Anode Free Zinc-Metal Batteries (AFZMBs): A New Paradigm in Energy Storage

Abstract

In the past few years, aqueous zinc-metal batteries (ZMBs) have gained much attention and can be regarded as a potential alternative to lithium-metal batteries owing to their high safety, nature of abundance, and environmental sustainability. However, several challenges persist, including dendrite formation, corrosion, and unwanted side reactions, before ZMBs can be fully utilized in practical applications. To circumvent these issues, anode free zinc-metal batteries (AFZMBs) have emerged as a next-generation energy storage system. This review provides a comprehensive analysis of recent developments in AFZMBs, including their working mechanisms, advantages over conventional ZMBs, and the challenges for practical implementation. It also highlights the key strategies, including current collector modification, electrolyte engineering, and 3D printing techniques to enhance zinc deposition uniformity and cycling stability. The review also explores how 3D printing technology can revolutionize the design of advanced current collectors and zinc-rich cathodes, optimizing material utilization and enhancing battery performance. Finally, with a future perspective of AFZMBs is concluded, highlighting the need for further research to address existing bottlenecks and fully unlock their potential for next-generation energy storage.

Keywords: 3D printing; advantages and challenges; anode free zinc‐metal batteries; current collector; electrolyte optimization; strategies.

Figure 1

Comparison of lithium, sodium, potassium, zinc, magnesium, calcium, and aluminum based on volumetric capacity, gravimetric capacity, and electrode potential, as well as their respective radar plots.^{[ 10 ]}

Scheme 1

An overview of the proposed review, mainly focusing on interfacial design, electrolyte optimization, and architecture modifications via 3D printing to address the challenges for AFZMBs.

Figure 2

Schematics illustrations and overview of a) ZMBs, and b) AFZMBs.

Figure 3

Comparison of ZMBs versus AFZMBs in terms of cost, safety, coulombic efficiency, and energy density.

Figure 4

Strategies to mitigate dendrite formation via surface engineering. a) Schematics illustration of Zn nucleation behavior on (a) bare Cu and b) modified C/Cu current collector for AFZMBs. c) Cycling stability of C/Cu during the Zn plating/stripping process in 3 m Zn(CF₃SO₃)₂ at a current density of 1 mA cm⁻² and 0.5 mAh cm⁻² plating capacity. d) Comparison of galvanostatic Zn plating profiles of Cu and modified Cu (C|Cu), with the inset highlighting the initial nucleation overpotential. e) cycling stability of anode‐free Zn‐MnO₂ battery at a current density of 1 mA cm⁻². Reproduced with permission.^{[ 27 ]} Copyright 2021, American Chemical Society. f) Schematic representation of the synthesis process of Cu@AOF. g) Schematic illustrations of Zn plating on bare Cu and Cu@AOF. h) Comparison of diffusion energy barriers for ZHS (001), AOF (111), Zn (111), and Cu (111). i) Long‐term cycling stability test at a current density of 1 A g⁻¹. j) Galvanostatic charge/discharge profiles of the assembled cell Cu@AOF ||Zn_0.5VO₂ at −20 °C. Reproduced with permission.^{[ 45 ]} Copyright 2023 Wiley‐VCH GmbH.

Figure 5

Schematic illustration of the 3D structured current collector introduced by zincophilic material. a) Schematic illustrations of Zn plating behavior on the surface of bare Zn and modified Zn anode. b) Cyclic voltammetry curves of the bare Zn versus modified Zn anode with Zn₃ V₃O₈ as the cathode at a scan rate of 0.5 mV s⁻¹. c) long‐term cycling stability in 3 m Zn(CF₃SO₃)₂ aqueous electrolyte at a current density of 2 A g⁻¹. Reproduced with permission.^{[ 55 ]} Copyright 2022, Elsevier. d) Schematic illustrations of Zn plating on bare Cu and modified ZA@3D‐nanoCu anode. e) Galvonstatic cycling profiles of ZA@3D‐nanoCu|Zn and Cu|Zn half cells in 2 m ZnBr₂. f) Schematic diagram of the assembled ZA@3D‐nanoCu|Br₂ battery, and g) Cycling stability of the assembled ZA@3D‐nanoCu|Br₂ battery. Reproduced with permission.^{[ 56 ]} Copyright 2023, Elsevier.

Figure 6

Strategies for the zincophilic materials by integrating 2D materials. a) Zn plating and nucleation behavior on two different surfaces, i.e., bare Zn and modified zincophilic Sb/Sb₂Zn₃@HI. b) Nucleation overpotential profiles on Zn, Cu, and Sb@Cu substrates, during Zn electrodeposition at a current density of 3 mA cm⁻² in 2 M ZnBr₂ electrolyte. Illustrations of stimulated analysis of current density distribution during Zn plating on c) bare Zn, d) Sb/Sb₂Zn₃@HI substrates at room temperature. e) Cycling stability of anode‐free Zn‐Br₂ battery with bare Zn and Sb/Sb₂Zn₃@HI at a current density of 10 mAh cm⁻² and 10 mA cm⁻², and f) digital images of the assembled Zn‐Br₂ battery with solar powered panel lighting at day and night. Reproduced with permission.^{[ 60 ]} Copyright 2023, Springer Nature. Zn plating behavior on g) bare Cu and h) modified Cu@Na‐MX@Sn substrates, respectively. i) Cyclic Voltammetry profiles of the assembled asymmetric cells with bare Cu and modified Cu@Na‐MX@Sn substrates at a scan rate of 0.5 mV s⁻¹. j) Nucleation overpotential profiles on bare Cu and modified Cu@Na‐MX@Sn at a current density of 1 mA cm⁻². k) Cyclic stability at a current density of 10 mA g⁻¹. Reproduced with permission.^{[ 61 ]} Copyright 2023, Elsevier.

