Silicon-Dominant Anode Foil Design for Directional Expansion
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Solution Overview
Problem
Conventional battery anodes are costly, cumbersome, and inefficient, limiting battery lifetime due to large volume changes during lithiation and delithiation, which cause electrical isolation and capacity loss in silicon-dominant anodes.
Innovation Solution
The method involves configuring anisotropic expansion of silicon-dominant anodes by controlling expansion direction using current collector foil thickness, material strength, and lamination processes, such as roll press and flat press, to restrict x- and y-direction expansion while allowing z-direction expansion, thereby maintaining electrical contact and reducing solid electrolyte interphase formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-dominant anodes undergo large volume changes during lithiation and delithiation, then battery energy density is improved, but electrical isolation and capacity loss occur reducing battery lifetime
Solution Approach 1:
The anode is segmented into multiple layers with different expansion characteristics. The graphite-containing anode layer is positioned between silicon-dominant anode layers, creating a multi-layer structure where each layer undergoes different volume changes during lithiation and delithiation. This segmentation prevents complete electrical isolation while maintaining high energy density.
Solution Approach 2:
The anode uses composite materials combining silicon with graphite and conductive additives. The graphite provides structural stability and maintains electrical conductivity during volume changes, while silicon provides high capacity. The conductive additives further ensure electrical connectivity is maintained throughout the cycling process.
2Ease of manufacture
If conventional battery anodes are used, then manufacturing is simpler, but they are costly and inefficient with limited battery lifetime
Solution Approach 1:
The multi-layer anode structure serves multiple functions simultaneously: the silicon-dominant layers provide high capacity, the graphite-containing layer provides structural stability and electrical connectivity, and the conductive additives ensure continuous electron transport. This multi-functionality achieves high efficiency without significantly complicating the manufacturing process.
3Reliability
If anode expansion is restricted in x- and y-directions, then electrical contact is maintained, but expansion in z-direction is allowed causing potential issues
Solution Approach 1:
The anode structure has different properties in different directions and layers. The in-plane direction (x-y) is constrained by the flexible substrate and adjacent layers to maintain electrical contact, while the through-thickness direction (z) allows expansion. This local quality differentiation resolves the contradiction between maintaining electrical contact and managing overall shape changes.
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
This approach enhances cycle life and energy density of lithium-ion batteries by minimizing lateral expansion and maintaining electrical conductivity, resulting in improved reliability and safety.
Implementation Method 1
configuring anisotropic expansion of silicon-dominant anodes by controlling expansion direction using current collector foil thickness, material strength, and lamination processes
Implementation Method 2
lamination processes, such as roll press and flat press, to restrict x- and y-direction expansion
Data Source
AI summary
Systems and methods are provided for managing anisotropic expansion of silicon-dominant anodes. An example battery may include a cathode, an electrolyte, and an anode, with the anode including a current collector and an active material on a surface of the current collector. One or more characteristics of the current collector may ensure meeting particular expansion criteria. The expansion criteria may include expanding less in one of x-y directions and z-direction while expanding more in other one of the x-y directions and the z-direction, the x-y directions being parallel to the surface of the current collector and perpendicular to a thickness of the active material. The one or more characteristics include at least material of the current collector.