(Keynote) MnPO4-Coating for Improved Long-Term Performance of Li(Ni0.4Co0.2Mn0.4)O2 in Ionic Liquid-Based Electrolytes

Abstract

MnPO4-coated LiNi0.4Co0.2Mn0.4O2 (MP-NCM) [1] is demonstrated to be a high performance lithium battery cathode material in combination with the room-temperature ionic liquid-based electrolyte consisting of LiTFSI-PYR14FSI (2:8 molar ratio). The MnPO4 coating acts as an ideal protective layer to physically prevent the contact between the NCM active material and the electrolyte, thus, successfully stabilizing the electrode/electrolyte interface and preventing detrimental side reactions even in conventional, carbonate-based electrolytes [2]. As a result, MP-NCM-based electrodes reveal greatly enhanced C rate capability and cycling stability – even under extreme conditions like extended operational potential windows, elevated temperature, and higher active material mass loadings. Employing an ionic liquid-based electrolyte allows for outstanding cycling stability of lab-scale pouch cells, offering a capacity retention of well above 85% after 2000 cycles. The superior electrochemical behavior of MP-NCM compared to as-synthesized NCM is assigned to the superior stability of the electrode/electrolyte interface and structural integrity when applying a MnPO4 coating, rendering this approach highly promising also for other state-of-the-art and next generation lithium battery cathodes.