Engineering a dual-porous Li-rich carbon-coated Si/SiOx nanosphere as a high-performance Li-ion battery anode†

Abstract

Silicon (Si)-based anodes receive broad attention for high energy-density lithium-ion batteries. However, huge volumetric expansion occurs during lithiation. Moreover, the loss of Li⁺ ions during cycling remains a challenge. Here, we develop a dual-porous carbon-coated Si (DP Si/SiO_x@Li–C) using a pore-forming agent and lithium source to create controllable pores in the carbon layer of porous Si/SiO_x, and supply Li⁺ to the anode. The dually porous structure accommodates the volumetric change and enables rapid ion transfer, while supplying abundant Li⁺ ions. The DP Si/SiO_x@Li–C anode exhibits a stable capacity of 809.8 mA h g⁻¹ after 100 cycles at 0.1 A g⁻¹, with a decay rate of only 0.093% per cycle, and a coulombic efficiency exceeding 99.2% when cycling 350 times at 0.5 A g⁻¹. These findings provide a new strategy for developing stable and easily-prepared Si anodes for Li-ion batteries.