A polymer electrolyte-skinned active material strategy toward high-voltage lithium ion batteries: a polyimide-coated LiNi0.5Mn1.5O4 spinel cathode material case
A polymer electrolyte-skinned active material strategy toward high-voltage lithium ion batteries: a polyimide-coated LiNi0.5Mn1.5O4 spinel cathode material case
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DOI：
10.1039/c2ee03389e
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发表时间：
2012-05-01
影响因子：
32.5
通讯作者：
Lee, Sang-Young
中科院分区：
文献类型：
--
作者：
Cho, Ju-Hyun;Park, Jang-Hoon;Lee, Sang-Young
介绍了一种对尖晶石型锂离子电池正极活性材料LiNi0.5Mn1.5O4（LNMO）进行表面改性的方法。这种策略是基于纳米结构的聚酰亚胺（PI）凝胶聚合物电解质（GPE）涂层。PI涂层通过4组分（均苯四甲酸二酐/联苯二酐/苯二胺/二氨基二苯醚）聚酰胺酸的热酰亚胺化成功地包裹了LNMO表面的大面积。与传统的金属氧化物涂层相比，不寻常的PI包裹层的显著特征是具有纳米厚度（类似于10 nm）的高度连续的表面覆盖和提供容易的离子传输。纳米结构调整的PI包裹层用作离子导电保护层以抑制不期望的界面副反应，有效地防止LNMO表面直接暴露于液体电解质。结果表明，PI包覆层在提高电池的高压性能和缓解LNMO与电解液界面放热反应方面起到了关键作用。值得注意的是，PI包裹的LNMO（PI-LNMO）的上级循环性能（在55 ℃下）通过定量分析锰（Mn）溶解、电池阻抗和在LNMO表面上形成的副产物的化学组成（具体地，氟化锂（LiF））而被非常详细地阐明。
A facile approach to the surface modification of spinel LiNi0.5Mn1.5O4 (LNMO) cathode active materials for high-voltage lithium ion batteries is demonstrated. This strategy is based on nanoarchitectured polyimide (PI) gel polymer electrolyte (GPE) coating. The PI coating layer successfully wrapped a large area of the LNMO surface via thermal imidization of 4-component (pyromellitic dianhydride/biphenyl dianhydride/phenylenediamine/oxydianiline) polyamic acid. In comparison to conventional metal oxide-based coatings, distinctive features of the unusual PI wrapping layer are the highly continuous surface coverage with nanometre thickness (similar to 10 nm) and the provision of facile ion transport. The nanostructure-tuned PI wrapping layer served as an ion-conductive protection skin to suppress the undesired interfacial side reactions, effectively preventing the direct exposure of the LNMO surface to liquid electrolyte. As a result, the PI wrapping layer played a crucial role in improving the high-voltage cell performance and alleviating the interfacial exothermic reaction between charged LNMO and liquid electrolyte. Notably, the superior cycle performance (at 55 degrees C) of the PI-wrapped LNMO (PI-LNMO) was elucidated in great detail by quantitatively analyzing manganese (Mn) dissolution, cell impedance, and chemical composition (specifically, lithium fluoride (LiF)) of byproducts formed on the LNMO surface.