Locally Concentrated LiPF 6 in a Carbonate-Based Electrolyte with Fluoroethylene Carbonate as a Diluent for Anode-Free Lithium Metal Batteries

作者：Tesfaye Teka Hagos, Balamurugan Thirumalraj, Chen−Jui Huang, Ljalem Hadush Abrha, Teklay Mezgebe Hagos, Gebregziabher Brhane Berhe, Hailemariam Kassa Bezabh, Jim Cherng, Shuo-Feng Chiu, Wei‐Nien Su, Bing‐Joe Hwang · 发表于：ACS Applied Materials & Interfaces · 年份：2019 · DOI：10.1021/acsami.8b21052 · 被引用次数：215 · 研究领域：Advanced Battery Materials and Technologies、Advancements in Battery Materials、Advanced Battery Technologies Research

Currently, concentrated electrolyte solutions are attracting special attention because of their unique characteristics such as unusually improved oxidative stability on both the cathode and anode sides, the absence of free solvent, the presence of more anion content, and the improved availability of Li + ions. Most of the concentrated electrolytes reported are lithium bis(fluorosulfonyl)imide (LiFSI) salt with ether-based solvents because of the high solubility of salts in ether-based solvents. However, their poor anti-oxidation capability hindered their application especially with high potential cathode materials (>4.0 V). In addition, the salt is very costly, so it is not feasible from the cost analysis point of view. Therefore, here we report a locally concentrated electrolyte, 2 M LiPF 6, in ethylene carbonate/diethyl carbonate (1:1 v/v ratio) diluted with fluoroethylene carbonate (FEC), which is stable within a wide potential range (2.5–4.5 V). It shows significant improvement in cycling stability of lithium with an average Coulombic efficiency (ACE) of ∼98% and small voltage hysteresis (∼30 mV) with a current density of 0.2 mA/cm 2 for over 1066 h in Li||Cu cells. Furthermore, we ascertained the compatibility of the electrolyte for anode-free Li–metal batteries (AFLMBs) using Cu||LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC, ∼2 mA h/cm 2 ) with a current density of 0.2 mA/cm 2 . It shows stable cyclic performance with ACE of 97.8 and 40% retention capacity at the 50th cycle, which i...