Dry Battery Electrode Roughness Control for Pouch Cells
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Solution Overview
Problem
Lithium secondary batteries with uneven electrode surfaces, caused by insufficient shear stress during dry manufacturing, can lead to operational issues in pouch cells due to increased surface roughness, affecting interfacial resistance and electrochemical properties.
Innovation Solution
A dry electrode with controlled surface roughness is achieved by ensuring uniform thickness and pattern spacing through precise application of shear stress during film formation, using a method that adjusts roller distance and speed ratio to satisfy specific thickness and pattern area ratios, resulting in improved electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dry method is used to manufacture the electrode, then the manufacturing process is simplified and productivity is improved, but the electrode surface becomes uneven with increased roughness
Solution Approach 1:
The patent applies preliminary pressing treatment to the electrode before it is fully formed during the dry manufacturing process. This preliminary action compacts the electrode material and smooths the surface early in the process, preventing excessive roughness from developing while maintaining the productivity benefits of the dry method.
Solution Approach 2:
The patent modifies process parameters including pressing force, pressing duration, and roller pressure during film formation to control surface roughness. By adjusting these parameters, the electrode achieves both the productivity of dry manufacturing and the surface uniformity required for pouch cell operation.
2Device complexity
If the electrode surface is left uneven from dry manufacturing, then manufacturing complexity is reduced, but interfacial resistance increases and electrochemical performance deteriorates
Solution Approach 1:
The pressing treatment is applied as a preliminary step during electrode formation rather than as a separate post-processing step. This integrates surface smoothing into the manufacturing flow, adding minimal complexity while significantly improving interfacial contact and electrochemical performance.
Solution Approach 2:
The patent introduces a pressing mechanism as an intermediary step between material deposition and final electrode formation. This intermediary action mediates between the simple dry manufacturing process and the requirement for high electrochemical performance by compacting and smoothing the electrode surface.
3Manufacturing precision
If pressing force is increased to reduce surface roughness, then surface uniformity improves, but electrode thickness variation increases
Solution Approach 1:
The pressing is applied preliminarily during film formation when the material is still pliable, allowing uniform compression across the electrode surface. This timing prevents excessive localized pressure that would cause thickness variation, while still achieving the surface uniformity needed for pouch cell operation.
Solution Approach 2:
The patent employs dynamic pressing where the pressure is applied progressively and uniformly across the electrode surface during formation, rather than as a static high-pressure step. This dynamic approach allows the electrode to conform uniformly to the pressing force, maintaining thickness uniformity while reducing surface roughness.
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 enables pouch-type lithium secondary batteries with reduced interfacial resistance, enhanced electronic and lithium ion conductivity, improved specific capacity, capacity retention, and coulombic efficiency.
Implementation Method 1
a surface of the electrode may have unevenness or irregularities due to reasons such as insufficient shear stress applied to the electrode
Data Source
AI summary
The present disclosure relates to a dry electrode for a lithium secondary battery with controlled surface roughness and a pouch-type lithium secondary battery including the same.