In July 2024, Professor Xie Jia and Lecturer Zeng Ziqi from Huazhong University of Science and Technology published a perspective article titled ‘Multilevel regulation of Li+-solvent interaction for fluorophosphate-based nonflammable electrolyte enabling lithium-ion batteries with long calendar life’ in the internationally renowned journal Chemical Engineering Journal. The article reveals that a multilevel regulation strategy involving solvents and anions can effectively mitigate the degradation of battery performance caused by the decomposition of fluoro-phosphates. This design concept was validated in a carbonate-based system. The standard lithium salt concentration (~1 M) electrolyte developed under this strategy enables the graphite anode to maintain 92.7% of its capacity after 200 stable cycles. Additionally, the graphite-NCM pouch cell showed no significant gas generation after half a year of cycling, with a capacity retention rate as high as ~96.5% after 600 cycles.
Product reference
Canrd, empowering your research journey to success! We are honored that Canrd products, ‘polyvinylidene fluoride (PVDF)’ and ‘N-methyl-2-pyrrolidone (NMP),’ contributed to the achievements of this research.
Research abstract
In the field of lithium-ion batteries (LIBs), the safety issues associated with flammable carbonate electrolytes urgently require innovative solutions. Studies have shown that non-flammable electrolytes can effectively prevent secondary hazards caused by the release of flammable substances following battery fires or explosions. Among these, fluoro-phosphate solvents have gained widespread attention due to their excellent flame retardancy and compatibility with carbonate electrolytes. However, these solvents are prone to reduction and form solid-electrolyte interphase (SEI) films with poor electron-blocking capabilities, making them difficult to be compatible with graphite anodes. Therefore, improving the reduction stability of fluoro-phosphates is crucial for their large-scale application. This article reveals that a multilevel regulation strategy involving solvents and anions can effectively mitigate the degradation of battery performance caused by the decomposition of fluoro-phosphate solvents, and this design concept was validated in a carbonate-based system. The standard lithium salt concentration (~1 M) electrolyte developed under this strategy enables the graphite anode to maintain 92.7% of its capacity after 200 stable cycles. Additionally, the graphite-NCM pouch cell showed no significant gas generation after half a year of cycling, with a capacity retention rate as high as ~96.5% after 600 cycles.
Key highlights
The article reveals that a multilevel regulation strategy involving solvents and anions can effectively mitigate the degradation of battery performance caused by the decomposition of fluoro-phosphate solvents. This design concept was validated in a carbonate-based system, providing new insights and guidance for the design of phosphate-based electrolytes.
Text analysis
Figure 1. (a) Electrostatic potential of solvent molecules. (b) Concept of solvent-anion synergistic regulation design. (c) Self-extinguishing strategy for mixed solvents proposed based on solvent boiling point and flash point. (d) Determination of basic solvent composition using the self-extinguishing strategy.
Figure 2. (a, b) Evaluation of electrolyte compatibility with the anode. (c) Interaction model of TFP with Li+. (d, e) Evaluation of electrolyte compatibility with the anode after adding EC. (f) Performance comparison of graphite anodes in TFP and TEP-based electrolytes.
Figure 3. (a, b) Compatibility of electrolytes with graphite anodes after replacing EC with PC and FEC. (c) Flame retardancy of the electrolyte. (d, e) Cycling performance of graphite anodes in PC and FEC systems. (f, g) Performance of graphite anodes in high lithium perchlorate electrolyte systems.
Figure 4. (a-d) Convolution proportions of different solvent molecules coordinating with Li+ in Raman spectra. (e) Coordination number of Li+ with anions and different solvent molecules in the electrolyte. (f) Changes in solvation structure of the electrolyte solvent after adding EC.
Figure 5. (a, b) Charge-discharge curves of the pouch cell at initial and during cycling. (c) Comparison of calendar life of the pouch cell with literature-reported data. (d) Cycling performance of the pouch cell. (e) Optical images of the pouch cell before and after cycling.
Summary and prospect
In summary, the article finds that a multilevel regulation strategy involving solvents and anions can effectively mitigate the degradation of battery performance caused by the decomposition of fluoro-phosphate solvents, with this design concept validated in a carbonate-based system. The developed electrolyte with a standard lithium salt concentration (~1 M) enables the graphite anode to maintain 92.7% of its capacity after 200 stable cycles. Additionally, the graphite-NCM pouch cell showed no significant gas generation after six months of cycling, with a capacity retention rate as high as ~96.5% after 600 cycles. This study provides new insights and guidance for the design of phosphate-based electrolytes.
Company introduction
Welcome to Canrd Company (Canrd stands for “Creating Avenues for New Research Development”，website: www.canrd.com ). We specialized in:
- Electrochemical experiment consumables, including coin cell cases, cathodes, anodes, electrodes, electrolytes, and various other materials.
- Battery cell research and development outsourcing, offering Custom-made electrodes, dry cells, finished battery cells, and battery cell testing.
- Test line equipment, such as coin cell equipment lines, pouch cell test lines, cylindrical cell test lines, and more.
We have strong research and development capabilities.If you are interested, please feel free to contact us at any time.
Phone：19867737979
Email：contact@canrd.com
Wechat：contactcanrd
Leave a Reply