Enhanced performance of Si-based Li-ion batteries through elastic cushioning with hollow graphene shells

Abstract

Silicon (Si) is a promising anode material for next-generation Li-ion batteries. The nanometer-sized Si could alleviate the pulverization caused by large volume changes during deep cycling. However, compression between agglomerated Si particles causes Si cracking and electrode failure. Considering this, we engineered a mechanical cushioning space between Si particles via elastic hollow graphene shells (GSs) to flexibly buffer volume changes and maintain the stability of the electrode structure. The stress generated from the Si volume expansion during lithiation was mechanically buffered and gently released by compression of the hollow space of the GS. In this Si/GS composite electrode, GS also reduced the local agglomeration of Si particles and effectively improved the overall conductivity. Considering these advantages, the designed Si/GS electrode showed an enhanced cycling performance with more than 1200 mA h g(-1) at 0.8 A g(-1) and an excellent rate capability of 1025 mA h g(-1) at 4 A g(-1) after 200 cycles.