Despite environmental benignancy, the Zn metal anode for aqueous zinc batteries is still hindered due to the instability of the anode/electrolyte interface, which originates from the electrolyte not having the ability to form a protective solid electrolyte interphase (SEI) on the anode. Herein, an SEI-forming electrolyte based on zinc sulfamate (Zn(NH2SO3)2) is proposed. Specifically, the sulfamate anion can be adsorbed on the anode easily to construct an anion-rich Helmholtz plane. With a lower unoccupied molecular orbital energy, NH2SO3 – would be preferentially electroreduced to form a stable SEI to suppress the parasitic reactions. Significantly, the Zn anode in the proposed electrolyte can achieve a high Coulombic efficiency of 99.65% for over 1000 cycles. Zn|| NH4V4O10 and Zn||I2 full batteries by adopting the sulfamate electrolyte can retain a high capacity retention of 95.0% for more than 5000 cycles at 5 A g–1, and 93.0% capacity retention for more than 100 cycles at 1 A g–1, respectively.
The practical applications of zinc metal batteries are plagued by the dendritic propagation of its metal anodes due to the limited transfer rate of charge and mass at the electrode/electrolyte interphase. To enhance the reversibility of Zn metal, a quasi-solid interphase composed by defective metal–organic framework (MOF) nanoparticles (D-UiO-66) and two kinds of zinc salts electrolytes is fabricated on the Zn surface served as a zinc ions reservoir. Particularly, anions in the aqueous electrolytes could be spontaneously anchored onto the Lewis acidic sites in defective MOF channels. With the synergistic effect between the MOF channels and the anchored anions, Zn2+ transport is prompted significantly. Simultaneously, such quasi-solid interphase boost charge and mass transfer of Zn2+, leading to a high zinc transference number, good ionic conductivity, and high Zn2+ concentration near the anode, which mitigates Zn dendrite growth obviously. Encouragingly, unprecedented average coulombic efficiency of 99.8% is achieved in the Zn||Cu cell with the proposed quasi-solid interphase. The cycling performance of D-UiO-66@Zn||MnO2 (~ 92.9% capacity retention after 2000 cycles) and D-UiO-66@Zn||NH4V4O10 (~ 84.0% capacity retention after 800 cycles) prove the feasibility of the quasi-solid interphase.
A eutectogel (ETG) based on immobilizing a zinc salt deep eutectic solvent (DES) in a silk protein backbone is prepared by a coagulating bath method as a solid electrolyte for Zn-ion hybrid supercapacitors (ZHSCs). The Zn salt DES is composed by ethylene glycol (EG), urea, choline chloride (ChCl), and zinc chloride (ZnCl 2 ) with a molar ratio of 6:10:3:3. A strong bonding of the DES liquid to the silk protein backbone is formed between protein macromolecules and the DES due to plenty of hydrogen bonds in both materials. The as-prepared ETG membrane is dense and has no obvious void defects, which possesses a fracture strength of 7.58 MPa and environmental stability. As a solid electrolyte, the ETG membrane exhibits a higher Zn 2+ transference number of about 0.60 and a high ionic conductivity (12.31 mS cm −1 at room temperature and 3.63 mS cm −1 at −20 °C). A ZHSC (Zn∥ETG∥C) with the silk protein-based ETG electrolyte is assembled by Zn and active carbon as the anode and the cathode, respectively, which delivers a specific capacitance of 342.8 F g −1 at a current density of 0.2 A g −1 and maintains excellent cycling stability with 80% capacitance retention after 20,000 cycles at a high current rate (5 A g −1 ) at room temperature. Moreover, the Zn∥ETG∥C device can safely work under a lower temperature of about −18 °C and damaging situations, such as folding states and even cutting tests. The interface evolutions between the Zn anode and the ETG electrolyte are explored, and it was found that a ZnCO 3 / Zn(CH 2 OCO 2 ) 2 solid electrolyte interphase is in situ formed on the Zn anode, which can inhibit the growth of Zn dendrites. This work provides a new way to fabricate advanced electrolytes for applications in Zn-ion hybrid supercapacitors.
Construction of high efficiency and stableLi metal anodes is extremely vital to the breakthrough of Li metal batteries. In this study, for the first time, groundbreaking in situ plasma interphase engineering is reported to construct high-quality lithium halides-dominated solid electrolyte interphase layer on Li metal to stabilize & protect the anode. Typically, SF 6 plasma-induced sulfured and fluorinated interphase (SFI) is composed of LiF and Li 2 S, interwoven with each other to form a consecutive solid electrolyte interphase. Simultaneously, brand-new vertical Co fibers (diameter: ≈5 µm) scaffold is designed via a facile magnetic-field-assisted hydrothermal method to collaborate with plasma-enhanced Li metal anodes (SFI@Li/Co). The Co fibers scaffold accommodates active Li with mechanical integrity and decreases local current density with good lithiophilicity and low geometric tortuosity, supported by DFT calculations and COMSOL Multiphysics simulation. Consequently, the assembled symmetric cells with SFI@Li/Co anodes exhibit superior stability over 525 h with a small voltage hysteresis (125 mV at 5 mA cm −2 ) and improved Coulombic efficiency (99.7%), much better than the counterparts. Enhanced electrochemical performance is also demonstrated in full cells with commercial cathodes and SFI@Li/Co anode. The research offers a new route to develop advanced alkali metal anodes for energy storage.
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