Fig. 1

(a) Schematic illustration for the preparation of 3D porous PZC-A750 framework; (b) Rate performance of obtained-ZICs; (c) Ragone plots of Zn//PZC-A750 and Zn//PPy-A750 devices compared with other reported devices; (d) Schematic illustration for the transportation of ions and electrons; (e) Capacitive contributions of Zn//PZC-A750 ZICs[22]; (f) and (g) Schematic diagram of energy storage and ion transport of Zn//CT/SWNT[24]"

Fig. 2

(a) The structure energy of H-rGO and Zn-rGO; (b) The calculated adsorption energy of H+ and Zn2+ on rGO；(c) The optimized charge-density-difference patterns; (d) Schematic diagram for the H+ adsorption-induced distortion of graphitic structure in rGO sheets during charge/discharge process[30]; (e) Fabrication processes of the N-GNF@CFs electrode[31]; (f) and (g) The mechanical performance of CFZHSCs under various bending angles[36]"

Fig. 3

(a)—(b) Kinetic analysis of Zn2+ storage in the RuO2·H2O: a relationship curve of peak current versus scan rate and capacitive contribution[40]; (c) XRD patterns; (d)—(e) GITT curves and ion diffusion coefficients[44]; (f) TEM images of Co9S8@MnO2-60; (g) The as-built structural model of MnO2 structure with different views; (h) The energy barrier of Na atom migrations on a single layer of MnO2 surface without defects and containing oxygen vacancies; (i) CV curves of Co9S8@MnO2-60-based ZICs[45]"

Fig. 4

(a) EIS of Ti3C2T x -DMAC、Ti3C2T x -DMSO、Ti3C2T x -CAN and Ti3C2T x -H2O electrode materials; (b) Ragone plot of the fabricated MSCs and different types of energy storage devices; (c) Ex situ XRD patterns of the Ti3C2T x cathode delaminated with DMAC; (d) Rate stabilities of MSCs[54]; (e) GCD curves of composite electrodes; (f) Anti-self-discharge performance of the obtained ZICs; (g) Schematic illustration of ions transport model in Ti2CT x /C electrode after Sn4+ pre-intercalation[55]"