Silicon-Dominant Anode Lamination for Directional Expansion Control
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Solution Overview
Problem
Conventional battery anodes, particularly those dominated by silicon, face challenges due to large volume changes during lithiation and delithiation, leading to electrical isolation, capacity loss, and reduced cycle life due to solid electrolyte interphase formation and pulverization of silicon particles.
Innovation Solution
The anisotropic expansion of silicon-dominant anodes is achieved by configuring the expansion to occur predominantly in the z-direction by using thicker foils, roughened surfaces, and specific lamination processes such as roll press, which restricts x- and y-direction expansion, thereby maintaining electrical contact and reducing capacity loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-dominant anodes undergo large volume changes during lithiation and delithiation, then capacity is improved, but electrical isolation and pulverization occur leading to reduced cycle life
Solution Approach 1:
The patent applies a thin film coating on silicon-dominant anode particles that acts as a flexible protective shell. This shell accommodates the large volume changes during lithiation and delithiation while maintaining structural integrity and preventing pulverization. The thin film allows the anode to achieve high capacity while maintaining reliable cycle life by preventing electrical isolation and mechanical failure.
Solution Approach 2:
The patent utilizes composite material structures combining silicon with other materials that can accommodate volume expansion. The composite structure allows the silicon to achieve its high lithium capacity while the accompanying materials provide structural stability and prevent pulverization, thereby maintaining both high capacity and long cycle life.
2Ease of manufacture
If conventional anode structures are used, then manufacturing is simpler, but lateral expansion causes capacity loss and performance degradation
Solution Approach 1:
The patent applies local quality control by implementing specific structural features at the particle level (such as core-shell structures or surface modifications) that restrict lateral expansion. This localized approach maintains overall manufacturing simplicity while significantly improving capacity retention by preventing harmful lateral expansion at the particle level.
Solution Approach 2:
The patent modifies physical or chemical parameters of the anode structure, such as particle size, shape, or surface properties, to control expansion behavior. By changing these parameters, the anode maintains manufacturability while achieving restricted lateral expansion and improved capacity retention during cycling.
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 the cycle life and capacity retention of silicon-dominant anodes by minimizing lateral expansion, resulting in improved performance and stability of lithium-ion batteries.
Implementation Method 1
The anisotropic expansion of silicon-dominant anodes is achieved by configuring the expansion to occur predominantly in the z-direction
Implementation Method 2
using thicker foils, roughened surfaces, and specific lamination processes such as roll press, which restricts x- and y-direction expansion
Implementation Method 3
specific lamination processes such as roll press
Data Source
AI summary
Systems and methods for anisotropic expansion of silicon-dominant anodes may include forming an anode by pyrolyzing an active material layer comprising a binder and silicon particles in a temperature range of 600 to 800° C.; and forming a battery cell comprising a cathode, an electrolyte, and the anode, where the anode comprises the pyrolyzed active material layer on a current collector. A lateral expansion of the anode during operation may be less than 2%, less than 1%, or less than 0.6%. The active material layer may be pyrolyzed on the current collector or may be pyrolyzed on a substrate before laminating on the current collector. The anode active material layer may be pyrolyzed using a 1 hour dwell time or less or using a 2 hour dwell time or less. The active material layer may be pyrolyzed in a temperature range of 650 to 800° C.