Secondary Battery Electrode Layout for Short-Circuit Suppression
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Solution Overview
Problem
Existing secondary batteries face challenges in achieving both the suppression of short circuits and an increase in battery capacity, with insufficient measures to address these issues.
Innovation Solution
The secondary battery design includes a positive electrode active material layer with reaction active and reaction less-active parts, where the positive electrode active material layer has the same dimension as the negative electrode active material layer, with the reaction less-active parts at the ends to prevent short circuits and enhance capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the positive electrode and negative electrode are made with the same dimensions to increase battery capacity, then the energy density improves, but the risk of short circuit increases due to positional deviation during stacking
Solution Approach 1:
The patent applies local quality by creating a reaction less-active part (inactive region) at specific locations on the positive electrode. This inactive region is formed by laser irradiation that removes or deactivates the active material in localized areas, creating zones with different functional properties. The inactive region acts as a buffer zone that prevents short circuits while maintaining overall electrode dimensional equality, thus resolving the contradiction between maximizing capacity and preventing short circuits.
Solution Approach 2:
The patent implements preliminary action by forming the inactive region on the positive electrode before the stacking process. The laser irradiation treatment is performed in advance to create protective zones that will prevent future short circuits. This preliminary modification of the electrode structure ensures that even if positional deviation occurs during stacking, the inactive regions will absorb the deviation without causing electrode contact and short circuits.
2Manufacturing precision
If laser cutting is used to cut the positive electrode to achieve stable manufacturability, then the manufacturing precision improves, but the battery capacity decreases due to loss of active material
Solution Approach 1:
The patent applies parameter changes by modifying the laser processing parameters to create an inactive region rather than completely cutting through the electrode. By controlling laser irradiation conditions (energy density, scanning speed, number of passes), the process removes or deactivates active material in a controlled manner to create protective zones without excessive material loss. This parameter optimization allows achieving both manufacturing precision and acceptable capacity retention.
Data Source
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AI summary
A secondary battery includes a negative electrode, a positive electrode, and an electrolytic solution. The negative electrode includes a negative electrode active material layer. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer has a same dimension as a dimension of the negative electrode active material layer in a width direction. The positive electrode active material layer includes a reaction active part in which charging and discharging reactions proceed, and a reaction less-active part in which the charging and discharging reactions proceed less easily than in the reaction active part. The reaction less-active part includes one end part, another end part, or both of the positive electrode active material layer in the width direction.