Quasi-Solid Electrolyte Interphase Boosting Charge and Mass Transfer for Dendrite-Free Zinc Battery

Highlights Defect engineering for constructing Zn2+ reservoir to anchor anions. The quasi-solid electrolyte interphase as Zn2+ reservoir boosting charge and mass transfer for dendrite-free zinc battery. A Coulombic efficiency of 99.8% was achieved in Zn||Cu cell. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-023-01031-7.

solvent. The uniform slurry was then coated onto a Ti foil and then vacuum-dried at 80 °C for 10 h. The loading mass of NH4V4O10 in the electrode was ~1.5 mg cm −2 .

S1.3 Assembly of Symmetric Cells and Full Cells
CR2025-type coin symmetric cells were assembled with identical electrodes of bare Zn or UiO-66@Zn, 1 M ZnSO4 and 1 M Zn(NH2SO3)2 electrolyte and glass fiber separators. Zn||MnO2 cells were assembled by using bare Zn or UiO-66@Zn as anodes, 1 M ZnSO4|1 M Zn(NH2SO3)2|0.2 M MnSO4 as the electrolyte, and glass fiber as separators. Zn||NH4V4O10 cells were assembled by using bare Zn or UiO-66@Zn as anodes, 1 M ZnSO4|1 M Zn(NH2SO3)2 as the electrolyte, and glass fiber as separators. All batteries were assembled in open air conditions and aged for 4 hours before performed electrochemical measurements.

S1.4 Material Characterizations
Powder X-ray diffraction (PXRD) patterns were recorded on an RIGAKU D/MAX 2550/PC instrument equipped with a copper Kα radiation (k = 1.54 Å) in a 2θ range from 5° to 55°. The water contact angle was measured at room temperature using a contact angle meter (SL200B, Solon Tech.). Raman spectra were determined on a Renishaw inVia Raman microscope with a 785 nm laser. Fourier transform infrared (FTIR) spectroscopy analysis was carried out using 100-FT-IR Spectrometer, Perkin-Elmer, with a wavenumber resolution of 4 cm −1 to characterize UiO-66. The zeta potential was measured using a Malvern Zetasizer Nano ZS90. Nitrogen adsorptiondesorption measurements at 77 K were performed on an Autosorb-iQ2-MP (Quantachrome Instruments) surface area analyzer. Prior to the measurement, the sample was outgassed under vacuum at 443 K for 12 h. Thermal gravimetric analysis (TGA) profiles and Thermal gravimetric analysis-differential scanning calorimetry (TGA-DSC) profiles were obtained on a SDT Q600 V8.2 Build 100 system under a mixture of nitrogen and oxygen from 308 K to 1073 K with a heating rate of 5 K min −1 . Zirconium and zinc ratio was collected by inductively coupled plasma optical emission spectrometer (ICP-OES, Agilent 5110). Sulfur and Nitrogen ratio was obtained by elemental analyzer (elementarvarioel cube). The morphologies were characterized using a field-emission scanning electron microscope (SEM, Hitachi S-4800) with an accelerating voltage of 3.0 kV and the energy dispersive spectroscopy (EDS). To prepare solid-like electrolyte@UiO-66, activated UiO-66 were fully soaked in 1 M ZnSO4|1 M Zn(NH2SO3)2 and collected by vacuum filtration. The in-situ optical observation of Zn deposition/dissolution behavior was carried out by pairing symmetrical Zn (or UiO-66@Zn) in a cell with a transparent quartz window (Kejing, STC-Q) and a current density of 10 mA cm -2 .
The ionic conductivity of the quasi-solid interphase was measured using two blocking electrodes (stainless steel). The ionic resistance Rb was tested by the EIS technique. Then the thickness of the quasi-solid interphase layer L, and the contact area S were measured. The ionic conductivity of the E@UiO-66 was evaluated according to the Based on the result of ICP-AES, the formula of E@D-UiO-66 is determined as Zr6O4(OH)4(BDC)4.72[Zn(NH2SO3)2]3.49(ZnSO4)4.189(H2O)20.4. In the TGA measurement, the initial two-step weight loss (in total of ~ 11.51%) up to 100°C is attributed to the decomposition of apparent H2O. The subsequent weight drop originates from the disintegration of MOF structure (leaves Zirconium Oxide), decomposition of zinc salts and water molecules in the pore channels. Inductively coupInductively coupled plasma mass-spectrometry (ICP-MS) analysis of E@D-UiO-66 confirmed a Zn:Zr ratio of 1:1.09. Elemental analysis (EA) of E@D-UiO-66 confirmed a N:S ratio of 1:3.8. The remaining weight (40.13%) corresponds to a mixture of ZrO2 and ZnO, and the value of x can be deduced from the following equation

