表面修饰用于抑制富镍锂离子阴极的界面寄生反应,Chemistry of Materials

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表面修饰用于抑制富镍锂离子阴极的界面寄生反应
Chemistry of Materials ( IF 7.2 ) Pub Date : 2019-03-29 00:00:00 , DOI: 10.1021/acs.chemmater.8b04200
Han Gao ₁ , Jiyu Cai ₂ , Gui-Liang Xu ₁ , Luxi Li ₃ , Yang Ren ₃ , Xiangbo Meng ₂ , Khalil Amine _{1,

4} , Zonghai Chen ₁

Affiliation

富镍锂镍锰钴氧化物（LiNi _x Mn _y Co _{1– x – y} O ₂，x≥0.5，NMCs）是用于锂离子电池的高容量阴极材料，但它们在高截止电位下的循环稳定性有限。在电池研究领域，已经对过渡金属的溶解，结构紊乱，颗粒破裂，表面膜增厚等各个方面的性能进行了研究。有趣的是，这些现象主要是在阴极材料的表面层观察到的，这意味着脱锂的NMC电极与非水电解质之间的某些界面寄生反应也可能促进了这些现象。在这项研究中，用TiO ₂化学修饰的LiNi _0.6 Mn _0.2 Co _0.2 O ₂（NMC 622）电极通过原子层沉积作为模型系统来证明界面寄生反应的临界性。界面寄生反应的抑制有效地降低了阴极表面膜电阻的升高，降低了过渡金属的溶解水平，降低了颗粒碎裂的水平，并减轻了NMC 622的阳离子混合。所有这些结果表明，谨慎进行通过表面改性设计界面层是提高高镍循环条件下富镍NMC耐久性的关键方法。

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Surface Modification for Suppressing Interfacial Parasitic Reactions of a Nickel-Rich Lithium-Ion Cathode

Ni-rich lithium nickel manganese cobalt oxides (LiNi_xMn_yCo_1–x–yO₂, x ≥ 0.5, NMCs) are high-capacity cathode materials for Li-ion batteries, but they exhibit limited cycling stability under high cutoff potentials. Various aspects, including transition metal dissolution, structural disordering, particle cracking, surface film thickening, etc., have already been investigated in terms of their performance degradation in the battery research community. Interestingly, these phenomena were primarily observed at the surface layer of the cathode material, implying that they may also be facilitated by some interfacial parasitic reactions between the delithiated NMC electrode and the non-aqueous electrolyte. In this study, LiNi_0.6Mn_0.2Co_0.2O₂ (NMC 622) electrodes chemically modified with TiO₂ via atomic layer deposition were used as a model system to demonstrate the criticalness of the interfacial parasitic reactions. The suppression of the interfacial parasitic reactions effectively reduced the hike of the cathodic surface film resistance, decreased the level of dissolution of transition metals, decreased the level of particle fragmentation, and mitigated the cation mixing of NMC 622. All of these results demonstrated that careful design of the interfacial layer by surface modifications is a key approach for improving the durability of Ni-rich NMCs under high-voltage cycling.

更新日期：2019-03-29

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