Fig. 1

Summary of strategies for improving low temperature performance of zinc-ion batteries"

Fig. 2

(a) ABF-STEM image of NH4V4O10-x ·nH2O cathode material; (b) NVOH atom resolution image along axis [100], green sphere is V atom, blue sphere is NH4+ ion, red sphere is O atom, yellow circle represents oxygen vacancy; (c) Intensity line outlines of corresponding columns in the figure (b); (d) Schematic diagram of Zn2+ (de-intercalation) of NH4V4O10-x ·nH2O cathode material; (e) Schematic diagram of the diffusion of Zn2+ in NH4V4O10-x ·nH2O, with oxygen vacancy at the end sites, red spheres are O atoms, blue spheres are N atoms (NH4+ ions), green spheres are Zn2+ ions, and gray spheres are V atoms [35]; (f) Diffusion diagram of Zn2+ in Zn0.3(NH4)0.3V4O10·0.91H2O with NH4+ vacancy, black dotted circle indicates NH4+ vacancy [10]; (g) Capacitance comparison diagram of VO-300 and CuVO-300 at 1 A/g current density[37]"

Fig. 3

(a) Schematic diagram of the rechargeable battery based on the cathode electrode of quinone, and corresponding redox chemistry character; (b) Current density and charge transfer resistance of PAQS and MmH electrodes with temperature; (c) Nyquist plots of PAQS electrodes obtained from electrochemical impedance spectroscopy measurements; (d) Micropolarization curves measured immediately after impedance measurements [41]"

Fig. 4

(a) Schematic diagram of structural evolution of water and electrolyte and design of low freezing point solution. Water networks connected by hydrogen bonds are easily converted to ice networks at 0 ℃. With the addition of ZnCl2, the strong interaction between ions and water destroys the hydrogen bond network, and the ionic interaction is enhanced. Electrolytes at criticalCZnCl2can operate at extremely low temperatures through equilibrium hydrogen bonding and ion interactions used to regulate freezing points; (b) Structure and redox mechanism of Zn||PANI batteries; (c) The interaction energy between ions and water, and the energy to form solvated Zn2+ configurations; (d) Operating temperature window of existing batteries[11]; (e) Differential scanning calorimetry (DSC) curve of 4 mol/L Zn(BF4)2 electrolyte solution; (f) Conductivity curve of 4 mol/L Zn(BF4)2 electrolyte solution with temperature change; (g) Different types of O—H…F hydrogen bond obtained from snapshots in molecular dynamics (MD) simulations; (h) The average hydrogen bond number of Zn(BF4)2 electrolyte solutions with different concentrations after 140 ns simulation time; (I) Ratio of different hydrogen bonds in Zn(BF4)2 electrolyte solutions with different concentrations[49]"

Fig. 5

(a) Negative electrostatic potential mapping of anions SO42-、 NO3-、Cl-、I-和CF3SO3-; (b) The complexes configurations and binding energies of SO42-- H2O、NO3--H2O、Cl--H2O、I--H2O和CF3SO3--H2O were obtained by DFT calculation; (c) The complexes configurations and binding energies of Zn2+- SO42-、Zn2+- NO3-、Zn2+- Cl-、Zn2+- I-和Zn2+- CF3SO3-were calculated by DFT calculation; (d) Capacity comparison between Zn|2 mol/L Zn(CF3SO3)2|V2O5 batteries and reported low temperature aqueous batteries[51]; (e) Snapshots of 4 mol/L ZnSO4 and (f) 4 mol/L Zn(TFSI)2 electrolytes during DFT-MD simulation (Red represents oxygen, gray represents zinc, yellow represents sulfur, white represents hydrogen, blue represents nitrogen, purple represents fluorine); (g) The average number of hydrogen bonds between water molecules at 4 mol/L ZnSO4 、Zn(TFSI)2 and water; (h) The variation curve of discharge capacity with the number of cycles at different coulomb rates (from 2 C to 30 C) and different temperatures (from 25 to -35 ℃)[54]"

Fig. 6

(a) Reaction process diagram of Zn||PQ-MCT battery; (b) Zn2+-DMF complexes contribute to the smooth deposition of zinc in Zn(OTf)2|DMF electrolyte; (c) DSC curves of 0.5 mol/L Zn(OTf)2/DMF electrolyte and (d) pure DMF electrolyte reduced to -140 ℃ (held for 10 minutes) at a rate of 5 ℃/min while liquid nitrogen cooling, and DSC curves from -140 ℃ scanning to 20 ℃ at a rate of 5 ℃/min[59]"

