In situ synthesis of MOF-derived carbon shells for silicon anode with improved lithium-ion storage

Silicon (Si) has been broadly investigated as a promising anode in lithium-ion batteries (LIBs). However, there is still a problem that the alloying reactions of Si and Li often cause structural failures and rapid degradation in capacity of the electrode. Herein, an in-situ encapsulation of Si nanoparticles forming metal-organic-framework (MOF) derived carbon shells has been developed to improve the performance and retain the structural integrity of the electrode. Using this strategy, a compact and robust interface was ensured between the Si nanoparticles and carbon shell while also reducing the unnecessary exposing areas simultaneously. Moreover, the pores in the MOF-derived carbon shells offered good channels for Li-ion penetration and diffusion. The resulted composite electrode exhibited excellent electrochemical performance and delivered a capacity of 3714 mAh g⁻¹ at 200 mA g⁻¹, and an outstanding reversible capacity of 820 mAh g⁻¹ at 5000 mA g⁻¹ even after 1000 cycles, Direct comparison between the encapsulated Si and naked Si revealed the significance of the MOF-derived carbon shells and its great potential for the next-generation high capacity LIBs.