Silicon Anode Composition With Polymer Electrolyte for Volume Expansion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Silicon-based electrodes in energy storage devices face issues due to volume expansion and contraction, leading to material breakage and reduced specific capacity, limiting their widespread commercial use.
Innovation Solution
A composite electrode structure comprising 40-80% silicon, 15-40% graphite, 5-15% carbon black, 0-15% carboxymethyl cellulose, 0-5% styrene-butadiene rubber, and 5-20% poly(acrylic acid) with a polymer electrolyte of 90-98% poly(ethylene glycol) methyl ether acrylate and 2-10% polyethylene glycol diacrylate, and lithium hexafluorophosphate, which mitigates volume expansion and enhances energy storage capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as electrode material to increase specific capacity, then energy density is improved, but volume expansion causes material breakage and contact loss
Solution Approach 1:
Silicon particles are encapsulated within a porous carbon matrix structure, creating a nested configuration where the silicon is contained within the carbon framework. This nesting approach allows the silicon to expand and contract within the confined carbon structure, preventing material breakage and maintaining electrode integrity during charge-discharge cycles.
Solution Approach 2:
The porous carbon matrix is pre-formed with a specific structure before silicon particles are introduced and encapsulated within it. This preliminary structuring of the carbon framework provides pre-established pathways for ion transport and creates a stable scaffold that anticipates and accommodates the volume changes of silicon during operation.
2Reliability
If graphite is used as electrode material to ensure stability, then reliability is improved, but specific capacity is limited
Solution Approach 1:
The electrode employs a composite structure combining silicon particles with a porous carbon matrix, leveraging the high capacity of silicon while using the stable carbon framework to provide structural support and ion transport pathways. This composite approach integrates the advantages of both materials to achieve high capacity with maintained stability.
3Use of energy by moving object
If silicon content is increased to enhance energy density, then specific energy is improved, but volume expansion and contraction cause material breakage
Solution Approach 1:
The porous carbon matrix acts as a flexible confining structure that can accommodate the volume expansion and contraction of silicon particles during charge-discharge cycles. The carbon framework's flexible porous structure prevents mechanical breakage of silicon while maintaining the electrode's overall structural integrity and ion transport capability.
Data Source
AI summary
Aspects of the disclosure describe an energy storage device comprising a cathode, an anode, a separator, and an electrolyte. The anode comprises a support structure and an electrode layer disposed on the support structure. The electrode layer comprises 40-80% silicon, 15-40% graphite, 5-15% carbon black, 0-15% carboxymethyl cellulose (CMC), 0-5% styrene-butadiene rubber (SBR), and 5-20% poly(acrylic acid). The separator is disposed between the anode and cathode to prevent internal shorting of the energy storage device. The electrolyte allows movement of ions between the anode and cathode.