Figure 7

Strategies to control interfacial reactions during Zn plating. a) Schematic representation of typical challenges faced during Zn plating on bare Cu. b) Zn plating and protection mechanism of PMMA: Zn coating layer. c) Cycling stability and coulombic efficiency of the half cells during Zn plating/stripping at a current density of 1 mA cm⁻². Reproduced with permission.^{[ 63 ]} Copyright 2023 Elsevier. d) Initial Zn plating/stripping profiles of bare Ti and modified NC‐Cu@Ti‐0.5 substrate. Inset Figure 3d shows the nucleation potential on bare Ti and modified NC‐Cu@Ti‐0.5, and e) Cycling stability and coulombic efficiency of bare Ti and modified NC‐Cu@Ti‐0.5. Reproduced with permission.^{[ 64 ]} Copyright 2024 American Chemical Society.

Figure 8

Strategies for the modification of electrolytes. a) Schematic representations for Zn plating at pristine electrolytes, i.e., 2 M ZnSO₄ and additive ZnF₂‐based electrolytes. b) Nucleation overpotential of Zn plating with different current densities. c) Cycling stability of the assembled cells using stainless steel and LiMn₂O₄ at a current density of 200 mA g⁻¹ in additive ZnF₂‐based electrolytes. Reproduced with permission.^{[ 66 ]} Copyright 2021 Wiley‐VCH GmbH. Schematic diagram illustrating the Zn²⁺ charge transfer behavior d) without LiI, and e) with modified LiI additive aqueous electrolyte. Reproduced with permission.^{[ 68 ]} Copyright 2024 The Royal Society of Chemistry. f) Schematic representation of the preparation of hybrid electrolyte, and highlighting its impact of hydrophobic protective interphase for Zn solvation structure. g) Digital images of water/PC mixture with different concentrations. h) Radial distribution function of Zn²⁺ solvation in hybrid Electrolyte. Reproduced with permission.^{[ 71 ]} Copyright 2022 American Chemical Society.

Figure 9

a) Schematic illustrations of the formation of an interfacial layer on Zn anode during Zn plating based on IDE‐H₂O electrolyte and in pristine aqueous electrolyte. b) Variation of cycle no. with coulombic efficiency. SEM images of Zn metal immersed in c) IDE‐H₂O electrolyte and d) pristine aqueous electrolyte for 15 days, highlighting the significant differences in surface morphology and corrosion behavior. Reproduced with permission.^{[ 74 ]} Copyright 2024 Elsevier. e) Schematic representations of soft‐acidic/hard‐basic TAA's Role in stabilizing low‐temperature aqueous electrolytes. Zn plating/stripping curves of Cu substrate with different temperature ranges in f) 1 m Zn(OTf)₂, and g) the modified ZT‐electrolytes at 0.2 mA cm⁻² and 0.5 mAh cm⁻². h) Digital and Post‐mortem SEM images of the Zn plated on a Cu substrate at 25 °C in 1 m Zn(OTf)₂ (Left) and modified ZT‐electrolytes (Right) at −40 °C, respectively. Reproduced with permission.^{[ 77 ]} Copyright 2024, The Royal Society of Chemistry.

Figure 10

a) Challenges of the current collector, and b) Schematic representation of cathode materials and their respective challenges for AFZMBs.

Figure 11

Strategies for 3D printed collectors via 3D printing. Schematic illustrations of Zn plating on a) 2D. b) SEM images and Zn plating distribution on 3D Ni. Reproduced with permission.^{[ 84 ]} Copyright 2021, Wiley‐VCH GmbH. c) Micro‐CT images of the 3D morphology of Zn plating on 3DGT and 3DGP. d) Volume variations in each layer along the z‐axis. e) In situ optical microscopic images of Zn plating on 3DGPT and bare Zn at a current density of 5 mA cm⁻². Reproduced with permission.^{[ 86 ]} Copyright 2022, Elsevier. f) Digital photographs depicting the mechanical flexibility of the 3DP‐ZA anode, shown in both flat (pristine) and bent conditions. g) Schematic representation of Zn plating on bulk‐ZA and 3DA‐ZA anode. Reproduced with permission.^{[ 94 ]} Copyright 2022, Elsevier, and h) Schematic illustrations of 3D printing scaffolds with layer‐by‐layer Ag % NPs distribution. Reproduced with permission.^{[ 95 ]} Copyright 2023 Wiley‐VCH GmbH.

Figure 12

Strategies for 3D printed cathode electrodes. a) Schematic illustrations for the preparation of 3D printed cathode electrodes for ZMBs. Reproduced with permission.^{[ 87 ]} Copyright 2021, Wiley‐VCH. b) SEM images of the 3D‐CM surfaces at different magnifications. Reproduced with permission.^{[ 96 ]} Copyright 2023, Wiley‐VCH. c) Schematic representation of the fabrication process for V₂O₅‐coated 3D‐printed carbon electrode. Reprinted with permission.^{[ 97 ]} Copyright 2021, Wiley‐VCH, and d) Schematic representation of the 3D printing stages, including embedded optical images depicting the collector, cathode, and anode inks used to fabricate 3D‐printed zinc‐ion micro‐batteries. Reproduced with permission.^{[ 88 ]} Copyright 2023, Wiley‐VCH.