title: Suppression of phase transition in LiTb(0.01)Mn(1.99)O4 cathodes with fast Li+ diffusion.
abstract: The structural characteristics of terbium-doped spinel LiTb(x)Mn(2-x)O(4) related to the electrochemical performance were studied as the cathode in lithium-ion batteries. We chose terbium as the dopant, which is a well-known mixed-valent cation (3+/4+), expecting that it would provide structural stabilization and improve the power density. LiTb(x)Mn(2-x)O(4) revealed that terbium doping significantly affected the lattice structure and lithium-ion diffusion during charge-discharge cycles, resulting in an enhanced capacity retention and rate capability at an extremely small amount of terbium doping (LiTb(0.01)Mn(1.99)O(4)). The absence of two-cubic phase formation in the delithiated state and a tetragonal phase in the overlithiated state, along with a reduced dimensional change of the main cubic phase during charge-discharge, provided LiTb(0.01)Mn(1.99)O(4) with structural stability at both room temperature and 60 °C. The fast lithium-ion diffusion resulted in reduced polarization, which became more conspicuous as the C rates increased. As a result, the power density of LiTb(0.01)Mn(1.99)O(4), which was similar to that of LiMn(2)O(4) at 1C (476.1 W·kg(-1) for LiMn(2)O(4) vs 487.0 W·kg(-1) for LiTb(0.01)Mn(1.99)O(4)), was greatly improved at higher C rates. For example, the power density of LiTb(0.01)Mn(1.99)O(4) was improved to 4000 and 6000 W·kg(-1) at 10 and 20, respectively, compared with 3120 and 3320 W·kg(-1) for pristine LiMn(2)O(4).
authors.affiliation: Department of Printed Electronics Engineering in the WCU Program, Sunchon National University, Sunchon, Chonnam 540-742, Korea.
authors.forename: Dong Kyu
authors.initials: DK
authors.lastname: Lee
authors.forename: Su Chul
authors.initials: SC
authors.lastname: Han
authors.forename: Docheon
authors.initials: D
authors.lastname: Ahn
authors.forename: Satendra Pal
authors.initials: SP
authors.lastname: Singh
authors.forename: Kee-Sun
authors.initials: KS
authors.lastname: Sohn
authors.forename: Myoungho
authors.initials: M
authors.lastname: Pyo