Development on High Energy Laminated Type Li Secondary Batteries Using Si-O-C Composite Anode and S/KB Composite Cathode with Glyme-Li Salt Solvate Ionic Liquid

Abstract

It is well known that sulfur is considered as a new generation cathode active materials of lithium secondary batteries because its abundance in nature, reversible electrochemical reaction with Li ion and very high theoretical specific capacity compared to the established commercial LCO electrodes (Li2S; 1166 mA h g-1, LiCoO2; 274 mA h g-1). We already introduced the Li-S battery prepared by the S/KB composite cathode and Li metal anode delivering high energy density of 200 Wh kg-1. In the previous work, 3D mesh structured Al foam was used as a substrate for the S/KB cathode active material to improve its loading amount. The S/KB composite cathode on the 3D mesh structured Al foam substrate was cycled with Li metal and glyme–Li salt solvate ionic liquid as an anode and an electrolyte. In this study, the S/KB composite cathode loaded on 3D mesh structured Al foam substrate was developed with Si-O-C composite anode. We have previously reported the Si-O-C composite anode which was prepared by electrodeposition technique using organic carbonate electrolyte. [1, 2] The Si-O-C composite achieved highly durable cycle ability with relatively high specific capacity showing 1045 mA h g-1-Si at the 2000th cycle and 842 mA h g-1-Si even at the 7200th cycle. Herein, we used specially treated Cu substrate showing high surface roughness to increase electrodeposited Si amount. The electrodeposited Si-O-C composite anode and the S/KB composite cathode were assembled with a Li activation electrode. The Li activation electrode was inserted for pre-activation process of the S/KB composite cathode and the Si-O-C composite anode. Afterwards, lithium pre-doping process of the full cell was carried out in aid of the Li activation electrode. As the result, we developed high energy laminated type lithium secondary battery using the Si-O-C composite anode and the S/KB composite cathode with glyme–Li salt solvate ionic liquid. Fig. 1 shows potential profiles of the S/KB composite cathode (a) and the Si-O-C composite anode (b) cycled by half-cell assembly for activation process. Furthermore, the loading amount of S/KB active material is succeeded to increase from 1.3 to 11.5 mg cm-2, which shows the promising potential on enlarging capacity of cathode. Acknowledgements This work was partly supported by Saitama Leading Edge Project “Development of community energy management system with secondary-batteries control for creating eco-towns”, Saitama Prefecture, Japan References [1] H. Nara, T. Yokoshima, T. Momma, T. Osaka, Energy Environ. Sci. 5 (2012) 6500-6505. [2] T. Osaka, H. Nara, T. Momma, T. Yokoshima, J. Mater. Chem. A 2 (2014) 883-896. Figure 1