Amorphous titanium dioxide and polyaniline dual modifying silicon for highly enhanced lithium-ion storage

Silicon (Si) anode material is promising in the next generation of lithium-ion batteries (LIBs) with high energy densities for its much higher capacity (4200 mAh/g) than that of commercial graphite (372 mAh/g). However, silicon anode material with low electronic conductivity suffers a huge volume variation and accompanies side reactions during alloyed and de-alloyed process. Here, we design an inner amorphous titanium dioxide (TiO₂) and an outer flexible conductive polyaniline (PANI) network dual modified Si@TiO₂@PANI material for LIBs, where the TiO₂ avoids the side reactions and the PANI network layer buffers the volume expansion and increases the electronic conductivity. The as-prepared Si@TiO₂@PANI exhibits a high initial discharge capacity of 3050 mAh/g and maintains 1583 mAh/g after 200 cycles at 0.5 A/g. It even delivers the discharge capacity of 1002 mAh/g after 600 cycles at 1 A/g, as well as an excellent rate ability with discharge capacity of 1890, 1260 and 432 mAh/g at the high current density of 1, 2 and 5 A/g, respectively. Our strategy shows that the innovative design of double buffer layers on Si can synergistically promote stability and accelerate kinetics of Li⁺ transport, offering novel resolution strategy to enhance the performance of Si-based anodes for LIBs.