Porous Carbon-Silicon Composite for Stable High-Capacity Anodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rechargeable metal-ion batteries face challenges in maintaining high electrochemical storage capacity and structural stability due to the large volumetric changes of silicon anode materials during charging and discharging, leading to capacity loss and mechanical stress.
Innovation Solution
A particulate material comprising a porous carbon framework with specific pore structures and a controlled ratio of silicon to pore volume, where nanoscale silicon domains are located within the micropores of the carbon framework, enhancing capacity retention and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon is used as anode material to achieve high capacity, then electrochemical storage capacity is improved, but structural stability deteriorates due to large volumetric changes during charging and discharging
Solution Approach 1:
The patent employs a porous carbon framework with controlled pore size (0.5-2 nm) and pore volume (0.3-1.5 cm³/g) to accommodate silicon domains. The porous structure allows silicon to expand and contract during lithiation/delithiation while maintaining overall structural integrity, resolving the contradiction between high capacity and structural stability.
Solution Approach 2:
The patent creates a composite material system consisting of silicon domains embedded within a carbon framework. This composite structure combines the high capacity of silicon with the structural stability of carbon, allowing the system to achieve both improved electrochemical storage capacity and maintained structural stability during cycling.
2Quantity of substance
If bulk silicon is used to maximize capacity, then electrochemical capacity is improved, but mechanical stress increases leading to fracturing and delamination
Solution Approach 1:
The patent divides silicon into nanoscale domains (5-50 nm) dispersed throughout the carbon framework rather than using bulk silicon. This segmentation reduces mechanical stress concentration during volume changes, preventing fracturing and delamination while maintaining high overall capacity through the distributed nanodomains.
Solution Approach 2:
The carbon framework acts as a flexible matrix that can accommodate the volume changes of silicon domains during charging and discharging. The framework's flexibility allows it to absorb mechanical stress without causing fracturing, while the nanoscale silicon domains maintain their electrochemical activity.
3Duration of action of stationary object
If silicon expansion is accommodated, then capacity retention is improved, but solid electrolyte interphase formation increases consuming lithium
Solution Approach 1:
The patent creates localized regions where silicon domains are embedded within the carbon framework, providing tailored accommodation for expansion only where needed. The carbon framework provides a stable local environment that minimizes unnecessary SEI formation on silicon surfaces, reducing lithium consumption while maintaining capacity retention.
Solution Approach 2:
The carbon framework serves as an intermediary between the silicon domains and the electrolyte. It provides a stable interface that reduces direct contact between silicon and electrolyte, minimizing SEI formation and lithium consumption while still allowing necessary lithium ion transport for electrochemical activity.
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 composite material achieves high reversible capacity retention over multiple charge-discharge cycles by accommodating silicon expansion within the porous carbon framework, minimizing solid electrolyte interphase formation, and maintaining structural integrity.
Implementation Method 1
nanoscale silicon domains located at least within the micropores of the porous carbon framework
Implementation Method 2
a porous carbon framework comprising micropores and optional mesopores
Implementation Method 3
When a graphite anode is charged, lithium intercalates between the graphite layers to form a material with the empirical formula LixC6
Implementation Method 4
an electroactive material, defined herein as a material which is capable of inserting and releasing metal ions during the charging and discharging of a battery
Implementation Method 5
the solid electrolyte interphase (SEI) layer that forms on the silicon surface does not have sufficient mechanical tolerance
Implementation Method 6
the solid electrolyte interphase (SEI) layer that forms on the silicon surface
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 total volume of at least 0.7 cm3/g and up to 2 cm3/g, wherein at least half of the total micropore and mesopore volume is in the form of pores having a diameter of no more than 1.5 nm; and (b) silicon located within the micropores and optional mesopores of the porous carbon framework in a defined amount relative to the total volume of the micropores and optional mesopores.