Sn-O-C composite anode for Li secondary battery synthesized by an electrodeposition technique using organic carbonate electrolyte

The Sn-O-C composite anode for the Li secondary battery was synthesized by electrodeposition using an organic carbonate solvent. The composite of Sn with organic/inorganic compounds was prepared by the simultaneous reaction of the reduction of Sn²⁺ ions and electrolysis of the mixture of ethylene carbonate and propylene carbonate. The galvanostatic potential transients for the electrodeposition of the Sn-O-C composite indicate that multiple steps of reactions corresponding to the electrochemical reduction of the tin precursor and the decomposition of organic solvents are involved. The morphology, crystalline structure and chemical composition of the as-deposited Sn-O-C composite anode were characterized to elucidate the mechanism of the synthesis of the buffering matrix enduring volume expansion. The electrochemical behavior of the Sn-O-C composite anode was investigated by cyclic voltammetry and galvanostatical charge/discharged tests. The discharge capacity of 465 mAh (g of Sn)^-1 was obtained at the 100th cycle showing 80% of the capacity retention after the 100th cycle. The discharge capacity was stable after the 50th cycle, where the phase transformation of the Sn element from Sn to Li _0.4Sn at the discharged state was found.