Specifically, the surfaces of lithium-ion battery electrodes evolve simultaneously with charge–discharge cycling (that is, in situ surface reconstruction and formation of a surface reaction layer (SRL)) that can lead to deterioration of performance 4, 5, 11. Structural and/or chemical rearrangements at surfaces determine the way a material interacts with its surrounding environment, thus controlling the functionalities of the material 6, 7, 8, 9, 10. This work sets a refined example for the study of surface reconstruction and chemical evolution in battery materials using combined diagnostic tools at complementary length scales.Ĭhemical evolution and structural transformations at the surface of a material directly influence characteristics relevant to a wide range of prominent applications including heterogeneous catalysis 1, 2, 3 and energy storage 4, 5. Furthermore, the surface reaction layer is composed of lithium fluoride embedded in a complex organic matrix. It was found that the surface reconstruction exhibits a strong anisotropic characteristic, which predominantly occurs along lithium diffusion channels. These are primarily responsible for the prevailing capacity fading and impedance buildup under high-voltage cycling conditions, as well as the first-cycle coulombic inefficiency.
Using correlated ensemble-averaged high-throughput X-ray absorption spectroscopy and spatially resolved electron microscopy and spectroscopy, here we report structural reconstruction (formation of a surface reduced layer, to transition) and chemical evolution (formation of a surface reaction layer) at the surface of LiNi xMn xCo 1−2xO 2 particles.
The present study sheds light on the long-standing challenges associated with high-voltage operation of LiNi xMn xCo 1−2xO 2 cathode materials for lithium-ion batteries.
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