Stable Li-ion battery anodes by in-situpolymerization of conducting hydrogel toconformally coat silicon nanoparticles

摘要

Silicon has a high-specific capacity as an anode material for Li-ion batteries, and muchresearch has been focused on overcoming the poor cycling stability issue associated with itslarge volume changes during charging and discharging processes, mostly through nanostructuredmaterial design. Here we report incorporation of a conducting polymer hydrogelinto Si-based anodes: the hydrogel is polymerized in-situ, resulting in a well-connected threedimensionalnetwork structure consisting of Si nanoparticles conformally coated by theconducting polymer. Such a hierarchical hydrogel framework combines multiple advantageousfeatures, including a continuous electrically conductive polyaniline network, binding with theSi surface through either the crosslinker hydrogen bonding with phytic acid or electrostaticinteraction with the positively charged polymer, and porous space for volume expansion of Siparticles. With this anode, we demonstrate a cycle life of 5,000 cycles with over 90%capacity retention at current density of 6.0Ag~(-1).