All-solid-state lithium-ion batteries (SLIBs) are considered as promising next generation energy storage system for electric vehicles [1]. However, as this application needs low internal cell resistance even at high charging/discharging currents, a meaningful selection of materials, material combinations and electrode design is absolutely essential. Commonly known prerequisites are (i) high ionic conductivity of the solid electrolyte, (ii) low charge transfer resistance at the electrode/electrolyte interface and (iii) large active surface area between electrolyte and electrode material.

This study aims on guidelines for selecting solid electrolytes and their electrode interfaces, and on determining targets for further SLIB development. A newly developed one-dimensional model for SLIBs is presented, based on a design concept with 3-D structured composite electrodes (see Fig.1). The expected performance is simulated by linking two phase transmission line models [2] for both composite electrodes with an ohmic resistance for the solid electrolyte. Variations of (i) electrical parameters, i.e. ionic and electronic conductivity, (ii) electrochemical parameters, i.e. charge transfer resistance, and (iii) microstructure parameters, i.e. active surface area and composite electrode thickness, indicate the most important material and design parameters for high-performance. Performance potential will be presented for various anorganic solid electrolytes, i.e., glassy types (Phosphates, Oxides and Sulfides (Li₇P₃S₁₁)) and crystalline types (LISICON, Garnets (Li₇La₃Zr₂O₁₂), Perovskites (Li_3xLa_2/3-xTiO₃)) and diverse electrode designs with different thickness and microstructure properties.

References:

[1] A. L. Robinson and J. Janek, Solid-state batteries enter EV fray, MRS Bulletin, 39, pp 1046-1047, (2014)                                     

[2] J. Illig et al., Modelling Graphite Anodes with Serial and Transmission Line Models, Journal of Power Sources, 282, 335-347, (2015)