Watermelon-like texture lithium titanate and silicon composite films as anodes for lithium-ion battery with high capacity and long cycle life

Abstract

Buffering the volume expansion of Si particles is considered to be an effective method for preparing Si based electrode with high capacity and prominent cycling performance. Here, watermelon-like texture Li4Ti5O12 (LTO) and Si composite film electrode was synthetized by magnetron co-sputtering using spinel LTO powder and crystalline Si wafer as the sputtering source. In the composite film electrode, LTO acts as watermelon pulp and Si acts as watermelon seed. The obtained composite film electrode endows a high reversible capacity of ~800 mAh g−1 at 100 mA g−1 with a capacity retention ~76% after 1000 cycles. The extraordinary electrochemical characteristics of the composite film electrode could be attributed to the role of LTO in watermelon pulp which prevents electrolyte from contacting with Si nanoparticles directly, easing the stress caused by periodic volume change and the multi-interface between LTO and Si as well as supplying efficient and rapid transport routes for Li-ions. The outcomes reveal the watermelon-like texture composite film is a promising high energy density and splendid long cycle stability anode material for lithium-ion batteries.