硅负极用单宁酸复合海藻酸基双网络粘结剂性能研究

Tannin acid enhanced alginate based double network composite binder for silicon anode

兼具高理论比容量与低工作电压的硅在高能量密度锂离子电池领域具有重大应用潜力,然而其在循环过程中存在巨大的体积变化,导致其循环性能急需提升。基于此,通过小分子单宁酸的引入,在海藻酸、聚乙烯吡咯烷酮双网络高分子体系中构建了氢键交联的动态网络,实现了一种兼具良好韧性与热稳定性的自修复海藻酸基双网络粘结剂,可以有效地缓冲硅颗粒在多次充放电循环过程中的巨大机械应力,进而支撑硅负极在0.2C电流密度下循环200圈后,仍然维持1675.9 mAh·g^(-1)的放电比容量,甚至在1C电流密度下的放电比容量仍保持在1173.1 mAh·g^(-1),说明单宁酸增强海藻酸基双网络粘结剂可以提升硅颗粒的电化学性能,有望推动硅电极的产业化进程。

Due to high theoretical specific capacity and low operating voltage,Silicon(Si)is expected to be a potential anode for lithium-ion batteries with high energy density.However,suffering from huge volume changes during the cycling process,the cycling performance of silicon is poor.To improve its electrochemical performance,an advanced self-healing alginate-polyvinyl pyrrolidone-tannin acid(Alg(Ni)-PVP-TA)with abundant hydrogen bond cross-linking was constructed via the introduction of tannin acid,and the toughness and thermal stability was enhanced,which could effectively alleviate the tremendous mechanical stress of silicon nanoparticles during multiple charge-discharge cycles.As a result,the silicon anode with the fabricated binder showed an enhanced electrochemical performance,namely a residual discharge specific capacity of 1675.9 mAh·g^(-1) after 200 cycles at the current density of 0.2C and 1173.1 mAh·g^(-1) at the current density of 1C.Therefore,the constructed Alg(Ni)-PVP-TA double network binder could enhance the electrochemical performance of the silicon anode,which is expected to promote the industrialization process of the silicon electrodes.