Suppressing the formation of Fe2P: Thermodynamic study on the phase diagram and phase transformation for LiFePO4 synthesis

被引：15
作者：
He, Lihua [1 ]
Xu, Shengming [1 ]
Zhao, Zhongwei [2 ]
机构：
[1] Tsinghua Univ, Inst Nucl & New Energy Technol, Beijing 100084, Peoples R China
[2] Cent South Univ, Sch Met & Environm, Changsha 410083, Hunan, Peoples R China
来源：
ENERGY | 2017年 / 134卷
基金：
中国国家自然科学基金;
关键词：
Lithium iron phosphate; Iron phosphide; Decomposition; Carbothermal reduction; Thermodynamics; LITHIUM IRON PHOSPHATE; AMMONIUM DIHYDROGEN PHOSPHATE; ELECTROCHEMICAL PERFORMANCE; CONDUCTIVITY; TEMPERATURE; REDUCTION; CAPACITY; OLIVINES; OXIDE;
D O I：
10.1016/j.energy.2017.06.036
中图分类号：
O414.1 [热力学];
学科分类号：
摘要：
Impurity of iron phosphide (Fe2P) may weaken the cycle performance of the LiFePO4 battery cell, and it is mandatory to get rid of this impurity in actual production. In order to suppress the formation of Fe2P, the phase transformation and thermodynamic analysis of Li2CO3-Fe2O3-NH4H2PO4-C/CO system for LiFePO4 synthesis were studied in this paper. The phase diagram for LiFePO4 synthesis indicated that LiFePO4 will be respectively decomposed to form FeP, Fe2P, and Fe3P at 718, 776, and 836 degrees C, corresponding with the insulating Li3PO4 being yielded. Considering the practical synthesis, the sintering temperature should be controlled below 776 degrees C to avoid the formation of Fe2P impurity in theory. The thermodynamic analysis successfully explained why the sintering temperature for pure LiFePO4 preparation currently controlled to be 650-750 degrees C. Besides the sintering temperature, adding excess of Li,resource is an effective measure to avoid the formation of Fe2P and other impurities. (C) 2017 Elsevier Ltd. All rights reserved.
引用
收藏
页码：962 / 967
页数：6
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