Journal of Energy Storage ( IF 8.9 ) Pub Date : 2023-07-07 , DOI: 10.1016/j.est.2023.108290
Mengyun Zhang , Li Wang , Yingqiang Wu , Jianhong Liu , Qiao Hu , Xiaodan Wang , Hong Xu , Xiangming He
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With much consideration on the stability of Ni-rich LiNixCoyMn1−x−yO2 (x > 0.5) cathode materials at high voltage, we use polyimides (PIs), a kind of mechanical, thermal and electrochemical performance all outstanding polymers, to coat LiNi0.6Co0.2Mn0.2O2 (NCM622) cathode materials via the self-growing method. The common cognition for the advantages of PI coatings is mainly about reduced interfacial side reactions, little transition metal dissolutions and a small amount of oxygen release, which prohibits the degradation of cathode materials and enhances electrochemical performance. However, the true state of PI coatings in LIBs at high voltage is not clear. Therefore, we resort to the electrochemically characterizing techniques combined with TEM, SEM, EDS, in-situ XRD and XPS to reveal the root cause of PI coatings. We find that the increment of electrochemical performance is the physical barrier interactions of PI coatings. Even at high voltage, PI coatings are stable without structural changes. These findings provide robust support for PI materials applied in LIBs, especially for coating high‑nickel materials to promote their commercialization.
中文翻译:
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聚酰亚胺:高电压下稳定的正极活性材料涂层
考虑到富镍LiNi x Co y Mn 1−x−y O 2 (x > 0.5)正极材料在高电压下的稳定性,我们采用了聚酰亚胺(PIs),它是一种机械、热学和电化学性能均优异的材料。出色的聚合物,可涂覆 LiNi 0.6 Co 0.2 Mn 0.2 O 2(NCM622)通过自生长方法的正极材料。人们对PI涂层优点的普遍认知主要是界面副反应减少、过渡金属溶解少、氧释放量小,抑制了正极材料的降解,增强了电化学性能。然而,高电压下LIB中PI涂层的真实状态尚不清楚。因此,我们采用结合TEM、 SEM 、EDS 、原位XRD的电化学表征技术和 XPS 揭示 PI 涂层的根本原因。我们发现电化学性能的提高是PI涂层的物理屏障相互作用。即使在高电压下,PI 涂层也很稳定,不会发生结构变化。这些发现为PI材料在锂离子电池中的应用,特别是涂层高镍材料以促进其商业化提供了有力的支持。