Abstract

Rod-like LiFe_1−xMn_xPO₄/C cathode with particle size of about 300–500 nm was fabricated successfully via simple hydrothermal method. By means of adjusting the manganese content of LiFe_1−xMn_xPO₄, the electrochemical property was studied to clarify the effect of manganese content. LiFe_1−xMn_xPO₄/C sample with x = 0.70 showed the superior specific discharge capacity of 153.1 mAh g⁻¹ at a rate of 0.1 C, and the electrochemical mechanism analyzed by electrochemical impedance spectra demonstrated that the LiFe_0.30Mn_0.70PO₄/C exhibited the smallest charge transfer impedance and the largest lithium-ion diffusion coefficient. With the increase of manganese content, the reduction of discharge capacity is attributed to the linear decrease of Mn²⁺/Mn³⁺ reduction reaction. When x = 0.80, the two discharge platforms located at 3.5 and 3.9 V, respectively, reach a maximum, which result from the reduction electromotive force of Fe²⁺/Fe³⁺ affected by the addition of manganese ions since the discharge platform of LiMnPO₄ is higher than that of LiFePO₄.

中文翻译：

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高锰含量的LiFe 1-x Mn x PO 4的放电电压和放电容量的研究

摘要

通过简单的水热法成功地制备了粒径约300–500 nm的棒状LiFe ₁ - _x Mn _x PO ₄ / C阴极。通过调节LiFe _{1- x} Mn _x PO ₄的锰含量，研究了电化学性质以阐明锰含量的影响。X  = 0.70的LiFe _{1- x} Mn _x PO ₄ / C样品在0.1 C的速率下显示出153.1 mAh g ^-1的优异比放电容量，并且通过电化学阻抗谱分析的电化学机理表明LiFe_0.30 Mn _0.70 PO ₄ / C表现出最小的电荷转移阻抗和最大的锂离子扩散系数。随着锰含量的增加，放电容量的降低归因于Mn ²⁺ / Mn ³⁺还原反应的线性降低。当x  = 0.80时，分别位于3.5 V和3.9 V的两个放电平台达到最大值，这是由于LiMnPO的放电平台导致Fe ²⁺ / Fe ³⁺的还原电动势受锰离子的添加​​影响而产生的。₄高于LiFePO ₄。