Zhang Ting, Li Yuejiao, Chen Nan, Wen Ziyue, Shang Yanxin, Zhao Yuanyuan, Yan Mingxia, Guan Minrong, Wu Feng, Chen Renjie
School of Material Science & Engineering, Beijing Institute of Technology, Beijing 100081, China.
Collaborative Innovation Center of Electric Vehicles in Beijing, Beijing 100081, China.
ACS Appl Mater Interfaces. 2021 Jan 13;13(1):681-687. doi: 10.1021/acsami.0c19075. Epub 2021 Jan 5.
High-energy-density Li-metal batteries are of great significance in the energy storage field. However, the safety hazards caused by Li dendrite growth and flammable organic electrolytes significantly hinder the widespread application of Li-metal batteries. In this work, we report a highly safe electrolyte composed of 4 M lithium bis(fluorosulfonyl)imide (LiFSI) dissolved in the single solvent trimethyl phosphate (TMP). By regulating the solvation structure of the electrolyte, a combination of nonflammability and Li dendrite growth suppression was successfully realized. Both Raman spectroscopy and molecular dynamics simulations revealed improved dendrite-free Li anode originating from the unique solvation structure of the electrolyte. Symmetric Li/Li cells fabricated using this nonflammable electrolyte had a long cycle life of up to 1000 h at a current density of 0.5 mA cm. Furthermore, the LiTiO/TMP-4/Li full cells also exhibited excellent cycling performance with a high initial discharge capacity of 170.5 mAh g and a capacity retention of 92.7% after 200 cycles at 0.2 C. This work provides an effective approach for the design of safe electrolytes with favorable solvation structure toward the large-scale application of Li-metal batteries.
高能量密度锂金属电池在储能领域具有重要意义。然而，锂枝晶生长和易燃有机电解质所带来的安全隐患严重阻碍了锂金属电池的广泛应用。在这项工作中，我们报道了一种由4 M双（氟磺酰）亚胺锂（LiFSI）溶解在单一溶剂磷酸三甲酯（TMP）中组成的高安全性电解质。通过调节电解质的溶剂化结构，成功实现了不燃性和抑制锂枝晶生长的结合。拉曼光谱和分子动力学模拟均表明，由于电解质独特的溶剂化结构，锂金属阳极实现了无枝晶生长。使用这种不燃性电解质制备的对称Li/Li电池在0.5 mA cm的电流密度下具有长达1000 h的长循环寿命。此外，LiTiO/TMP-4/Li全电池也表现出优异的循环性能，在0.2 C下初始放电容量高达170.5 mAh g，200次循环后容量保持率为92.7%。这项工作为设计具有良好溶剂化结构的安全电解质以推动锂金属电池的大规模应用提供了一种有效方法。
