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| Study on the improvement of the "electrode/electrolyte" interface in sodium ion batteries by sodium difluorophosphate |
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Received:November 19, 2024
Revised:December 10, 2024
Accepted:January 03, 2025
Published Online:January 21, 2025
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| DOI： |
| KeyWord:sodium-ion batteries; electrolyte additive; sodium difluorophosphate; "electrode/electrolyte" interface; high voltage ; high temperature |
| Author | Institution |
| HUANG Qiujie |
Zhuhai Smoothway Electronic Materials Co.,Ltd. |
| MAO Chong |
Zhuhai Smoothway Electronic Materials Co.,Ltd. |
| PAN Dongyou |
Zhuhai Smoothway Electronic Materials Co.,Ltd. |
| YANG Lewen |
Zhuhai Smoothway Electronic Materials Co.,Ltd. |
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| Abstract: |
| Compared to lithium-ion batteries, sodium-ion batteries offer several advantages, including abundant resource availability, cost-effectiveness, and superior rate performance. However, under extreme conditions such as high voltage and elevated temperatures, the stability of the electrode/electrolyte interface becomes a critical factor limiting the battery's cycle performance. In this study, sodium difluorophosphate (NaPO?F?, acronym NaDFP) was introduced as a functional additive. This additive works synergistically with commonly used functional additives such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC) to facilitate the formation of stable solid electrolyte interface (SEI) and cathode electrolyte interface (CEI) films. Experimental results demonstrate that incorporating NaDFP into the electrolyte significantly enhances the performance of NaNi?/?Fe?/?Mn?/?O?||Hard carbon pouch cells. The modified electrolyte formulation resulted in improved initial capacity and first-cycle Coulombic efficiency. Notably, under high-voltage conditions (2.0–4.0V) and a charge/discharge current density of 1.0C at 45°C, the battery achieved an impressive capacity retention rate of 96% after 400 cycles. This remarkable performance is attributed to the SEI and CEI films formed through the synergistic interactions of NaDFP, VC, and FEC. These specialized interface layers significantly reduce interfacial impedance, mitigate side reactions at the electrode/electrolyte interface, and ultimately enhance the cycling stability of sodium-ion batteries under high voltage and high temperature conditions. |
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