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

The nickel-rich cathode LiNi0.8Co0.1Mn0.1O2 (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 degrees C) and low temperature (-10 degrees 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 degrees 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.

Automated summary

A low-cost electrolyte additive, phenylboronic acid (PBA), was used to improve the performance of NCM811 cathode at high voltage and low temperature. PBA constructed a highly conductive and steady cathode electrolyte interphase (CEI) film, leading to enhanced cycling capacity and improved discharge capability at low temperature.