Highly Reversible Aqueous Zinc Metal Anode Enabled By Interface Controllable Engineering

Zinc metal anodes（ZMAs）exhibit multiple merits of high theoretical capacity(820 mAh g^-1),moderate redox potential（-0.762 V vs.SHE）,abundant reserves（0.0075%in earth crust）,and compatibility with aqueous electrolytes.ZMAs in a suitable battery system,including an electrolyte and a highperformance cathode electrode,can deliver an excellent electrochemical performance.The employment of ZMAs in aqueous zinc metal batteries（AZMBs）endows them with high energy densities,low budget,and high operational safety.Nowadays,ZAMBs become a resurgent electrochemical energy storage technique complementary to fire-prone Li-ion batteries for powering high-tier wearable/implantable electronics with rigorous safety requirements.Regrettably,the troublesome dendrites growth and water-triggered corrosion reactions on the Zn surface during electroplating/stripping cycles seriously deteriorate the reversibility of ZMAs,which substantially weakens the energy efficiencies of the AZMBs,casting a shadow on commercial viability.To address these challenging issues and promote the actual deployment of AZMBs,the main research efforts aiming at effective technical routes have been made.（1）Herein,an intriguing ions sieve（IS）consisting of 3D intertwined bacterial cellulose,designed on the surface of ZMAs（Zn@IS）through an in-situ self-assembly route,is first present to be effective in inhibiting dendrites-growth of ZMAs.Experimental analyses together with theoretical calculations suggested that:the IS coating can facilitate the desolvation of[Zn（H₂O）₆]²⁺clusters via a strong interplay with Zn ions,weaken hydrogen evolution reaction of ZMAs,and homogenize the ions flux with the abundant nanopores serving as ions tunnels,synergistically enabling dendrite-free Zn deposition on the Zn@IS anodes.Consequently,a lifespan up to 3000 h at a cutoff capacity of 0.25 mAh cm^-2 was observed in Zn@IS||Zn@IS symmetric cell.Application-wise,pairing with exemplified carbon-nanotubes@MnO₂ cathode,the full ZMBs acquired a boosted rechargeability with a much higher capacity retention over 73.3%after 3000 cycles compared to the counterpart with pristine MZA（21%）.（2）We employed the cost-effective and eco-friendly prulan polysaccharide（Pul）as an electrolyte additive to simultaneously realize weakened HER and homogeneous zinc deposition by modulating the thermodynamic stability of the electrolyte as well as the dense stacking structure of the anode surface.As a result,symmetric cells assembled with the Pul additive electrolyte achieved an impressive plating/stripping performance of over 1800 h at a current density of 1 m A cm^-2 and a plating capacity of 0.5 mAh cm^-2 without significant voltage fluctuations,which is approximately four times longer than cells employing pure zinc sulfate electrolyte.Moreover,when tested at higher cutoff capacity 2.5 mAh cm^-2,the much better cycling performance more than 650 h was obtained.To further evaluate its practical application,a CNTs@MnO₂|Zn full cell was assembled with the Pul additive electrolyte,which exhibited excellent cycling stability with≈85.4%capacity retention at room temperature over 2000 cycles,much higher than the cell assembled with pure zinc sulfate electrolyte（malfunction after 1600 cycles）.（3）An effective Helmholtz plane（HP）reconstruction mechanism on ZMAs in ZnSO₄electrolyte activated by zinc pyrrolidone carboxylate（PCA-Zn）additive is proposed.Systematical experiments together with numerical simulations identified that the dissociated PCA^-anions with bis-zincophilic-terminal preferentially adhere to the ZMAs surface with carboxyls serving as anchors to replace H₂O and SO₄^2-,reshaping an H₂O/SO₄^2--repellent HP to restrain water-triggered side reactions.Meanwhile,the other free zincophilic carbonyl terminals of PCA^-anions endow the restructured HP with spatial confinement effect on Zn²⁺,effectively suppressing their rampant in-plane diffusion and homogenizing ions flux during Zn deposition.Moreover,the HP exhibits a self-repair behavior against unexpected electrode surface damage upon cycling.Benefiting from the multifunctional HP that enables more stable ZMAs/electrolyte interphasial chemistry,an electroplating/stripping lifespan over 480 h in the Zn||Zn symmetric cell cycling with a commercial-grade cutoff capacity of 10 mAh cm^-2at a high current density of 10 m A cm^-2is realized,accounting for significantly boosted rechargeability（89.7%capacity retention after 5000 cycles）of the carbon-cloth@polyaniline||ZMA full AZMBs than that with PCA-Zn-free electrolyte（malfunction after only 960 cycles）.