Compatibility between Lithium Bis(oxalate)borate‐Based Electrolytes and a LiFe0.6Mn0.4PO4/C Cathode for Lithium‐Ion Batteries

• Published in: Energy technology (Weinheim, Germany) Germany), 2017-03, Vol.5 (3), p.406-413
• Main Authors: Zhao, Qiuping, Li, Xiangfei, Tang, Fengjuan, Zhao, Dongni, Du, Songli, Geng, Shan, Tian, Yuqin, Li, Shiyou
• Format: Article
• Language: English
• Subjects: anodes; Cathodes; Compatibility; Electrochemistry; Electrolytes; Lithium; Lithium-ion batteries; phosphates; Rechargeable batteries; sulfur; Transition metals
• ISSN: 2194-4288; 2194-4296
• DOI: 10.1002/ente.201600307

The lithium transition‐metal phosphate LiFe0.6Mn0.4PO4 has two operating potentials, 3.5 V and 4.1 V, which is favorable for increasing the energy and power densities of lithium‐ion batteries (LIBs). To study the compatibility between LiFe0.6Mn0.4PO4 and electrolytes, lithium bis(oxalate)borate (LiBOB) is chosen as the lithium salt, based upon ethylene carbonate (EC), dimethyl carbonate (DMC), and dimethyl sulfite (DMS) as the supporting electrolyte solvents. The electrochemical performances of lithium hexafluorophosphate (LiPF6)‐based and LiBOB‐based electrolytes are compared. The combination of LiBOB and DMS can facilitate the formation of an effective passivation film. In addition, LiBOB‐EC/DMS electrolyte exhibits better cycle and rate performance. The results suggest that LiBOB‐EC/DMS electrolyte has good compatibility with LiFe0.6Mn0.4PO4, which makes it an attractive electrolyte for rechargeable LIBs based upon LiFe0.6Mn0.4PO4 cathodes. Excellent performance: Lithium‐ion batteries (LIBs) using the olivine‐structured lithium transition‐metal phosphate LiFe0.6Mn0.4PO4 show unstable cycle performance with traditional electrolytes. Changing to lithium bis(oxalate)borate in ethylene carbonate/dimethyl sulfite (LiBOB‐EC/DMS) leads to better performance due to a synergistic effect between LiBOB and DMS, with excellent film‐forming properties during electrochemical cycling.