Performance of All Solid Li-Air Battery

Abstract

The Li–Air battery converts the electrochemical reactions of lithium and O2 into electrical energy and has been receiving attention as the next generation battery because of its high theoretical specific energy of 3400 Wh kg-1. The high specific energy of the Li–Air battery can be attributed to the reaction in the cathode where only Li and O2 are needed, and it is an order of magnitude higher than that of the future generation Li ion battery that is predicted to reach at most 400 Wh kg-1. In the cathode, the carbon particles are used to provide electron conductivity as well as the surface area for the reactions, and the electrolytes are necessary to transport Li+ ions between the anode and cathode [1]. The pore distribution of the cathode is reported to influence the capacity [2], and the lifetime of the battery is reported to be limited by the stability of electrolyte [3]. To ensure higher stability against the oxidative conditions, the ionic liquid-based electrolytes are often used [4]. However, even the ionic liquid is known to decompose at the oxidative environment of the Li-Air battery operation conditions. To increase the cycle lifetime of the Li-Air battery, more stable form of electrolyte in cathode is desired. By constructing an all solid Li-Air battery which consists of Li metal, solid electrolyte, and oxide cathode, the source of cathode degradation can be greatly reduced by eliminating the liquid electrolyte and carbon in the cathode. The oxide material which showed both electronic and ionic conductivity in the order of 10-4 S/cm was used as the cathode. The cathode material was ball milled to obtain sub-micron sized particles and the surface area in the order of 10 m2/g. The cathode was coated to obtain a 10 μm cathode layer, and the layer was sintered onto a LATP (Lithium aluminum titanium phosphate) electrolyte layer. The Li metal was then attached to the cathode/electrolyte to form an all solid Li-Air battery. To operate the Li-Air battery, the Li metal was isolated from the O2 environment to which the cathode was exposed. The performance of the battery was evaluated in a O2 filled chamber which had the relative humidity up to 100%. The discharge and charge curves were analyzed to evaluate the feasibility and the cycle lifetime of the all solid Li-Air battery. The composition of the discharge product and the possible reaction mechanism will be presented. The strategy to increase the specific energy and cycle lifetime of the battery will be also discussed. [1] D. Aurbach, B. D. McCloskey, L. F. Nazar and P. G. Bruce, Nat . Energy , 2016, 1, 1–11. [2] N. Ding, S. W. Chien, T. S. A. Hor, R. Lum, Y. Zong and Z. Liu, J. Mater. Chem. A , 2014, 2, 12433–12441. [3] S. A. Freunberger, Y. Chen, Z. Peng, J. M. Griffin, L. J. Hardwick, F. Barde, P. Novak and P. G. Bruce, J. Am. Chem. Soc., 2011, 133, 8040–8047. [4] N. Mozhzhukhina, A. Y. Tesio, L. P. Mendez De Leo and E. J. Calvo, J. Electrochem. Soc., 2017, 164, A518–523.