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TECHNOLOGY

Details

How PowerCube works

During the charging and discharging processes, the following reactions take place in both sides of the cell:

At positive side

During charging
VO2++H2O→VO2++2H++ e
During discharging
VO2++2H++e→VO2++H2O

E0= 1.0 V

At negative side

During charging
V3+ + 2e →V2+
During discharging
V2+→ V3+ + 2e

E0= -0.255 V

Overall reaction

V2+ + VO2+ + 2H+ ↔ V3+ + VO2+ + H2O
E0= 1.255 V

Unlike lithium-ion and lead acid batteries, flow batteries work differently. The liquid electrolyte are stored outside the battery in external tanks. This give flow batteries flexibility to design power (which depends on the size of the battery stack) and energy (which depends on the volume of electrolyte stored in tanks) independently. There are different chemistries available in flow batteries, out of which all-vanadium flow battery stores vanadium metal ions at different oxidation states in two tanks. Vanadium flow battery is one of the mature and proven technology in the market and provides more than 25 years of life and stable performance. The working principle is simple. Vanadium has four oxidation states, out of which V2+ and V3+ serve as negative redox couple whereas VO2+(V4+) and VO2+(V5+)serve as positive redox couple. The oxidation states of the vanadium ions continuously changes during charging (V4+ to V5+ and V3+ to V2+) and discharging (V5+ to V4+ and V2+ to V3+) and battery works for infinite cycles with no capacity fade and electrolyte degradation. In addition, V-Flow uses unique additive mixture on the electrolyte that improves the thermal stability and allows to increase the energy density by 25% compared to others.

TECHNOLOGY AND COST COMPARISON

Compared to Lead acid and Li-ion batteries, PowerCube provides:
  • Levelised cost of storage (LCOS) as low as 10 cents/kWh
  • Lifespan of 25 years, 24 X 7 operation
  • Operation from -10 to +55◦ C without active cooling
  • Constant power and energy guarantee over the lifetime
  • Modular design with flexibility of changing the power and energy independently, even after installation
  • 100% depth of discharge
  • No safety issues with over-charging or over-discharging, non-toxic chemistry
  • No thermal runaway
  Lead Acid Batteries Lithium ion Batteries V-Flow Power Cube
Lifetime 2-3 years 3-8 years 25 years
Environmental & safety issue Lead is an issue Highly flammable No emission,not flammable
Energy density (Wh/Kg) 30 100-150 25-30
Performance degradation Yes Yes Non degradation, stable performance guarantee
Maintenance Frequent Frequent Very low maintenance
Storage cost - LCOS($/cycle/Kwh) 0.31 0.21 0.10

Case Study: V-Flow vs Li-ion Solution

Research & Publications

You can find out more about our research and scientific proof of our technology here.