Electro-chemo-mechanical design of polymer matrix in composited LiNi_0.8Co_0.1Mn_0.1O₂ cathode endows solid-state batteries with superior performance

Nickel-rich LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode material has been widely concerned due to its high voltage, high specific capacity and excellent rate performance, which is considered as one of the most promising cathode materials for the next generation of high-energy–density solid-state lithium batteries. However, serious electro-chemo-mechanical degradation of Nickel-rich cathode during cycling, especially at a high voltage (over 4.5 V), constrains their large-scale application. Here, using the multi-physical simulation, highly-conductive polymer matrix with spontaneous stress-buffering effect was uncovered theoretically for reinforcing the electrochemical performance of composited NCM811 cathode through the visualization of uniform concentration distribution of Li-ion coupled with improved stress field inside NCM811 cathode. Thereupon, polyacrylonitrile (PAN) and soft polyvinylidene fluoride (PVDF) were selected as the polymer matrix to fabricate the composited NCM811 cathode (PVDF-PAN@NCM811) for improving the electrochemical performance of the solid-state NMC811|Li full cells, which can maintain high capacity over 146.2 mA h g⁻¹ after 200 cycles at a high voltage of 4.5 V. Suggestively, designing a multifunctional polymer matrix with high ionic conductivity and mechanical property can buffer the stress and maintain the integrity of the structure, which can be regarded as the door-opening avenue to realize the high electrochemical performance of Ni-rich cathode for solid-state batteries.