Improving Cycle Life of Ni-Rich Li-Ion Battery Cathodes by Using Compartmentalized Anode and Cathode Electrolytes.

Abstract

As new, ever more energy-dense battery materials are being developed, it is becoming increasingly challenging for electrolytes to cater for both requirements set by the anode and cathode. Ethylene carbonate plays a key role in forming a stable solid-electrolyte-interphase on the graphite anodes, but in combination with nickel-rich cathodes, such as LiNi0.8Mn0.1Co0.1O2 (NMC811), it leads to excessive cathode oxygen loss at high voltage. In this work, the study proposes a cell design, where different electrolytes are compartmentalized in the anode and the cathode. An ionically conductive polymer electrolyte membrane is used to prevent two electrolytes from mixing. NMC811 versus graphite full cells using this electrolyte achieved a capacity retention of 85.1% over 520 cycles compared to 61.7% for control systems using a standard carbonate electrolyte under the same conditions. In addition, it is shown that cells using the compartmentalized electrolyte show less transition metal cross-over from the cathode to the anode and less impedance build-up during cycling. Overall, this cell design proposed in this work allows to independently optimize the anode and cathode electrolyte and holds the promise to better support the diverging electrolyte requirements of next-generation anodes and cathodes.