A Model-Based Insight into Electrolyte Behaviour in Aqueous Zinc-Ion Batteries

Abstract

Next-generation batteries strive for the optimal fit in performance, cost, and environmental safety. Within recent times, a whole playground of different material systems and working principles were investigated. Consumer alkaline batteries with a metallic zinc anode and manganese dioxide cathode achieve excellent energy densities of [1], yet their development stalled due to their limited rechargeability. Switching the aqueous electrolyte from alkaline KOH to, for example, mild electrolytes, however, showed a reversible charge/discharge mechanism at the cathode [2]. This achievement highly increased the research interest in zinc-ion batteries in the last decade, and many successful systems were proposed [3], [4].Aqueous metal batteries face a series of challenges. The limited stability window of water, as well as unwanted precipitation reactions, deteriorate the battery performance and increase aging reactions. The electrolytes composition and the concentration-dependent complex formation governs its performance. Within Zinc-air batteries, we performed model-based optimization studies of pH adjusted electrolytes [5].Yet, to our knowledge, there is no modelling work done for zinc-ion batteries. Within our contribution, we combine a description of complex formation with a dynamic cell model. The electrolyte speciation significantly influences the transport properties of the electrolyte as well as its stability. With our cell model, we predict the performance and rate-dependent behavior of commonly used materials. With this, we identify system-requirements and pitfalls in the ongoing optimization of aqueous zinc-ion batteries.This work is supported by the Federal Ministry of Education and Research (BMBF) via the project ZIB. Literature [1] S. Clark, N. Borchers, Z. Jusys, R. J. Behm, and B. Horstmann, Aqueous Zinc Batteries. 2020.[2] C. Xu, B. Li, H. Du, and F. Kang, “Energetic Zinc Ion Chemistry: The Rechargeable Zinc Ion Battery,” Angew. Chemie Int. Ed., vol. 51, no. 4, pp. 933–935, Jan. 2012, doi: 10.1002/anie.201106307.[3] B. Tang, L. Shan, S. Liang, and J. Zhou, “Issues and Opportunities Facing Aqueous Zinc-ion Batteries,” Energy Environ. Sci., pp. 3288–3304, 2019, doi: 10.1039/c9ee02526j.[4] J. Huang, Z. Guo, Y. Ma, D. Bin, Y. Wang, and Y. Xia, “Recent Progress of Rechargeable Batteries Using Mild Aqueous Electrolytes,” Small Methods, vol. 3, no. 1, p. 1800272, Jan. 2019, doi: 10.1002/smtd.201800272.[5] S. Clark et al., “Designing Aqueous Organic Electrolytes for Zinc-Air Batteries: Method, Simulation, and Validation,” Adv. Energy Mater., vol. 10, no. 10, p. 1903470, Mar. 2020, doi: 10.1002/aenm.201903470. Figure 1: Schematic of the interaction of the evaluation of electrolyte composition and the cell model. Illustration on the left adapted from [1] Figure 1