Investigation of reduced lithium titanate spinel as insertion host for rechargeable batteries

Abstract

Rechargeable batteries based on reversible zinc electrodeposition in mildly acidic electrolytes have recentlygained popularity, primarily because of their cost-benefit and high theoretical energy density achievable. However,issues associated with dendrite growth and the corrosion of zinc metal anodes still remain major technical roadblocksthat must be overcome to ensure battery safety. Here we propose, for the first time, reduced lithium titanate (LTO) as aviable alternative anode that is capable of reversible ion intercalation at ~0.20 V vs. Zn/Zn2+. Reduced LTO was preparedvia simple thermochemical reduction at a mild temperature using sodium borohydride. This led to a significantreduction in the crystallite size and a drastic enhancement in the electrical conductivity, resulting in a distinct enhancementin the zinc insertion kinetics in the aqueous electrolytes, delivering a fair discharge capacity of 100mAh g？1. Structural and morphological studies confirmed that reduced LTO served as a zero-strain host for ionic intercalation. This study offers an interesting approach for developing novel intercalation hosts for rechargeable batteries based onabundant multivalent metal cations.