Electrode Sheet Elastic Modulus Gradient for Break Prevention
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Solution Overview
Problem
The high tension required to prevent wrinkling and meandering of electrode sheets during manufacturing of power storage devices leads to breaks at the boundary between exposed and active material layers, increasing manufacturing costs and reducing productivity.
Innovation Solution
An electrode sheet with a current collector having a substantially rectangular shape and an active material layer, where the elastic modulus of the region adjacent to the exposed portion in the width direction is higher than that in the longitudinal direction, reducing stress concentrations and preventing breaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If high tension is applied to the electrode sheet material to prevent wrinkling and meandering during high-speed movement, then the electrode sheet maintains its shape and position, but breaks occur at the boundary between the exposed portion and the active material layer
Solution Approach 1:
The patent applies local quality by creating a transition zone with gradually changing active material layer thickness adjacent to the exposed portion. This transition zone has intermediate thickness that provides gradual mechanical property transition, preventing sudden stress concentration at the boundary while maintaining the necessary tensile strength during high-speed processing.
Solution Approach 2:
The patent implements preliminary action by pre-forming the transition zone during the electrode sheet manufacturing process, before the high-tension handling occurs. This pre-established gradient structure proactively prepares the boundary region to withstand subsequent high-tension operations without breaking.
2Quantity of substance
If the exposed portion width is reduced to increase the active material layer region, then the capacity of the power storage device increases, but the boundary between exposed portion and active material layer becomes more vulnerable to breaks under tension
Solution Approach 1:
The patent uses local quality by creating a spatially varying active material layer thickness, where the transition zone has intermediate thickness between the exposed portion and the full-thickness active material region. This localized gradient structure increases active material quantity while maintaining boundary reliability through gradual property transition.
3Productivity
If the electrode sheet material is moved at high speed to increase productivity, then the manufacturing efficiency increases, but the tension required to prevent wrinkling causes breaks at the boundary
Solution Approach 1:
The patent implements preliminary action by pre-forming the transition zone during electrode sheet manufacturing, before high-speed handling occurs. This pre-established gradient structure proactively prepares the boundary to withstand subsequent high-tension operations, enabling high-speed productivity without breaks.
Data Source
AI summary
A positive electrode active material layer is formed on at least one surface of a positive electrode current collector having a substantially rectangular planar shape. The positive electrode current collector includes an exposed portion in a partial region in a longitudinal direction and at an end portion of the partial region in a width direction, and a positive electrode lead is to be connected to the exposed portion. In a region in which the positive electrode active material layer is formed, an elastic modulus of a first region adjacent to the exposed portion in the width direction is larger than elastic moduli of second regions adjacent to the exposed portion and the first region in the longitudinal direction.