Extensible Member Short Bar Overcharge Protection
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Solution Overview
Problem
Prismatic rechargeable batteries for hybrid electric vehicles face safety challenges due to varying heat dissipation efficiencies and increased sizes, making it difficult to prevent overcharging-related issues.
Innovation Solution
A rechargeable battery design that includes a case with external electrode terminals that short-circuit when an overcharging condition is detected, using an extensible member and short bar configuration to maintain the short circuit state, potentially incorporating electrical conductors and materials that melt upon current flow to ensure safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery size is increased to meet high-capacity demands, then the battery capacity is improved, but the heat dissipation efficiency deteriorates and safety becomes difficult to secure
Solution Approach 1:
The battery system is divided into multiple individual battery units, each equipped with its own extensible member and short bar safety mechanism. This segmentation allows each unit to independently manage its thermal and safety conditions, preventing heat accumulation from compromising the entire system.
Solution Approach 2:
The extensible member acts as an intermediary mechanism between the battery's internal pressure system and the external short circuit protection system. When internal pressure increases due to overheating or overcharging, the extensible member expands to bridge the gap and activate the short bar, providing automatic safety intervention without requiring external monitoring systems.
2Temperature
If prismatic batteries are used instead of cylindrical batteries, then heat dissipation efficiency and safety are improved, but the ability to provide high-capacity batteries is limited
Solution Approach 1:
The invention merges the advantages of prismatic battery geometry (superior heat dissipation and safety) with the ability to achieve high capacity by combining multiple prismatic units in series or parallel configurations. Each unit maintains its thermal management benefits while the system as a whole achieves the required capacity.
Solution Approach 2:
Instead of increasing the dimensions of a single prismatic battery (which would compromise heat dissipation), the solution transitions to a multi-unit modular arrangement, adding capacity through the number of units rather than the size of individual units. This dimensional approach preserves the thermal benefits of small prismatic cells while achieving system-level high capacity.
3Reliability
If current interrupt devices are applied to prevent overcharging, then safety is improved, but the devices are not applicable to prismatic batteries for HEV
Solution Approach 1:
The battery system provides its own safety function through the extensible member and short bar mechanism, eliminating the need for external current interrupt devices. The system self-monitors its internal pressure state and automatically activates short circuit protection when needed, making the safety mechanism inherently adaptable to all battery types including HEV applications.
Solution Approach 2:
Instead of using active electronic control systems to prevent overcharging (current interrupt devices), the invention uses a passive mechanical expansion mechanism that responds to the physical consequences of overcharging (internal pressure increase). This inverted approach provides universal applicability across different battery chemistries and types without requiring type-specific control logic.
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 prevents overcharging by ensuring a persistent short circuit, thereby enhancing the safety and heat dissipation efficiency of the battery, as demonstrated by voltage and temperature graphs showing rapid voltage drop and controlled temperature changes during short-circuiting.
Implementation Method 1
an extensible member extending from the case and at least a portion of the short bar being on the extensible member with a gap therebetween. The extensible member is configured to couple the short bar electrically to the first electrode in response to an overcharging condition of the rechargeable battery
Implementation Method 2
The extensible member may include an electrical conductor
Implementation Method 3
at least one of the extensible member or the short bar may be configured to melt when the extensible member and the short bar conduct an electrical current in response to the overcharging condition
Data Source
AI summary
A rechargeable battery includes a case, a first electrode coupled to the case, a second electrode coupled to the case and the second electrode having a portion extending outside of the case, a short bar electrically coupled to the portion of the second electrode, and an extensible member extending from the case and at least a portion of the short bar being on the extensible member with a gap therebetween. The extensible member is configured to couple the short bar electrically to the first electrode in response to an overcharging condition of the rechargeable battery, thereby short-circuiting the first and second electrodes via the short bar.