Lithium Battery Electrode Safety Layer for Overheating Resistance
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Solution Overview
Problem
Rechargeable lithium batteries face safety issues such as overheating and explosion due to internal short circuits, overcharge, and physical stress, which can lead to thermal and physical hazards.
Innovation Solution
An electrode for rechargeable lithium batteries is designed with a current collector, a safety functional layer containing a heat-expandable polymer and an active material with a particle diameter of less than or equal to 2 μm, which increases internal resistance and prevents overheating and explosion by restricting lithium ion and electron flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrode structure is used, then excellent battery performance is achieved, but thermal safety and physical safety deteriorate due to overheating and explosion risks
Solution Approach 1:
The safety functional layer is pre-formed on the current collector before the active material layer is applied. This layer contains heat-expandable polymer particles and fine active material particles that are prepared in advance to respond to thermal and mechanical stresses, preventing overheating and explosion before they can occur
Solution Approach 2:
The safety functional layer acts as an intermediary between the current collector and the active material layer. It includes heat-expandable polymer particles that expand to block ion transport pathways during thermal stress, and fine active material particles that increase internal resistance, thereby mediating the response to prevent harmful effects
2Reliability
If internal resistance is increased to prevent overheating, then thermal safety is improved, but battery performance may deteriorate
Solution Approach 1:
The safety functional layer is positioned locally between the current collector and the active material layer, rather than uniformly throughout the electrode. This localized placement allows internal resistance to be increased only where needed for safety, while the rest of the electrode maintains its normal conductivity and performance characteristics
Solution Approach 2:
The safety functional layer changes the physical parameters of the electrode by introducing heat-expandable polymer particles that expand upon heating, and fine active material particles that increase internal resistance. These parameter changes occur dynamically in response to thermal and mechanical stress, preventing overheating while minimizing impact on normal battery performance
3Reliability
If a safety functional layer with heat-expandable polymer is added, then thermal safety is improved, but device complexity increases
Solution Approach 1:
The safety functional layer combines multiple functions into a single layer: it provides thermal protection through heat-expandable polymer particles, electrical resistance control through fine active material particles, and mechanical stability. This merging of functions into one integrated layer reduces the overall complexity compared to having separate components for each function
Solution Approach 2:
The safety functional layer is a composite material containing heat-expandable polymer particles, fine active material particles, and binder. This composite structure integrates multiple materials with different properties into a single functional layer that provides both safety and performance benefits without requiring complex multi-layer structures
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 electrode effectively suppresses overheating and explosion during thermal exposure, penetration, crush, and impact, while maintaining excellent battery performance and cycle life, ensuring thermal and physical safety.
Implementation Method 1
the safety functional layer includes a heat-expandable polymer
Implementation Method 2
increases internal resistance of the battery at the issues such as heat exposure, penetration, crush, impact, etc.
Data Source
AI summary
The present invention relates to an electrode for a rechargeable lithium battery, and a rechargeable lithium battery including the same, the electrode including a current collector, a safety functional layer on the current collector, and an active material layer on the safety functional layer, wherein the functional safety layer comprises a heat-expandable polymer and an active material having a particle diameter of less than or equal to 2 μm.