Laminated Battery Current Collector With Rough Coating for Short Blocking
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Solution Overview
Problem
Secondary batteries face issues with internal short circuits causing temperature rises due to foreign contaminants, leading to peeling of the composite material layer from the current collector, which affects capacity retention and electric resistance.
Innovation Solution
A current collector with a laminate structure featuring a resin layer and metal layers with a rough surface and a resin coat layer, where the resin layer melts to increase pressure on the metal layer, thereby blocking current and enhancing adhesion of the composite material layer, reducing electric resistance and improving capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the composite material layer is firmly bonded to the current collector, then capacity retention rate improves, but the current collector cannot block internal short circuits effectively
Solution Approach 1:
The current collector surface is segmented into protruding parts and recessed parts, creating a rough surface structure. The composite material layer is bonded to both the resin coat layer and the exposed protruding parts of the metal layer, providing multiple bonding paths that maintain adhesion even when the metal layer breaks to block short circuits.
Solution Approach 2:
The resin coat layer acts as an intermediary between the composite material layer and the metal layer. It provides adhesive bonding to the composite material layer while allowing the metal layer to break for short circuit protection. The resin layer also serves as a buffer that absorbs stress from volume changes of the active substance.
2Strength
If the metal layer is made thicker to prevent peeling, then adhesion improves, but the current collector cannot break to block short circuit current
Solution Approach 1:
The metal layer has non-uniform thickness with protruding parts and recessed parts. The protruding parts provide strong bonding points for the composite material layer, while the recessed parts with thinner metal layer break more easily to block short circuits. This local variation in thickness allows both strong adhesion and effective short circuit protection.
3Reliability
If a rough surface is created to reduce voids and improve bonding, then capacity retention improves, but manufacturing complexity increases
Solution Approach 1:
The surface morphology of the metal layer is changed by controlling the thickness parameters during fabrication. By adjusting the thickness of the metal layer and the resin coat layer, a rough surface with protruding and recessed parts is created. This parameter-based approach achieves improved bonding and short circuit protection through a relatively simple laminate structure.
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 effectively blocks internal short circuits, maintains capacity retention, and decreases electric resistance, especially under low temperature conditions, by utilizing the resin coat layer's adhesive properties and the exposed protruding parts to increase contact area.
Implementation Method 1
the heat generated by the short circuit current melts the resin layer and the resin coat layer so as to increase the volume of the resin layer and the volume of the resin coat layer
Implementation Method 2
melts the resin layer and the resin coat layer so as to increase the volume of the resin layer and the volume of the resin coat layer
Implementation Method 3
it was confirmed that the resin coat layer present on the rough surface part of the metal layer made the composite material layer be hardly peeled off
Implementation Method 4
the protruding part exposed from the resin coat layer which increases the contact area of the composite material layer with the current collector
Implementation Method 5
particularly under the low temperature condition, the resin coat layer is shrunk so as to be capable of drawing the composite material layer near the current collector
Data Source
Figure 1
Figure 2~3
AI summary
The present disclosure provides a current collector of a secondary battery in which the current inside the battery is easily blocked at the time of inside short circuit, and in which the capacity retention rate and the decreasing rate of the electric resistance are outstanding. The current collector herein disclosed includes a laminate structure in which a resin layer and a metal layers formed on the both surfaces of the resin layer are laminated. The surface of the metal layer includes a rough surface part provided with a plurality of protruding parts and a plurality of recessed parts. On the rough surface part, a resin coat layer is formed, and at least one part of the protruding part among the plurality of protruding parts includes an exposed part that is exposed from the resin coat layer.