MIT Safety Element for Battery Thermal Runaway Prevention
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Solution Overview
Problem
Lithium ion secondary batteries are prone to swelling, firing, or explosion due to temperature rises from external impacts or overcharging, as the positive electrode active material is sensitive to voltage, leading to enhanced reactivity with the electrolyte, especially with increased energy density.
Innovation Solution
A safety element with Metal-Insulator Transition (MIT) characteristic material, such as vanadium-based oxides, is connected between the positive and negative electrodes, which abruptly changes resistance at elevated temperatures, allowing electric current to flow and safely discharge the battery, preventing explosions or fires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the battery energy density is increased to improve performance, then the operating voltage and energy storage capacity are improved, but the reactivity between the positive electrode and electrolyte is enhanced, increasing the risk of firing or explosion at elevated temperatures
Solution Approach 1:
The patent introduces an MIT material as an intermediary component connected between the positive and negative electrodes. This mediator remains insulating at normal temperatures (avoiding harmful reactions) but becomes conductive at elevated temperatures, providing a safe discharge path that prevents the harmful effects of high reactivity while preserving the high energy density benefits.
Solution Approach 2:
The patent utilizes the temperature-dependent resistance parameter change of MIT material. The material's electrical resistance changes from high (insulating) at normal temperatures to low (conductive) at elevated temperatures. This parameter change allows the system to maintain high energy density operation under normal conditions while automatically activating a safety mechanism when temperature rises, thus managing the reactivity hazard without reducing energy density.
2Reliability
If a safety mechanism is added to prevent firing or explosion at elevated temperatures, then battery safety is improved, but current leakage may occur at normal use temperatures
Solution Approach 1:
The patent employs MIT material that undergoes a phase transition at a specific temperature threshold. Below this threshold, the material remains in an insulating phase, preventing current leakage during normal use. When the temperature rises above the threshold, the material transitions to a conductive phase, enabling current flow to discharge the battery and prevent thermal runaway. This phase transition mechanism ensures safety activation only when needed, eliminating unnecessary energy loss.
Solution Approach 2:
The safety mechanism is designed to be dynamic rather than static. The MIT material's electrical conductivity dynamically responds to temperature changes, being insulating during normal operation and becoming conductive only when temperature exceeds the safety threshold. This dynamic behavior ensures that the safety mechanism activates only under hazardous conditions, preventing current leakage during normal use while providing protection when needed.
3Power
If the resistance of the safety element is lowered to allow current flow at elevated temperatures, then battery discharge capability is improved, but current leakage occurs at normal use temperatures
Solution Approach 1:
The patent utilizes the temperature-dependent resistance parameter change of MIT material. The material's electrical resistance changes from high (insulating) at normal temperatures to low (conductive) at elevated temperatures. This parameter change allows the system to maintain high energy density operation under normal conditions while automatically activating a safety mechanism when temperature rises, thus managing the reactivity hazard without reducing energy density.
Solution Approach 2:
The safety mechanism is designed to be dynamic rather than static. The MIT material's electrical conductivity dynamically responds to temperature changes, being insulating during normal operation and becoming conductive only when temperature exceeds the safety threshold. This dynamic behavior ensures that the safety mechanism activates only under hazardous conditions, preventing current leakage during normal use while providing protection when needed.
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 MIT safety element effectively prevents battery explosions or fires by discharging the battery at elevated temperatures without causing current leakage at normal use temperatures, ensuring safety and maintaining battery functionality.
Implementation Method 1
material having a Metal-Insulator Transition (MIT) characteristic where resistance abruptly drops at or above a certain temperature
Data Source
AI summary
Disclosed are a safety element for a battery, which is provided with material having a Metal-Insulator Transition (MIT) characteristic where resistance abruptly drops at or above a certain temperature, and a battery with such a safety element. This battery with an MIT safety element is turned into a stable discharged state when it is exposed to an elevated temperature or a battery temperature rises due to external impact, so that it can ensure its safety.