Electrochemical properties of bismuth composite electrode are investigated as potential negative electrode for lithium ion batteries. The electrode shows severe capacity decay typically observed in the case of alloy-based materials, using a conventional carbonate-based electrolyte solution. The electrode maintained only 10% of the theoretical capacity after 25 cycles of lithiation/delithiation process. The electrode shows poor coulombic efficiency of < 90% during the initial 15 cycles. On the other hand, the bismuth composite electrode shows excellent cycling performance in the 2M LiBH4 in THF solution. The electrode maintained > 98% of reversible capacity, even after 50 cycles. The bismuth electrode cycled in the LiBH4 electrolyte maintained relatively large bismuth particles compared with the electrode cycled in the carbonate-based electrolyte. In situ FTIR study proved the carbonate-based electrolyte forms passivation layer < 0.7 V vs. Li, while the LiBH4 electrolyte does not passivate the electrode surface. (c) 2018 The Electrochemical Society.