Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 45: Nonaqueous Liquid/Solid Interfaces
O 45.4: Talk
Wednesday, March 18, 2015, 12:15–12:30, HE 101
Lithium Ion Transport in LiMn2O4 Nanowire Cathode of Lithium Ion Battery — •Soyeon Lee1,3, Yoshifumi Oshima2,3, and Kunio Takayanagi1,3 — 1Tokyo Tech., Tokyo, Japan — 2JAIST, Ishikawa, Japan — 3JST-CREST, Tokyo, Japan
Structural phase transition of electrode materials in lithium ion batteries causes capacity decrease. In order to avoid capacity decrease, it is essential to understand mechanism of transport of lithium ions and phase transition in the electrode. In the present work, a lithium ion battery with the LiMn2O4 nanowire, as a positive electrode, was developed specially for in-situ observation by a sub-50pm resolution electron microscope. The LiMn2O4 (LMO) electrode consists of a single nanowire or of a bundle of nanowires, which contacts with ionic liquid electrolyte (ILE) on a Li4Ti5O12 negative electrode. The nanowire electrode is free standing, being suspended between Pt and ILE; little manganese (Mn) ions can dissolves from LMO into the electrolyte to cause capacity decrease. The nanowire battery was proved after in-situ observation to work without capacity degradation at high charge/discharge rate (fully charged within 24 minutes), and structure of LMO transformed reversibly while the cyclic voltammetry between 3.5-5.5 V (vs Li/Li+). The structure of the nanowire at the area of ILE/LMO contact showed cubic to tetragonal phase transformation, while the other area, non-equilibrium structure change has occurred by high charge/discharge rate. Our developed nanowire battery and in-situ study have revealed the nanowire battery can work reversibly without capacity decrease for high-rate charge/discharge operation