Low-Concentrated Lithium Hexafluorophosphate Ternary-based Electrolyte for a Reliable and Safe NMC/Graphite Lithium-Ion Battery,The Journal of Physical Chemistry Letters

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Low-Concentrated Lithium Hexafluorophosphate Ternary-based Electrolyte for a Reliable and Safe NMC/Graphite Lithium-Ion Battery
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2021-02-16 , DOI: 10.1021/acs.jpclett.0c03736
Georgios Nikiforidis _{1,

2} , Mohamed Raghibi ₁ , Adnan Sayegh ₁ , Mérièm Anouti _{1,

2}

Affiliation

Current commercial lithium-ion battery (LIB) electrolytes are heavily influenced by the cost, chemical instability, and thermal decomposition of the lithium hexafluorophosphate salt (LiPF₆). This work studies the use of an unprecedently low Li salt concentration in a novel electrolyte, which shows equivalent capabilities to their commercial counterparts. Herein, the use of 0.1 M LiPF₆ in a ternary solvent mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFE) (3EC/7EMC/20TFE, by weight) is investigated for the first time in LiNi_1/3Mn_1/3Co_1/3O₂ (NMC111)/graphite pouch cells. In solution, the Li⁺ transport number and diffusion are governed by the Grotthuss mechanism, with transport properties being independent of salt concentration. The proposed electrolyte operates in a wide temperature window (0–40 °C), is nonflammable (self-extinguishing under 2 s), and shows adequately fast wetting (4 s). When incorporated into the NMC/graphite pouch cell, it initially forms a solid electrolyte interphase (SEI) with minimal gas formation followed by a comparable battery performance to standard LiPF₆ electrolytes, validated by a high specific capacity of 165 mAh g^–1, Coulombic efficiencies of 99.3%, and capacity retention of 85% over 700 cycles.

中文翻译：

低浓度六氟磷酸锂三元电解质，用于可靠，安全的NMC /石墨锂离子电池

当前的商用锂离子电池（LIB）电解质受六氟磷酸锂盐（LiPF ₆）的成本，化学不稳定性和热分解的严重影响。这项工作研究了在新型电解质中使用前所未有的低锂盐浓度，这显示了与商业同类产品相当的功能。在此，在碳酸亚乙酯（EC），碳酸乙基甲基酯（EMC）和1,1,2,2-四氟乙基2,2,2-三氟乙基醚（TFE）的三元溶剂混合物中使用0.1 M LiPF ₆（首次在LiNi _1/3 Mn _1/3 Co _1/3 O ₂（NMC111）/石墨袋式电池中研究了3EC / 7EMC / 20TFE（按重量计）。在解决方案中，Li ⁺转运数量和扩散受格罗特斯机制控制，转运特性与盐浓度无关。建议的电解液在较宽的温度范围（0–40°C）下运行，不易燃（在2 s内自动熄灭），并具有足够快的润湿性（4 s）。当掺入到NMC /石墨袋式电池中时，它最初形成的固态电解质中间相（SEI）具有最少的气体形成，然后具有与标准LiPF ₆电解质相当的电池性能，并通过165 mAh g ^–1的高比容量验证，库仑在700个循环中，效率为99.3％，容量保持率为85％。

更新日期：2021-02-25

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