Tuning the structural and electrochemical performance of LiZnVO4 anode via alkaline earth doping for efficient and reversible energy storage behavior in Li-ions batteries

Abstract

Anode materials of LiZn_1-xSr_xVO₄ (x = 0, 0.0025, 0.005, 0.0075, 0.01) samples were directly synthesized by sol-gel technique. Rietveld refinement of the XRD data confirmed the induced lattice stain and expanded cell volume in the rhombohedral structure of Sr-doped LiZnVO₄. The surface topography and morphology of the as-prepared materials was envisaged by FESEM and HRTEM inspections. The pure LZVO consists of tiny granular particles (100–200 nm) decorating larger grains (1–3 μm). Oppositely, the particles of 1 % Sr-doped LZVO have more ordered shape, higher porosity and less agglomeration, resulting smaller particle size. TEM micrographs for pure LZVO show irregular cubic crystals with nanometric particle size, ranging between 20 and 50 nm. While, 1 %Sr-doped LZVO nanoparticles appear as quasi-circular like shape with narrower particle size range from 10 to 20 nm. The O–V–O vibrational modes of VO₄ group and stretching vibration of Zn–O bond of the samples were interpreted by FTIR. The chemical composition and valences of the samples were determined by XPS. The optimized cell of 1 % Sr-doped LZVO anode showed initial specific discharge capacity 864 vs. 671.2 mAhg⁻¹ for LiZnVO₄. The battery of LiZn_0.99Sr_0.01VO₄ revealed optimum EIS parameters with the lowest charge transfer resistance, R_ct value (34.13Ω). Moreover, this battery demonstrated the best cycling performance, maintaining a significant discharge capacity of approximately 145 mAhg⁻¹ even after 100 cycles.