The energy density of thermal energy storage (TES) systems generally varies widely depending on the specific technology used, but it is typically much lower than that of lithium-ion batteries.
Thermal Energy Storage Energy Density:
- Sensible heat TES systems, which store energy by raising the temperature of a medium like water or solid materials, have relatively low energy densities, generally around 10 to 50 kWh per ton (equivalent to roughly 10–50 kWh/1000 kg), or about 25 kWh/m³ for typical sensible heat storage materials.
- Phase Change Materials (PCMs), which store energy via solid-liquid phase transitions, offer higher energy densities, on the order of 100 kWh/m³ (e.g., ice), providing greater storage capacity at a given volume.
- Thermo-chemical storage (TCS) can reach even higher energy densities, up to about 250 kWh per ton, with high efficiencies and operation temperatures above 300°C.
- A recent advanced form of sorption-based thermal battery demonstrated an ultrahigh energy density of about 1580 Wh/kg (or 1.58 kWh/kg), which is roughly 5.7 MJ/kg, for space heating applications — a record value for thermal storage of this type.
Lithium-Ion Batteries Energy Density:
- Typical commercial lithium-ion batteries have energy densities around 100 to 265 Wh/kg (0.1 to 0.265 kWh/kg), and volumetric energy densities of about 250 to 700 Wh/L, depending on the battery chemistry and design.
Comparison:
| Storage Type | Energy Density (Wh/kg) | Energy Density (Wh/L or kWh/m³) |
|---|---|---|
| Sensible Heat TES | ~10–50 kWh/ton (~10–50 Wh/kg) | ~25 kWh/m³ (~25,000 Wh/m³) |
| Phase Change Material TES | ~100 kWh/m³ (~100,000 Wh/m³) | ~100 kWh/m³ |
| Thermo-chemical Storage (TCS) | ~250 kWh/ton (~250 Wh/kg) | Varies, potentially higher |
| Advanced Sorption Thermal Battery | ~1580 Wh/kg (1.58 kWh/kg) | Not precisely volumetric stated |
| Lithium-Ion Batteries | 100 – 265 Wh/kg | 250 – 700 Wh/L (250,000 – 700,000 Wh/m³) |
- Lithium-ion batteries far exceed common TES technologies in gravimetric energy density, typically offering several hundred Wh/kg, compared to TES sensible heat storage that is an order of magnitude lower.
- Volumetrically, lithium-ion batteries also possess higher energy densities, roughly several hundred Wh per liter, whereas sensible heat TES is usually less energy-dense by volume, though PCMs and thermo-chemical systems improve this somewhat.
- The exception is the novel sorption thermal battery system with an energy density (~1580 Wh/kg) exceeding that of lithium-ion batteries by about 6 times, representing a breakthrough in thermal storage density. However, this technology is likely still in development and for specific applications like space heating rather than general electrical energy storage.
In summary:
- Conventional TES systems generally have much lower energy densities than lithium-ion batteries, especially on a gravimetric basis.
- Phase change materials and thermo-chemical TES improve energy density but still mostly remain below lithium-ion battery levels.
- New advanced sorption-based thermal storage approaches have demonstrated energy densities surpassing lithium-ion batteries, suggesting promising developments for thermal energy storage technology in the future.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-energy-density-of-thermal-energy-storage-compare-to-lithium-ion-batteries/
