LDH nanocrystal@amorphousness core–shell structure derived from LDH → LDO transformation: Synergistically enhanced energy stored for LIBs anode

Abstract

With the emergence of advanced electronics and appliances, there is a growing demand for high power/energy density and cyclic stability of Li-ion batteries (LIBs), which stimulates the development of high-performance electrode materials. Herein, we proposed and implemented a novel strategy of employing the LDH → LDO intermediate-transformation amorphization to improve the performance of LDH as LIBs anode. In this work, flower-like NiCo-LDH nanoparticles (LDHRT) are synthesized for the first time by co-precipitation using triethanolamine (TEA) as an alkali source and H2O2 as a size-controlling reagent. Then, the unique LDH nanocrystal@amorphousness core–shell structure was obtained by fine-tuning the heat treatment, which significantly improved the electrochemical properties of the material. The layered structure of LDH and the internal defects of the amorphous phase provide abundant transport channels and a larger accommodation space for Li+, improving the rate capability and capacity of LIBs. In addition, the surface amorphous layer and the reduced size of LDHRT nanocrystals effectively alleviate the volume effect, improving the cycling stability of the electrode material. As a result, superior capacity (1821.3 mAh g−1 at 0.1 A g−1), rate capability, and cyclic stability (∼687.7 mAh g−1 at 0.5 A g−1 after 500 cycles, with the average capacity attrition rate of 0.092 %) were achieved. The Li+ diffusion coefficient and capacity retention rate (after 300 cycles) are higher than nearly 3 orders of magnitude and 50.12 % compared to the LDHRT, respectively. This study has opened a simple, safe, and economical new avenue for developing high-performance electrode materials.