Silicon is a most promising next generation lithium ion battery electrode material, due to its ~10 times higher specific capacity (3600 mAh/g) than graphite (372 mAh/g). However, silicon experiences large volume change (~400%) during lithium insertion, causing it to fracture and detach from current collector, rendering prototypical lithium-silicon batteries to lose most of their capacity in less than 10 charge-discharge cycles. A solution to the capacity and stability issues posed by the significant volume expansion upon lithiation of silicon is critical to the success of high capacity lithium ion batteries.
This silicon/PANi composite utilizes a doped, intrinsically conductive, 3D cross-linked polyaniline as matrix, which could function as both the conductive binder and the polymer electrolyte for silicon-based electrodes. Previous study for a similar silicon-based three-dimensional conducting polymer composite demonstrated increased electrochemically performance due to short diffusion paths and good 3D connectivity, and resulted in a marked improvement in cyclability, with over 90% capacity retention after 5,000 cycles.
This composite is made by encapsulating silicon particles in an in-situ polymerized 3D-crosslinked conductive polyaniline framework. This Si/PANi composite not only allows fast electrical and ionic transport, but also provides free space to allow giant volume expansion. This Si/PANi composite provides a ready-to-use electrochemically active silicon composite that would increase the capacity of conventional lithium ion battery, and improve the cycle-life of Si-based anodes.