Patterned Electrode Assemblies for Bendable Lithium-Ion Batteries
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Solution Overview
Problem
Conventional lithium-ion batteries suffer from damage and performance degradation due to unbalanced shear forces and stress when bent, limiting their flexibility and safety for wearable electronics applications.
Innovation Solution
The development of flexible lithium-ion batteries with patterned electrodes, featuring a positive and negative current collector with longitudinal rails and spaced active segments, which localizes bending stresses to specific areas, maintaining relatively unstressed regions for the active materials, thereby enhancing flexibility and adhesion while minimizing capacity reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If simple bending is applied to the layered battery structure, then the battery can be flexed for wearable applications, but unbalanced shear forces and stress cause damage to electrode material and separator
Solution Approach 1:
The battery structure is segmented into multiple independent layers (positive electrode, separator, negative electrode, current collectors) that can deform independently. This segmentation allows each layer to accommodate bending stress separately, preventing cumulative stress damage that would occur in a rigid monolithic structure.
Solution Approach 2:
Different regions of the battery structure are designed with different properties - the electrode materials and separator are positioned to withstand compressive stress, while the current collectors are designed to handle tensile stress during bending. This local differentiation of mechanical properties allows the battery to flex without damaging sensitive components.
2Strength
If the battery layers are made thicker to improve structural integrity, then strength increases, but flexibility and bendability decrease
Solution Approach 1:
The battery structure is designed to dynamically adapt its mechanical response during bending. The layered construction allows the structure to flex and deform in real-time under applied stress, rather than resisting deformation statically. This dynamic flexibility is achieved through the thin-layered architecture that can bend without breaking, unlike thicker rigid structures.
Solution Approach 2:
The battery employs a composite layered structure combining different materials (electrode materials, separator, current collectors) with complementary mechanical properties. This composite architecture provides both the strength needed for structural integrity and the flexibility required for bending, as each material layer contributes its specific mechanical characteristics to the overall structure.
3Stability of the object's composition
If cumulative tensile stress is distributed throughout the battery during bending, then structural coherence is maintained, but electrode material and solid electrolyte interface are damaged
Solution Approach 1:
The current collectors are specifically designed with enhanced mechanical properties to locally bear the tensile stress during bending, while the electrode materials and separator are positioned in regions experiencing less tensile stress. This spatial differentiation of stress distribution protects the sensitive electrode materials from damage while maintaining overall structural coherence.
Solution Approach 2:
The current collectors act as intermediary structural elements that mediate between the external bending forces and the sensitive electrode materials. They absorb and distribute tensile stresses, protecting the electrode-active material interfaces from direct mechanical damage while maintaining electrical connectivity and structural integrity.
Data Source
AI summary
Flexible lithium-ion batteries include patterned electrode assemblies configured to partition bending stresses when the lithium-ion battery is flexed by localizing high bending stresses. The patterned electrode assemblies can include a patterned current collector and active material or patterned active material formed on a current collector that is not patterned.