Stabilizing Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode by generating ion-conductive polymer coating layer with 1, 3-dioxolane introducing electrolyte for lithium-ion batteries

Abstract

The employment of electrolyte-film forming additive is a facile and effective strategy to improve the cycling performance of aggressive Nickel-rich layered oxide cathode LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode for high energy lithium-ion batteries (LIBs). Here we report a homogeneous and dense polymer cathode-electrolyte-interface (CEI) film generated via in-situ electrooxidation polymerization of 1, 3-Dioxolane (DOL) in a conventional carbonate-based electrolyte. It is found that the electrolyte modification with 15% DOL is the most effective in balancing the interfacial stability and Li-ion diffusion kinetics of NCM811 cathode, while also achieving its comparable rate capability and greatly improving cycling performance. Morphological and elemental characterizations demonstrate that the 15% DOL-derived CEI layer not only alleviates the impacts of harmful interfacial reactions and hinders the particle disintegration, but also suppresses the irreversible lattice transition of the NCM811 cathode surface to the inactive rock salt phase. Moreover, it is proved that the F-rich interfacial layer displays excellent Li-ion transport kinetics. As a result, the cell exhibits high capacity retention of 85.2% and 78.1% after 200 cycles at cut-off voltages of 4.3 V and 4.5 V at 1 C in the 15% DOL-modified electrolyte. Therefore, creating a stable and effective Li-ion conductive interfacial protective film on the cathode surface by optimizing an electrolyte functional additive is an economical and available approach to develop the highly stabilized Ni-rich cathode for high-energy LIBs applications.