The Chemistry That Stores Energy Without Catching Fire
The lithium-ion battery's dominance of the energy storage market rests on its combination of high energy density, good cycle life, and the manufacturing maturity that decades of consumer electronics and automotive investment have produced. Its commercial limitation in the grid-scale long-duration energy storage application, whose four to sixteen hour discharge duration requirements differ fundamentally from the two to four hour cycles that most deployed lithium-ion grid storage addresses, is not primarily the cost per kilowatt-hour of installed capacity but the safety profile of lithium-ion chemistry at the scale and duration that long-duration grid storage requires. A lithium-ion battery system storing multiple megawatt-hours of energy in a grid-connected installation carries the thermal runaway risk whose consequences in a densely packed battery enclosure include the exothermic chain reactions that produce the fires whose suppression requires specialised firefighting infrastructure and whose occurrence creates the insurance, siting, and regulatory complications that grid-scale lithium-ion storage developers manage as a standard commercial challenge. Zinc-based battery chemistries, whose aqueous electrolyte and non-flammable zinc electrode create a fundamentally non-flammable electrochemical system, offer the long-duration grid storage application an alternative whose safety profile eliminates the thermal runaway risk at the cost of a lower energy density that the grid application's space constraints can typically accommodate at acceptable economic terms.
Zinc-ion batteries use a water-based electrolyte in which zinc ions shuttle between a zinc anode and a cathode material during charge and discharge cycles. The aqueous electrolyte is non-flammable under all operating conditions that grid storage encounters, eliminating the combustion risk that lithium-ion's organic electrolyte creates. Zinc is an abundant, low-cost metal whose global mining production is approximately fourteen million tonnes annually, creating a raw material supply that scales with energy storage deployment without the geographic concentration and supply chain risk that lithium, cobalt, and nickel create for lithium-ion battery supply chains. The zinc electrode's theoretical energy density is lower than lithium's but sufficient for the stationary grid storage application where the weight and volume per unit of stored energy matter far less than in mobile applications where every kilogram of battery mass directly reduces the vehicle payload or range that the storage system's weight displaces.
Eos Energy and the Znyth Commercial Platform
Eos Energy Enterprises is the US zinc-based battery company whose commercial trajectory most directly reflects the current state of the long-duration zinc battery market. Its Znyth technology, a zinc hybrid cathode chemistry whose aqueous electrolyte uses a proprietary blend of water, halides, additives, and buffering agents that enhances zinc solubility and prevents the dendrite formation that has historically limited zinc electrode cycle life, has been commercialised in the Z3 battery module whose bipolar electrode design reduces internal resistance and improves round-trip efficiency compared with monopolar zinc battery designs. Eos's Z3 system targets the four to sixteen hour discharge duration market where its aqueous chemistry's non-flammable safety profile and its lower raw material cost relative to lithium-ion create the commercial differentiation that its target utility-scale, microgrid, and commercial and industrial customers can translate into lower insurance costs, simplified siting approvals, and the operational reliability that multi-day grid storage requirements demand. Its manufacturing facility in Turtle Creek, Pennsylvania and its US-sourced supply chain create the domestic manufacturing position that the US Inflation Reduction Act's domestic content requirements support for the utility-scale storage market.
Zinc8 Energy Solutions, a Canadian zinc-air battery company, takes a different approach to zinc-based long-duration storage whose zinc-air chemistry uses atmospheric oxygen as the cathode reactant rather than a solid cathode material, creating a system whose energy capacity is determined by the volume of zinc fuel rather than by the electrochemical cell stack size. The zinc-air architecture's separation of energy capacity from power capacity allows the storage duration to be extended by adding zinc fuel without increasing the electrochemical stack, creating a scalable long-duration storage system whose economics differ from flow battery scaling models and whose twenty thousand hour operating life claim substantially exceeds the cycle life of conventional battery systems whose calendar and cycle degradation affects their economic performance over the decade-scale operational lifetime that grid storage investment requires.
