Dual Electrolyte Design for Lithium-Ion Batteries

Abstract

Lithium-ion batteries (LIBs) are today the most used energy storage for portable electronics and electric vehicles – but are laden with concerns of materials scarcity and availability. The development of high-voltage cobalt-free cathode active materials such as LiNi0.5Mn1.5O4 (LNMO) represents one promising route for next-generation LIBs due to their combination of high capacity and low cost. Combining LNMO with conventional LIB electrolytes based on carbonate solvents, however, typically leads to severe capacity fading due to a range of different degradation mechanisms1, not the least due to the wide electrochemical stability window (ESW) needed for a graphite//LNMO cell.Here we use the rather novel route to design LIB cells by utilizing two different electrolytes to together cover the full ESW2. The separation of the two electrolytes is assured by designing them to be immiscible, either chemically or more mechanically, while for the functionality of the cell we also monitor the evolution of a stable solid electrolyte interphase (SEI) at the anode side and a stable cathode electrolyte interphase (CEI) at the cathode side. This proof-of-concept study allows us to shine light on the best ways to design a dual electrolyte cell.References K. Guo et al. , “ High‐Voltage Electrolyte Chemistry for Lithium Batteries ”, Small Science 2, 2100107 (2022). S. He et al. , “ Design of a Dual-Electrolyte Battery System Based on a High-Energy NCM811-Si/C Full Battery Electrode-Compatible Electrolyte ”, ACS Appl Mater Interfaces 13, 54069–54078 (2021).