在该研究中，课题组人员展示了一种通过表面固体反应逆转富镍层状氧化物（NLO）不稳定的本质的方式，通过这种方式重建的表面晶格很稳定，且耐受副反应和理化磨损，导致改善的循环性能。具体来说，研究人员合成了控制形态的La(OH)3纳米壳，其厚度控制在纳米精度，以作为Li+捕获者，诱导与NLO表面晶格的可控反应，从而将颗粒碎屑转换为一个具有局部Ni/Li无序的外延层，通过将氧化性的Ni3+转变为稳定的Ni2+，同时实现Li缺陷和Ni稳定化。
进一步研究表明，在代表性的NLO材料LiNi0.83Co0.07Mn0.1O2中，表面稳定和电荷转移之间实现了优化平衡，这是因为表面工程导致容量保留大幅提高，且具有优秀的比容量和很强的抑制NLO颗粒开裂的能力。他们的研究强调了表面化学在确定化学和结构行为之间的重要性，为控制表面晶格、以实现用于高能锂离子电池稳定的NLO铺平了道路。
据介绍，富镍层状氧化物（NLO）被认为是最有前途的新一代高能锂离子电池（LIB）阴极材料，然而由于其固有的界面和结构不稳定导致循环次数不足，其实际应用受到了很多挑战。
附：英文原文
Title: Surface Lattice Modulation through Chemical Delithiation toward a Stable Nickel-Rich Layered Oxide Cathode
Author: Si-Qi Lu, Qinghua Zhang, Fanqi Meng, Ya-Ning Liu, Jianjun Mao, Sijie Guo, Mu-Yao Qi, Yan-Song Xu, Yan Qiao, Si-Dong Zhang, Kecheng Jiang, Lin Gu, Yang Xia, Shuguang Chen, GuanHua Chen, An-Min Cao, Li-Jun Wan
Issue&Volume: March 24, 2023
Abstract: Nickel-rich layered oxides (NLOs) are considered as one of the most promising cathode materials for next-generation high-energy lithium-ion batteries (LIBs), yet their practical applications are currently challenged by the unsatisfactory cyclability and reliability owing to their inherent interfacial and structural instability. Herein, we demonstrate an approach to reverse the unstable nature of NLOs through surface solid reaction, by which the reconstructed surface lattice turns stable and robust against both side reactions and chemophysical breakdown, resulting in improved cycling performance. Specifically, conformal La(OH)3 nanoshells are built with their thicknesses controlled at nanometer accuracy, which act as a Li+ capturer and induce controlled reaction with the NLO surface lattices, thereby transforming the particle crust into an epitaxial layer with localized Ni/Li disordering, where lithium deficiency and nickel stabilization are both achieved by transforming oxidative Ni3+ into stable Ni2+. An optimized balance between surface stabilization and charge transfer is demonstrated by a representative NLO material, namely, LiNi0.83Co0.07Mn0.1O2, whose surface engineering leads to a highly improved capacity retention and excellent rate capability with a strong capability to inhibit the crack of NLO particles. Our study highlights the importance of surface chemistry in determining chemical and structural behaviors and paves a research avenue in controlling the surface lattice for the stabilization of NLOs toward reliable high-energy LIBs.
DOI: 10.1021/jacs.2c13787
