Battery Pack Architecture Parallel Cell Thermal Runaway Prevention
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Solution Overview
Problem
Existing battery systems face challenges in compact design and thermal runaway prevention when cells are connected in parallel, as they tend to increase in size and risk thermal runaway due to adjacent cell defects, which conventional solutions like TCO or PTC devices struggle to address within stringent size and cost constraints.
Innovation Solution
A battery system with multiple cells connected in parallel, utilizing thermal switch devices (TCO or PTC) electrically coupled to each cell via rigid-flex circuit boards, which prevent thermal runaway by limiting current flow when temperature exceeds a threshold, and a protection circuit to safeguard against failure modes, allowing for a more compact assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple battery cells are connected in parallel to increase power capacity, then the power output is improved, but the overall size of the battery system increases
Solution Approach 1:
The patent transitions from a planar arrangement of battery cells to a three-dimensional stacked configuration. Multiple cells are arranged vertically in layers rather than spreading out horizontally, allowing the battery system to maintain high power capacity while reducing the overall footprint and thickness of the battery pack.
Solution Approach 2:
The patent implements a nested structure where battery cells are stacked within each other in vertical layers. The cells are arranged in a compact configuration where one cell is positioned above another, similar to nested dolls, maximizing space utilization and reducing the overall volume required for the same power capacity.
2Reliability
If thermal switch devices are added to each battery cell to prevent thermal runaway, then safety is improved, but the device complexity and cost increase
Solution Approach 1:
The rigid-flex circuit board serves multiple functions simultaneously: it provides electrical interconnection between battery cells, acts as a structural support framework, and serves as the mounting substrate for thermal switch devices. This multi-functionality reduces overall system complexity by consolidating multiple components into a single integrated structure.
Solution Approach 2:
The patent combines the electrical connection function and the thermal protection function into a single integrated system. The thermal switch devices are directly mounted on the circuit board that already connects the cells electrically, merging the protection mechanism with the existing electrical architecture rather than adding separate independent protection systems.
3Reliability
If conventional TCO or PTC devices are integrated into the battery system to address adjacent short circuit conditions, then thermal runaway prevention is improved, but the assembly size and cost constraints are worsened
Solution Approach 1:
The patent employs flexible circuit boards to mount thermal switch devices in a thin, flexible configuration that conforms to the compact battery cell arrangement. This allows the protection devices to be integrated into the limited space available in the battery assembly without requiring bulky housing or additional structural support.
Solution Approach 2:
The rigid-flex circuit board acts as an intermediary structure that bridges the battery cells and the thermal switch devices. It provides a compact platform that brings the protection devices into close proximity with the cells they protect, enabling effective thermal runaway prevention while maintaining compact overall dimensions.
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 thermal runaway and cell shorts while maintaining a compact design, reducing impedance and assembly volume, thus enhancing the safety and efficiency of battery systems in consumer products.
Implementation Method 1
each thermal switch device is either a temperature cut off (TCO) device or a positive temperature coefficient (PTC) device
Implementation Method 2
each thermal switch device is either a temperature cut off (TCO) device or a positive temperature coefficient (PTC) device
Data Source
AI summary
A battery system includes a plurality of battery cells connected in parallel. Each battery cell includes a positive and negative tab. The battery system also includes a plurality of thermal switch devices (e.g., temperature cut off (TCO) or positive temperature coefficient (PTC) devices). Each thermal switch device is electrically coupled to a respective cell. The battery system further includes a rigid-flex circuit board comprising a plurality of rigid regions. Each rigid region is physically and electrically connected to an adjacent rigid region by a respective flexible region. Each rigid region is electrically coupled to respective positive and negative tabs of a respective battery cell. Each thermal switch device prevents abnormal current flow (e.g., by limiting the flow of current at high temperatures) between a first battery cell that is coupled to the thermal switch device and a second battery cell that is adjacent to the first battery cell.