Phase-Transition Solid Electrolyte for Battery Thermal Shutdown
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing all-solid secondary batteries lack an effective shutdown mechanism to prevent thermal runaway without additional external devices, as the solid electrolyte layer does not melt at high temperatures, making it difficult to provide a shutdown function.
Innovation Solution
Incorporating a phase-transition solid electrolyte material that undergoes a phase transition from a high-ionic conductivity first phase to a low-ionic conductivity second phase upon heating, which is integrated into the battery structure, allowing for a shutdown function without additional devices, using sulfide-based materials like Li2S and P2S5, and specific sulfide compositions represented by Formulas (4) to (6) to manage ionic conductivity and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a non-aqueous electrolyte lithium-ion rechargeable battery is designed to have higher energy density, then the energy storage capacity is improved, but the safety mechanism becomes more difficult to implement effectively
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte material by transitioning from a liquid non-aqueous electrolyte to a solid electrolyte with phase transition capability. The solid electrolyte undergoes a phase transition at a specific temperature (e.g., melting point around 100-150°C), changing from a solid state with high ionic conductivity to a liquid state with low viscosity, thereby shutting down the charge reaction and preventing thermal runaway while maintaining high energy density
Solution Approach 2:
The solid electrolyte material serves dual functions: it acts as the ion transport medium for high energy density and simultaneously provides the safety shutdown mechanism through its inherent phase transition property. When the battery temperature reaches the phase transition temperature, the solid electrolyte automatically melts and shuts down the charge reaction, eliminating the need for additional external safety devices
2Device complexity
If an all-solid secondary battery is designed without additional safety devices to simplify structure, then the device complexity is reduced, but the shutdown function becomes difficult to achieve
Solution Approach 1:
The solid electrolyte is designed to perform multiple functions simultaneously: it serves as the ion conductive medium for battery operation and as the safety shutdown component through its phase transition. This multi-functionality eliminates the need for separate safety devices, simplifying the overall battery structure while ensuring the shutdown function is achieved
Solution Approach 2:
The solid electrolyte material is selected or designed with a specific phase transition temperature that is lower than the decomposition temperature of the cathode active material. Upon heating to this transition temperature, the solid electrolyte undergoes a phase change from solid to liquid, dramatically reducing its ionic conductivity and shutting down the charge reaction, thereby providing the shutdown function without additional devices
3Stability of the object's composition
If the solid electrolyte layer is designed to maintain structural stability at high temperature, then the structural integrity is improved, but the shutdown function through melting becomes impossible
Solution Approach 1:
The solid electrolyte is designed with a specific phase transition temperature (melting point) that is lower than the decomposition temperature of the cathode active material. At normal operating temperatures, the solid electrolyte maintains its solid structure and ionic conductivity. When the temperature reaches the phase transition point, it melts and shuts down the charge reaction, providing the shutdown function while maintaining structural integrity at operating conditions
Solution Approach 2:
The solid electrolyte utilizes its phase transition property from solid to liquid at a specific temperature to achieve the shutdown function. The phase transition temperature is carefully selected to be below the decomposition temperature of the cathode active material, ensuring that the solid electrolyte melts and shuts down the charge reaction before any decomposition reactions occur, thereby providing both structural stability during operation and effective shutdown 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 phase-transition solid electrolyte material effectively suppresses heat generation and thermal runaway by reducing ionic conductivity at elevated temperatures, preventing decomposition reactions and ensuring safety by integrating the shutdown function into the battery structure without external components.
Implementation Method 1
upon heating, the phase-transition solid electrolyte material undergoes a phase transition from a first phase to a second phase, and the second phase has an ionic conductivity that is less than an ionic conductivity of the first phase
Data Source
AI summary
An all-solid secondary battery includes: a cathode layer including a cathode active material; an anode layer; and a solid electrolyte layer disposed between the cathode layer and the anode layer, wherein at least one of the cathode layer, the anode layer, or the solid electrolyte layer includes a phase-transition solid electrolyte material, wherein upon heating, the phase-transition solid electrolyte material undergoes a phase transition from a first phase to a second phase, and the second phase has an ionic conductivity less than the ionic conductivity of the first phase.