Liquefied gas electrolytes for wide-temperature lithium metal batteries,Energy & Environmental Science

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Liquefied gas electrolytes for wide-temperature lithium metal batteries
Energy & Environmental Science ( IF 32.4 ) Pub Date : 2020-06-17 , DOI: 10.1039/d0ee01446j
Yangyuchen Yang _{1,

2,

3,

4} , Yijie Yin _{1,

2,

3,

4} , Daniel M. Davies _{2,

3,

4,

5} , Minghao Zhang _{2,

3,

4,

5} , Matthew Mayer _{2,

3,

4,

5} , Yihui Zhang _{1,

2,

3,

4} , Ekaterina S. Sablina _{1,

2,

3,

4} , Shen Wang _{2,

3,

4,

5} , Jungwoo Z. Lee _{4,

6,

7} , Oleg Borodin _{4,

8,

9,

10,

11} , Cyrus S. Rustomji _{4,

6,

7} , Y. Shirley Meng _{1,

2,

3,

4,

5}

Affiliation

The momentum in developing next-generation high energy batteries calls for an electrolyte that is compatible with both lithium (Li) metal anodes and high-voltage cathodes, and is also capable of providing high power in a wide temperature range. Here, we present a fluoromethane-based liquefied gas electrolyte with acetonitrile cosolvent and a higher, yet practical, salt concentration. The unique solvation structure observed in molecular dynamics simulations and confirmed experimentally shows not only an improved ionic conductivity of 9.0 mS cm⁻¹ at +20 °C but a high Li transference number (t_Li⁺ = 0.72). Excellent conductivity (>4 mS cm⁻¹) was observed from −78 to +75 °C, demonstrating operation above fluoromethane's critical point for the first time. The liquefied gas electrolyte also enables excellent Li metal stability with a high average coulombic efficiency of 99.4% over 200 cycles at the aggressive condition of 3 mA cm⁻² and 3 mA h cm⁻². Also, dense Li deposition with an ideal Li–substrate contact is seen in the liquefied gas electrolyte, even at −60 °C. Attributed to superior electrolyte properties and the stable interfaces on both cathode and anode, the performances of both Li metal anode and Li/NMC full cell (up to 4.5 V) are well maintained in a wide-temperature range from −60 to +55 °C. This study provides a pathway for wide-temperature electrolyte design to enable high energy density Li–metal battery operation between −60 to +55 °C.

中文翻译：

宽温度锂金属电池的液化气电解质

下一代高能电池的开发势头要求电解质与锂（Li）金属阳极和高压阴极兼容，并且还能够在宽温度范围内提供高功率。在这里，我们介绍了一种基于氟甲烷的液化气电解质，并带有乙腈助溶剂和更高但实用的盐浓度。在分子动力学模拟中观察到并经实验证实的独特溶剂化结构不仅显示了+20°C时离子电导率提高了9.0 mS cm ^-1，而且还显示出较高的Li迁移数（t _{Li ⁺} = 0.72）。优异的电导率（> 4 mS cm ^-1）是在-78至+75°C的温度下观察到的，这首次证明了在氟甲烷临界点以上的操作。液化气电解质还具有出色的锂金属稳定性，在3 mA cm ^-2和3 mA h cm ^-2的侵蚀性条件下，在200个循环中具有99.4％的高平均库仑效率。同样，即使在-60°C的条件下，在液化气电解质中也可以看到具有理想的Li-衬底接触的密集Li沉积。归因于优异的电解质性能以及阴极和阳极上的稳定界面，Li金属阳极和Li / NMC全电池（高达4.5 V）的性能在-60至+55°的宽温度范围内都能得到很好的维持C。这项研究为宽温度电解质设计提供了一条途径，以使高能量密度的锂金属电池能够在-60至+55°C之间工作。

更新日期：2020-07-15

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