Nonaqueous Battery Structure Retainer Prevents Electrode Expansion
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Solution Overview
Problem
Nonaqueous electrolyte secondary batteries face capacity degradation due to expansion of the negative electrode active material during charging, which compresses the separator and positive electrode, causing electrolyte expulsion and deteriorating cycle characteristics, especially when using high-capacity active materials like alloys or Si oxides.
Innovation Solution
Incorporating a porous insulating layer with a structure retainer between the positive and negative electrodes, along with a structure retainer in the positive electrode mixture layer, to prevent expansion of the negative electrode active material, thereby maintaining electrolyte retention and improving cycle characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity active materials like alloys or Si oxides are used in the negative electrode, then battery capacity is improved, but the active material expands during charging causing separator compression and electrolyte expulsion
Solution Approach 1:
The patent applies preliminary anti-action by introducing a structure retainer into the negative electrode active material layer before charging occurs. This structure retainer pre-establishes a counteracting force that prevents expansion of the active material during charging, thereby preventing separator compression and electrolyte expulsion before they can occur. The structure retainer acts in advance to counterbalance the expansion pressure that would otherwise damage the battery structure.
Solution Approach 2:
The structure retainer serves as an intermediary element between the negative electrode active material and the separator. It mediates the interaction by absorbing or counteracting the expansion force generated by the high-capacity active material, thereby protecting the separator from compression and preventing electrolyte expulsion. The structure retainer acts as a buffer that decouples the expansion of the active material from the compression of the separator.
2Quantity of substance
If the negative electrode active material expands during charging, then more lithium ions can be intercalated (higher capacity), but the positive electrode and separator are compressed causing void collapse and electrolyte expulsion
Solution Approach 1:
The structure retainer is incorporated into the negative electrode active material layer before charging to preemptively counteract expansion. This preliminary anti-action prevents the transmission of expansion forces to the separator, maintaining separator structure stability while allowing high lithium ion intercalation capacity.
Solution Approach 2:
The structure retainer acts as an intermediary that absorbs the expansion pressure from the negative electrode active material, preventing it from compressing the separator. This intermediary element allows the active material to expand freely for high capacity while protecting the separator structure from damage.
3Duration of action of moving object
If repeated charging/discharging cycles are performed, then battery operation is sustained, but cumulative expansion causes progressive separator compression and capacity degradation
Solution Approach 1:
The structure retainer provides preliminary anti-action that prevents expansion at each charging cycle, thereby preventing cumulative damage to the separator. This ensures that repeated charging/discharging cycles can be performed without progressive capacity degradation, extending battery operation duration while maintaining reliability.
Solution Approach 2:
The structure retainer serves as a protective intermediary that absorbs expansion forces during each charging cycle, preventing progressive compression of the separator. This intermediary protection allows sustained battery operation over many cycles without the cumulative damage that would otherwise lead to capacity degradation.
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 prevents electrolyte expulsion and enhances cycle stability by retaining the structure of the positive electrode and porous insulating layer, leading to improved battery performance and extended cycle life even with high-capacity active materials.
Implementation Method 1
The nonaqueous electrolyte is contained at least in the porous insulating layer
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, a porous insulating layer, and nonaqueous electrolyte. The porous insulating layer is interposed between the positive electrode and the negative electrode. The nonaqueous electrolyte is contained at least in the porous insulating layer. The mixture layer of the positive electrode and the porous insulating layer each include a structure retainer.