Li2ZnTi3O8/C anode with high initial Coulombic efficiency, long cyclic life and outstanding rate properties enabled by fulvic acid

Abstract Industrialized anode materials for Li-ion batteries (LIBs) require high initial Coulombic efficiency (ICE), long cyclic life and outstanding rate properties. Herein, fulvic acid (FA) with the elements of C, H, O, N and S was adopted as the carbon precursor to mix with Li2ZnTi3O8 (LZTO) followed by carbonizing to optimize the electrochemical performance of the LZTO anode. At a weight ratio of 0.28 for FA/LZTO, the product carbonized at 800 °C reveals high ICE of 88.0%, remarkable rate capabilities (lithiation/delithiation capacities of 195.4/191 and 143.5/143.5 mAh g−1 at 0.1 and 1.6 A g−1, respectively). After undergoing 1000 cycles at 0.5 A g−1, the retained reversible capacity is 215.3 mAh g−1. The excellent performance suitable for industrial power LIBs associates with the N and S co-doped discontinuous carbon coating layers, small carbon bumps and membranes on the LZTO particle surface. The carbon material facilitates electron transfer and the exposed LZTO surface maintains the good Li-ion migration of LZTO. Particularly, the NO3− radicals yielded favor to boost the Li-ion diffusion by transforming into the solid state electrolytes of Li3N and LiNxOy in the lithiation process.