Mesoporous Si infiltrated with Ga and encapsulated with carbon improves the anode performance of lithium ion batteries

Silicon (Si) has become a promising anode for next-generation lithium-ion batteries due to its high theoretical specific capacity (4200 mA h g −1 ). However, large volume changes and fragility during cycling lithiation-delithiation have resulted in severe capacity degradation. To depress the drastically volumetric change of silicon and boost the cycling charge-discharge performance, we synthesized Ga@pSi@C composite anode by means of magnesiothermic reduction on aerogel silica, encapsulation with dopamine, infiltration with liquid metal gallium, and carbonization. On the one hand, gallium serves as a self-healing component as well as a good conductive material. On the other hand, the carbon shell acts as a mechanical constraint and support. Using this strategy, the synthesized Ga@pSi@C composite anode can effectively suppress the fragmentation of silicon particles during cycles. As a result, the initial discharging capacity of Ga@pSi@C anode delivers a capacity of 2113 mA h g −1 at the first cycle with initial Coulombic efficiency (CE) of 75.3 %, which can retain a capacity of 1262 mA h g −1 after 100 cycles. A reversible capacity of 834 mA h g −1 can be maintained after 300 cycles at a current density of 2000 mA g −1 . The infiltration-encapsulation strategy may provide new idea for improving the performance of anode materials besides porous silicon.