Insights into the Dual Role of Lithium Difluoro(oxalato)borate Additive in Improving the Electrochemical Performance of NMC811||Graphite Cells

Ni-rich layered oxides (LiNixMnyCozO2, x ≥ 0.6, x+y+z=1) are promising positive electrode materials for high energy density lithium-ion batteries thanks to their high specific capacity. However, large-scale application of Ni-rich layered oxides was hindered by its poor structural and interfacial stability, especially during cycling at high cut-off potential (i.e., ≥ 4.3 V, vs Li+/Li). Herein, we demonstrated that lithium difluoro(oxalato)borate (LiDFOB) as a film forming additive plays a dual role on the electrode | electrolyte interphase formation in a LiNi0.83Mn0.05Co0.12O2||graphite cell, meaning it can not only be reduced on the graphite negative electrode but also oxidized on the nickel-rich oxide LiNi0.83Mn0.05Co0.12O2 positive electrode cycled at high cut-off potential (4.4 V, vs Li+/Li) prior to typical carbonate-based electrolyte components. As a result, the addition of 1.5 wt% LiDFOB greatly reduces the polarization and improves the cycling stability of the LiNi0.83Mn0.05Co0.12O2||graphite cell,...