Stabilization xLi{sub 2}MnO{sub 3}{sm_bullet}(1-x)LiMO{sub 2} electrode surfaces (M=Mn, Ni, Co) with mildly acidic, fluorinated solutions.
It has been demonstrated previously that Li{sub 2}MnO{sub 3}-stabilized LiMO{sub 2} electrodes [xLi{sub 2}MnO{sub 3} {sm_bullet} (1?x)LiMO{sub 2}, M=Mn, Ni, Co] can provide anomalously high electrochemical capacities ({approx}250 mAh/g) if charged to high potentials (>4.6 V). High-voltage charging results in an irreversible capacity loss on the initial charge/discharge cycle; it also damages the electrode surface, leading to a high cell impedance. In this paper, we report that preconditioning 0.1Li{sub 2}MnO{sub 3} {sm_bullet} 0.9LiMn{sub 0.256}Ni{sub 0.372}Co{sub 0.372}O{sub 2} electrode powders [alternatively Li{sub 1.048}(Mn{sub 0.333}Ni{sub 0.333}Co{sub 0.333}){sub 0.952}O{sub 2} in Li{sub 1+x}M{sub 1?x}O{sub 2} notation] with extremely mild acidic solutions of NH{sub 4}PF{sub 6}, (NH{sub 4}){sub 3}AlF{sub 6}, and NH{sub 4}BF{sub 4} salts in water and methanol (pH 6-6.5) leads to remarkable cycling stability of both lithium half-cells and full lithium-ion cells when repeatedly charged to high voltages ({ge} 4.5 V). The enhanced electrochemical performance is attributed to stabilized electrode surfaces that are etched and passivated by fluorinated species. The low-temperature behavior of unconditioned and preconditioned electrodes is presented.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- EE
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 968484
- Report Number(s):
- ANL/CSE/JA-60490
- Journal Information:
- J. Electrochem. Soc., Journal Name: J. Electrochem. Soc. Journal Issue: 4 ; 2008 Vol. 155; ISSN 0013-4651; ISSN JESOAN
- Country of Publication:
- United States
- Language:
- ENGLISH
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