高于商品化纯Si电极的电化学性能.