An Ultrafast, Durable, and High-Loading Polymer Anode for Aqueous Zinc-Ion Batteries and Supercapacitors

Abstract

With high theoretical capacities (820 mAh g−1 and 5855 mAh cm−3), suitable electrochemical potential (−0.763 V vs standard hydrogen electrode), low cost, and rich abundance of component materials, aqueous zinc-ion batteries (ZIBs) and capacitors (ZICs) have exhibited great promise for grid-level energy storage and other stationary applications. Zn metal as excessive Zn are often used to compensate for the uncontrollable dendritic growth, corrosion behaviour, and low Coulombic efficiency (CE) of the Zn metal. As such, most of the ZIBs and ZICs developed using these electrode materials exhibited actual device energy and power densities that were significantly lower than the corresponding theoretical values. Another key performance metric that needs to be improved in ZIBs is their high-rate charge and discharge. In addition to the dendrite-derived problems commonly experienced in batteries based on other metal anodes, ZIBs are disadvantaged by hydrogen gas evolution from water decomposition especially under high-rate charge/discharge, leading to poor cycle life.Herein, an ultrafast, stable, and high-loading polymer anode for aqueous Zn-ion batteries and capacitors (ZIBs and ZICs) is developed by engineering both the electrode and electrolyte. The anode polymer is rationally prepared to have a suitable electronic structure and a large π-conjugated structure, whereas the electrolyte is manufactured based on the superiority of trif late anions over sulfate anions, as analyzed and confirmed via experiments and simulations. This dual engineering results in an optimal polymer anode with a low discharge potential, near-theoretical capacity, ultrahigh-loading capability (≈50 mg cm−2), ultrafast rate (100 A g−1), and ultralong lifespan (one million cycles). Its mechanism involves reversible Zn2+/proton co-storage at the carbonyl site. When the polymer anode is coupled with cathodes for both ZIB and ZIC applications, the devices demonstrate ultrahigh power densities and ultralong lifespans, far surpassing those of corresponding Zn-metal-based devices. Figure 1