Stabilization of the Interface between a PEO-Based Lithium Solid Polymer Electrolyte and a 4-Volt Class Cathode, LiCoO<sub>2</sub>, by the Addition of LiPF<sub>6</sub> as a Lithium Salt
Sou Taminato,
Akino Tsuka,
Kento Sobue,
Daisuke Mori,
Yasuo Takeda,
Osamu Yamamoto,
Nobuyuki Imanishi
Affiliations
Sou Taminato
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Akino Tsuka
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Kento Sobue
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Daisuke Mori
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Yasuo Takeda
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Osamu Yamamoto
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Nobuyuki Imanishi
Graduate School of Engineering, Mie University, Tsu 514-8507, Japan
Here, the time dependence of the interfacial resistance for Li/polyethylene oxide (PEO)-Li(CF3SO2)2N (LiTFSI)-LiPF6/LiCoO2 cells was measured to investigate the stabilization effect of LiPF6 on the interface between a solid polymer electrolyte (SPE) and a 4-volt class cathode, LiCoO2. Impedance measurements under the applied potentials between 4.1 V and 4.4 V vs. Li/Li+ indicated that the addition of LiPF6 to LiTFSI was effective in improving the stability at high potentials such as 4.4 V vs. Li/Li+. In contrast, the resistance of the non-doped PEO-LiTFSI/LiCoO2 interface increased with time under the lower potential of 4.1 V vs. Li/Li+. Fairly good cycle performance was obtained for the LiPF6-doped cell, even at a cut-off voltage of 4.5 V vs. Li/Li+.
