Porous Electrode Buffer for Flexible Battery Cycle Life
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Solution Overview
Problem
Lithium-ion secondary batteries face degradation in charge and discharge cycle characteristics due to repeated expansion and contraction of active materials, leading to separation between the current collector and active material, which deteriorates the battery's performance, especially when used in flexible or bendable devices.
Innovation Solution
An electrode member comprising a current collector, an active material, and a porous body with spaces larger than the active material, where the active material is located within these spaces, and the porous body includes carbon fibers and resin, along with flake-like metal powder, to prevent separation and maintain electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If active material is used for electrode of secondary battery, then charge and discharge capacity is improved, but repeated expansion and contraction causes separation between current collector and active material, deteriorating cycle characteristics
Solution Approach 1:
The patent employs a porous body as a buffer structure between the active material and current collector. This porous body contains spaces larger than the active material, allowing the active material to expand and contract freely during charge and discharge cycles without causing separation from the current collector, thereby maintaining reliable electrical connection while preserving high capacity
Solution Approach 2:
The porous body acts as an intermediary layer between the active material and current collector. It mediates the mechanical stress caused by expansion and contraction, absorbing these stresses within its porous structure and preventing direct transmission to the current collector interface, thus avoiding separation and maintaining stable electrical connection
2Adaptability or versatility
If secondary battery is made flexible for bendable devices, then adaptability to device form changes is improved, but repeated bending causes separation between current collector and active material, promoting deterioration
Solution Approach 1:
The porous body provides a compliant, cushioning structure that can accommodate bending deformations. When the flexible battery is bent, the porous structure deforms elastically and absorbs mechanical stress, preventing the active material from separating from the current collector even under repeated bending conditions
Solution Approach 2:
The porous body is pre-configured as a cushioning structure before the battery is subjected to bending. This beforehand cushioning prepares the electrode to absorb and distribute mechanical stresses from bending, preventing separation and deterioration before they can occur during actual use in flexible devices
Data Source
AI summary
To inhibit degradation of charge and discharge cycle characteristics of a secondary battery. To suppress generation of defects due to expansion and contraction of an active material in a negative electrode. To inhibit deterioration of an electrode due to changes in its form. An electrode member including a current collector, an active material, and a porous body is used. The porous body is in contact with one surface of the current collector and includes a plurality of spaces. The active material is located in the space in the porous body. The space has a larger size than the active material.