Rechargeable Aqueous Lithium-Ion Battery Zn/LiFePO4 for Large Scale Energy Storage

1. Introduction Rechargeable aqueous lithium batteries (RALBs) are promising alternative to bypass safety issues of lithium-ion batteries (LIBs) with organic electrolyte. Furthermore, fast lithium diffusion in aqueous electrolyte media could allow for the operations under high electric current conditions required for high power supply [1] . J. Dahn et al [2] reported on a VO 2 /LiMn 2 O 4 rechargeable aqueous battery, based on the “rocking chair” concept adopted from LIBs. However, this type of batteries had serious issues with cyclability. Here, we report for the first time on a system comprising an intercalation LiFePO 4 (LFP) cathode and a Zn metal anode in an aqueous electrolyte, and on large-scale RALB based on this concept with enhanced cycle performance and energy density. 2. Experimental All electrochemical tests were carried out using galvanostat/potentiostat VMP3 (Biologic) and two-electrode Swagelok-type cells and a rolled cylindrical battery configuration (ca. 600 mAh per cell). The commercial LiFePO 4 (Hohsen Co, Japan) powder and zinc foil (Good Fellow, England) were used as cathode and anode, respectively. Graphite (Sigma Aldrich) and stainless steel (SUS316) rods were used as current collectors for the positive and negative sides, respectively. Absorptive glass mat (AGM) acted as a separator. The electrolyte was a mixed aqueous solution of zinc and lithium salts. Galvanostatic charge/discharge cycling was performed at various current densities from 0.6 C to 60 C (1 C corresponds to a current density of 170 mA g -1 ) at room temperature and the voltage cutoffs 1.0-1.4 V vs . Zn 2+ /Zn. 3. Results and discussion The electrochemical performance of Zn|LFP is presented in Fig. 1 . The battery exhibited discharge capacities of 75 mAhg -1 and 43 mAhg -1 at high current densities of 30 C and 60 C, respectively, and maintained excellent stability and coulombic efficiency with a capacity of 102 mAhg -1 after 300 cycles when cycled at 6 C ( Fig. 1b) . The large scale battery (stack of cylindrical cells) showed 590 mAh/cell capacity at the initial cycle and could maintain 550 mAh/cell capacity after 10 cycles as shown in Fig. 1c . The further details of these studies will be presented at the Meeting. Acknowledgments This research was supported by the “Nazarbayev University Corporate Fund of Social Development” grant. References 1. Wei Tang, Yuping Wu, Kian Ping Loh, Energy Environ. Sci., 6 (2013) 2093–2104 2. W. Li, J.R. Dahn, D.S. Wainwright, Science 264 (1994) 1115-1118.