In the present work, the study of atomic defects in LiFePO₄ is achieved by Rietveld refinements. Several LiFePO₄ samples are synthesized by using a sol‐gel process with varying calcination times and argon flow rates. Quantitative analysis of XRD patterns through Rietveld refinements confirms 2 % antisite defects in the LiFePO₄ sample. However, for the first time, we have observed antisite defects in LiFePO₄ prepared through a sol‐gel process at a higher temperature of 700 °C. Two samples identified as LFP−A and LFP−B are further studied by electrochemical analysis and electrochemical impedance spectroscopy to examine the effect of the antisite defects on the electrochemical performances and Li‐ion diffusion of LiFePO₄. Sample LFP−B with 2 % antisite defects shows, at 0.1 C rate, a lower discharge capacity of 138 mAh g⁻¹ as compared to 150 mAh g⁻¹ for LFP−A. LFP−B also shows shorter cycle life as well as rate capability at all of the C rates studied. Li‐ion diffusion coefficients of LFP−A and LFP−B in initially prepared electrodes are found to be 1.669×10⁻¹³ and 1.198×10⁻¹³ cm² s⁻¹, respectively, whereas the diffusion coefficients after 200 cycles are 0.968×10⁻¹³ and 0.436×10⁻¹³ cm² s⁻¹, respectively.

中文翻译：

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溶胶-凝胶合成的LiFePO4在高温下的反位缺陷：对锂离子扩散的影响

在当前的工作中，通过Rietveld精炼完成了LiFePO ₄中原子缺陷的研究。通过使用具有不同煅烧时间和氩气流速的溶胶-凝胶工艺合成了几个LiFePO ₄样品。通过Rietveld精修对XRD模式进行的定量分析证实了LiFePO ₄样品中2％的反位缺陷。但是，我们首次在700°C的高温下通过溶胶-凝胶法制备的LiFePO _4出现了反位缺陷。通过电化学分析和电化学阻抗谱进一步研究了鉴定为LFP-A和LFP-B的两个样品，以检验反位缺陷对LiFePO ₄的电化学性能和锂离子扩散的影响。。具有2％的抗位点缺陷的样品LFP-B在0.1 C速率下显示的放电容量为138 mAh g ^-1，而LFP-A的放电容量为150 mAh g ^-1。LFP-B还显示出更短的循环寿命以及在所有研究的C速率下的速率能力。初步制备的电极中LFP-A和LFP-B的锂离子扩散系数分别为1.669×10 ^-13和1.198×10 ^-13  cm ²  s ^-1，而200个循环后的扩散系数为0.968×。分别为10 ^-13和0.436×10 ^-13  cm ²  s ^-1。