Boosting anode performance of mesoporous Si by embedding copper nano-particles

Abstract

Si anode of lithium-ion battery with high lithium storage capacity has been widely studied. However, its large volume expansion (∼300%) and low conductivity lead to poor cycle stability. In this work, embedding Cu nano-particles into the mesoporous Si (denoted as Cu@MP-Si) provides a new strategy to improve both cycle stability and rate capability, which were fulfilled via handlings of magnesiothermic reduction, impregnation and hydrogenation reduction. The prepared Cu@MP-Si sample delivers a charge-discharge capacity of 1559 mA h g−1 after 100 cycles, at the same time offers greatly enhanced rate capability from that of MP-Si. SEM-EDS and TEM observations on the sample after 100 cycles identified the still perfectly dispersed Cu nano-particles. The roles played by Cu can be summarized as two aspects: on one hand, the highly dispersed Cu nano-particles in the pores support the architecture of MP-Si effectively, ensure that Si is not easily fractured. Copper with strong ductility also relieves the stress caused by volume expansion of Si, effectively increasing the cycle life of anode. On the other hand, those highly dispersed Cu nano-particles lay a favorable pathway for mass transportation in the MP-Si so that the lithium diffusion coefficient and charge transfer rate can be significantly improved. It also improves the rate performance of Si-based anode.