Li-Ion Anode Composition for High-Loading Silicon Expansion Control
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Solution Overview
Problem
Existing rechargeable batteries, particularly those with high-capacity (nano)composite anode and cathode powders, face challenges in achieving stable performance due to moderate to high volume changes during charge-discharge cycles, which leads to poor cycle stability and limited capacity utilization, especially at moderate to high areal loadings.
Innovation Solution
The development of improved battery electrodes involves the use of Si-comprising active material particles with specific size and volume expansion characteristics, combined with optimized conductive additive materials and polymer binders that stabilize the anode electrode against volume expansion while maintaining electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity (nano)composite powders are used to increase electrode capacity, then cell energy density improves, but volume changes during charge-discharge cycles cause poor cycle stability
Solution Approach 1:
The patent applies nesting by placing Si-comprising particles inside a carbon coating layer, which is further protected by a shell structure. This nested configuration allows the high-capacity Si particles to undergo volume expansion/contraction while being contained and supported by the surrounding carbon and shell layers, thereby maintaining electrode integrity over multiple cycles.
Solution Approach 2:
The patent uses composite materials by combining Si-comprising particles with carbon coating and shell structures. This composite approach allows the Si particles to provide high capacity while the carbon and shell components accommodate volume changes and maintain structural stability, resolving the contradiction between capacity and cycle stability.
2Productivity
If moderate to high areal loadings are used to improve cell energy density, then manufacturing efficiency improves, but performance stability deteriorates due to volume changes
Solution Approach 1:
The patent employs flexible shells by using a carbon coating layer and shell structure that can elastically deform to accommodate the volume expansion and contraction of Si particles during charging and discharging. This flexible enclosure allows high areal loading to be applied without compromising performance stability, as the shell absorbs mechanical stress.
Solution Approach 2:
The patent applies parameter changes by modifying the physical and chemical properties of the shell and binder materials to optimize their mechanical characteristics. By adjusting parameters such as shell thickness, material composition, and binder properties, the electrode can withstand high areal loadings while maintaining performance stability through controlled mechanical response to volume changes.
3Ease of manufacture
If conventional binders and mixing protocols are used with new charge-storing particles, then manufacturing simplicity is maintained, but electrical connectivity and performance are poor
Solution Approach 1:
The patent applies parameter changes by optimizing the composition and properties of binders and conductive additives. Specifically, the binder is formulated with enhanced adhesive properties and the conductive additive content and distribution are adjusted to ensure adequate electrical connectivity. These parameter modifications allow conventional manufacturing processes to produce high-performance electrodes without sacrificing simplicity.
Solution Approach 2:
The patent uses composite materials by combining conventional binder and conductive additive components in optimized ratios and configurations. This composite approach enhances electrical connectivity and mechanical adhesion while maintaining compatibility with existing manufacturing protocols, resolving the contradiction between ease of manufacture and performance.
4Quantity of substance
If Si-comprising particles with high volume expansion are used to increase capacity, then energy density improves, but electrode structural stability deteriorates
Solution Approach 1:
The patent applies nesting by placing Si-comprising particles inside a carbon coating layer that is further enclosed by a shell structure. This nested configuration allows the high-capacity Si particles to undergo volume expansion/contraction while being contained and supported by the surrounding carbon and shell layers, thereby maintaining electrode integrity over multiple cycles.
Solution Approach 2:
The patent employs flexible shells by using a carbon coating layer and shell structure that can elastically deform to accommodate the volume expansion and contraction of Si particles during charging and discharging. This flexible enclosure allows high capacity to be achieved while maintaining structural stability, as the shell absorbs mechanical stress.
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 stability and rate performance of Li-ion battery cells, particularly at high areal loadings, by effectively managing volume changes and maintaining electrical connectivity, thereby improving overall battery efficiency and lifespan.
Implementation Method 1
comprises a polymer binder that is configured to bind the Si-comprising active material particles and the conductive additive material particles together to stabilize the anode electrode against the volume expansion
Implementation Method 2
comprises conductive additive material particles... while maintaining an electrical connection between the metal current collector and the Si-comprising active material particles
Data Source
AI summary
In an embodiment, a Li-ion battery cell comprises an anode electrode with an electrode coating that (1) comprises Si-comprising active material particles, (2) exhibits an areal capacity loading in the range of about 3 mAh/cm2 to about 12 mAh/cm2, (3) exhibits a volumetric capacity in the range from about 600 mAh/cc to about 1800 mAh/cc in a charged state of the cell, (4) comprises conductive additive material particles, and (5) comprises a polymer binder that is configured to bind the Si-comprising active material particles and the conductive additive material particles together to stabilize the anode electrode against volume expansion during the one or more charge-discharge cycles of the battery cell while maintaining the electrical connection between the metal current collector and the Si-comprising active material particles.