Electrochemical Device Resistance Control Layer Thermal Runaway
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrochemical devices, such as secondary batteries, face safety issues due to potential explosions or ignitions caused by temperature rises within their outer packages, which can lead to thermal runaway and internal short circuits, despite the use of safety valves that do not always act stably.
Innovation Solution
An electrochemical device with a multilayer structure of positive and negative electrodes separated by a separator, where at least one electrode has a resistance control layer at its edge, with a resistance value that allows for a controlled internal short circuit current between 0.09 C to 1 C, preventing thermal runaway and ensuring safety by moderating self-discharge and shifting active materials to more thermostable regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If safety valves are installed to release gases when internal pressure rises, then gas release function is improved, but reliability is worsened because safety valves do not always act stably
Solution Approach 1:
The patent introduces a resistance control layer as an intermediary component between the positive and negative electrodes. This layer mediates the electrical interaction by providing controlled resistance, preventing direct short circuits while allowing controlled current flow. The resistance control layer acts as a mediator that stabilizes the system behavior, replacing the unreliable safety valve mechanism with a passive electrical resistance-based protection system.
Solution Approach 2:
The patent replaces the mechanical safety valve system with an electrical resistance-based control mechanism. Instead of using mechanical components (safety valves) to release pressure, the invention uses electrical resistance properties of the resistance control layer to regulate current flow and prevent thermal runaway, substituting mechanical protection with electrical property-based protection.
2Stress or pressure
If outer packages are inflated by internal pressures before safety valves act, then pressure release is delayed, but harmful factors are worsened because electrode matrixes deform causing internal short circuits
Solution Approach 1:
The resistance control layer is pre-installed between the electrodes during manufacturing, performing preliminary protective action before any abnormal conditions occur. This layer is already in place to control current flow and prevent short circuits before pressure buildup or thermal runaway can cause electrode deformation, acting in advance to prevent the harmful sequence of events.
Solution Approach 2:
The patent converts the potentially harmful effect of internal pressure and current flow into a beneficial protective mechanism. The resistance control layer utilizes the natural current flow and pressure conditions to maintain controlled resistance, transforming what could be dangerous short-circuit conditions into a controlled protective state that prevents thermal runaway.
3Reliability
If resistance control layer is added to electrodes, then safety is improved by controlling internal short circuit current, but device complexity is worsened
Solution Approach 1:
The resistance control layer is merged with the electrode structure itself, combining the functional electrode material with the protective resistance-controlling properties in a single integrated component. This merging eliminates the need for separate protective components, reducing overall device complexity while maintaining safety functions.
Solution Approach 2:
The resistance control layer serves multiple functions simultaneously: it acts as part of the electrode structure, provides electrical resistance control, prevents short circuits, and contributes to safety against thermal runaway. This multi-functionality reduces the need for additional separate components, thereby not increasing device complexity despite the added safety capability.
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 controlled internal short circuit current range significantly improves the safety of the electrochemical device by preventing explosions and ignitions in high-temperature atmospheres, ensuring the device's stability and reliability.
Implementation Method 1
when the electrochemical device is placed in a dangerous temperature atmosphere by a temperature rise within the outer package, the separator thermally shrinks, so that the positive and negative electrodes in the electrode matrix come into electrical contact with each other through the resistance control layer
Implementation Method 2
the resistance control layer has a resistance value as a total resistance value of the electrode matrix falling in such a range that an estimated internal short circuit current between the positive and negative electrodes is equivalent to 0.09 C to 1 C
Implementation Method 3
the electrochemical device in accordance with the present invention can generate moderate self-discharge, so as to shift active materials used in the electrochemical device to more thermostable regions
Data Source
AI summary
An electrochemical device having an electrode matrix including a multilayer structure laminating positive and negative electrodes with a separator interposed therebetween; wherein at least one of the positive and negative electrodes has a resistance control layer at least at an edge part exposed when the separator thermally shrinks on a surface on the separator side; and wherein the resistance control layer has a resistance value as a total resistance value of the electrode matrix falling in such a range that an estimated internal short circuit current between the positive and negative electrodes is equivalent to 0.09 C to 1 C.