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Executive Summary: What are the Top 10 Flow Battery Companies & Startups to Watch in 2026?

  1. TerraFlow (USA): develops long-duration, fire-safe flow battery systems (vanadium and organic chemistries) that provide 10+ hours of discharge and real-time power conditioning for data centers and grid applications.​
  2. Zenthos (USA): building next-generation aluminum-CO2 flow batteries that combine grid-scale, long-duration energy storage with simultaneous carbon capture using abundant materials.​
  3. QuadriE (Netherlands): developing low-cost organic redox flow batteries with a proprietary high-energy-density reactor concept to deliver highly sustainable and economical long-duration storage.​
  4. ZH Energy (China): ZH Energy develops a non-fluorinated polybenzimidazole (PBI) ion exchange membrane for flow batteries.​
  5. Poseidon (Italy): creates a scalable redox flow battery using earth-abundant materials and a storage-as-a-service model to deliver sustainable long-duration energy storage.​
  6. Litricity (Germany): a deep-tech startup developing a highly scalable liquid, water-based battery that stores electricity in an aqueous solution for long-duration, grid-stabilizing applications.​
  7. Compular (Sweden): provides software tools that use molecular dynamics and AI to optimize liquid electrolytes, helping battery developers design better flow batteries and other electrolyte systems faster.​
  8. HalioGen Power (UK): develops a membraneless redox flow battery using abundant, non-flammable materials to offer resilient, sustainable, and affordable long-duration energy storage.​
  9. Tharam-Thiran (India): manufactures a sulfur-iron flow battery that uses abundant, low-cost electrolytes to deliver safe, long-duration backup beyond 20 hours.​
  10. Aqua-Cell Energy (Canada): builds industrial saltwater flow batteries that use low-cost saline electrolytes to provide 12-24 hours of long-duration storage as a safer, more affordable alternative to lithium-ion systems.​

 

 

Meet Emerging Flow Battery Companies & Startups to Watch in 2026

We hand-picked startups to showcase in this report by filtering for their technology, founding year, location, funding, and other metrics. These emerging flow battery startups work on solutions ranging from saltwater and aluminum-CO2 designs to sustainable redox chemistries and membrane innovations.

1. TerraFlow – Long Duration Organic Flow Battery

  • Founding Year: 2024
  • Location: Bellville, TX, USA

US-based startup TerraFlow develops long-duration organic flow batteries for commercial and grid-scale energy storage. The startup’s batteries utilize organic chemistry to combine two flow battery chemistries that include vanadium and organically sourced materials. It offers higher cycles without risk of thermal runaway or degradation.

The modular systems integrate instant power supply and uninterruptible backup. It also offers real-time harmonic filtering into a single platform that enables flexible and resilient power delivery for data centers, utilities, and industrial operations.

The startup’s battery uses non-flammable electrolytes. The battery offers higher rapid response to load changes and full-discharge capabilities than traditional lithium-ion batteries in safety, cycle life, and environmental sustainability.

The startup’s flow battery solutions enhance grid stability, maximize renewable energy use, and reduce both infrastructure costs and environmental impact for long-term value in high-demand energy environments.

2. Zenthos – Aluminum-CO2 flow batteries

  • Founding Year: 2023
  • Location: Albuquerque, NM, USA

US-based startup Zenthos develops aluminum-CO2 flow batteries that combine high-density energy storage with integrated carbon capture. The startup offers a modular and long-duration solution for grid and site-scale applications. The technology stores energy by moving ions between two stable electrodes within a sealed, non-flammable system.

Zenthos achieves up to 24 hours of discharge capacity and operates reliably in extreme temperatures down to -40°C. The startup utilizes recycled aluminum and in-situ CO2 sequestration during battery operation.

It enables supply chain resilience through reliance on abundant domestic metals. Zenthos creates a non-thermal runaway design that enhances safety and longevity.

Zenthos’ sustainable and scalable energy storage platform enables demand-charge management, renewables integration, and microgrid deployments, supporting the transition to a cleaner and more resilient energy ecosystem.

3. QuadriE – Aqueous Organic Redox Flow Batteries

  • Founding Year: 2022
  • Location: Eindhoven, Netherlands

Dutch startup QuadriE develops aqueous organic redox flow batteries for sustainable and cost-effective stationary energy storage.

It uses organic redox couples in an aqueous electrolyte that undergo reversible oxidation and reduction reactions to store and release energy. The battery’s proprietary cell reactor concept enhances energy density.

QuadriE’s reactor design and the use of synthesizable organic redox materials reduce the overall costs of flow batteries. This creates a reliable system that balances fluctuations between energy production and consumption.

The startup’s technology offers a sustainable alternative to traditional energy storage solutions. This supports the integration of renewable energy sources and stabilizes power supply networks.

4. ZH Energy – PBI Flow Battery

  • Founding Year: 2021
  • Location: Shenzhen, China

ZH Energy is a Chinese startup that develops a non-fluorinated polybenzimidazole (PBI) ion exchange membrane for flow batteries. It utilizes modifications of engineering plastic to achieve a balance of proton conductivity, vanadium ion selectivity, mechanical strength, and cost efficiency.

The startup’s membrane attains commercial-level proton conductivity while reducing vanadium ion permeability by an order of magnitude. This makes it especially suited for vanadium redox and titanium-bromine flow battery applications.

The startup features an ultra-thin 25 μm thickness and enhances tensile and puncture strength. The startup’s membrane offers sustained reliability and operational durability.

