Spinel LiMn2−x Si x O4 (x < 1) through Si4+ substitution as a potential cathode material for lithium-ion batteries

Abstract

Spinel LiMn2−x Si x O4 (x< 1, through substituting Mn4+ with Si4+ in cubic spinel LiMn2O4) was synthesized successfully by a facile sol-gel method. The as-prepared LiMn2−x Si x O4 consisted of pores with large size distribution range from a few nanometers to over 200 nm and possessed specific surface area of 8.76 m2 g−1. Results of X-ray powder diffraction and X-ray photoelectron spectroscopy confirmed that Si atoms entered the host lattice. As a cathode material for rechargeable lithium-ion batteries, spinel LiMn2−x Si x O4 exhibited excellent structural reversibility and integrity during the charging-discharging process. The result indicated that substitution of Mn4+ by Si4+ in spinel LiMn2O4 material effectively alleviated the phase transition caused by Jahn-Teller effect. The initial discharge capacity of the as-prepared spinel LiMn2−x Si x O4 was 147 mA h g−1 over the voltage range of 1.5–4.8 V. However, after 51 cycles, the specific capacity was 88 mA h g−1 with capacity retention of 60 %. More work is needed to understand the effects of substituting Mn4+ by Si4+ and to improve the cyclic stability.