Kenichi Takeyama

New organodisulfide—polyaniline composite cathode for secondary lithium battery

A new composite cathode used for high-energy density secondary lithium batteries is developed, which consists of 2,5-dimercapto-1,3,4-thiadiazole (organodisulfide), polyaniline, and gel electrolyte. Polyaniline works to promote the redox reaction of the organodisulfide in the composite electrode, providing the cyclic voltammogram showing a narrower peak-potential separation of 0.5 V between cathode and anode peaks. The lithium cell using the composite cathode and gel electrolyte based on acrylonitrile—methylacrylate copolymer has over 3.0 V cell voltage with 303 Wh kg−1 cathode energy density at a current density of 0.1 mA cm−2 at room temperature. In practice, a model cell with 80 μm thick lithium anode, 50 μm thick gel electrolyte, and 170 μm thick composite cathode is expected to deliver 220 Wh kg−1 cell energy density at 0.1 mA cm−2.

Lithium deposit morphology from polymer electrolytes

Lithium deposit morphology has been observed for polymer electrolytes employing ethylene oxide (EO)-propylene oxide (PO) copolymers as host polymers. The effects of polymer compositions such as the host polymer skeleton, the weight ratio of host polymer to liquid electrolyte, etc. were studied on suppressing dendritic morphology of lithium deposition. To suppress dendrites, stiff and elastic polymer electrolytes were suitable, which employed host polymers with Mw > 16000 before cross-linking and EOPO < 5 and contained liquid electrolyte of less than 70 wt%.

Li+ adsorption on a metal electrode from glymes

Abstract The free energy profiles have been computed as Li + approaches to a model electrode in dimethoxyethane (DME) and diglyme using Monte Carlo statistical mechanics simulations. For the approach of Li + from the outer Helmholtz plane to the electrode, the free energy increases more rapidly in diglyme than in DME. The coordination numbers for Li + are six for both the solvents; DME works as a bidentate ligand but diglyme works as a tridentate one. The configuration changes of the first solvation shell show that one DME molecule is shed for Li + adsorption but not for diglyme. The presence of electrode hinders the motion of diglyme chains. The suitability of both the solvents for the models of polyethylene oxides are also discussed in this work.