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"Best Yet” Battery Design to Stabilise Solar Power for Grid
"Best Yet” Battery Design to Stabilise Solar Power for Grid
WRITTEN BY SANDRA HENDERSON | 05 MAY 2013
...“In this new battery, the positive electrode is concentrated lithium polysulfide in organic solvent and the negative electrode is metallic lithium. The polysulfide solution is stored in a separated tank; when the battery needs to be charged or discharged, the solution would flow to the battery and electrochemical reactions happen. In downtime, the liquid positive electrode stays in the tank,” explains Yi Cui, an associate professor at Stanford and member of the Stanford Institute for Materials and Energy Sciences (SIMES). “This design is easy to scale up. The materials, such as lithium and sulphur and solvent, are all relatively cheap.”
The new battery furthermore solves the low energy density issue. Traditional flow batteries used in grid-scale energy storage, such as vanadium flow battery (VRB), typically display low solubility of active materials in water solvents, and the voltage is limited by the small stability-window of water (1.23 V). “In our new system, the solubility of active materials is much higher than VRB. The voltage is also close to twice of that of conventional flow batteries,” Cui says.
The most expensive component in previous system designs is the ion-selective membrane widely used in flow batteries to keep two electrolytes from intermixing. “By forming a high-quality passivation layer on the surface of the lithium negative electrode, the direct chemical reaction between lithium and the polysulfide solution is avoided and the system is free-of-membrane,” Cui says. This new approach could significantly lower the overall cost of the system further, which could reduce the total cost of electricity generated from solar compared with other energy storage systems.”
In lab tests, Cui and his team achieved 2400 cycles with an energy density of 37 Wh/L and 1500 cycles with an energy density of 71 Wh/L. According to the nanoscale materials expert with a PhD from Harvard, 2400 cycles is equivalent to 6.6-year operation, based on daily operation. “The energy density of our batteries is likely to go much higher over time, which will help reduce the cost greatly,” he says. The energy density of traditional vanadium flow battery by comparison is only 30 Wh/L, indicating that the cycling and energy density of the new system are “very attractive for grid-level application,” making it an “attractive candidate for large-scale energy storage, such as solar power plants, wind farms and buildings.” The system’s low-cost materials combined with a long cycle life and high energy density could enable the intermittent solar energy to become a stable supply of grid electricity. “The simple design also significantly reduces the cost of energy storage and its applications can be extended to other stationary energy storage systems such as those used in load balancing and peak shaving for the grid,” Cui adds.
Confident about...
WRITTEN BY SANDRA HENDERSON | 05 MAY 2013
...“In this new battery, the positive electrode is concentrated lithium polysulfide in organic solvent and the negative electrode is metallic lithium. The polysulfide solution is stored in a separated tank; when the battery needs to be charged or discharged, the solution would flow to the battery and electrochemical reactions happen. In downtime, the liquid positive electrode stays in the tank,” explains Yi Cui, an associate professor at Stanford and member of the Stanford Institute for Materials and Energy Sciences (SIMES). “This design is easy to scale up. The materials, such as lithium and sulphur and solvent, are all relatively cheap.”
The new battery furthermore solves the low energy density issue. Traditional flow batteries used in grid-scale energy storage, such as vanadium flow battery (VRB), typically display low solubility of active materials in water solvents, and the voltage is limited by the small stability-window of water (1.23 V). “In our new system, the solubility of active materials is much higher than VRB. The voltage is also close to twice of that of conventional flow batteries,” Cui says.
The most expensive component in previous system designs is the ion-selective membrane widely used in flow batteries to keep two electrolytes from intermixing. “By forming a high-quality passivation layer on the surface of the lithium negative electrode, the direct chemical reaction between lithium and the polysulfide solution is avoided and the system is free-of-membrane,” Cui says. This new approach could significantly lower the overall cost of the system further, which could reduce the total cost of electricity generated from solar compared with other energy storage systems.”
In lab tests, Cui and his team achieved 2400 cycles with an energy density of 37 Wh/L and 1500 cycles with an energy density of 71 Wh/L. According to the nanoscale materials expert with a PhD from Harvard, 2400 cycles is equivalent to 6.6-year operation, based on daily operation. “The energy density of our batteries is likely to go much higher over time, which will help reduce the cost greatly,” he says. The energy density of traditional vanadium flow battery by comparison is only 30 Wh/L, indicating that the cycling and energy density of the new system are “very attractive for grid-level application,” making it an “attractive candidate for large-scale energy storage, such as solar power plants, wind farms and buildings.” The system’s low-cost materials combined with a long cycle life and high energy density could enable the intermittent solar energy to become a stable supply of grid electricity. “The simple design also significantly reduces the cost of energy storage and its applications can be extended to other stationary energy storage systems such as those used in load balancing and peak shaving for the grid,” Cui adds.
Confident about...
http://www.solarnovus.com/index.php?option=com_content&view=article&id=6516:best-yet-battery-design-to-stabilise-solar-power-for-grid-&catid=52:applications-tech-research&Itemid=247
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