Double core—shell nanostructured Sn-Cu alloy as enhanced anode materials for lithium and sodium storage

Sn-based alloy materials are considered as a promising anode candidate for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), whereas they suffer from severe volume change during the discharge/charge process. To address the issue, double core—shell structured Sn-Cu@SnO2@C nanocomposites have been prepared by a simple co-precipitation method combined with carbon coating approach. The double core—shell structure consists of Sn-Cu multiphase alloy nanoparticles as the inner core, intermediate SnO2 layer anchored on the surface of Sn-Cu nanoparticle and outer carbon layer. The Sn-Cu@SnO2@C electrode exhibits outstanding electrochemical performances, delivering a reversible capacity of 396 mA·h·g−1 at 100 mA·g−1 after 100 cycles for LIBs and a high initial reversible capacity of 463 mA·h·g−1 at 50 mA·g−1 and a capacity retention of 86% after 100 cycles, along with a remarkable rate capability (193 mA·h·g−1 at 5000 mA·g−1) for SIBs. This work provides a viable strategy to fabricate double core—shell structured Sn-based alloy anodes for high energy density LIBs and SIBs.