Gel Electrolyte Layer Thermal Buffer for Battery Safety
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Solution Overview
Problem
Lithium ion secondary batteries face issues with thermal runaway due to heat transfer from the negative electrode to the positive electrode during external or internal short circuits, leading to potential thermal decomposition and safety risks.
Innovation Solution
Incorporating a gel-like electrolyte layer with specific heat capacity and particle composition between the positive and negative electrodes to absorb heat generated at the negative electrode and prevent its transfer to the positive electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon, tin, or compound thereof is used as negative electrode active material to increase capacity, then the theoretical capacity is improved, but the heat generation during discharge increases and thermal runaway risk occurs
Solution Approach 1:
A gel electrolyte layer is introduced as an intermediary substance between the negative electrode and positive electrode. This gel electrolyte contains heat-absorbing particles that act as a thermal buffer, absorbing excess heat generated during discharge and preventing direct heat transfer to the positive electrode, thus resolving the contradiction between high capacity and heat generation
Solution Approach 2:
The physical state of the electrolyte is changed from liquid to gel form, and heat-absorbing particles are incorporated into the gel matrix. This parameter change enables the electrolyte to not only conduct ions but also absorb and retain heat, transforming the electrolyte's function to simultaneously address both capacity and thermal management requirements
2Temperature
If heat is generated in the negative electrode during external or internal short circuit, then the temperature increases, but the separator film is broken by heat and short circuit is extended
Solution Approach 1:
The gel electrolyte layer with heat-absorbing particles is pre-installed between the electrodes as a protective buffer. During external or internal short circuits, this pre-positioned thermal buffer absorbs the generated heat before it can reach the separator film, preventing separator breakdown and short circuit extension, thus resolving the contradiction between temperature increase and reliability
3Loss of energy
If heat is propagated from negative electrode to positive electrode, then thermal decomposition reaction occurs, but safety risk increases
Solution Approach 1:
The gel electrolyte layer serves as a thermal intermediary that absorbs and retains heat through its gel matrix and incorporated heat-absorbing particles. This intermediary layer intercepts heat propagation from the negative electrode, preventing thermal decomposition of the positive electrode and eliminating the safety risk, thus resolving the contradiction between heat transfer and thermal decomposition
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 solution effectively suppresses thermal decomposition reactions by absorbing heat at the negative electrode, enhancing the safety and reliability of lithium ion secondary batteries by preventing excessive heat transfer to the positive electrode.
Implementation Method 1
incorporating a gel-like electrolyte layer with specific heat capacity and particle composition between the positive and negative electrodes to absorb heat generated at the negative electrode
Implementation Method 2
prevent its transfer to the positive electrode
Data Source
Figure 1
Figure 2~3
Figure 4A~4D
AI summary
A gel electrolyte layer is provided between a positive electrode and a second electrode. The gel electrolyte layer is a layer containing particles, a resin material, and a polymer compound for retaining the resin material, and having a heat capacity per unit area of 0.0001 J/Kcm2 or more and a heat capacity per unit volume of 3.0 J/Kcm3 or less.