Surface Adsorption of Polyethylene Glycol to Suppress Dendrite Formation on Zinc Anodes in Rechargeable Aqueous Batteries

Abstract

Aqueous metal batteries routinely suffer from the dendritic growth at the anode, leading to significant capacity fading and ultimately, battery failure from short‐circuit. Herein, we utilize polyethylene glycol to regulate dendrite growth and improve the long‐term cycling stability of an aqueous rechargeable lithium/zinc battery. PEG200 in the electrolyte decreases the corrosion and chronoamperometric current densities of the zinc electrode up to four‐fold. Batteries with pre‐grown dendrites also perform significantly better when PEG is present in the electrolyte (41.4 mAh g−1 vs. 7.9 mAh g−1 after 1000 cycles). X‐ray diffraction and electron microscopy studies show that dendrites in the PEG‐containing electrolyte have been inhibited, leading to much smaller/smoother surface features than those of the control. The facile preparation process of the aqueous electrolyte combined with low cost and vast performance improvement in batteries of all sizes indicates high upscaling viability.

Fabrication of Zinc Anodes for Aqueous Lithium‐Ion Batteries by Supersonic Cold Spraying

“…The current density profile with respect to time (1 hour) is shown in Figure 2a. [21] SEM images after this duration clearly show that supersonic zinc anode has smaller and more packed dendrites than the planar anode (Figures 2c,d). [20][21][22] During the CA test, and charging of aqueous hybrid batteries, zinc ions deposit non-uniformly on the zinc anode surface which leads to the formation of sharp zinc dendrites.…”

“…The apparent higher surface area of supersonic zinc anode suggests that the supersonic zinc anode provides approximately 40 % higher surface area than the planar anode. [20][21][22] During the CA test, and charging of aqueous hybrid batteries, zinc ions deposit non-uniformly on the zinc anode surface which leads to the formation of sharp zinc dendrites. It is appropriate to assume Wenzel's model in this contact angle measurements since the magnitude of a water droplet (in mm range) is much larger than the roughness scale of the samples (in μm range).…”

“…[20][21][22] During the CA test, and charging of aqueous hybrid batteries, zinc ions deposit non-uniformly on the zinc anode surface which leads to the formation of sharp zinc dendrites. [21] We have shown that after about 100 seconds, the dendrites morphology transitions from flake-like primary structure to 'mossy' secondary dendritic structure. [23][24][25] XRD on the planar and supersonic zinc anode before and after 1 hour of CA shows the presence of peaks associated with the zinc metal (Figure 2b).…”

Inhibition of Zinc Dendrite Growth in Zinc‐Based Batteries

“…This phenomenon results in severe concentrationp olarization.T his uneven distribution of zincates can thereby control the deposition process of zinc. [47] Wenjing Lu got her Bachelor's degree Dr.Huamin Zhang currently serves as a full professor at the Dalian Institute of Chemical Physics (DICP), Chinese Academy of Science (CAS). In other words, the inhomogeneity in the surfacem orphology of zincbased electrodes easily brings about the formation of dendrites.T his inhomogeneity is causedb yt he free diffusiono f zinc ions on the electrode surface.…”

“…[15,22,24,25,47,64] The reason why the addition of polymers can inhibitt he continuous formation and growth of zinc dendrites lies in their adsorption on the surface of the zincbased electrodes. [15,22,24,25,47,64] The reason why the addition of polymers can inhibitt he continuous formation and growth of zinc dendrites lies in their adsorption on the surface of the zincbased electrodes.…”