(Battery Division Technology Award) Dendrite-Free Architected Zinc Anodes: Enabling Sustainable, Safe, Scalable, Rechargeable, and Manufacturable Next-Generation Aqueous Batteries
Authors: Rolison Debra R. , Long Jeffery W. , Parker Joseph F. 
Published: December 2024

Architected electrodes are a design concept in which the key transport functions of electrochemistry—electrons, ions, molecules—are wired in three-dimensions (3D) throughout the volume of an ultraporous, high surface-area scaffold [1–3]. Our focus on nonperiodic architectural variants such as foams and sponges and our ability to 3D-wire elementary transport and reaction processes at nanoscopic, mesoscopic, and macroscopic levels transforms how active materials and electrode architectures are designed for higher-performance electrochemical energy storage, particularly for applications with challenging power demands. Twelve years ago, we applied these design concepts to overcome the major impediment to rechargeable Zn-based aqueous batteries: growth of zinc dendrites sufficiently long to pierce the cell separator. We did so by adapting a simple emulsion/suspension-based protocol and coupled it with thermal treatments to anneal and fuse ~50 mm Zn particles into a “sponge” form factor with size and shape control [4,5].

The structural characteristics of the sponge impart three key advantages. First, the fused metallic zinc core maintains long-range electronic conductivity within the electrode volume throughout charge–discharge even to deep utilization of zinc—the shell of zinc oxide that deposits on the walls does not disrupt electron transport within. Secondly, the sponge interior provides 100s of cm2 of electrified interface per cm2 of cross-sectional area thus lowering local current density and distributing it more uniformly, providing a measure of morphological control. An ancillary benefit arises because a more uniformly electroreacting zinc presents a more uniform current distribution across the cell to its paired electrode, thereby easing its morphological stress. Thirdly, the confined internal void volume controls Zn/Zn²⁺/zincate precipitation/dissolution dynamics and product redistribution because zincate supersaturates at lower concentrations, assisting morphological control. Ensuring more uniform reactivity controls how metal converts to zinc oxide at the surface of the zinc network during discharge and then reverts to metal upon recharge.

Until the introduction of the zinc sponge, the challenges of shape change, dendrite formation, and parasitic reactions were addressed―with only limited success―using various electrolytes and additives. While such components are less essential when using zinc sponge as the negative electrode, we verified that additives that promote ZnO deposition over those that increase zincate solubility prove advantageous for preserving the sponge architecture after extensive cycling to technologically relevant depths-of-discharge, while also maintaining coulombic efficiency. The down-selected electrolyte/electrode additives further enhance the performance and applicability of this advanced anode in various alkaline cell configurations, including demonstrating that nickel–zinc sponge cells deliver lithium-ion–competitive performance at the system-level [7].

We emphasize the need to fabricate practical architected electrodes using “low tech” strategies (bench-top; scalable) because manufacturability accelerates efforts toward commercialization. Each successive generation of the Zn sponge anode over the past ten years has been further optimized (and patented) such that the current sponge formulation is rapidly processed at scale with form factor control (Fig. 1) and can be fabricated at sizes necessary for relevant large-scale energy-storage applications, such as 1 mm–thick 100 cm2 plates [8]

By successfully using an architected, sponge form factor to suppress zinc dendritic growth in alkaline electrolyte, we show that zinc-based rechargeable batteries can now play a significant role as inexpensive, low supply-risk, safe batteries in the global effort to electrify transportation and grid storage.

[1] B. Dunn, J.W. Long, D.R. Rolison, and H.S. White, “Three-dimensional battery architectures.” Chem. Rev., 104, 4463–4492 (2004).

[2] J.W. Long and D.R. Rolison, “Architectural design, interior decoration, and 3D plumbing en route to multifunctional nanoarchitectures.” Acc. Chem. Res., 40, 854–862 (2007).

[3] D.R. Rolison, J.W. Long, J.C. Lytle, A.E. Fischer, C.P. Rhodes, T.M. McEvoy, M.E. Bourg, and A.M. Lubers, “Multifunctional 3D architectures for energy storage and conversion.” Chem. Soc. Rev., 38, 226–252 (2009).

[4] J.F. Parker, C.N. Chervin, E.S. Nelson, D.R. Rolison, and J.W. Long, “Wiring zinc in three dimensions re-writes battery performance—Dendrite-free cycling.” Energy Environ. Sci., 7, 1117–1124 (2014).

[5] D.R. Rolison, J.F. Parker, and J.W. Long, “Zinc electrodes for batteries.” US Patent 10,008,711 (Sept 1, 2020).

[6] J.F. Parker, I.R. Pala, C.N. Chervin, J.W. Long, and D.R. Rolison, “Minimizing shape change at Zn sponge anodes in rechargeable Ni–Zn cells: Impact of electrolyte formulation.” J. Electrochem. Soc.,
163, A351–A355 (2016).

[7] J.F. Parker, C.N. Chervin, I.R. Pala, M. Machler, M.F. Burz, J.W. Long, and D.R. Rolison, “Rechargeable nickel–3D zinc batteries: An energy-dense, safer alternative to lithium-ion.” Science, 356, 415–418 (2017).

[8] R.H. DeBlock, J.F. Parker, J.W. Long, D.R. Rolison, and C.N. Chervin, “Fabrication and fusion of zinc particles in porous electrodes.” US Patent 11,710,818 (July 25, 2023).