CO2 Cooling for Energy Storage Safety
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Solution Overview
Problem
High-energy density batteries, such as lithium-ion and lithium-polymer batteries, face safety issues due to thin separators prone to cracking and low thermal stability, leading to potential short circuits and uncontrolled temperature increases, which can result in fires and explosions, especially with flammable organic solvents used as electrolytes.
Innovation Solution
A method utilizing a control device with temperature, pressure, and possibly state-of-charge sensors to rapidly deploy a pressurized gaseous circulating medium, like carbon dioxide, which exploits the positive Joule-Thomson effect for efficient cooling and fire suppression, preventing critical temperature rises and potential fires by targeting the energy storage device with a controlled cooling system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thin separators are used to increase energy density, then energy per volume is improved, but thermal stability and reliability deteriorate
Solution Approach 1:
A gel layer is introduced as an intermediary substance between the electrodes and thin separator. This gel layer acts as a protective intermediary that prevents direct contact between electrodes when the separator fails, while allowing ionic transport to continue. The gel layer compensates for the reduced mechanical stability of thin separators without compromising energy density.
Solution Approach 2:
The gel layer serves as a pre-positioned protective cushion between the electrodes. Before any potential short circuit can occur due to separator failure, the gel layer is already in place to prevent direct electrode contact. This beforehand cushioning mechanism ensures that even if the thin separator fails, catastrophic short circuits are prevented.
2Ease of manufacture
If polyolefinic separators are used for lithium batteries, then manufacturing ease is improved, but thermal stability deteriorates
Solution Approach 1:
The system uses a composite structure combining the polyolefinic separator with a gel layer containing inorganic particles and binders. This composite material approach maintains the manufacturing advantages of polyolefins while adding thermal stability through the gel layer that remains stable at higher temperatures and prevents electrode contact even when the separator melts.
3Reliability
If fuses are installed to protect against short circuits, then reliability is improved, but response speed deteriorates due to fuse inertia
Solution Approach 1:
The gel layer is pre-positioned between the electrodes before any short circuit can occur. This preliminary protective measure is always in place, eliminating the need for delayed response systems like fuses. When a short circuit attempt occurs, the gel layer immediately prevents electrode contact without any response delay.
Solution Approach 2:
The gel layer converts the potential harmful effect of separator failure into a benign situation. Instead of allowing direct short circuits when separators fail, the gel layer absorbs the mechanical stress and prevents contact, transforming what would be a catastrophic failure mode into a non-critical event that doesn't require rapid protective intervention.
4Quantity of substance
If separator thickness is reduced to increase energy density, then energy per volume is improved, but susceptibility to cracking deteriorates
Solution Approach 1:
The gel layer serves as a protective intermediary that compensates for the vulnerability of thin separators. Even when cracks develop in the thin separator, the gel layer fills and seals these cracks, preventing them from progressing into catastrophic failures. This intermediary protection allows the use of thinner separators without increasing crack susceptibility risks.
Solution Approach 2:
The gel layer provides beforehand cushioning against crack propagation. Before cracks can lead to electrode contact and short circuits, the gel material is already in place to absorb and distribute mechanical stresses, preventing crack propagation and protecting the thin separator structure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents catastrophic temperature increases and potential fires by rapidly cooling the energy storage device before a malfunction occurs, enhancing safety and reducing the need for expensive fire protection measures.
Implementation Method 1
A method utilizing a control device with temperature, pressure, and possibly state-of-charge sensors to rapidly deploy a pressurized gaseous circulating medium, like carbon dioxide, which exploits the positive Joule-Thomson effect for efficient cooling and fire suppression
Data Source
Figure 1
Figure 2
AI summary
The arrangement has an air conditioning unit (1) and an energy storage unit (2), where the air conditioning unit includes a circulation medium that is accommodated in a container (3). The circulation medium consists of carbon dioxide, where the circulation medium is discharged from the container by a control device (4). The control device feeds the circulation medium of the air conditioning unit to the energy storage unit. The energy storage unit is partially surrounded by a casing that is designed as an inflatable balloon. An independent claim is also included for a method for cooling or removing heat from an energy storage unit by using an arrangement.