Characterization and electrochemical properties of Li+ ion-ezchanged products of hollandite-type Ky(Mn1-zCoz)O2 for rechargeable lithium battery electrodes
Hollandite-type (K0.01Li0.42)MnO2.08 and its Co-doped (K0.04Li0.34) (Mn0.85 Co0.15)O2.07 have been synthesized by Li+ion-exchange of α-K0.14Mn1-xCoxO2·zH2O (x=0-0.15, 2=0.15-0.21) in a LiNO3/LiCl molten salt at 300℃, and characterized by X-ray diffraction (XRD), chemical analysis, N2-sorptmetric and electrochemical measurements. XRD measurements and chemical analysis indicated that almost all the K+ions and hydrogens of the structural waters in the 2×2 tunnels of the precursor α-MnO2 were exchanged by Li+ions in the molten salt, resulting in Li+-type α-MnO2 and its Co-doped one including Li+ions as well as Li2O in the 2×2 tunnels. N2-sorptmetric measurements revealed that the Li+ion-exchanged products have a mesopore structure as well as a micropore one, in the range of 1-10 nm, and the BET surface area of the precursor α-K0.14Mn1-xCoxO2 decreased with Li+ion-exchanging, probably due to the incorporation of Li2O molecules in the 2×2 tunnels. The chemical diffusion coefficients of lithium for the Li+ion-exchanged products increased by about one-order of magnitude with Li+ion-exchanging. The Li+ion-exchanged products provided higher initial discharge capacities and better recharge efficiencies than the parent materials, probably due to the structural stability with the existence of Li2O in the 2×2 tunnels.
Hollandite manganese ozide Li+ ion-ezchange Molten salt Electrochemical lithium insertion
Yoshihiro Kadoma Satoru Oshitari Koichi Ui Naoaki Kumagai
Department of frontier materials and functional engineering, Graduate School of Engineering, Iwate U Department of frontier materials and functional engineering, Graduate School of Engineering, Iwate U
国际会议
The 16th International Conference on Solid State Ionics(第十六届国际固态离子学会议)
上海
英文
1710-1713
2007-07-01（万方平台首次上网日期，不代表论文的发表时间）