The Long-Duration Storage Market Opportunity
The commercial opportunity for long-duration energy storage is driven by the operational requirements of electricity grids whose renewable energy penetration is increasing the frequency and duration of periods during which generation exceeds demand and the periods during which demand exceeds renewable generation output. A grid with fifty percent or more renewable penetration experiences the daily mismatch between solar generation, which peaks at midday when demand is lower and produces nothing at night when evening demand peaks, that two to four hour lithium-ion storage can partially address for daily cycling but cannot address for the multi-day periods of low wind and solar output that renewable-heavy grids must manage through some combination of storage, dispatchable generation, and demand response. The four to one hundred hour discharge duration market that zinc-based and other long-duration storage technologies address is the fastest-growing segment of the grid storage market whose growth is directly proportional to the renewable energy penetration of the grids being served.
Top 10 Companies in Zinc-Based Long-Duration Energy Storage Globally
- Eos Energy Enterprises: US zinc hybrid cathode battery company with the Znyth Z3 system targeting four to sixteen hour grid, microgrid, and commercial storage; its US manufacturing in Pennsylvania, non-flammable aqueous chemistry, and IRA-compliant domestic content create the commercial long-duration zinc storage position in the utility and commercial market whose safety and supply chain advantages over lithium-ion are commercially significant.
- Zinc8 Energy Solutions: Canadian zinc-air battery company with twenty thousand hour operating life and scalable energy capacity through zinc fuel volume; its zinc-air chemistry separation of power and energy capacity creates the long-duration storage architecture whose marginal cost of additional storage hours is lower than electrochemical stack-based systems.
- EnerPoly: Swedish zinc-ion battery company with aqueous zinc-ion chemistry for stationary storage; its Scandinavian manufacturing and its grid storage focus create the European long-duration zinc storage commercial position whose regulatory environment and electricity market structure favour non-lithium chemistry alternatives.
- ZincFive: US zinc-nickel battery company with UPS and data centre battery backup applications; its zinc-nickel chemistry whose fifteen minute to two hour discharge duration and non-flammable safety profile address the uninterruptible power supply market where fire risk in densely occupied data centre facilities makes non-flammable battery chemistry a procurement priority.
- Salient Energy: Canadian zinc-ion battery startup with aqueous zinc-ion cells targeting residential and commercial storage; its focus on the behind-the-meter storage market where safety certification and installation simplicity matter creates the zinc-ion commercial pathway in the consumer-adjacent storage segment that residential solar-plus-storage adoption is developing.
- Renais Power: UK zinc battery developer with zinc-based flow battery technology for long-duration grid applications; its flow battery architecture separates the zinc electrolyte from the power stack in a configuration whose degradation behaviour differs from solid-electrode zinc batteries and whose scalability follows the flow battery scaling model that vanadium flow batteries have demonstrated commercially.
- Urban Electric Power: US zinc-manganese dioxide battery company with rechargeable alkaline chemistry for stationary storage; its manganese dioxide cathode and zinc anode in an alkaline electrolyte create the rechargeable alkaline battery whose raw material abundance and non-toxicity provide the environmental and supply chain profile that its commercial grid storage customers value.
- Verdagy: US electrolyser and energy storage company with interests in zinc-based storage alongside its primary electrolyser business; its electrochemical engineering expertise and its grid storage market relationships create the commercial context for zinc-based long-duration storage within a broader electrochemical energy storage and conversion company.
- Imprint Energy: US printed zinc battery company with printed zinc-manganese oxide batteries for IoT and wearable applications; its printing-based manufacturing and its thin, flexible battery form factor create the zinc battery commercial position in the IoT sensor and wearable device market where the printed battery's geometric flexibility and non-toxic chemistry serve the application requirements that coin cell lithium batteries do not address.
- Gelion: Australian zinc-bromide battery company with gel electrolyte technology for stationary storage; its gel zinc-bromide chemistry that reduces the bromine handling complexity of conventional zinc-bromide flow batteries and its Australian market focus create the Pacific region zinc-based long-duration storage commercial position.