Lithium Battery Shutdown Layer for Thermal Runaway Prevention
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Solution Overview
Problem
Rechargeable lithium batteries face safety challenges due to internal short circuits, which can lead to exothermic reactions, electrolyte decomposition, and thermal runaway, potentially causing battery explosions.
Innovation Solution
The implementation of a rechargeable lithium battery design that includes a negative electrode with a negative functional layer containing flake-shaped polyethylene particles and a positive electrode with a positive active material layer comprising composite oxides of lithium and metals like cobalt, manganese, and nickel, along with a compound represented by Chemical Formula 1 (LiFe1-xMxPO4).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional battery structure is used, then the battery can store and provide electrical energy, but it is susceptible to internal short circuits causing thermal runaway and safety hazards
Solution Approach 1:
The patent applies preliminary anti-action by incorporating a negative functional layer containing polyethylene particles that proactively prevent thermal runaway before it occurs. When temperature increases, the polyethylene particles melt and close ion channels, shutting down electrochemical reactions and preventing the harmful thermal runaway sequence from developing
Solution Approach 2:
The negative functional layer acts as an intermediary between the negative active material layer and the electrolyte/separator system. This intermediate layer with temperature-responsive polyethylene particles mediates ion transport, allowing normal operation at safe temperatures while blocking ion flow when temperature rises to prevent thermal runaway
2Productivity
If the battery operates at higher temperatures to improve reaction rate, then energy output increases, but thermal runaway risk increases
Solution Approach 1:
The patent uses parameter changes by incorporating polyethylene particles with a specific melting point that triggers a phase change at elevated temperatures. This parameter-based response allows the battery to maintain high reaction rates at normal operating temperatures while automatically shutting down when temperature exceeds safe thresholds, preventing thermal runaway
Solution Approach 2:
The negative functional layer exploits phase transitions of polyethylene particles, which melt from solid to liquid at specific temperatures. This phase transition causes the particles to close ion channels, automatically reducing reaction rate and shutting down electrochemical reactions when temperature rises to unsafe levels
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
This design enhances the stability and safety of the rechargeable lithium battery by improving the reaction rate according to temperature, enabling an early shutdown function and effectively preventing electrical chemical reactions during thermal runaway.
Implementation Method 1
the negative functional layer includes flake-shaped polyethylene particles... improving the reaction rate according to temperature, enabling an early shutdown function and effectively preventing electrical chemical reactions during thermal runaway
Data Source
AI summary
Disclosed is a rechargeable lithium battery including a positive electrode including a positive active material layer; and a negative electrode including a negative active material layer and a negative functional layer on the negative active material layer, wherein the functional layer includes flake-shaped polyethylene particles, and the positive active material layer includes a first positive active material including one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and a combination thereof, and a second positive active material including a compound represented by Chemical Formula 1 and. In Chemical Formula 1, 0.90≤a≤1.8, 0≤x≤0.7, and M is Mg, Co, Ni, or a combination thereof.LiaFe1-xMxPO4 Chemical Formula 1