Morphology-controlled solvothermal synthesis of LiFePO4 as a cathode material for lithium-ion batteries
Morphology-controlled solvothermal synthesis of LiFePO4 as a cathode material for lithium-ion batteries
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DOI：
10.1039/c0jm01346c
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发表时间：
2010-09
影响因子：
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通讯作者：
Shi‐Yong Yang;Xufeng Zhou;Jiangang Zhang;Zhaoping Liu
中科院分区：
文献类型：
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作者：
Shi‐Yong Yang;Xufeng Zhou;Jiangang Zhang;Zhaoping Liu
以H3 PO 4、LiOH·H2O和FeSO 4·7 H2O为前驱体，在水-聚乙二醇（PEG）二元溶剂中，采用溶剂热法选择性合成了LiFePO 4（LFP）纳米粒子（粒径约50 nm）、纳米片（厚度100 nm，宽度800 nm）和微米片（厚度300 nm，宽度3 μm）。LFP颗粒的形态和尺寸强烈依赖于合成参数，如PEG与水的体积比、温度、浓度和进料顺序。碳包覆的纳米颗粒和纳米片可以在0.1C速率下提供>155 mAh g−1的放电容量（即17 mA g−1的电流密度）;相比之下，碳包覆的微片在0.1C速率下的放电容量低至110 mAh g−1。碳包覆的纳米颗粒、纳米片和微片的锂离子扩散系数分别计算为6.4 × 10−9、4.2 × 10−9和2.2 × 10−9 cm 2 s−1。当导电Super P碳（SP）的含量增加到30重量%时，所制备的电极可在高达20 C的速率下充放电。在20 C下经过1000次循环后，纳米颗粒电极可以保持其初始容量（126 mAh g-1）的89%，纳米板电极与初始容量（129 mAh g-1）相比显示出79%的容量保持率，微板电极保留了其初始容量（63.5 mAh g-1）的80%。
LiFePO4 (LFP) nanoparticles (∼50 nm in size), nanoplates (100 nm thick and 800 nm wide) and microplates (300 nm thick and 3 μm wide) have been selectively synthesized by a solvothermal method in a water–polyethylene glycol (PEG) binary solvent using H3PO4, LiOH•H2O and FeSO4•7H2O as precursors. The morphology and size of the LFP particles were strongly dependent on synthetic parameters such as volume ratio of PEG to water, temperature, concentration, and feeding sequence. The carbon coated nanoparticles and nanoplates could deliver a discharge capacity of >155 mAh g−1 at 0.1C rate (i.e. 17 mA g−1 of current density); in comparison, the carbon coated microplates had a discharge capacity as low as 110 mAh g−1 at 0.1C rate. The Li-ion diffusion coefficients of the carbon coated nanoparticles, nanoplates, and microplates were calculated to be 6.4 × 10−9, 4.2 × 10−9, and 2.2 × 10−9 cm2 s−1, respectively. When the content of conductive Super P carbon (SP) was increased to 30 wt.%, the prepared electrodes could charge–discharge at a rate as high as 20C. Over 1000 cycles at 20C, the nanoparticle electrode could maintain 89% of its initial capacity (126 mAh g−1), the nanoplate electrode showed 79% capacity retention compared to an initial capacity (129 mAh g−1), and the microplate electrode retained 80% of its initial capacity (63.5 mAh g−1).