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SPIRAL REDOX FLOW BATTERY

Next-Generation Long-Duration Energy Storage

A compact, cylindrical energy storage system with an environmentally friendly electrolyte — designed for stable power distribution, high power density, cost-effective manufacturing, and minimal operating costs.

Renewable energy is now the most cost-effective form of electricity generation — but it is inherently intermittent. Solar power only generates electricity when the sun is shining, and wind turbines only produce energy when the wind is blowing. Without reliable large-scale energy storage, surplus renewable energy is wasted, power grids become unstable, and fossil-fuel backup plants remain necessary.

Europe urgently needs a safer, lower-cost, and highly scalable solution for long-duration energy storage to complete the energy transition.

German Innovation for Europe's Energy Future

Overview Fields of application

  • Utility-Scale Long-Duration Energy Storage:
    Storing excess solar and wind energy for hours or days.
  • Grid Stabilization:
    Providing reliable baseload power and peak shaving.
  • Industrial Microgrids:
    Ensuring energy independence and security for large manufacturing plants.
  • Backup Power:
    Delivering uninterrupted, long-duration backup power for large consumers such as data centers and hospitals.
  • Insular & Off-Grid Solutions:
    Serving as the energy storage component of completely self-sufficient energy systems for remote communities or isolated facilities.

Innovative Cell Technology + Scalable System Architecture = Long-Duration Energy Storage for Tomorrow

Revolutionary Lightweight Design

The SW-RFB replaces heavy graphite plates with thin conductive foils. This reduces weight and material costs while enabling efficient high-volume manufacturing.
Built on Spiraltec's proven industrial spiral-winding and resin potting technologies.

Safe & Durable System Architecture

Hermetic resin potting instead of gaskets
Leak-proof and low-maintenance design
20+ year operational lifetime without capacity degradation

Sustainable & Resource-Efficient

Vanadium-free electrolyte
The water-based electrolyte completely eliminates the risk of thermal runaway, fire, and toxic gas emissions.
Free from lithium, cobalt, nickel and other critical raw materials

Scalable Energy Storage Platform

Independent scaling of power and energy capacity
flexible design: Easy capacity expansion through larger electrolyte tanks
Ideal for long-duration storage

The Spiraltec SW-RFB is more than a battery — it is a platform for enabling reliable renewable energy at scale. By combining safer chemistry, lower-cost materials, scalable modular design, and long operational life, the technology offers a realistic path toward affordable, long-duration energy storage for Europe and global renewable grids.

The Challenge: Limitations of Current Energy Storage

1. Lithium-Ion and Sodium-Ion Batteries: Safety and Sustainability Challenges

Lithium-ion (Li-ion) batteries currently dominate the short-duration energy storage market, while sodium-ion (Na-ion) batteries are becoming increasingly important. However, both technologies face significant challenges when used for utility-scale energy storage:

• Fire and safety risks: Both lithium-ion and sodium-ion batteries are susceptible to thermal runaway. In the event of a fire, they are difficult to extinguish and release highly toxic and corrosive gases, including hydrogen fluoride (HF).

As a result, utility-scale energy storage systems require sophisticated monitoring, control, and fire protection systems.

• Critical raw materials: Lithium-ion batteries rely on critical raw materials such as lithium, cobalt, and nickel, many of which are sourced under challenging or ethically questionable conditions.

• Limited operational lifetime: Their energy storage capacity gradually declines with each charge and discharge cycle.
2. Conventional Vanadium Redox Flow Batteries (VRFB)

Conventional redox flow batteries overcome the safety and lifespan limitations of other battery technologies, but they introduce their own challenges:

• Heavy and expensive: Conventional VRFBs are based on bulky graphite bipolar plates and heavy compression frames (plate-and-frame design).

These components account for a significant share of the battery's weight and volume, making manufacturing, transportation, and installation more complex. Utility-scale energy storage systems therefore require large and costly building infrastructure.

• Critical raw materials and geopolitical dependence: Vanadium is a critical and expensive raw material with highly volatile market prices. In addition, the supply chain is heavily concentrated geographically, with around 90% of global production originating from China, Russia, and South Africa.

• Leakage risk: Conventional gasket sealing systems are prone to leakage. Escaping vanadium electrolyte is highly toxic and extremely corrosive, posing significant safety and environmental risks.

The Solution: Spiraltec's Spiral-Wound Redox Flow Battery (SW-RFB)

Building on long-standing expertise in spiral-wound membrane technology, Spiraltec is developing a revolutionary, highly scalable energy storage platform: the Spiral-Wound Redox Flow Battery (SW-RFB). By redesigning the battery architecture from the ground up, we have eliminated the heavy frames and expensive materials of conventional flow batteries, creating a lightweight, safe, and truly sustainable solution for utility-scale energy storage.

Lightweight electrode design

• Uses thin graphite-coated copper foils

• Reduces weight and material cost significantly

Permanent hermetic sealing

• Potting resin creates a maintenance-free seal

• Prevents leaks and long-term mechanical failure

Vanadium-free electrolyte

• Developed with Allegro Energy

• Non-hazardous and non-aggressive chemistry

• Compatible with low-cost materials

The SW-RFB is designed specifically for utility-scale, long-duration energy storage.

• Long operational life

• No lithium, cobalt, or vanadium

• No thermal runaway or fire risk

• Minimal degradation over time

• Fully modular and scalable to GW level

• Low maintenance requirements

• Recyclable and environmentally friendly

Unlike lithium-ion batteries, the SW-RFB separates energy capacity from power output. This means storage duration can be increased simply by adding more electrolyte — without redesigning the battery system.

Cooperation

Are you interested in further developing the product together with us

or testing our prototype RFB at your company?

Please contact us:

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