Preparation of Cu₆Sn₅-encapsulated carbon microsphere anode materials for Li-ion batteries by carbothermal reduction of oxides

A novel process was proposed to prepare Cu₆Sn ₅-encapsulated carbon microsphere (CM/Cu₆Sn₅) anode materials for the first time through inverse emulsion polymerization of resorcinol-formaldehyde (RF) performed in the presence of CuO and SnO ₂ powders (1.2:1 molar ratio), followed by carbonization and carbothermal reduction in an inert atmosphere. The oxides powder were encapsulated within the carbon gel microspheres and the elemental Sn and Cu were reduced from their oxides by the carbonized RF gel to form crystalline Cu ₆Sn₅ alloy within carbon microspheres. The CM/Cu ₆Sn₅ presented much better cycleability than that of Cu₆Sn₅ alloy powder. The proposed process paves an effective way to prepare high-performance alloy/C microspheres composite anode materials for lithium-ion batteries.