Shenzhen Key Laboratory of Advanced Energy Storage, Southern University of Science and Technology, Shenzhen, 518055, P. R. China.
Department of Mechanical and Energy Engineering, Southern University of Science and Technology, Shenzhen, 518055, P. R. China.
Adv Mater. 2023 May;35(21):e2212308. doi: 10.1002/adma.202212308. Epub 2023 Apr 2.
Pushing the limit of cutoff potentials allows nickel-rich layered oxides to provide greater energy density and specific capacity whereas reducing thermodynamic and kinetic stability. Herein, a one-step dual-modified method is proposed for in situ synthesizing thermodynamically stable LiF&FeF coating on LiNi Co Mn O surfaces by capturing lithium impurity on the surface to overcome the challenges suffered. The thermodynamically stabilized LiF&FeF coating can effectively suppress the nanoscale structural degradation and the intergranular cracks. Meanwhile, the LiF&FeF coating alleviates the outward migration of O (α<2), increases oxygen vacancy formation energies, and accelerates interfacial Li diffusion. Benefited from these, the electrochemical performance of LiF&FeF modified materials is improved (83.1% capacity retention after 1000 cycles at 1C), even under exertive operational conditions of elevated temperature (91.3% capacity retention after 150 cycles at 1C). This work demonstrates that the dual-modified strategy can simultaneously address the problems of interfacial instability and bulk structural degradation and represents significant progress in developing high-performance lithium-ion batteries (LIBs).
提高截止电位的极限值可以使富镍层状氧化物提供更高的能量密度和比容量，而降低热力学和动力学稳定性。在此，提出了一种一步双改性方法，通过在 LiNiCoMnO 表面原位合成热力学稳定的 LiF 和 FeF 涂层，来捕获表面的锂离子杂质，从而克服所面临的挑战。热力学稳定的 LiF 和 FeF 涂层可以有效地抑制纳米级结构降解和晶间裂纹。同时，LiF 和 FeF 涂层减轻了 O（α<2）的向外迁移，增加了氧空位形成能，并加速了界面 Li 扩散。因此，LiF 和 FeF 改性材料的电化学性能得到了提高（在 1C 下 1000 次循环后容量保持率为 83.1%），即使在高温苛刻工作条件下（在 1C 下 150 次循环后容量保持率为 91.3%）也是如此。这项工作表明，双改性策略可以同时解决界面不稳定性和体相结构降解的问题，代表了开发高性能锂离子电池（LIBs）的重要进展。
