Battery Separator Surface Roughness Ratio for Lamination Alignment
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries face issues with lamination misalignment during production, particularly at the interface between the negative electrode active material layer and the separator, leading to suboptimal charging/discharging capacity and potential internal short circuits.
Innovation Solution
Controlling the surface roughness ratio between the negative electrode active material layer and the separator to a range of 0.15 to 0.85, and between the positive electrode active material layer and the separator to a range of 0.15 to 1.5, to enhance the dynamic friction coefficient and prevent lamination misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separator made of soft material such as polyolefine is used, then the separator can hold non-aqueous electrolyte and provide ion conductivity, but foreign pieces and electrode fragments can pass through the separator causing internal short circuits
Solution Approach 1:
The patent applies composite materials by combining a polyolefine separator base material with inorganic fine particles (such as alumina, silica, or titania) to form a breathable surface protection layer. This composite structure maintains the ion conductivity of the polyolefine while adding mechanical strength and filtration capability to prevent foreign pieces and electrode fragments from causing internal short circuits.
Solution Approach 2:
The patent utilizes porous materials by forming a breathable surface protection layer with controlled porosity on the separator surface. The porous structure allows ion transport while the inorganic fine particles provide mechanical reinforcement to block larger particles such as foreign pieces and electrode fragments, thus preventing internal short circuits while maintaining ion conductivity.
2Manufacturing precision
If elements are precisely laminated in the lamination process, then lamination misalignment is prevented and active materials are adequately utilized, but the manufacturing process becomes more difficult to control
Solution Approach 1:
The patent applies self-service by designing the separator with a breathable surface protection layer that inherently provides frictional resistance to prevent lamination misalignment. The surface properties of the separator itself create the necessary grip during lamination without requiring external fixation mechanisms or complex process controls, allowing the separator to 'self-correct' alignment issues during the lamination process.
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
Effectively suppresses lamination misalignment during the manufacturing process, ensuring better utilization of active materials and preventing internal short circuits, thereby improving the charging/discharging capacity and reliability of non-aqueous electrolyte secondary batteries.
Implementation Method 1
a value (which will be referred to as a surface roughness ratio) RA (=Rzjis (2)/Rzjis(1)) for the ratio between the surface roughness (Rzjis(1)) of the surface of the negative electrode active material layer on the side in contact with the separator and the surface roughness (Rzjis(2)) of the surface of the separator on the side in contact with the negative electrode active material layer is 0.15 to 0.85
Data Source
AI summary
A non-aqueous electrolyte secondary battery of the invention has a power generating element with a single-cell layer which comprises a positive electrode including a positive electrode active material layer formed on a surface of a positive electrode collector, a negative electrode including a negative electrode active material layer formed on a surface of a negative electrode collector and a separator disposed between the positive electrode the negative electrode and containing a non-aqueous electrolyte, in which a value RA (=Rzjis (2)/Rzjis(1)) for the ratio between the surface roughness (Rzjis(1)) of the surface of the negative electrode active material layer on the side in contact with the separator and the surface roughness (Rzjis(2)) of the surface of the separator on the side in contact with the negative electrode active material layer is 0.15 to 0.85.