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High-Energy-Density Lithium Metal Batteries with Impressive Li+ Transport Dynamic and Wide-Temperature Performance from −60 to 60 °C
Small ( IF 13.0 ) Pub Date : 2023-03-15 , DOI: 10.1002/smll.202300571
Ran Han 1, 2 , Zhicheng Wang 3 , Dan Huang 3 , Fengrui Zhang 3 , Anran Pan 2 , Haiqi Song 2 , Yumeng Wei 2 , Yang Liu 2 , Lei Wang 2 , Yajie Li 1 , Jingjing Xu 3 , Jianchen Hu 4 , Xiaodong Wu 3
Affiliation  

High-energy-density Li metal batteries (LMBs) with Nickel (Ni)-rich cathode and Li-metal anode have attracted extensive attention in recent years. However, commercial carbonate electrolytes bring severe challenges including poor cycling stability, severe Li dendrite growth and cathode cracks, and narrow operating temperature window, especially hardly work at below −40 °C. In this work, a 2.4 m lithium difluoro(oxalato)borate (LiDFOB) in ethyl acetate (EA) solvent with 20 wt% fluorocarbonate (FEC) (named 2.4m-DEF) is designed to solve Li+ transport dynamic at low temperature and improve interfacial stability between electrolyte with Li anode or Ni-rich cathode. Beneficial lower freezing point, lower viscosity, and higher dielectric constant of EA solvent, the electrolyte exhibits excellent Li+ transport dynamic. Relying on the unique Li+ solvation structure, more DFOB anions and FEC solvents are decomposed to establish a stable solid electrolyte interface at electrolyte/electrode. Therefore, LiNi0.9Co0.05Mn0.05O2 (NCM90)/Li LMB with 2.4m-DEF enables excellent rate capability (184 mA h g−1 at 30 C) and stable cycling performance with ≈93.7% of capacity retention after 200 cycles at 20 C and room temperature. Moreover, the NCM90/Li LMB with 2.4m-DEF exhibits surprising ultra-low-temperature performance, showing 173 mA h g−1 at −40 °C and 152 mA h g−1 at −60 °C, respectively.

中文翻译:

高能量密度锂金属电池,具有令人印象深刻的 Li+ 传输动态和 -60 至 60 °C 的宽温性能

近年来,具有富镍(Ni)正极和锂金属负极的高能量密度锂金属电池(LMB)引起了广泛关注。然而,商业碳酸盐电解质带来了严峻的挑战,包括循环稳定性差、锂枝晶生长和正极裂纹严重、工作温度窗口窄,特别是在-40℃以下难以工作。在这项工作中, 设计了在含有 20 wt% 氟碳酸盐 (FEC) 的乙酸乙酯 (EA) 溶剂中的 2.4 m 二氟草酸硼酸锂 (LiDFOB)(称为 2.4m-DEF)来解决Li +低温传输动态并提高电解质与锂阳极或富镍阴极之间的界面稳定性。得益于EA溶剂的较低凝固点、较低粘度和较高介电常数,该电解质表现出优异的Li +传输动力学。依靠独特的Li +溶剂化结构,更多的DFOB-阴离子和FEC溶剂被分解,在电解质/电极处建立稳定的固体电解质界面。因此,具有2.4m-DEF的LiNi 0.9 Co 0.05 Mn 0.05 O 2 (NCM90)/Li LMB可实现优异的倍率性能(184 mA hg -130 C)和稳定的循环性能,在 20 C 和室温下循环 200 次后容量保持率约为 93.7%。此外,具有2.4m-DEF的NCM90/Li LMB表现出令人惊讶的超低温性能,在-40°C下显示出173 mA hg -1 ,在-60°C下显示出152 mA hg -1
更新日期:2023-03-15
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