The Synergetic Effect of Lithium Bisoxalatodifluorophosphate and Fluoroethylene Carbonate on Dendrite Suppression for Fast Charging Lithium Metal Batteries.,Small

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The Synergetic Effect of Lithium Bisoxalatodifluorophosphate and Fluoroethylene Carbonate on Dendrite Suppression for Fast Charging Lithium Metal Batteries.
Small ( IF 13.0 ) Pub Date : 2020-06-10 , DOI: 10.1002/smll.202001989
Pengcheng Shi _{1,

2} , Fanfan Liu ₂ , YueZhan Feng ₃ , Jiafeng Zhou _{1,

2} , Xianhong Rui ₁ , Yan Yu _{2,

4,

5}

Affiliation

Fluorinated solid‐electrolyte interphase (SEI) derived from fluoroethylene carbonate (FEC) is particularly favored for dendrite suppression in lithium metal batteries because of the high Young's modulus (≈64.9 Gpa) and low electronic conductivity (10⁻³¹ S cm⁻¹) of LiF. However, the transportation ability of Li⁺ in this fluorinated SEI under high current densities is limited by the low ionic conductivity of LiF (≈10⁻¹² S cm⁻¹). Herein, by rational design, 0.1 m lithium bisoxalatodifluorophosphate (LiDFBOP) is adopted to modify fluorinated SEI in FEC based electrolyte for fast charging lithium metal batteries. Benefiting from the synergetic effect of LiDFBOP and FEC, a fluorinated SEI rich in LiF and Li_x PO_y F_z species can be yielded, which can further improve the stability and ionic conductivity of SEI for fast Li⁺ transportation. Meanwhile, the average coulombic efficiency for Li plating/stripping is improved from 92.0% to 96.7%, thus promoting stable cycling of Li||Li symmetrical batteries with dendrite free morphologies, even at high current densities (3.0 mA cm⁻²) and high plating/stripping capacities (3.0 mAh cm⁻²). More attractively, in practical Li||LiNi_0.6Co_0.2Mn_0.2O₂ batteries, the cycling life at 1C and rate capacities at 6C are also significantly improved. Therefore, the synergetic effect of LiDFBOP and FEC provides great potential for achieving advanced lithium metal batteries with fast charging ability.

中文翻译：

双氧杂硼酸二氟磷酸锂和碳酸氟乙烯酯对快速充电锂金属电池树突抑制的协同作用。

衍生自碳酸氟代亚乙酯（FEC）的氟化固体电解质中间相（SEI）特别适用于抑制锂金属电池中的枝晶，因为其杨氏模量高（≈64.9Gpa）和电子电导率低（10 ^-31 S cm ^-1）。 LiF。然而，Li的运输能力⁺在该氟化的SEI下高电流密度是由的LiF的低离子传导率（≈10限于^-12小号厘米^-1）。在此，通过合理设计，0.1 m采用双氧杂十二烷基二氟磷酸锂（LiDFBOP）来改性FEC基电解液中的氟化SEI，以对锂金属电池快速充电。得益于LiDFBOP和FEC的协同作用，可以制得富含LiF和Li _x PO _y F _z 物种的氟化SEI ，可以进一步提高SEI的稳定性和离子电导率，从而实现Li ^+的快速迁移。同时，用于锂电镀/剥离的平均库仑效率从92.0％提高到96.7％，从而即使在高电流密度（3.0 mA cm ^-2）和高电流密度下，也可促进具有无枝晶形态的Li || Li对称电池的稳定循环电镀/剥离容量（3.0 mAh cm ^-2）。更有吸引力的是，在实用的Li || LiNi _0.6 Co _0.2 Mn _0.2 O ₂电池中，在1C时的循环寿命和在6C时的倍率容量也显着提高。因此，LiDFBOP和FEC的协同作用为实现具有快速充电能力的高级锂金属电池提供了巨大的潜力。

更新日期：2020-07-28

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