The membrane is environmentally friendly, which eliminates perfluorinated compound (PFC) pollution, and is both green and biodegradable. ZH Energy drives both the flow battery industry’s technological progress and its transition toward cost-effective, sustainable energy storage solutions.

5. Poseidon – Sustainable Redox Flow Battery

  • Founding Year: 2022
  • Location: Assemini, Italy

Italian startup Poseidon offers a redox flow battery that uses zinc-hydrogen peroxide chemistry and a seawater-based electrolyte to provide a cost-efficient, durable, and scalable energy storage solution.

The startup’s technology operates by circulating these earth-abundant active materials in liquid form through an external cell where reduction and oxidation reactions produce electricity. The energy and power are independently scalable with adjustments in the volume of electrolyte and cell stack size.

Poseidon offers up to 15,000 charge-discharge cycles with no self-discharge. The battery uses non-flammable and non-toxic materials to reduce environmental impact. The system’s patent-pending configuration minimizes supply chain constraints and offers effortless scalability. This benefits medium-sized enterprises experiencing variable energy needs.

 

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6. Litricity – Water-based Redox Flow Battery

  • Founding Year: 2020
  • Location: Grafelfing, Germany

German startup Litricity develops a water-based redox flow battery that stores electrical energy using two liquid salt solutions housed in separate tanks.

It pumps through electrochemical stacks to bind and release electrons. This technology achieves efficient long-term storage by allowing independent scaling of power and capacity.

The startup’s battery maintains minimal self-discharge and offers high energy and power densities compared to conventional lithium-ion systems. The battery operates safely due to its non-toxic and non-flammable water-based composition.

The startup offers affordable energy solutions across large-scale applications up to the gigawatt-hour range. It also supports fast charging and discharging cycles alongside superior cycle stability and efficiency.

7. Compular – Liquid Electrolyte Optimization

  • Founding Year: 2020
  • Location: G0teborg, Sweden

Swedish startup Compular optimizes liquid electrolytes through its molecular dynamics simulation platform, Compular Lab. The software models atomistic interactions in liquid electrolytes to predict key physical and electrochemical properties such as ionic conductivity, diffusivities, transference number, density, viscosity, electrical mobility, and HOMO-LUMO levels.

The startup’s automated workflows enable battery R&D professionals to execute complex simulations with minimal setup. This produces reliable insights without requiring prior expertise in atomistic modeling.

The patented analysis methodology reveals microscopic structural dynamics, including lithium-ion solvation and coordination patterns. This allows researchers to understand electrolyte behaviors at a fundamental level.

Then provide precise predictive data and structural insights, allowing material scientists and engineers to identify and compare optimal electrolyte compositions rapidly.

8. HalioGen Power – Membraneless Redox Flow Battery

  • Founding Year: 2023
  • Location: Manchester, UK

UK-based startup HalioGen Power develops a membraneless redox flow battery that eliminates the need for expensive, non-recyclable membranes and flammable components. It utilizes a chemistry that directly separates charge without a physical barrier.

The startup’s technology operates across a broad power range from 10 kW to multiple megawatts. It delivers over 10 hours of discharge per cycle and maintains reliability, durability, and efficiency for more than 20 years.

The startup’s battery outputs stable energy in environments ranging from -5°C to 50°C without requiring a cooling system. It removes the costly membrane component and optimizes the battery for high energy density.

HalioGen Power reduces system installation footprint and eliminates cooling overhead. This offers an affordable and scalable solution for commercial and industrial energy storage.

9. Tharam-Thiran – Iron-Sulfur Redoc Flow Battery

  • Founding Year: 2020
  • Location: Chennai, Tamil Nadu

Indian startup Tharam-Thiran develops an iron-sulfur redox flow battery that addresses energy storage for both grid and off-grid renewable applications. The startup utilizes a scalable and modular flow battery architecture.

The technology decouples power from energy by enabling flexible capacity expansion simply by increasing the electrolyte volume. The proprietary membrane engineering matches the specific chemistry of iron and sulfur for improved system durability and cost optimization.

With the use of abundant, non-toxic materials instead of rare earth metals, the startup achieves an economical solution for long-duration storage exceeding 20 hours. It supports applications such as rural electrification, renewable energy time-shifting, and load balancing.

10. Aqua-Cell Energy – Salt Water Flow Batteries

  • Founding Year: 2025
  • Location: Toronto, Canada

Canadian startup Aqua-Cell Energy offers modular saltwater flow batteries that enable affordable, long-duration solar power storage for commercial buildings, industrial facilities, and grid operators.

The technology circulates saltwater through a battery stack, where it stores energy via an electrochemical process and later releases electricity by reversing the flow.

The startup includes the use of low-cost, abundant saltwater as the electrolyte and reliance on membrane technology adapted from water-treatment supply chains. This allows for scalable, safer deployment and cost reductions compared to lithium-ion and pumped hydro alternatives.

Each battery offers 12 to 24 hours of stable storage, which is scalable simply by increasing saltwater volume, providing flexibility and minimizing reliance on scarce minerals.

Discover All Emerging Flow Battery Startups

The 10 flow battery startups showcased in this report are only a small sample of all startups we identified through our data-driven startup scouting approach. Download our free Industry Innovation Reports for a broad overview of the industry or get in touch for quick & exhaustive research on the latest technologies & emerging solutions that will impact your company in 2026!