Effect of iron‑phosphorus ratio on the structure and electrochemical performance of non-stoichiometric carbon-coated LiFePO4 cathode materials

IF 3.3 4区材料科学 Q3 CHEMISTRY, PHYSICAL

Solid State Ionics Pub Date : 2025-09-02 DOI:10.1016/j.ssi.2025.117009

Zijun Fang , Guorong Hu , Ke Du , Zhongdong Peng , Quanjun Fu , Haifeng Wang , Xiyuan Jiang , Yanbing Cao

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引用次数: 0

Abstract

In this paper, non-stoichiometric LiFe_xPO₄/C (x = 0.965, 0.97, 0.975, 0.98) was prepared by high-temperature solid-phase method combined with spray drying. The effects of regulating Fe/P ratio on the crystal structure, morphology and electrochemical properties of LiFePO₄ cathode materials were studied. The structure and morphology of the synthesized materials were characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that the Fe/P ratio has a great influence on the lattice parameters, micro-stress and degree of antisite defects of LiFePO₄ in structure; it also affects the particle size and carbon layer quality in morphology. Therefore, among the four stoichiometric ratios in the experiment, LiFe_0.97PO₄/C has the most stable crystal structure and the best carbon layer quality, and exhibits the best electrochemical performance, with a discharge capacity of 159.23 mAh/g at a 0.1C rate, a discharge capacity of 122 mAh/g at a 5C rate, and a maximum lithium ion diffusion coefficient of 1.22 × 10⁻¹⁴ cm² s⁻¹.

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铁磷比对非化学计量碳包覆LiFePO4正极材料结构和电化学性能的影响

本文采用高温固相法结合喷雾干燥法制备了非化学计量的LiFexPO4/C （x = 0.965, 0.97, 0.975, 0.98）。研究了铁磷比对LiFePO4正极材料晶体结构、形貌和电化学性能的影响。利用x射线衍射仪（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）对合成材料的结构和形貌进行了表征。结果表明：铁磷比对LiFePO4的晶格参数、微观应力和结构反位缺陷程度有较大影响；在形貌上也影响颗粒大小和碳层质量。因此，在实验的四种化学计量比中，LiFe0.97PO4/C具有最稳定的晶体结构和最佳的碳层质量，并表现出最佳的电化学性能，在0.1C倍率下放电容量为159.23 mAh/g，在5C倍率下放电容量为122 mAh/g，最大锂离子扩散系数为1.22 × 10−14 cm2 s−1。

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来源期刊

Solid State Ionics 物理-物理：凝聚态物理

CiteScore

6.10

自引率

3.10%

发文量

152

审稿时长

58 days

期刊介绍： This interdisciplinary journal is devoted to the physics, chemistry and materials science of diffusion, mass transport, and reactivity of solids. The major part of each issue is devoted to articles on: (i) physics and chemistry of defects in solids; (ii) reactions in and on solids, e.g. intercalation, corrosion, oxidation, sintering; (iii) ion transport measurements, mechanisms and theory; (iv) solid state electrochemistry; (v) ionically-electronically mixed conducting solids. Related technological applications are also included, provided their characteristics are interpreted in terms of the basic solid state properties. Review papers and relevant symposium proceedings are welcome.