Surface Modification of the LiFePO4Cathode for the Aqueous Rechargeable Lithium Ion Battery.
The LiFePO4surface is coated with AlF3via a simple chemical precipitation for aqueous rechargeable lithium ion batteries (ARLBs). During electrochemical cycling, the unfavorable side reactions between LiFePO4and the aqueous electrolyte (1 M Li2SO4in water) leave a highly resistant passivation film, which causes a deterioration in the electrochemical performance. The coated LiFePO4by 1 wt % AlF3has a high discharge capacity of 132 mAh g-1and a highly improved cycle life, which shows 93% capacity retention even after 100 cycles, whereas the pristine LiFePO4has a specific capacity of 123 mAh g-1and a poor capacity retention of 82%. The surface analysis results, which include X-ray photoelectron spectroscopy and transmission electron microscopy results, show that the AlF3coating material is highly effective for reducing the detrimental surface passivation by relieving the electrochemical side reactions of the fragile aqueous electrolyte. The AlF3coating material has good compatibility with the LiFePO4cathode material, which mitigates the surface diffusion obstacles, reduces the charge-transfer resistances and improves the electrochemical performance and surface stability of the LiFePO4material in aqueous electrolyte solutions.
Department of Energy and Chemical Engineering, Incheon National University , 12-1, Songdo-dong, Yeonsu-gu, Incheon 22012, Korea.
Artur
A
Tron
Advanced Batteries Research Center, Korea Electronics Technology Institute , 68 Yatap-dong, Bundang-gu, Seongnam, Gyeonggi-do 13509, Korea.
Yong Nam
YN
Jo
Centre for Energy Convergence Research, Korea Institute of Science and Technology , Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul, 02792, Korea.
Si Hyoung
SH
Oh
Department of Energy and Chemical Engineering, Incheon National University , 12-1, Songdo-dong, Yeonsu-gu, Incheon 22012, Korea.
Yeong Don
http://orcid.org/0000-0002-1615-689X
YD
Park
Department of Energy and Chemical Engineering, Incheon National University , 12-1, Songdo-dong, Yeonsu-gu, Incheon 22012, Korea.
Junyoung
http://orcid.org/0000-0001-9965-5709
J
Mun
AlF3; LiFePO4; aqueous rechargeable lithium battery; coating; surface modification