Constructing a reliable solid‐electrolyte interphase (SEI) is imperative for enabling highly reversible zinc metal (Zn0) electrodes. Contrary to conventional “bulk solvation” mechanism, we found the SEI structure is dominated by electric double layer (EDL) adsorption. We manipulate the EDL adsorption and Zn2+ solvation with ether additives (i.e. 15‐crown‐5, 12‐crown‐4, and triglyme). The 12‐crown‐4 with medium adsorption on EDL leads to a layer‐structured SEI with inner inorganic ZnFx/ZnSx and outer organic C−O−C components. This structure endows SEI with high rigidness and strong toughness enabling the 100 cm2 Zn||Zn pouch cell to exhibit a cumulative capacity of 4250 mAh cm−2 at areal‐capacity of 10 mAh cm−2. More importantly, a 2.3 Ah Zn||Zn0.25V2O5⋅n H2O pouch cell delivers a recorded energy density of 104 Wh Lcell−1 and runs for >70 days under the harsh conditions of low negative/positive electrode ratio (2.2 : 1), lean electrolyte (8 g Ah−1), and high‐areal‐capacity (≈13 mAh cm−2).
The chlorine-based redox reaction (ClRR) could be exploited to produce secondary high-energy aqueous batteries. However, efficient and reversible ClRR is challenging, and it is affected by parasitic reactions such as Cl2 gas evolution and electrolyte decomposition. Here, to circumvent these issues, we use iodine as positive electrode active material in a battery system comprising a Zn metal negative electrode and a concentrated (e.g., 30 molal) ZnCl2 aqueous electrolyte solution. During cell discharge, the iodine at the positive electrode interacts with the chloride ions from the electrolyte to enable interhalogen coordinating chemistry and forming ICl3-. In this way, the redox-active halogen atoms allow a reversible three-electrons transfer reaction which, at the lab-scale cell level, translates into an initial specific discharge capacity of 612.5 mAh gI2−1 at 0.5 A gI2−1 and 25 °C (corresponding to a calculated specific energy of 905 Wh kgI2−1). We also report the assembly and testing of a Zn | |Cl-I pouch cell prototype demonstrating a discharge capacity retention of about 74% after 300 cycles at 200 mA and 25 °C (final discharge capacity of about 92 mAh).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.