Battery Electrode Layer Geometry to Prevent Edge Lithium Plating
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Solution Overview
Problem
Secondary batteries face issues with lithium precipitation due to thickness differences in active material layers on substrates, which degrade battery performance.
Innovation Solution
The electrode for a secondary battery features a substrate with active material layers having a lower layer and an upper layer, where the edge of the lower layer has an inclined surface with decreasing thickness, and the upper layer covers this edge with a cut surface at an angle greater than the substrate's surface angle, ensuring uniform thickness without exposing the lower layer's end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If active material layers are formed on two opposite surfaces of the substrate to increase battery capacity, then the battery capacity is improved, but thickness differences occur at the edges of the substrate leading to lithium precipitation
Solution Approach 1:
The patent applies local quality by creating different thickness profiles at different locations of the active material layer. The edge portions of the active material layer are designed with gradually decreasing thickness toward the substrate edge, while the central portion maintains uniform thickness. This local variation in thickness distribution prevents lithium precipitation at edges while preserving overall battery capacity.
Solution Approach 2:
The patent employs asymmetry by making the active material layer thickness non-uniform across the substrate surface. Specifically, the thickness of the active material layer decreases asymmetrically from the center toward the edges, creating a controlled thickness gradient that prevents lithium precipitation at the edges while maintaining sufficient capacity in the central region.
2Quantity of substance
If the active material layer thickness is increased to enhance battery performance, then the energy density is improved, but lithium precipitation occurs at the edges degrading battery characteristics
Solution Approach 1:
The patent implements local quality by varying the active material layer thickness according to location. The central region maintains greater thickness for high energy density, while the edge regions have gradually reduced thickness to prevent lithium precipitation. This spatially differentiated thickness distribution simultaneously achieves high energy density and maintains battery reliability.
Solution Approach 2:
The patent applies parameter changes by modifying the thickness parameter of the active material layer as a function of position. The thickness parameter transitions from a constant value to a position-dependent value that decreases toward the edges, creating a thickness gradient that prevents lithium precipitation while preserving overall energy density.
Data Source
AI summary
An electrode for a secondary battery includes a substrate, an active material layer including a lower layer on the substrate, and an upper layer on the lower layer, wherein an edge of the lower layer has an inclined surface having a thickness that decreases toward an end of the lower layer, and wherein the upper layer has a cut surface on the inclined surface and at an end of the upper layer, and an angle defined between the cut surface and an upper surface of the substrate is larger than an angle defined between the inclined surface and the upper surface of the substrate.