Low-Temperature LiCoO₂||Graphite Batteries Enabled by Multi-Salt and Acetone-Ester Solvent Regulation

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-ion battery performance degrades significantly at low temperatures due to slow desolvation and unstable interfaces.
• Developing electrolytes that maintain high performance across diverse temperature ranges is crucial for advanced energy storage applications.

Purpose of the Study:

• To design and evaluate a novel fluorinated-solvent-free electrolyte (FBN-442) for improved low-temperature and high-rate performance in lithium-ion batteries.
• To elucidate the role of tailored solvation structures in optimizing ion transport and interfacial stability.

Main Methods:

• Formulation of a new electrolyte (FBN-442) using specific salts (LiFSI/LiODFB) and additives (LiNO3) in a mixed solvent (acetone, methyl acetate, vinylene carbonate).
• Utilized theoretical calculations and comprehensive experimental analyses to understand solvation structure and interfacial properties.
• Tested electrode performance (graphite and LiCoO2) and validated electrolyte performance in pouch cells at low temperatures (-40 °C).

Main Results:

• The FBN-442 electrolyte demonstrated a tailored solvation structure that promoted salt dissociation, moderate Li+ affinity, and effective film formation.
• Optimized solvation balanced ion transport and interfacial charge transfer, leading to dense, inorganic-rich interphase layers.
• Graphite and LiCoO2 electrodes showed significantly improved low-temperature and high-rate performance, with pouch cells retaining 78% capacity at -40 °C.

Conclusions:

• Solvation-structure regulation is critical for enhancing lithium-ion battery performance at low temperatures.
• The FBN-442 electrolyte offers a promising solution for reliable, high-energy lithium-ion battery operation across wide temperature ranges.
• This work paves the way for developing robust batteries for demanding environmental conditions.