Rechargeable Zinc Batteries: Overcoming Challenges And Unlocking Opportunities For Next-Gen Energy Storage

Whereas lithium is very limited, physically concentrated, and has many problems with security (thermal runaway, fires); zinc has a lot more use, costs much less, and has no security issue.

Zinc batteries work on aqueous electrolytes and gross liquid electrolyte solvent combustibility, which is a security risk associated with Li-ion cells, which use organic solvents; therefore, zinc provides high theoretical volumetric capacity (5,855 Ah/L) and low redox potentials, thus appealing for high-energy density applications.

For many years now (more than a few) zinc based rechargeable batteries (primarily nickel zinc and zinc air) have been limited products due to the following three major issues: dendrite formation, hydrogen evolution due to parasitic nature of the reaction, and changing shapes.

The formation of dendrites occurs with zinc during the recharge phase. When recharging zinc batteries unevenly deposits the zinc creates dendritic structures that can go through the separator of the zinc cell and cause a short circuit.

The electrochemical reaction that occurs in the cell and the production of hydrogen gas is another side reaction that results in loss of moisture in the cell causing limited cycle life.

The shape of the zinc electrode will change during the cycling process as the active material is redistributed and results in capacity loss and mechanical failure.

Zinc batteries have typically had a limitation with regard to the number of cycles to fewer than 200 - 300 deep cycles as compared to Li-ion batteries which provide 1000 - 2000 cycles.

A wave of interdisciplinary research - spanning materials science, nanoengineering, and electrochemistry - is systematically dismantling these barriers.

3D Structured Zinc Anodes: Researchers at the University of Maryland and the U.S. Army Research Laboratory developed porous, sponge-like zinc anodes that accommodate volume changes and promote uniform deposition, essentially eliminating dendrite growth. These anodes have demonstrated over 1,500 cycles at high depth of discharge.

Electrolyte Additives and "Zinc-Phobic" Coatings: Adding trace amounts of organic or inorganic additives (e.g., sodium dodecyl sulfate, bismuth oxide) to the electrolyte modifies the zinc deposition morphology. More advanced approaches use "zinc-phobic" coatings that steer deposition into planar, dense layers.

High-Performance Separators: The polymer-ceramic composite separator incorporates new nanocellulose- or Metal-Organic Framework (MOF)-reinforced separators that prevent dendrite penetration while permitting rapid ionic transport.

Side-Reaction Suppression: Researchers have proven that by optimizing the use of the buffer pH and adding corrosion inhibitors (such as indium or tin compounds), there has been a significant decrease in hydrogen evolution from unforeseen electrochemical reaction(s) in recently developed prototype hydrogen batteries with operational Coulombic efficiencies of over 99.7%.

With these advances, rechargeable zinc batteries are finding their commercial sweet spots - not head-to-head with Li-ion in EVs, but in massive, underserved markets.

1. Stationary Energy Storage (Grid and Residential)

Long-duration storage (4–12 hours) remains a challenge due to lithium-ion's high costs per kilowatt-hour of use. In contrast, zinc-based batteries - particularly those using the zinc-air or zinc-bromine chemistries - have lower raw materials costs and have proven to be non-flammable, making them a great fit for utility-scale backup and solar-plus-storage applications. Many start-ups in China and the U.S., including Eos Energy Enterprises and Zinc8 Energy Solutions, have begun deploying megawatt scale-based battery systems.

2. Wearables and IoT Devices

Flexible, thin-film zinc batteries are excellent candidates for use in devices such as smartwatches, medical patches, and environmental sensors. The aqueous electrolyte within these batteries is safe for use on human skin, and the ability to the batteries can also be printed on flexible substrates should lead to multiple manufacturing methods that lithium-ion cannot match. For example, researchers at the National University of Singapore recently printed a rechargeable zinc battery onto a contact lens.

3. Replacement for Lead-Acid

Lead-acid batteries are still the predominant battery type for use as backup power, for use in golf carts and forklifts, and among others; however, they typically have very low energy density and pose significant threats to the environment due to their toxicity. On the other hand, zinc batteries have been found to store double the amount of energy compared to a lead-acid battery when compared, will typically have a much longer cycle life than lead-acid batteries, and could be recycled without any of the hazardous materials associated with lead. The majority of the forklift producers are presently testing zinc-nickel battery packs.
 

While progress is undeniable, commercialization remains in the early innings. Key remaining challenges include:

Scaling up uniform electrode manufacturing - lab breakthroughs often rely on exotic additives or complex processing that increase cost.

Standardization - unlike Li-ion with well-established 18650/21700 formats, zinc batteries lack industry-wide form factors.

Long-term calendar life - most published studies show cycle life, but real-world aging under partial charge, temperature swings, and intermittent use remains unproven.

However, investment is accelerating. In 2025 alone, venture funding for zinc battery startups surpassed $400 million, and the U.S. Department of Energy's "Long Duration Storage Shot" specifically targets zinc as a priority chemistry. China, meanwhile, has included zinc-air batteries in its 14th Five-Year Plan for energy storage.

Although zinc batteries are designated as being second-tier to lithium ion, they will not "kill" them; they will simply have many applications that have been deemed unqualified for lithium or for which lithium is too costly on a large scale or even potentially hazardous when used in consumer goods. By capitalizing on the attribute characteristics of zinc batteries in conjunction with recent advances, they will be the second foundation/block in the emerging post lithium energy storage ecosystem.