Tungsten-Doped Vanadium Oxide Separator for Thermal Runaway Prevention
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Solution Overview
Problem
Rechargeable lithium batteries are prone to explosion when excessively heated due to high internal temperatures, which existing technologies have not effectively addressed.
Innovation Solution
A separator for rechargeable lithium batteries incorporating a phase transition material, such as tungsten-doped vanadium oxide (VO2), that transitions from an insulator to a conductor at temperatures between 67° C. to 75° C., creating a short circuit to prevent or delay battery explosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional separator is used in a rechargeable lithium battery, then the battery can operate normally, but the battery may explode when excessively heated due to high internal temperature
Solution Approach 1:
The separator incorporates a phase transition material that undergoes an insulator-to-conductor phase transition at a specific temperature range (67-75°C). When the battery temperature exceeds this range, the material transitions from insulating to conductive state, creating a short circuit that prevents further temperature increase and avoids battery explosion. This phase transition mechanism provides automatic thermal protection without requiring external control systems.
Solution Approach 2:
The invention changes the electrical conductivity parameter of the separator material based on temperature. The phase transition material exhibits low electrical conductivity at normal operating temperatures (maintaining separator function) and high electrical conductivity at elevated temperatures (creating short circuit for protection). This parameter change enables the separator to adapt its function dynamically in response to temperature conditions.
2Reliability
If the phase transition temperature is set too low, then the separator activates early to prevent explosion, but the battery cannot operate at higher temperatures normally
Solution Approach 1:
The phase transition temperature parameter is precisely controlled within the 67-75°C range through material composition adjustment. This parameter selection ensures the separator remains insulating during normal battery operation (below 67°C) and only transitions to conductive state when temperature exceeds the safe operating range, thus maintaining both early protection activation and normal operating versatility.
3Temperature
If doped vanadium oxide is used as phase transition material, then the insulator-to-conductor transition occurs at the desired temperature range, but the material composition becomes more complex
Solution Approach 1:
The invention uses doped vanadium oxide (VO2 with tungsten doping) as the phase transition material. The doping process introduces tungsten atoms into the vanadium oxide crystal structure, which modifies the phase transition temperature to the desired 67-75°C range. While this creates a composite material with more complex composition, it enables precise temperature control of the protection mechanism.
Solution Approach 2:
The material composition parameters (doping concentration, atomic ratio) are optimized to achieve the target phase transition temperature range. By controlling the doping level of tungsten in vanadium oxide, the invention precisely tunes the electrical and thermal properties to trigger protection at the desired temperature while maintaining material processability.
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 separator effectively prevents or delays battery explosion by transitioning to a conductor at elevated temperatures, thereby stopping temperature increase and preventing further heat buildup.
Implementation Method 1
The phase transition material has an insulator-to-conductor phase transition temperature of from about 67° C. to about 75° C.
Implementation Method 2
The separator effectively prevents or delays battery explosion by transitioning to a conductor at elevated temperatures, thereby stopping temperature increase and preventing further heat buildup.
Data Source
AI summary
A separator for a rechargeable lithium battery including a tungsten-doped vanadium oxide (VO2) phase transition material and the rechargeable lithium battery including the separator. Here, an explosion possibility of the rechargeable lithium battery including the separator may be prevented and delayed when the battery is excessively heated.