Asymmetric Electrode Assembly for Secondary Battery Swelling
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Solution Overview
Problem
Secondary batteries containing lithium titanium oxide (LTO) as a negative electrode active material experience significant swelling during storage at high temperatures, leading to potential leakage and performance deterioration due to the increased extent of swelling in the discharged state compared to the charged state.
Innovation Solution
The electrode assembly design features a positive electrode coating portion with a larger area than the negative electrode coating portion, ensuring all LTO materials participate in charge/discharge operations, forming a solid electrolyte interface (SEI) film, which suppresses gas generation and prevents swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lithium titanium oxide (LTO) is used as negative electrode active material, then charge/discharge performance is improved, but swelling occurs during storage at high temperature
Solution Approach 1:
The patent applies asymmetry by making the positive electrode coating portion larger than the negative electrode coating portion. This asymmetric design ensures that all LTO materials in the smaller negative electrode coating portion fully participate in charge/discharge operations, forming complete SEI films that prevent gas generation and swelling during high-temperature storage.
2Reliability
If area of positive electrode coating portion is larger than negative electrode coating portion, then swelling prevention is improved, but electrode design complexity increases
Solution Approach 1:
The patent changes the geometric parameter of the electrode coating portions by setting the area ratio of the positive electrode coating portion to the negative electrode coating portion within a specific range (1.01 to 1.21). This parameter adjustment ensures complete SEI film formation on LTO surfaces while maintaining a relatively simple electrode structure with minimal design complexity.
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 effectively prevents secondary battery swelling by ensuring all LTO materials react with additives and electrolytes, reducing gas generation and maintaining battery performance and integrity, especially at high temperatures.
Implementation Method 1
all materials of the LTO may react with an additive and electrolyte. As a result of the reaction, a coating film, called a solid electrolyte interface (SEI) film, is formed on the surface of the negative electrode
Data Source
AI summary
The invention relates to an electrode assembly for a secondary battery which reduces the swelling of the battery. The electrode assembly according to the invention comprises a positive electrode (110) having a positive electrode coating portion (112) on at least one surface thereof, a negative electrode (120) having a negative electrode coating portion (122) including lithium titanium oxide on at least one surface thereof, and a separator (130) disposed between the positive electrode and the negative electrode, wherein the area of the positive electrode coating portion is larger than that of the negative electrode coating portion. This arrangement means that all of the lithium titanium oxide coated on the negative electrode participates in the charge/discharge operations, thereby reducing the reaction between the lithium titanium oxide and electrolyte and the resultant generation of gas.