Controlled swelling behavior and stable cycling of silicon/graphite granular composite for high energy density in lithium ion batteries

The severe swelling behavior of silicon-based electrodes caused by the large volume expansion of Si associated with Li still prevents the practical implementation of Si. Here, we report the amorphous carbon coated silicon/graphite granule ([email protected]) as an attractive anode material to control the swelling behavior and achieve improved electrochemical properties. With the structural uniqueness including inner buffer space, large contact area of silicon and graphite, and the uniform surface carbon coating layer, the [email protected] electrode exhibits stable cycling performance and regulated electrode swelling behavior. [email protected] shows high reversible capacity of 1150 mA h g−1 and improved initial Coulombic efficiency of 85%. We evaluate [email protected] from a practical point of view through the characterization of pouch full cells prepared with LiCoO2 as a cathode with a high areal capacity of 3.4 mA h cm−2. The electrode prepared with the [email protected] of 10% and graphite of 90% ([email protected] 10% electrode) exhibits a stable cycling performance with a capacity retention of 71% over 500 cycles at 1 C-rate. Furthermore, the [email protected] 10% electrode exhibits stable electrode swelling behaviors comparable to the graphite electrode, indicating an initial expansion of 16.0% at a charged state and a cycling expansion of 6.7% over 50 cycles.