Construction of Low‐Impedance and High‐Passivated Interphase for Nickel‐Rich Cathode by Low‐Cost Boron‐Containing Electrolyte Additive

Abstract The nickel‐rich cathode LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) possesses the advantages of high reversible specific capacity and low cost, thus regarded as a promising cathode material for lithium‐ion batteries (LIBs). However, the capacity of the NCM811 decays rapidly at high voltage due to the extremely unstable electrode/electrolyte interphase. The discharge capability at low temperature is also impaired because of the increasing interfacial impedance. Herein, a low‐cost film‐forming electrolyte additive with multi‐function, phenylboronic acid (PBA), was employed to modify the interphasial properties of the NCM811 cathode. Theoretical calculation and experimental results showed that PBA constructed a highly conductive and steady cathode electrolyte interphase (CEI) film through preferential oxidation decomposition, which greatly improved the interfacial properties of the NCM811 cathode at room (25 °C) and low temperature (−10 °C). Specifically, the capacity retention of NCM811/Li cell was increased from 68 % to 87 % after 200 cycles with PBA additive. Moreover, the NCM811/Li cell with PBA additive delivered higher discharge capacity under −10 °C at 0.5 C (173.7 mAh g −1 vs. 111.1 mAh g −1 ). Based on the improvement of NCM811 interphasial properties by additive PBA, the capacity retention of NCM811/graphite full‐cell was enhanced from 49 % to 65 % after 200 cycles.