Boosted electrochemical performance of Li_2ZnTi_3O_8 enabled by ion-conductive Li_2ZrO_3 concomitant with superficial Zr-doping

摘要

The poor electronic and ionic conductivities restrict the application of Li2ZnTi3O8 (LZTO) especially at high current rates. In this work, LZTO is modified with (LiZrO3)-Zr-2 (LZO) by simply reacting LiNO3 and Zr(NO3)(4).5H(2)O 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 degrees 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.