High-power durability of LiCoO2 thin film electrode modified with amorphous lithium tungsten oxide
High-power durability of LiCoO2 thin film electrode modified with amorphous lithium tungsten oxide
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DOI：
10.1016/j.jpowsour.2017.04.036
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发表时间：
2017-06-30
影响因子：
9.2
通讯作者：
Kawamura, Junichi
中科院分区：
文献类型：
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作者：
Hayashi, Tetsutaro;Matsuda, Yasutaka;Kawamura, Junichi
为了研究非晶态锂钨氧化物(LWO)层的电化学性能，采用脉冲激光沉积法制备了非晶态LWO修饰的LiCoO2(LCO)薄膜电极，并将其暴露在潮湿环境中。非晶态LWO修饰的LCO在20C的快速充放电倍率下的容量保持率高达80%，而裸LCO在20C的充放电倍率下的容量保持率为0%。电化学阻抗谱表明，循环测试后，LWO修饰的LCO的界面电阻比未修饰的LCO低。X射线光电子能谱(XPS)、扫描电子显微镜(STEM)和电子能量损失谱(EELS)测试表明，裸LCO电极表面有Li2CO3的存在，LCO一次粒子表面有较厚的降解CoO结构的表面层。XPS、STEM和EELS表明LWO改性的LCO表面存在少量Li2CO3，LCO层保持在正常状态，LWO层在测试后保持非晶态LWO状态。因此，非晶态LWO保护层有助于抑制LCO的退化，并通过锂离子导体保持非晶态LWO状态，从而产生高功率耐久性。(C)2017爱思唯尔B.V.保留所有权利。
To investigate electrochemical performances of an amorphous lithium tungsten oxide (LWO) layer, an amorphous LWO-modified LiCoO2 (LCO) thin film electrode is fabricated by pulsed laser deposition and is exposed under a humid environment. The amorphous LWO-modified LCO exhibits high capacity retention of 80% at a rapid charge-discharge rate of 20 C. Conversely, the bare LCO exhibits capacity retention of 0% at the rates of 20 C. Electrochemical impedance spectroscopy demonstrates that the LWO-modified LCO maintains a low interfacial resistance after the cycling test compared with the bare LCO. Xray photoemission spectroscopy (XPS), scanning transmission microscopy (STEM), and electron energy loss spectroscopy (EELS) indicate the presence of Li2CO3 on the surface of the bare LCO electrode and a thick degraded surface layer of CoO structure on the surface of LCO primary particle after electrochemical tests. XPS, STEM, and EELS indicate the presence of low amounts of Li2CO3 on the surface of the LWO-modified LCO, the LCO layer remains in a normal state, and LWO layer maintains the amorphous LWO state after the tests. Thus, the amorphous LWO protective layer contributes to suppressing the degradation of LCO and maintaining an amorphous LWO state with a lithium ion conductor, resulting in high power durability. (C) 2017 Elsevier B.V. All rights reserved.