MnPO₄-coated LiNi_0.4Co_0.2Mn_0.4O₂ (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.

References

[1] Z. Chen, D. Chao, J. Liu, M. Copley, J. Lin, Z. Shen, G.-T. Kim, S. Passerini, J. Mater. Chem. A, 5, 2017, 15669

[2] Z. Chen, G.-T. Kim, D. Bresser, T. Diemant, S. Jeong, M Copley, R. J. Behm, J. Lin, Z. Shen, Stefano Passerini, Energy & Environmental Science (2018) submitted