This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. To this end, a number of electrolyte formulations have been developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl butyrate-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalato)borate (LiBOB), which have been shown to result in improved high-temperature resilience of all carbonate-based electrolytes.
Improved performance has been demonstrated of Li-ion cells with methyl butyrate-based electrolytes, including 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %); 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 4% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + lithium oxalate; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% VC; and 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 0.10M LiBOB. These electrolytes have been shown to improve performance in MCMB-LiNiCoO2 and graphite-LiNi1/3Co1/3Mn1/3O2 experimental Li-ion cells.
A number of LiPF6-based mixed carbonate electrolyte formulations have been developed that contain ester co-solvents, which have been optimized for operation at low temperature, while still providing reasonable performance at high temperature. For example, a number of ester co-solvents were investigated, including methyl propionate (MP), ethyl propionate (EP), methyl butyrate (MB), ethyl butyrate (EB), propyl butyrate (PB), and butyl butyrate (BB) in multicomponent electrolytes of the following composition: 1.0M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (20:60:20 v/v %) [where X = ester co-solvent]. [“Optimized Car bon - ate and Ester-Based Li-Ion Electrolytes,” NASA Tech Briefs, Vol. 32, No. 4 (April 2008), p. 56.] Focusing upon improved rate capability at low temperatures (i.e., –20 to –40 ºC), this approach was optimized further, resulting in the development of 1.20M LiPF6 in EC+EMC+MP (20:20:60 v/v %) and 1.20M LiPF6 in EC+EMC+EB (20:20:60 v/v %), which were demonstrated to operate well over a wide temperature range in MCMBLiNiCoAlO2 and Li4Ti5O12-LiNiCoAlO2 prototype cells.
This work was done by Marshall C. Smart and Ratnakumar V. Bugga of Caltech for NASA’s Jet Propulsion Laboratory
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to: Innovative Technology Assets Management JPL Mail Stop 202-233 4800 Oak Grove Drive Pasadena, CA 91109-8099 E-mail:
This Brief includes a Technical Support Package (TSP).
Use of Additives To Improve Performance of Methyl Butyrate-Based Lithium-Ion Electrolytes
(reference NPO-47537) is currently available for download from the TSP library.
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Overview
The document is a technical report from the Jet Propulsion Laboratory (JPL) at the California Institute of Technology, focusing on advancements in lithium-ion battery technology, particularly through the use of additives in methyl butyrate-based electrolytes. It addresses the challenges faced in developing rechargeable batteries for plug-in hybrid electric vehicles (PHEVs) and future NASA missions, emphasizing the need for improved performance across a wide temperature range.
The report outlines several technical barriers identified by the Department of Energy (DoE), including a narrow operating temperature range, limited battery life, and poor abuse tolerance. Current lithium-ion systems operate effectively between -40°C and +40°C, but there is a pressing need for batteries that can function in more extreme conditions, specifically from -60°C to +60°C. This capability is crucial for future space missions, such as those exploring Mars and the outer planets, where low temperatures are a significant concern for landers, rovers, and other equipment.
The document highlights the development of advanced electrolytes that can enhance the performance of lithium-ion batteries, aiming for long life characteristics of up to 5,000 cycles over a 10-year lifespan. The report also discusses the importance of high voltage stability in these electrolyte systems, which would allow operation at voltages up to 5V with high specific energy cathode materials.
In summary, the report presents a comprehensive overview of ongoing research and development efforts to create more robust lithium-ion batteries capable of operating in extreme temperatures. It emphasizes the potential applications of these advancements in both commercial and aerospace sectors, showcasing the innovative approaches being taken to overcome existing limitations in battery technology. The findings aim to contribute to the broader goal of enhancing energy storage solutions for various applications, ultimately supporting the transition to more sustainable energy systems and enabling ambitious space exploration missions.
