Chemical Vapor Treatment on High Nickel Cathode Towards Improved Battery Performance

One of the recent strategies to improve battery performance is to remove the residual lithium compounds (RLCs) from the cathode surface. Ni-rich cathode materials easily absorb moisture and CO₂ that forms RLCs such as LiOH and Li₂CO₃. Such RLC deteriorates the active material's integrity and reduces the Li-ion diffusion coefficient which leads to poor battery cycling performance. Development of Li₃PO₄ as a robust cathode electrolyte interphase (CEI) is another strategy that can provide a physical barrier between the cathode and liquid electrolyte to prevent a solid-liquid interfacial reaction, prevent intergranular cracking and phase transformation, and enable fast lithium-ion transport and high Young’s modulus. We reported chemical vapor treatment on NMC811. The surface impurities such as lithium carbonate (Li₂CO₃) and lithium hydroxide get removed after the reaction with an atomic layer depostion-precursor forming Li₃PO₄, releasing CO₂, CH_4, and O₂. In addition, the strong covalent bonding of the PO^4- group contributes to high thermal stability, low charge transfer resistance, and high voltage performance. As a result, CVT on NMC811 showed improved electrochemical performance and better rate capability compared to bare NMC811.<br/><b>Keyword</b>s: chemical vapor treatment, high nickel cathode, cathode electrolyte interphase, longer, and high-rate capability