Thermal Insulating Layer for Lithium Battery Safety
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Solution Overview
Problem
Lithium batteries face safety issues due to the flammability of organic solvents and heat generation during discharge, leading to potential explosions, as oxygen expelled from the positive electrode reacts with the electrolyte, increasing internal temperature.
Innovation Solution
A lithium battery design incorporating a thermal insulating layer composed of inorganic materials, thermal activation materials, and a binder on the electrode plates, which reduces conductivity and enhances safety by initiating a cross-linking reaction at elevated temperatures to block lithium ion diffusion and decrease electrolyte conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If organic solvents with high-voltage endurance are used in the lithium battery system, then the energy density and voltage are improved, but the flammability increases leading to safety issues
Solution Approach 1:
A thermal insulating layer comprising inorganic material, thermal activation material, and binder is introduced as an intermediary between the electrode plates and the electrolyte. This layer acts as a mediator that blocks the direct interaction between oxygen expelled from the positive electrode and the organic electrolyte solvent, preventing the harmful reaction while allowing the battery to maintain its high energy density characteristics
Solution Approach 2:
The invention converts the harmful thermal runaway process into a beneficial protective mechanism. When temperature increases, the thermal activation material undergoes cross-linking reaction to form a gel structure that blocks ion diffusion and decreases electrolyte conductivity, effectively stopping the harmful thermal runaway while utilizing the temperature increase itself as the triggering mechanism for protection
2Temperature
If the temperature of the lithium battery increases, then the discharge capacity may be improved, but the conductivity increases leading to thermal runaway and potential explosion
Solution Approach 1:
The thermal insulating layer provides dynamic protection that adapts to temperature changes. At normal operating temperatures, the layer remains in its initial state allowing normal battery function. When temperature increases to dangerous levels, the thermal activation material undergoes cross-linking reaction to form a gel structure that dynamically blocks ion diffusion and decreases electrolyte conductivity, automatically adjusting the protection level based on temperature conditions
Solution Approach 2:
The invention utilizes parameter changes in the thermal insulating layer's physical and chemical properties in response to temperature changes. The thermal activation material undergoes cross-linking reaction that changes the layer's structure from a permeable state to a gel state, fundamentally changing its ion transport properties and electrolyte conductivity to prevent thermal runaway
3Reliability
If a thermal insulating layer is added to the battery structure, then the safety is improved, but the device complexity increases
Solution Approach 1:
The thermal insulating layer is constructed as a composite material system comprising inorganic material (for thermal insulation), thermal activation material (for temperature-responsive cross-linking), and binder (for structural integrity). This composite structure integrates multiple functions—thermal insulation, temperature sensing, and active protection—into a single layer, reducing the need for separate safety components and minimizing structural complexity while maximizing safety benefits
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 thermal insulating layer effectively decreases electrolyte conductivity and enhances safety by blocking lithium ion diffusion, reducing the risk of heat-induced explosions and improving the overall safety of lithium batteries.
Implementation Method 1
initiating a cross-linking reaction at elevated temperatures to block lithium ion diffusion and decrease electrolyte conductivity
Implementation Method 2
The first thermal insulating layer is located on one of the first surface and the second surface, wherein the first thermal insulating layer is comprised of an inorganic material, a thermal activation material and a binder
Data Source
AI summary
A lithium battery is provided. The lithium battery comprises an positive electrode plate having a first surface, a negative electrode plate having a second surface, a first thermal insulating layer and a separator. The first surface is opposite to the second surface. The thermal insulating layer is disposed on one of the first surface and the second surface. The thermal insulating layer is comprised of an inorganic material, a thermal activation material and a binder. The separator is disposed between the positive electrode plate and the negative electrode plate.