二氟磷酸锂 (LiPO2F2)：有助于提高锂离子电池低温性能的电解质添加剂,ACS Applied Energy Materials

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二氟磷酸锂 (LiPO2F2)：有助于提高锂离子电池低温性能的电解质添加剂
ACS Applied Energy Materials ( IF 5.4 ) Pub Date : 2022-09-07 , DOI: 10.1021/acsaem.2c02658
Lucheng Li ₁ , Weixia Lv ₁ , Jun Chen ₁ , Caijian Zhu ₁ , Sydorov Dmytro ₂ , Qian Zhang ₁ , Shengwen Zhong ₁

Affiliation

_{在碱性电解质（1 M LiPF 6} + 碳酸二甲酯（DMC）/碳酸甲乙酯（EMC）/碳酸亚丙酯（PC）/氟代碳酸亚乙酯（FEC ）中引入了一种有前景的二氟磷酸锂（LiPO ₂ F ₂ ）锂盐)) 通过在低温下改变其浓度来提高锂离子电池的电化学性能。实验表明，LiPO ₂ F ₂能明显提高电解液的离子电导率，尤其是。与相同条件下的基线（6.29、5.14、4.62、3.77 和 3.15 mS cm ^{-1 ）相比，含 2 wt % LiPO}₂ F ₂的电解质（2 LiPO₂ F ₂ ) 为 7.18、5.32、5.23、4.04 和 3.57 mS cm ^–1。由此可见，综合低温电化学性能明显提高。添加 2 wt % LiPO ₂ F ₂的电解液在 0.2C 时的比放电容量在 25 至 -40 °C 范围内分别为 161.4、157.2、148.9 和 137.5 mAh g ^-1 ，与碱性电解质（分别为 145.3、149.4、135.1 和 107.0 mAh g ^–1）。此外，添加 LiPO ₂ F ₂可以深刻地促进阴极-电解质界面（CEI）薄膜的组成和形态特征；即添加LiPO ₂ F ₂前为不均匀的烷基羧酸锂；之后，它变成了均匀的LiF薄膜，同时新薄膜将促进Li ⁺在电解液中的传输，进一步提高电池在低温下的电化学性能。在-40℃相同电流密度下，50次循环后比放电容量为81.97 mAh g ^-1，而在相同温度下，基础电解质电池的比放电容量仅为33.37 mAh g ^-1; 也就是说，放电容量在 -40 °C 时提高了惊人的 145.6%。综上所述，含LiPO ₂ F ₂的锂离子电池可以满足超低温条件下的应用要求。

"点击查看英文标题和摘要"

Lithium Difluorophosphate (LiPO2F2): An Electrolyte Additive to Help Boost Low-Temperature Behaviors for Lithium-Ion Batteries

A promising lithium salt of Li difluorophosphate (LiPO₂F₂) is introduced and added to the basic electrolyte (1 M LiPF₆ + dimethyl carbonate (DMC)/ethyl methyl carbonate (EMC)/propylene carbonate (PC)/fluoroethylene carbonate (FEC)) to enhance the electrochemical performance of lithium-ion batteries by changing its concentration at low temperatures. Experiments show that LiPO₂F₂ can obviously improve the electrolyte’s ionic conductivity, especially. Compared with the baseline (6.29, 5.14, 4.62, 3.77, and 3.15 mS cm^–1) under the same conditions, the ionic conductivities of the 2 wt % LiPO₂F₂-containing electrolyte (2 LiPO₂F₂) are 7.18, 5.32, 5.23, 4.04, and 3.57 mS cm^–1. From this, it is clear that the integrated low-temperature electrochemical performances have been significantly improved. The specific discharge capacities of the 2 wt % LiPO₂F₂-added electrolyte at 0.2C are 161.4, 157.2, 148.9, and 137.5 mAh g^–1 in the range from 25 to −40 °C, which are significantly much higher compared with the basic electrolyte (145.3, 149.4, 135.1, and 107.0 mAh g^–1, respectively). Additionally, the addition of LiPO₂F₂ can promote profoundly the composition and morphology characteristics of the cathode–electrolyte interface (CEI) film; namely, it is a uneven lithium alkyl carboxylate before the addition of LiPO₂F₂; after that, it becomes an even LiF film, and meanwhile, the new film will facilitate Li⁺ transport in the electrolyte, further boosting the eletrochemical performance of the cells under low temperatures. At −40 °C under the same current density, the specific discharge capacity is 81.97 mAh g^–1 after 50 cycles, while at the same temperature, the specific discharge capacity of the basic electrolyte battery is only 33.37 mAh g^–1; that is, the discharge capacity has a staggering 145.6% improvement at −40 °C. In conclusion, the lithium-ion batteries containing LiPO₂F₂ may meet the application requirements of ultra-low-temperature conditions.

更新日期：2022-09-07

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