Performance enhancement of Sn–Co alloys for lithium-ion battery by electrochemical dissolution treatment

• Electrodeposition-electrochemical dealloying was used for creating nanopores.
• Binder-free nanoporous Sn-Co alloy electrode was fabricated on smooth Cu foil.
• The composition and pore structure of Sn-Co alloy can be facilely controlled.
• The electrochemical performance of Sn-Co alloy electrode was greatly improved.

Three sets of Sn–Co alloy materials with improved porous structure are designed and facilely prepared via a two-step strategy comprising of electrodeposition followed by electrochemical dissolution treatment. The structure, composition and morphology of the Sn–Co alloy materials are investigated by scanning electron microscopy, X-ray diffraction and atomic absorption spectrophotometer. The electrochemical performance of the Sn–Co alloy materials as negative electrode materials for lithium-ion battery was tested by cyclic voltammetry, galvanostatic charge–discharge cycling and rate capability test. It is found that the resultant Sn–Co alloy materials after electrochemical dissolution treatment have porous structure and higher specific capacity than those of the as-deposited Sn–Co alloy materials. The initial capacity of a porous Sn–Co alloy sample attains 1109 mA h g−1, and remains 580 mA h g−1 after 70 cycles. This performance improvement can be mainly attributed to the formation of optimized porous structure during electrochemical dissolution treatment, which can buffer the great volume fluctuation of Sn phase during cycling and therefore reduce cracking and shelling of the materials.