In order to verify the inhibitory effect of molecule-crowded electrolytes on dendrite growth, the zinc deposition behavior of bare Zn symmetrical batteries with and without molecule-crowded electrolytes was tracked by SEM characterization. When the current density is 4 mA/cm
2 and the capacity is 1 mAh/cm
2, the surface of the bare zinc anode exhibits a rough surface with some protrusions and zinc nanosheets (
Figs. 3a and
b). Alternatively, the zinc anode exhibiting molecule-crowded electrolytes exhibits a smooth and flat appearance (
Figs. 3c and
d), indicating the existence of a uniform and dense SEI layer on the zinc anode. This further indicates that the SEI layer can inhibit the growth of zinc dendrites [
34]. However, the cross-sectional SEM image shows series dendrite growth on the exposed surface of the zinc anode. The morphological characterization and electrochemical results suggest that bare Zn with molecule-crowded electrolytes exhibits superior dendrite inhibition performance than Zn without molecule-crowded electrolytes, owing to its more uniform nucleation and lower nucleation overpotential. Therefore, XRD was used to further determine the deposition behavior of zinc with and without molecule-crowded electrolytes. As shown in
Fig. 3e, compared with pure Zn metal without molecule-crowded electrolytes, the (002) crystal surface is obviously enhanced after 30 h cycling of Zn metal with molecule-crowded electrolytes, which proves the transformation of zinc deposition mode from (101) crystal plane to (002) crystal plane in a molecularly crowded electrolyte environment. In addition, Raman spectroscopy further demonstrated the inhibition effect of molecular crowded electrolyte on byproducts. As shown in
Fig. 3f, compared with pure zinc metal with molecular crowded electrolyte, the Zn metal shows an obvious peak related to Zn
4(OH)
6SO
4·XH
2O (ZHS) at a Raman shift of about 988 cm
−1 after being cycled for 30 h with zinc sulfate electrolyte, and the Zn metal shows no obvious peaks of zinc metal in the Raman spectra after being cycled with molecular crowded electrolyte for 30 h, demonstrating the excellent stability. And the chemical composition of the interfacial phase was further studied by XPS spectra. It can also be determined that the interface is mainly composed of ZnF
2 (
Fig. 3g). Moreover, the growth of ZHS was inhibited (Fig. S6 in Supporting information). In order to prove the stability of Zn anode with molecular crowded electrolyte, we carried out an external experiment. In detail, we soaked pure zinc with and without molecular crowded electrolyte for 10 days, respectively (Fig. S7 in Supporting information). It was found that zinc anode surface produced similar protective layer, while the surface of zinc metal was seriously corroded by zinc sulfate. And the SEM images showed a more uniform stack of zinc sheets in the molecularly crowded electrolyte (Fig. S8 in Supporting information). Further, according to the XRD (Fig. S9 in Supporting information) and Raman (Fig. S10 in Supporting information) spectroscopy, the inhibition effect on ZHS-related byproduct can be proved, which further indicates that the molecular-crowded electrolyte promotes the formation of ZnF
2-containing layer, thus forming a stable SEI layer and inhibiting the growth of byproduct. DFT calculations were carried out for the adsorption behaviors of Zn
2+, ClO
4–, and OTF
– on different Zn crystal planes (
Fig. 3h). As elucidated, the adsorption energies of Zn
2+, ClO
4–, and OTF
– on different Zn planes are −0.81 eV, −4.65 eV and −4.87 eV on (101) crystal plane, which are all significantly lower than those of Zn
2+, ClO
4–, OTF
– on (002) crystal plane (−0.47, −3.21, and −3.31 eV), respectively. Therefore, the introduction of a molecularly crowded electrolyte preferentially adsorbed on the (101) zinc surface and deposited on the (002) crystal plane. In addition, XRD and SEM results further confirm that Zn
2+ ions are more likely to be deposited into nucleation on the (002) crystal plane than on the (101) crystal planes.