Influences of co-sputtered carbon on the electrochemical performance of SiO/C thin film anodes for lithium-ion batteries

Abstract

Silicon suboxide (SiOx) is a promising anode material for lithium-ion batteries due to its high theoretical capacity (∼2400 mA h g-1) and good cycle performance. However, the volume effect during cycling and the poor intrinsic electronic conductivity restrict its practical application. Since SiO thin films with carbon additive are able to cope with these limitations, we have synthesized SiO/C thin film anodes containing various carbon contents by magnetron co-sputtering. Among the as-deposited electrodes, SiO/C-80 with a thickness of 1.15 μm showed superior electrochemical performance with an initial coulombic efficiency of ∼72%, a maximum reversible specific capacity of 1223 mA h g-1 and a capacity retention of 82.0% ± 0.5% after 750 cycles at a current density of 1 A g-1. The co-sputtered carbon is uniformly dispersed inside the film, which enhances the electronic conductivity and enables higher reversible capacity during the initial cycles. Meanwhile, the co-sputtered carbon plays a role in buffering volume change and maintaining electrode structure during further cycling. These results demonstrated that the SiO/C thin film anode has the application prospect as an anode material for lithium-ion batteries.