Non-Expendable Regulator Enables Durable and Deep Cycling Aqueous Zinc Batteries

Unstable electrode/electrolyte interface with irreversible Zn deposition and hydrogen reactions have severely damage the cycle life of aqueous zinc-metal batteries (ZMBs), which is closely related to interfacial environment and deposition behavior of Zn2+. In this work, a series of rare earth chlorides (RCl3) are proposed as non-expendable regulators to address the above problems. Specifically, rare earth cations (R3+) with high adsorption energy can simultaneously isolate the adsorbed polar H2O molecule layer at the anode interface and regulate uniform Zn deposition behavior by electrostatic shielding. Meanwhile, Cl- binds H2O molecules via the weak hydrogen bonds, thus further inhibiting water-related side reactions. Consequently, the optimized Zn||Zn symmetric cell can stably cycle for over 8000 cycles at 5 mA cm-2. Surprisingly, the Zn anode with 68.3% zinc utilization also can be operated over 130 h. Even under harsh condition of low N/P ratio of 2.6:1 and high mass-loading cathode of 12.57 mg cm-2, the NH4V4O10||Zn pouch cell preserves nearly all its capacity after 300 cycles. Further, a low N/P ratio pouch cell with a more respectable capacity of 37.3 mAh preserves deep cycling for 180 cycles. This study sheds light on non-expendable additives to develop highly durable and deep cycling ZMBs. The electrostatic shielding effect of rare earth cation (R3+) eliminates dendrite growth, while the weak hydrogen bond between Cl- and H2O inhibits water-related side reactions. The electrolytes using RCl3 as non-expendable regulator guarantee highly durable and deep cycling AZMBs. image