磷酸铁锂正极废料的热分离及其再循环利用

Thermal Separation and Recycling of Lithium Iron Phosphate Cathode Waste

磷酸铁锂正极废料的传统回收过程存在资源消耗巨大、步骤繁琐、产生二次污染的问题。采用无水乙醇作为溶剂,对磷酸铁锂正极废料进行热溶,实现了活性物质与集流体的无损、有效分离,并对不同煅烧温度下LiFePO4再生正极材料的物相结构及电化学性能进行了表征。结果表明,不同温度下煅烧所得再生LiFePO4正极材料均为纯相,在450℃下预烧4 h,接着在650℃煅烧10 h的正极材料显示出最大的衍射峰强度。室温下,在2.5~4.3 V电压区间内,恒流充放电测试结果表明,经650℃煅烧10 h的正极材料呈现出137.8 mA·h/g的最大放电比容量,经100次循环后容量保持率为92.8%,库仑效率接近99%。该正极材料的电化学交流阻抗谱也表现出130Ω的最小电荷转移阻抗。这一无水乙醇热溶法也为同类材料的回收提供了一个新的分离思路。

Problems in the conventional recycling process of lithium iron phosphate cathode waste include huge resource consumption,tedious steps,and secondary pollution.Using absolute ethanol as the solvent,lithium iron phosphate cathode waste was thermally dissolved to achieve the non-destructive and effective separation of the active substance from the current collector,and the phase structure and electrochemical properties of the regenerated LiFePO_4 cathode material at different calcination temperatures were characterized.The results show that the regenerated LiFePO_4 cathode materials obtained by calcination at diffe-rent temperatures have a pure phase,and the cathode material obtained by pre-calcination at 450°C for 4 h followed by calcination at 650°C for 10 h shows the maximum diffraction intensity.The constant-current charge/discharge test results at room temperature in 2.5~4.3 V voltage range show that the cathode material calcined at 650°C for 10 h exhibits the maximum discharge specific capacity of 137.8 mA·h/g,a capacity retention rate of 92.8%after 100 cycles,and a Coulombic efficiency close to 99%.The electrochemical impedance spectroscopy of this cathode material also exhibits a minimum charge transfer impe-dance of 130Ω.The absolute ethanol thermal dissolution method also provides a new separation way for the recovery of similar materials.