Super-Reversible CuF2 Cathodes Enabled by Cu2+-Coordinated Alginate
Date of Original Version
Copper fluoride (CuF2) has the highest energy density among all metal fluoride cathodes owing to its high theoretical potential (3.55 V) and high capacity (528 mAh g−1). However, CuF2 can only survive for less than five cycles, mainly due to serious Cu-ion dissolution during charge/discharge cycles. Herein, copper dissolution is successfully suppressed by forming Cu2+-coordinated sodium alginate (Cu-SA) on the surface of CuF2 particles during the electrode fabrication process, by using water as a slurry solvent and sodium alginate (SA) as a binder. The trace dissolved Cu2+ in water from CuF2 can in situ cross-link with SA binder forming a conformal Cu-SA layer on CuF2 surface. After water evaporation during the electrode dry process, the Cu-SA layer is Li-ion conductor but Cu2+ insulator, which can effectively suppress the dissolution of Cu-ions in the organic 4 m LiClO4/ethylene carbonate/propylene carbonate electrolyte, enhancing the reversibility of CuF2. CuF2 electrode with SA binder delivers a reversible capacity of 420.4 mAh g-1 after 50 cycles at 0.05 C, reaching an energy density of 1009.1 Wh kg-1. Cu2+ cross-link polymer coating on CuF2 opens the door for stabilizing the high-energy and low-cost CuF2 cathode for next-generation Li-ion batteries.
Publication Title, e.g., Journal
Xia, Jiale, Zeyi Wang, Nuwanthi D. Rodrig, Bo Nan, Jiaxun Zhang, Weiran Zhang, Brett L. Lucht, Chongyin Yang, and Chunsheng Wang. "Super-Reversible CuF2 Cathodes Enabled by Cu2+-Coordinated Alginate." Advanced Materials 34, 43 (2022). doi: 10.1002/adma.202205229.