Recent Accepted Papers


 An end-capped poly(ethylene carbonate)-based concentrated electrolyte for stable cyclability of lithium battery

Electrochimica Acta (11 Feb 2019)
YoichiTominaga*, Yukino Kinno and Kento Kimura

     An end-capped poly(ethylene carbonate) (PEC) having acetate groups (PEC-Ac) was synthesized as a novel polymer matrix for improving the thermal stability and oxidative stability.  A concentrated PEC-Ac electrolyte with 120 mol% of LiFSI had a good conductivity of approximately 10-6 S/cm at 40 °C with an excellent Li transference number ( t+) of 0.8.  Linear sweep voltammetry measurement for the PEC-Ac electrolyte indicates that the oxidation tolerance is more than 5 V, and is greater than that of the original PEC-based electrolyte.  A battery test for the LiFePO4 cell using the PEC-Ac electrolyte was conducted for the first time, finding good capacities ranging from 130 to 160 mAh/g and stable cyclability for more than 60 cycles.

 Mechanical and degradation properties in alkaline solution of poly(ethylene carbonate)/poly(lactic acid) blends

Polymer (20 Jan 2019)
Nur AzriniRamle and YoichiTominaga*

      Thin films of PEC/PLA blend exhibiting improved toughness and biodegradability in alkaline solutions were prepared by a simple solution casting method.  With the addition of 50 wt% PEC, the toughness of PEC/PLA blend was improved to a peak value of 45.8 MJ/m 3 , in contrast to 6.7 MJ/m 3  for neat PLA.  Young's modulus of PEC/PLA blends at low PEC ratio were fairly similar to that of neat PLA.  Addition of more than 40 wt% of PEC enhanced the biodegradability of PLA in alkaline solution.  The weight loss of hydrolysed PEC/PLA blends changed non-linearly with the addition of PEC, and depended strongly on PLA crystallinity and the ratio of PEC to PLA.

Tuneable Shape-Memory Property of Composite based on Nanoparticulated Plant Biomass, Lignin, and Poly(ethylene carbonate) 

Soft Matter (26 Oct 2018)
Kazuhiro Shikinaka*, Yudai Funatsu, Yuki Kubota, Yoichi Tominaga*, Masaya Nakamura, Ronald R. Navarro and Yuichiro Otsuka

     In this article, we propose a thermally responsive shape-memory polymer (SMP) consisting of poly(ethylene carbonate) and non-deteriorated lignin nanoparticles. This SMP was obtained readily by thermal kneading and melt molding without requiring any chemical reaction. The shape-recovering properties of the SMP can be tuned by changing the feed ratio of the components. The estimation of viscoelasticity, thermal and mechanical properties of the SMP reveals that the stepwise structural transitions in the SMP rendered the dynamic shape-recovering behavior.

Understanding electrochemical stability and lithium ion-dominant transport of concentrated poly(ethylene carbonate) electrolyte

ChemElectroChem (5 Oct 2018)
Kento Kimura, Yoichi Tominaga

     Ion-conductive solid polymer electrolytes (SPEs) are important materials for implementing safer energy storage. In the present study we show that a concentrated SPE composed of poly(ethylene carbonate) (PEC) and lithium bis(fluorosulfonyl)imide (LiFSI) has high oxidation tolerance and prevents aluminum corrosion. These properties enable cycling of a LiMn2O4 cell charged above 4 V; battery operation above 4 V is difficult for conventional polyether electrolytes because of their poor electrochemical stability. Mechanistic studies imply that an aggregated solvation structure, in which a large portion of the carbonyl groups interact with Li ions, is correlated with the enhanced electrochemical stability. The studies suggest that relatively rigid structure of PEC induces an increase in conductivity with increasing salt concentration. The increase in conductivity enables concentrated electrolyte with reasonable conductivity and high Li transference number.


Ion-conductive, thermal and electrochemical properties of poly(ethylene carbonate)-Mg electrolytes with glyme solution

Chemistry Letters (23 July 2018)  Open Access
Azlini Aziz, Nobuko Yoshimoto, Kazuhiro Yamabuki, Yoichi Tominaga*

     Poly(ethylene carbonate) (PEC)-based polymer electrolytes incorporated with magnesium bis(trifluoromethanesulfonyl) imide (Mg(TFSI)2) and triethylene glycol dimethylether (triglyme, G3) were investigated their ion-conductive, thermal, structural and electrochemical properties. The highest conductivity was 5.2×10-6 Scm-1 at 80 oC for 40/60 of PEC/0.5 M Mg(TFSI)2-G3 (PEC/G3-0.5 M). The addition of G3 enhanced the conductivity and Mg deposition/dissolution process by enhancing the ionic mobility and the formation of appropriate solvation structure in PEC.