Fig.1

Construction strategies for Zn powder anodes. Zn powder bulk design: dimensional reduction strategy and gradient construction; Coating structure modification; Conductive network construction; 3D design for Zn powder anodes: 3D printing and electrospinning; Rheological design for Zn powder anodes: Semi-liquid anodes and soft solid anodes"

Fig. 2

Bulk design of Zn powder anodes. (a) A strategy for obtaining two-dimensional (2D) Zn powders by dimensionality reduction engineering[27]; Gradient designed Zn powder anodes[28]: (b)—(e) Cross-sectional SEM images of the gradient Zn powder anode following Zn deposition of 3 h, 6 h, 9 h, and 12 h; (f) Comparison of cycling performance of symmetric cells with different Zn powder anodes at 1 mA/cm2/1 mAh/cm2; (g) A digital photograph showing the flexibility of the gradient Zn powder anode"

Fig. 3

The mechanism of In in Zn powder anodes. (a) Schematic diagram of Zn@In powder anodes inhibiting hydrogen evolution and corrosion processes; (b) Calculation of charge densities and binding energies of Zn atoms on Zn and In substrates; (c) Cycling performance (285 h) of the pZn/In symmetric cell at 10 mA/cm2 and 2.5 mAh/cm2[29]; (d) CA curves of Zn foil and In-coated Zn powder anode[30]; (e) Activation energy values of Zn powder anode and In-coated Zn powder anode; (f) SEM image of the In-coated Zn powder anode after 1000 cycles[31]; (g) Schematic diagram of the preparation of Zn-EGaIn capillary suspension[32]"

Fig. 4

The mechanism of different coating materials on Zn powder anodes. MXene@Zn composite[33]: (a) Schematic illustration of the MXene@Zn composite; (b) Typical electrochemical galvanostatic charge-discharge profiles of symmetric Zn-P batteries at 1 mAh/cm2; (c) Atomic arrangements of Ti terminated surface of Ti3C2T x (0002) and Zn deposits (0002) and their small lattice mismatch; Bi@Zn composite[34]: (d) Rate performance of the Bi@Zn powder anode and the bare Zn powder anode; (e) Cycling performance (585 h) of the Bi@Zn symmetric cell at 15 mA/cm2 and 7.5 mAh/cm2 (DOD=45%); Nitrogen doped carbon (NC)[35]: (f) The adsorption energies of the Zn atom on both the Zn (002) surface and the NC layer; (g) Models of NC layer and Zn atom-NC layer, and interfacial charge-density model of Zn atom-NC layer; Polyethylene glycol coating on the Zn powder surface[36]: (h), (i) SEM images of Zn-P and Zn-P/PEG after different cycles"

Fig. 5

Construction of the conductive networks in Zn powder anodes. (a) Fabrication process and structural characteristics of the 3D conductive carbon networks[40]; (b)—(e) Elemental mappings of C, O and Zn elements in the Zn powder-graphene composite anode[41]; Construction of the conductive networks by coating the surface of Zn powder with CuO[42]: (f) Adsorption energies of Zn2+ with different substrates; (g) HRTEM image of the CuO@Zn powder; (h) Rate performance of full cells at different current densities (0.5—3 A/g)"

Fig. 6

3D printed Zn powder anodes. Application of traditional 3D printing technology in Zn powder anodes[43]: (a) Schematic of the fabrication process of 3D printed Zn powder anodes; Morphology comparison after 50 cycles between (b), (c) bare Zn powder anode and (d), (e) 3D printed Zn powder anode; Hydrogel-modified 3D printed anodes[44]: In-situ optical microscopy images of (f) 3D printed Zn and (g) 3D Zn@ZAP during the deposition process; Application of 3D printed Zn powder anodes in Zn micro-batteries[45]: (h) Illustration of 3D printing of micro-electrodes; (i) Digital image of 3D printed micro-electrodes"

Fig. 7

Novel 3D-printed Zn powder anodes. 3D cold-trap environment printed Zn powder anodes[46]: (a) Schematic of the process of 3D cold-trap environment printed Zn powder anodes; SEM images of (b) 3D-printed MXene/Zn-P aerogel, (c) 3DCPP-MXene/Zn-P aerogel, and (d) 3DCEP-MXene/Zn-P aerogel; Microfluidic-assisted 3D printed Zn powder anodes[47]: (e) Schematic of the preparation process of microfluidic synthesis 3D printing Zn powder anode; (f) Schematic illustration of the synthesis mechanism for MXene/CuTHBQ; (g) The differential charge density at the interfacial region between MXene and Cu-THBQ; (h) Schematic of the EDL structure of bare Zn and M3DP-MXene/Cu-THBQ/Zn-P"

Fig. 8

Electrospinning strategy for Zn powder anodes[48]: (a) 3D porous Zn anodes (PF@Zn) prepared by electrospinning; (b), (c) SEM images of PF@Zn; (d) XRD patterns of bare Zn and PF@Zn before and after 20 cycles; (e) Rate performance of bare Zn and PF@Zn(0.5—3 mA/cm2); Contact angle tests of (f) bare Zn and (g) PF@Zn"

Fig. 9

Rheological structure design of Zn powder anodes. (a) SEM image of SLA; Rheological properties of SLA at (b) 1% and (c) 10% strain[49]; (d) Schematic of a full cell using the semi-solid Zn powder-based slurry anode; (e) Cycling stability of the full cell with replaceable slurry measured every 150 cycles at 1 A/g[50]; (f) Ion transfer numbers and (g) Arrhenius curves and activation energies of ss-ZnP and s-ZnP; (h) Rate performance of the NH4V4O10 ‖ss-ZnP and NH4V4O10 ‖s-ZnP full cells[51]"