Electrode Assembly Safety Layer for Battery Thermal Runaway
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Solution Overview
Problem
Rechargeable lithium batteries used in electric vehicles face safety concerns due to rapid internal temperature rises during high-capacity and fast charging, which can lead to thermal runaway and potential explosions, particularly from internal short circuits caused by sharp needle conductors.
Innovation Solution
An electrode assembly with a safety functional layer containing an extinguishing capsule, comprising a core of substituted or unsubstituted halogen compounds and a polymer compound shell, is applied to the uncoated regions of the laminate, which suppresses temperature rise and prevents explosions by releasing the halogen compound when the temperature exceeds a certain threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the battery capacity is increased to achieve high energy density, then the energy density is improved, but the internal temperature rise during operation increases leading to thermal runaway risk
Solution Approach 1:
The patent applies preliminary action by pre-installing extinguishing capsules within the electrode assembly structure before any thermal runaway can occur. These capsules contain fire-suppressing agents that are positioned to automatically activate when temperature thresholds are exceeded, preventing the propagation of thermal runaway rather than addressing it after initiation.
Solution Approach 2:
The extinguishing capsules serve as an intermediary substance between the electrode components and the thermal runaway process. When activated by temperature increase, the capsules release fire-suppressing agents that intervene in the thermal runaway chain reaction, blocking heat transfer and preventing explosion without requiring changes to the electrode's energy storage function.
2Speed
If the battery is designed for fast charging to improve charging speed, then the charging speed is improved, but the internal temperature rise accelerates increasing safety risks
Solution Approach 1:
The patent implements beforehand cushioning by incorporating extinguishing capsules that act as a safety buffer before fast charging can cause dangerous temperature rises. The capsules are strategically positioned within the electrode assembly to provide immediate fire suppression coverage, cushioning against the thermal effects of rapid charging before they can lead to thermal runaway.
3Reliability
If the electrode assembly structure is modified to include safety features, then the safety is improved, but the complexity of the structure increases
Solution Approach 1:
The patent applies merging by integrating the safety function directly into the existing electrode assembly structure. The extinguishing capsules are incorporated within the laminate configuration of the electrodes and separator, combining the energy storage function with the safety function in a unified structure rather than adding separate safety systems that would increase complexity.
Solution Approach 2:
The electrode assembly structure serves multiple functions simultaneously: it stores energy through the electrode laminate and provides safety through the integrated extinguishing capsules. This multi-functionality allows the same structural elements to fulfill both energy storage and thermal runaway prevention roles, avoiding the need for separate dedicated safety components.
4Reliability
If the battery thickness is increased to accommodate safety features, then the safety is improved, but the portability and energy density are reduced
Solution Approach 1:
The patent applies local quality by placing extinguishing capsules only in specific critical regions within the electrode assembly where thermal runaway is most likely to initiate or propagate. Rather than uniformly distributing safety features throughout the entire battery volume, the capsules are strategically positioned at locations that provide maximum safety effectiveness with minimum space consumption, maintaining thin overall battery profile.
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
The solution effectively reduces or prevents battery explosions and improves safety by suppressing thermal runaway, while maintaining high energy density without significantly increasing the battery's thickness.
Implementation Method 1
reducing or suppressing direct temperature rise when an internal short circuit occurs
Data Source
AI summary
Disclosed are an electrode assembly, a manufacturing method thereof, and a rechargeable lithium battery, the electrode assembly including a unit laminate including a positive electrode and a negative electrode; an uncoated region covering at least a portion of the unit laminate; and a safety functional layer on at least a portion of the uncoated region. The safety functional layer includes an extinguishing capsule, the extinguishing capsule is a core including a substituted or unsubstituted halogen compound; and a shell surrounding the core and including a polymer compound.