Fig. 7

(a) Molecular models for simulating interactions between water molecules and different terminal groups in polymers; (b) Formation technology of δ-MgVO battery and the schematic diagram of working principle of Zn||δ-MgVO battery; (c) SEM images of lyophilized PVA/G gel electrolyte. Ragone diagram of (d) area and (e) volume compared with previously reported energy storage devices [68]; (f) Synthesis schematic diagram of PVA-B-G; (g) Integrated 3D network of polycomplexation in PVA-B-G and photographs of PVA-B-G films; (h) Photographs of PVA-B-G that have been shaped into the desired shape; (i) SEM images of freeze-dried PVA-B-G. Ragone diagram of (j) area and (k) volume of PVA-B-G battery compared with previously reported energy storage battery [69]"

Fig. 8

(a) Schematic diagram of interfacial reactivity of Z-PAAM and ZL-PAAM (Z represents Zn2+, L represents Li+); (b) Rate performance of Zn||LiFePO4 at -20 and 25 ℃ [70]; (c) Various hydrogen bonds are formed between alginic acid, EG and water molecules; (d) Different hydrogen bond interactions are formed between alginate, EG and water molecules; (e) Cycle performance of Zn||MnO2 batteries at 1.6 A/g, 25 ℃ and -20 ℃ [44]. (f) Specific capacity and (g) cycle stability of Zn||[EMIM]PF6-PEDOT：PSS|Bi2S3 batteries compared with other reported aqueous ZIBs[45]; (h) Schematic diagram of synthesis route of hydrogel electrolyte. Electrolytes are synthesized by polymerization of sodium acrylate with ammonium persulfate (APS) initiator and then immersion in the mixed solution of 6 mol/L KOH and 0.2 mol/L Zn(CH3COO)2[75]"

Fig. 9

(a) Schematic diagram of PAMPS-K/MC hydrogel obtained by simple solvent substitution method[79]; (b) Schematic diagram of strong hydrogen bond between EG-waPUA、H2O and PAM in EG-waPUA/PAM double-crosslinked hydrogel; (c) DFT analysis of the interaction between H2O, PAM and EG-waPUA in EG-waPUA/PAM double crosslinked hydrogel through multiple hydrogen bond; (d) Cyclic performance tests were performed on PAM and AF cells at 20, 0 and -20 ℃ at 0.3 A/g[34]"

Fig. 10

(a) Comparison of the capacities of ZnCF||PANI batteries with EG and without EG at different temperatures; (b) Cycling performance of solid-state fiber-optic ZnCF||PANI batteies at -20 ℃ at 1.0 A/g[87]; Photographs and SEM images of zinc foil surface after 500 cycles with (c) unmodified electrolyte and (d) EG&Et2O modified electrolyte; (e) Cycling characteristics of Zn||MnO2 batteries without additives and electrolyte with 1% Et2O and different content of EG additives at -10 ℃ and current density of 3 A/g[88]; (f) Schematic diagram of preparation of GG/SA and GG/SA/EG hydrogel electrolytes; (g) Discharge capacity of hydrogel electrolytes containing GG, GG/SA and GG/SA/EG at 25, 0 and -20 ℃[90]; (h) Schematic diagram of synthesis of CT3G30 hydrogel electrolyte; (i) SEM images of freeze-dried CT3G30; (j) Energy density diagrams of area and (k) volume of CT3G30 hydrogel Zn||MnO2 battery compared with those previously reported at different temperatures[91]"

Fig. 11

(a) Schematic diagram of zinc electrolyte surface evolution with or without additive CH3COONH4; (b) Long life cycle performance of Zn||Zn symmetrical batteries in ZnSO4: CH3COONH4 and ZnSO4 electrolytes at -10 ℃. (c) Cycling performance diagram of Zn||Ac capacitor in ZnSO4: CH3COONH4 electrolyte at -10 ℃ [96]"

Fig. 12

(a) Schematic diagrams of electrolytes and electrolyte-electrode-interphase structures; (b) A snapshot of the system evolution at -70 ℃, with red, white, green and dark gray spheres representing O, H, Cl and Zn atoms, respectively; (c) Coulomb efficiency of Zn||Ti battery galvanizing/stripping at 1 mA/cm2 and 0.5 mAh/cm2[102]"

Table 1

Comparison of physicochemical properties and performances of low-temperature zinc ion batteries"