Improved Cycling Stability of LiNi0.8Co0.1Mn0.1O2 Cathode Material via Variable Temperature Atomic Surface Reduction with Diethyl Zinc. Issue 7 (9th December 2021) - Saha, Arka
Abstract: High‐Ni‐rich layered oxides [e.g., LiNi x Co y Mn z O2 ; x > 0.5, x + y + z = 1] are considered one of the most promising cathodes for high‐energy‐density lithium‐ion batteries (LIB). However, extreme electrode–electrolyte reactions, several interfacial issues, and structural instability restrict their practical applicability. Here, a shortened unconventional atomic surface reduction (ASR) technique is demonstrated on the cathode surface as a derivative of the conventional atomic layer deposition (ALD) process, which brings superior cell performances. The atomic surface reaction (reduction process) between diethyl‐zinc (as a single precursor) and Ni‐rich NMC cathode [LiNi0.8 Co0.1 Mn0.1 O2 ; NCM811] material is carried out using the ALD reactor at different temperatures. The temperature dependency of the process through advanced spectroscopy and microscopy studies is demonstrated and it is shown that thin surface film is formed at 100 °C, whereas at 200 °C a gradual atomic diffusion of Zn ions from the surface to the near‐surface regions is taking place. This unique near‐surface penetration of Zn ions significantly improves the electrochemical performance of the NCM811 cathode. This approach paves the way for utilizing vapor phase deposition processes to achieve both surface coatings and near‐surface doping in a single reactor to stabilize high‐energy cathode materials. Abstract : The variable temperature atomic surface reduction process of NCM811 cathode with di‐ethyl zinc using the atomic layer deposition technique results in surface coating to near surface doping of Zn atoms in a single reactor to stabilize the Ni‐rich NCM811 cathode for high energy output.