Boosted electrochemical performance of Li2ZnTi3O8 enabled by ion-conductive Li2ZrO3 concomitant with superficial Zr-doping

Abstract

The poor electronic and ionic conductivities restrict the application of Li2ZnTi3O8 (LZTO) especially at high current rates. In this work, LZTO is modified with Li2ZrO3 (LZO) by simply reacting LiNO3 and Zr(NO3)4·5H2O on the surface of the as-prepared LZTO particles to improve the electrochemical performance. The modified LZTO with a LZO/LZTO mass ratio of 0.008 and sintered at 750 °C for 5 h exhibits greatly enhanced rate capabilities (acquiring reversible capacities of 196.1, 175.9, 154.9, 135.1, 109.8, and 223.6 mAh g−1 at 100, 200, 400, 800, 1600, and 100 mA g−1, respectively), and outstanding long-term cyclability (retaining a capacity of 199.2 mAh g−1 after 600 cycles at 500 mA g−1). On the basis of detailed characterizations on structure and composition as well as DFT calculations, the dispersed LZO nanoparticles and LZO coating bridge the LZTO particles to facilitate Li+ migration among the LZTO particles, while the superficial Zr4+ doping in LZTO promotes electron transfer, resulting in the simultaneously ameliorated electronic and ionic conductivities of LZTO, as well as alleviated polarization.