Non-aqueous Electrolyte Battery Tab Design for Short Circuit Prevention
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Solution Overview
Problem
Lithium-ion secondary batteries face issues with lithium deposition as dendrites on the negative electrode, leading to short circuits and reduced reliability, especially when the separator shrinks at high temperatures, and existing solutions like insulating tape do not fully prevent lithium ion diffusion and short circuits.
Innovation Solution
A non-aqueous electrolyte secondary battery design where the positive electrode active material layer on the positive electrode tab extends beyond the leading end of the negative electrode active material layer, with a reduced amount of active material at the tab's end, and an insulating member is used to prevent direct contact between the positive and negative electrodes, reducing lithium ion transfer and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the positive electrode is disposed more inward than the negative electrode to prevent lithium dendrite deposition, then lithium deposition is reduced, but the negative electrode becomes exposed at the periphery causing short circuit risk when separator shrinks at high temperature
Solution Approach 1:
An insulating tape is introduced as an intermediary substance between the positive electrode lead-out tab and the negative electrode. This tape prevents direct contact and potential short circuits while allowing the positive electrode to maintain its inward disposition for dendrite prevention. The insulating tape specifically covers the peripheral portion where the positive electrode is disposed more inward than the negative electrode.
Solution Approach 2:
The insulating treatment is applied locally only to the peripheral portion of the positive electrode where it is disposed more inward than the negative electrode, rather than covering the entire electrode. This localized approach prevents short circuits at the critical interface while maintaining optimal lithium ion transfer pathways in the central regions.
2Object-affected harmful factors
If insulating tape is adhered to the tapered portion of positive electrode coating end to prevent short circuit, then short circuit risk is reduced, but lithium ion diffusion is not fully prevented and dendrite deposition may still occur
Solution Approach 1:
Instead of applying insulating tape to the tapered portion of the positive electrode coating end (conventional approach), the insulating tape is applied to the peripheral portion of the positive electrode where it is disposed more inward than the negative electrode. This inverted approach simultaneously addresses both short circuit prevention and lithium ion diffusion control by positioning the insulating barrier at the actual interface between positive and negative electrodes.
3Reliability
If the positive electrode active material layer extends beyond the negative electrode active material layer at the tab end, then lithium ion transfer is reduced, but the device complexity increases
Solution Approach 1:
The positive electrode active material layer is designed to extend beyond the negative electrode active material layer at the tab end in advance, creating a built-in structural feature that prevents lithium ion transfer to exposed negative electrode portions. This preliminary design eliminates the need for additional insulating structures at this specific location, reducing overall device complexity while maintaining reliability.
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 lithium deposition as dendrites and reduces the risk of short circuits, enhancing the battery's reliability and safety by limiting lithium ion transfer and conductivity, even under high temperature conditions.
Implementation Method 1
a separator, and a positive electrode laminated on the negative electrode through the separator
Implementation Method 2
an insulating member extending in the drawing direction of the positive electrode tab from a part of the positive electrode lead-out tab
Data Source
Figure 1A~1D
Figure 2A~2B
Figure 3A~3B
AI summary
To provide a non-aqueous electrolyte secondary battery capable of preventing formation of lithium on a negative electrode during charging and preventing a short circuit between positive and negative electrodes due to contraction of a separator at high temperature. A non-aqueous electrolyte secondary battery includes a negative electrode in which a negative electrode active material layer is formed on a negative electrode collector, and a positive electrode laminated on the negative electrode through a separator, in which a positive electrode active material layer is formed on a positive electrode collector. The positive electrode active material layer on a surface of a positive electrode tab drawn from the positive electrode collector has a region which extends in a drawing direction of the positive electrode tab, exceeding a leading end line of a vertically projected negative electrode active material layer opposed to the positive electrode active material layer and in which an existing amount of the positive electrode active material layer is reduced toward its leading end portion.