Segmented Ceramic Cathode Structure for Bendable Lithium Batteries
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Solution Overview
Problem
Thin lithium secondary batteries face breakage of the active material plate when subjected to bending loads, leading to reduced output and potential swelling or overlapping of broken pieces.
Innovation Solution
A lithium secondary battery design featuring a sheet-like current collector with a plate-like ceramic sintered compact active material plate joined via a conductive joint layer, incorporating non-joint regions around the joint regions to prevent deformation and breakage, and using a conductive carbon layer for increased conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a sintered plate is used as a positive electrode active material layer to increase capacity, then the battery capacity is improved, but the sintered plate breaks when the battery bends, leading to reduced output and potential swelling
Solution Approach 1:
The active material plate is divided into multiple active material plate elements that are spaced from one another on the current collector. This segmentation allows the elements to move independently during bending, preventing breakage while maintaining overall battery capacity. The spacing between elements creates non-joint regions that accommodate deformation without causing structural failure.
Solution Approach 2:
The conductive joint layer is applied selectively only in joint regions where active material plate elements contact the current collector, rather than covering the entire surface. This localized application maintains electrical connectivity where needed while leaving non-joint regions flexible to accommodate bending deformation, thus preventing breakage during flexing.
2Length of moving object
If the active material plate is made thinner to reduce battery thickness, then the battery becomes more suitable for flexible devices, but the plate becomes more prone to breakage under bending loads
Solution Approach 1:
By dividing the thin active material plate into multiple spaced elements, the structure gains flexibility to bend without breaking. Each thin element can deform independently, and the spacing between elements creates buffer zones that prevent stress concentration, thereby maintaining strength despite reduced thickness.
Solution Approach 2:
The non-joint regions between active material plate elements and around their perimeters act as cushioning zones that absorb bending stress before it reaches the brittle ceramic material. This pre-planned stress absorption prevents breakage in thin plates that would otherwise be too fragile for flexible applications.
3Power
If the conductive joint layer covers the entire surface of the active material plate to ensure good electrical contact, then electrical conductivity is improved, but the plate cannot deform during bending, leading to breakage
Solution Approach 1:
The conductive joint layer is applied locally only in joint regions where active material plate elements contact the current collector, rather than covering the entire surface. This selective application maintains necessary electrical conductivity at contact points while leaving non-joint regions free to deform during bending, thus resolving the contradiction between conductivity and flexibility.
Solution Approach 2:
The joint layer is segmented into discrete contact regions rather than forming a continuous coating. This segmentation allows the active material plate elements to move and deform independently in non-joint regions while maintaining electrical connection at the segmented joint regions, enabling both good conductivity and bending flexibility.
Data Source
Figure 1~3
Figure 4
AI summary
A positive electrode (2) of a lithium secondary battery (1) includes a sheet-like positive electrode current collector (21) having conductivity, and a positive electrode active material plate (22) that is a plate-like ceramic sintered compact joined to the positive electrode current collector (21) via a conductive joint layer (23). The positive electrode active material plate (22) includes at least one active material plate element (24). This at least one active material plate element (24) is joined to the positive electrode current collector (21). A main surface of the active material plate element (24) that opposes the positive electrode current collector (21) includes a joint region in which the conductive joint layer (23) exists between the positive electrode current collector (21) and the active material plate element and a non-joint region in which the conductive joint layer (23) does not exist between the positive electrode current collector (21) and the active material plate element. The non-joint region is arranged around the joint region. Accordingly, it is possible to suppress deformation and breakage of the active material plate element (24) when the lithium secondary battery (1) becomes deformed.