Nonaqueous Battery Electrode Structure for Electrolyte Leakage Control
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Solution Overview
Problem
Existing nonaqueous electrolyte secondary batteries face challenges in preventing the leakage of the nonaqueous electrolyte solution due to rapid volume changes in the negative electrode active material during high-rate charging and discharging, leading to performance degradation.
Innovation Solution
The battery design incorporates a damming portion and a liquid retaining portion in the negative electrode composite material layer, where the damming portion contains a negative electrode active material with a higher electrical potential and greater expansion/contraction ratio than the liquid retaining portion. This configuration allows for controlled opening and closing of the electrolyte solution passage by adjusting the State Of Charge (SOC), preventing leakage and facilitating infiltration of the electrolyte solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spacers are arranged between secondary batteries to apply binding pressure to end portions of electrode bodies, then leakage of nonaqueous electrolyte solution is suppressed, but infiltration of electrolyte solution into the electrode body is also suppressed
Solution Approach 1:
The negative electrode active material layer is divided into two distinct regions: a damming portion at the end that contacts the electrolyte solution passage and a liquid retaining portion at the center. This segmentation allows the damming portion to control electrolyte solution flow while the liquid retaining portion maintains infiltration capability, resolving the contradiction between preventing leakage and enabling infiltration.
Solution Approach 2:
Different regions of the negative electrode active material layer are赋予 different properties: the damming portion has higher electrical potential and greater expansion/contraction ratio to control electrolyte solution passage opening/closing, while the liquid retaining portion has lower electrical potential and smaller expansion/contraction ratio to maintain infiltration. This local differentiation resolves the contradiction by assigning specific functions to specific regions.
2Reliability
If binding pressure is applied to end portions of electrode bodies, then high-rate degradation is suppressed, but battery performance recovery becomes difficult
Solution Approach 1:
The damming portion is designed with high expansion/contraction ratio characteristics that allow it to dynamically change its blocking function based on SOC. During normal operation, it maintains a blocked state to prevent leakage. During recovery processing, it can open to allow electrolyte solution infiltration, enabling both degradation suppression and performance recovery.
Solution Approach 2:
The damming portion automatically performs the function of controlling electrolyte solution passage opening and closing based on its inherent expansion and contraction properties during charging and discharging, without requiring external control mechanisms. This self-regulating behavior enables both leakage prevention and recovery capability.
3Reliability
If the electrolyte solution passage is closed to prevent leakage, then battery resistance increase is suppressed, but infiltration processing for recovery becomes very difficult
Solution Approach 1:
The electrical potential and expansion/contraction ratio parameters of the negative electrode active material are strategically selected for the damming portion to enable it to change its physical state (expanded/blocked vs. contracted/open) based on SOC. This parameter optimization allows the passage to be blocked during normal use but open during recovery, resolving the contradiction between preventing leakage and enabling infiltration.
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 suppresses the leakage of the nonaqueous electrolyte solution during normal use and allows easy infiltration during recovery, thereby maintaining favorable battery performance and solving high-rate degradation issues.
Implementation Method 1
the negative electrode active material expands or contracts as a result of intercalation or deintercalation of charge carriers in charging or discharging
Implementation Method 2
the damming portion contains a negative electrode active material of which an electrical potential relative to the positive electrode active material is high and a ratio of expansion or contraction due to an increase or decrease in SOC
Data Source
AI summary
A nonaqueous electrolyte secondary battery includes an electrode body and a nonaqueous electrolyte solution. An electrolyte solution passage is a flow passage through which the nonaqueous electrolyte solution flows between the inside and the outside of the electrode body. A region of a negative-electrode composite material layer in contact with the electrolyte solution passage is a damming portion and a region located on the center side relative to the damming portion is a liquid retaining portion. The damming portion contains a negative electrode active material of which an electrical potential relative to a positive electrode active material is high and a ratio of expansion or contraction due to an increase or decrease in SOC is high, when compared to a negative electrode active material contained in the liquid retaining portion. The electrolyte solution passage can be closed by the damming portion in a charge state where the damming portion expands.