Microporous Carbon Composite Anodes for Silicon Volume Change
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Solution Overview
Problem
Existing rechargeable metal-ion batteries face challenges in maintaining high electrochemical storage capacity due to mechanical stress and volume changes in anode materials like silicon, leading to capacity loss over charge-discharge cycles.
Innovation Solution
A particulate material comprising a porous carbon framework with specific pore structures and a carefully controlled pore size distribution, combined with an electroactive material located within the micropores of the framework, enhances mechanical strength and electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to achieve high electrochemical capacity, then the theoretical maximum specific capacity increases to about 3,600 mAh/g, but large volumetric changes occur during charging and discharging causing mechanical stress and capacity loss
Solution Approach 1:
The silicon anode material is divided into fine particles with a D90 diameter of no more than 10 μm. This segmentation reduces the overall volumetric change experienced by each individual particle during lithiation and delithiation, thereby minimizing mechanical stress and preventing fracturing while maintaining high electrochemical capacity.
Solution Approach 2:
A porous carbon framework is introduced as the anode material structure. The porous structure accommodates the volumetric expansion and contraction of silicon during charge-discharge cycles, providing mechanical tolerance and preventing structural degradation. The porous carbon also maintains electrical conductivity and facilitates ion transport.
2Reliability
If the anode material structure is optimized to withstand volume changes, then mechanical strength and capacity retention improve, but the complexity of the material structure increases
Solution Approach 1:
A composite material structure is employed combining silicon-based electroactive material with a porous carbon framework. The carbon framework provides mechanical strength and structural stability to accommodate volume changes, while the silicon components deliver high electrochemical capacity. This composite approach achieves both reliability and performance without excessive complexity.
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
The proposed solution improves the mechanical performance and electrochemical capacity retention of the anode material, allowing for high volumetric loadings of electroactive material while withstanding repeated volume changes during battery cycles.
Implementation Method 1
the porous carbon framework is sufficiently resilient to withstand repeated volume changes over multiple charge-discharge cycles without substantial loss of capacity
Implementation Method 2
an electroactive material, defined herein as a material that is capable of inserting and releasing metal ions during the charging and discharging of a battery
Data Source
AI summary
This invention relates to particulate electroactive materials comprising a plurality of composite particles, wherein the composite particles comprise: (a) a porous carbon framework including micropores and optional mesopores having a combined total volume of at least 0.7 cm3/g, wherein at least half of the micropore/mesopore volume is in the form of pores having a diameter of no more than 1.5 nm; and (b) an electroactive material located within the micropores and/or mesopores of the porous carbon framework. The D90 particle diameter of the composite particles is no more than 10 nm.