Electrolyte Development and Optimization: A Case Study for Wide Operating Temperature and Fast Charge Applications
Authors: Guillot Sarah Lucienne , Usrey Monica Lee , Kerber Brian M , Du Peng , Zhou Liu (Amy) , Sriramulu Suresh 
Published: December 2024

The properties and composition of the electrolyte play key roles in performance of lithium-ion batteries, through the impact of the electrolyte on ion mobility as well as on the chemical makeup of the electrode-electrolyte interfaces. Electrolyte formulation and optimization of solvents, salts, and additives offer a powerful tool to improve cell performance by customizing the stability and transport properties of the electrolyte as well as the nature of the electrode-electrolyte interface. Orbia’s Battery Materials Innovation Center located in Madison, WI (formerly Silatronix), has substantial experience in electrolyte component design and synthesis, formulation and optimization for specific applications, and rigorous performance testing.

In this poster, we will provide case studies of our electrolyte customization methods applied to support the high performance of 4.3V Gr/NMC811 batteries operating under extreme conditions (wide temperature range and fast charge), which remain challenges for safe and stable cell operation. Our approach involves 1) starting with a large library of fluorinated molecules that can be used in liquid electrolytes with known stability properties; 2) screening molecules for beneficial intrinsic physical/electrochemical properties, and performance as components in simple electrolyte formulations in short coin cell and pouch cell tests; 3) refined screening with the most promising candidates in simple electrolyte formulations under a variety of test conditions with multilayer pouch cells; and 4) iterative pouch cell testing with complex electrolyte formulations for optimum performance.

In addition to screening and testing for performance, throughout the development and optimization process we also probe structure-function relationships of electrolyte components, through post-mortem cell analyses such as electrode surface, gas composition, and extracted electrolyte analyses as well as specialized model systems to probe specific scientific hypotheses, such as solvation studies and isotopic labeling of solvents for identification of gas species origins.

In the examples of wide operating temperature and fast charge, using the above process we identified several promising electrolyte formulations containing novel fluorinated solvents that showed reduced capacity loss during 4C fast charge cycling in Gr/NMC811 pouch cells. Through optimizing the electrolyte composition and components, additional performance improvements were demonstrated in 4C fast charge cycling as well as 0°C cycling stability tests with electrolytes containing the novel fluorinated material KDC-403. Investigations using post-mortem and model system analyses were performed to develop a mechanistic understanding of the impact of KDC-403 on solvation and interfacial transport, which we hypothesize provide the driving force for improved performance. Overall, we demonstrate a successful application of our electrolyte development process, resulting in an electrolyte optimized for superior wide temperature operation and fast charge applications.

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