Lithium-Ion Battery Electrode Rolling Process for High Density
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Solution Overview
Problem
Increasing the capacity of lithium-ion secondary batteries while preventing degradation in storage characteristics due to cracking of active material particles during rolling or pressurizing processes, and overcoming the difficulty of achieving high tap density without particle cracking.
Innovation Solution
A method involving multiple rolling sub-steps with different types of rolls, including rubber and metal rolls, to gradually increase the density of composite particles and form a high-capacity electrode active material layer without cracking, using a squeegee for uniform distribution and heat-rolling for bonding, and controlling the weight per unit area to ensure stable manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If pressure is raised during the rolling step or pressurizing step to increase the density of active material particles, then the capacity of the battery is improved, but cracking occurs in the active material particles leading to degradation in storage characteristics
Solution Approach 1:
The rolling process is divided into multiple rolling steps with progressively increasing pressure. The first rolling step applies a first pressure, and the second rolling step applies a higher second pressure. This segmentation allows the active material particles to be compacted gradually without sudden stress that would cause cracking, thus achieving high density while maintaining storage characteristics.
2Quantity of substance
If the tap density of active material particles is significantly increased to achieve high capacity, then the capacity is improved, but it becomes difficult to manufacture and may still cause cracking
Solution Approach 1:
Composite particles are prepared in advance by mixing and granulating active material particles and binder at a predetermined ratio. This preliminary preparation creates particles with optimal properties for subsequent rolling, making the manufacturing process easier and enabling achievement of high tap density without causing cracking during the rolling 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
This method effectively increases the density of the active material layer, enhancing the capacity of lithium-ion secondary batteries while maintaining storage characteristics by preventing particle cracking and reducing manufacturing costs through energy savings and eliminating the drying step.
Implementation Method 1
rolling the composite particles supplied onto the collector to form an active material layer. The rolling step includes a first rolling sub-step involving first rolling, and a second rolling sub-step to be performed after the first rolling sub-step
Implementation Method 2
rolling the composite particles while applying heat thereto, thus manufacturing an electrode
Data Source
AI summary
The present invention discloses a method of manufacturing a lithium-ion secondary battery electrode. The method includes the steps of: supplying composite particles (1), each containing an active material (2) and a binder (4), onto a sheet collector (42); and rolling the composite particles (1) supplied onto the collector (42), thus forming an active material layer (44). The rolling step includes a first rolling sub-step involving first rolling, and a second rolling sub-step to be performed after the first rolling sub-step. Rubber rolls (R1) are preferably used in the first rolling sub-step.