Low Profile Pressure Disconnect for Li-Ion Battery Safety
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Solution Overview
Problem
Lithium ion batteries face challenges in achieving higher energy density and lower manufacturing costs while ensuring safety, as densely packed cells risk cascading failures leading to explosions and fires due to abuse, and existing venting and pressure disconnect technologies are inadequate in preventing flashback and premature vent opening.
Innovation Solution
The design includes a casing with a deflectable dome structure and a fuse assembly positioned externally, which electrically isolates lithium ion battery components upon pressure buildup, combined with a vent structure and flame arrestor to manage pressure and prevent fires, allowing for directional flexibility and lower activation pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium ion cells are densely packed to achieve higher energy density, then energy density is improved, but the risk of cascading failures leading to explosions and fires increases
Solution Approach 1:
The battery system is divided into multiple independent battery packs, each with its own pressure disconnect device and venting system. This segmentation isolates potential failures to individual packs, preventing cascading failures across the entire battery system while maintaining high energy density through close packing of protected cells.
Solution Approach 2:
A pressure disconnect device acts as an intermediary safety mechanism between the battery cells and the external environment. When internal pressure exceeds a threshold, the device disconnects the electrical circuit and directs pressure through a controlled path to a venting system, preventing uncontrolled thermal runaway and fire propagation to adjacent cells.
2Stress or pressure
If existing venting and pressure disconnect technologies are used, then pressure release is achieved, but flashback prevention and premature vent opening control are inadequate
Solution Approach 1:
The pressure disconnect device is pre-configured with a disconnect mechanism that activates before the vent opens. When pressure reaches a threshold, the electrical circuit is immediately disconnected and the vent path is prepared, preventing flashback by ensuring no electrical ignition source remains when the vent opens. This preliminary action ensures reliable operation without premature venting.
3Ease of manufacture
If higher energy density is achieved through denser cell packing, then manufacturing cost per kWh is reduced, but safety risks from thermal runaway increase
Solution Approach 1:
The battery system is divided into multiple independent battery packs, each with its own pressure disconnect device and venting system. This segmentation isolates potential failures to individual packs, preventing cascading failures across the entire battery system while maintaining high energy density through close packing of protected cells.
Solution Approach 2:
A pressure disconnect device acts as an intermediary safety mechanism between the battery cells and the external environment. When internal pressure exceeds a threshold, the device disconnects the electrical circuit and directs pressure through a controlled path to a venting system, preventing uncontrolled thermal runaway and fire propagation to adjacent cells.
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
This design effectively prevents cascading failures by isolating electrical components and managing pressure, reducing the risk of explosions and fires, while enabling higher energy density and lower manufacturing costs through safer and more reliable venting mechanisms.
Implementation Method 1
a pressure disconnect device associated with the container/assembly... adapted, in response to a build-up of pressure within the container/assembly beyond a threshold pressure level
Implementation Method 2
a flame arrestor positioned in proximity to the vent structure... configured and dimensioned to reduce the temperature of an exiting gas stream below its auto-ignition temperature
Data Source
AI summary
Casings for lithium ion batteries are provided that include a container or assembly that defines a base, side walls and a top or lid, and a vent structure associated with the container or assembly. A flame arrestor may be positioned in proximity to the vent structure. The lithium ion battery may also include a pressure disconnect device associated with the casing. The pressure disconnect device may include a deflectable dome-based activation mechanism, and the deflectable dome-based activation mechanism may be configured and dimensioned to prevent burn through, e.g., by increasing the mass of the dome-based activation mechanism, adding material (e.g., foil) to the dome-based activation mechanism, and combinations thereof. Burn through may also be avoided, at least in part, based on the speed at which the dome-based activation mechanism responds at a target trigger pressure.