S1.5 Electrochemical Measurements
Cyclic voltammetry (CV) curves and Linear Sweep Voltammetry (LSV) were conducted on an electrochemical workstation (CHI 660D) with a voltage window of 1.0 to 1.8 V at different scan rates. The galvanostatic charge/discharge (GCD) measurements were performed by a battery test system (LAND, CT-2001A). Electrochemical impedance spectra (EIS) were measured in a frequency range from 100 kHz to 1 mHz. Zn||Cu (or UiO-66@Cu) half cells were assembled to evaluate the Coulombic efficiency (CE) of Zn plating/stripping.

Method 1:
A fixed amount of Zn was deposited on UiO-66@Cu or bare Cu foil, followed by stripping Zn until the voltage reached up to 0.6 V.

Method 2:
In order to carry out an accurate CE, a method proposed by Wang et al. was adopted. According to the protocol, a fixed Zn capacity of 4 mA h cm −2 was deposited onto the Cu substrate as a "zinc reservoir" and then cell repeated the plating/stripping process for 25 cycles with 1 mA h cm −2 , followed by stripping away the remaining Zn to calculate the average CE.
The transference number of Zn 2+ (tZn 2+ ) was determined by the EIS technique and the potentiostatic polarization. Symmetrical bare Zn (or ND-UiO-66@Zn, D-UiO-66@Zn) battery cells were polarized by a constant voltage bias of 10 mV (ΔV) for 90min. The initial current (I0) and the steady-state current (ISS) were recorded in combination with the interfacial resistance before (R0) and after (RSS) the potentiostatic polarization. The tZn 2+ thereby could be calculated by the following equation

S1.6 Computational Section
Our DFT calculations are performed with Vienna Ab initio Simulation Package (VASP) in this work [1], and the PBEsol with D3 dispersion correction is used as the electron exchange-correlation potential [2,3]. The cutoff energy of plane wave basis is 500 eV. The structure is fully relaxed until the Hellmann-Feynman force on each atom is converged to be lower than 0.05eV/Å, and the total energy is converged to 10 -6 eV during self-consistent calculations. The Brillouin zone is sampled using 2*2*2 Gamma centered k-point mesh. The calculation for defect free UiO-66 is performed in a unit cell with 4 Zn clusters and 24 linkers, and 4 Zn clusters with 8 missing linkers are select to be defected structure. The binding energy is calculated with: Where is the energy for UiO-66 with 8 missing linkers, is the energy of a single molecular to be adsorbed and is the energy after the atoms are adsorbed.
The simulation of electrochemical Zn deposition process is realized by simulation software COMSOL Multiphysics 5.6 with Electrodeposition Tertiary Nernst-Planck. The ions flux was given by the Nernst-Planck equation and the boundary conditions for the electrodes were given by the Butler-Volmer equation. The other boundaries are natural boundaries with no flux. The Zn 2+ concentration was set to 2 M in the initial state and the resulting ionic concentration was time dependent. The diffusion coefficient of Zn 2+ in the electrolyte was set to 3.93 e −11 m 2 s −1 . The current density was set as 20 A m −2 The ionic mobilities are defined by Nernst-Einstein equation. The density and molar mass of Zn metal was 7.14 kg m −3 and 65.00 g mol −1 .