Core-Shell Composite Anode for Fast-Charging Lithium-Ion Cells
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Solution Overview
Problem
Current lithium ion batteries (LIBs) employ conventional graphite anodes that are limited in capacity and unable to support fast charging due to their mechanical and electrical constraints during lithiation and de-lithiation processes.
Innovation Solution
The development of composite anode materials comprising core-shell particles with conductive cores made of metalloids like silicon or tin, surrounded by shells that allow for expansion and interconnected by carbon fibers for enhanced electrical conductivity, and incorporating ionic conductive materials to manage mechanical stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional graphite anodes are used, then structural stability is maintained, but capacity and fast charging ability are limited
Solution Approach 1:
The anode is segmented into multiple functional layers: metalloid cores for lithium insertion, carbon shells for structural stability, and conductive polymer coatings for electron transport. This segmentation allows each layer to specialize in one function, enabling high capacity while maintaining structural integrity during fast charging cycles
Solution Approach 2:
The patent employs composite materials combining metalloid particles (silicon, tin, or germanium) with carbon matrices and conductive polymers. The metalloid provides high lithium capacity, the carbon matrix provides structural stability, and the conductive polymer ensures rapid electron transport, collectively achieving both high capacity and fast charging performance
2Quantity of substance
If metalloid particles are used to increase capacity, then lithium ion capacity improves, but mechanical expansion during lithiation causes structural degradation
Solution Approach 1:
Metalloid particles are nested within carbon shells, which are further coated with conductive polymer layers. This nested structure allows the metalloid to expand during lithiation while the carbon shell and polymer coating provide mechanical confinement and prevent structural degradation, maintaining stability throughout charge-discharge cycles
Solution Approach 2:
The carbon shells and conductive polymer coatings act as flexible protective layers that can accommodate the volume expansion of metalloid particles during lithiation. These shells maintain structural integrity while allowing the metalloid core to expand and contract, preventing particle disintegration and maintaining long-term stability
3Stability of the object's composition
If shells are added to accommodate expansion, then structural stability improves, but ionic conductivity may be reduced
Solution Approach 1:
The carbon shells are designed with porous structures that provide ion transport pathways. These pores allow lithium ions to diffuse through the shell to reach the metalloid core while the shell maintains structural stability. The porous architecture ensures that ionic conductivity is not significantly reduced despite the presence of the protective shell
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 configuration enables high-capacity, fast charging lithium ion batteries by maintaining electrical and ionic conductivity while accommodating mechanical expansion and contraction, outperforming conventional graphite anodes in terms of capacity and charging speed.
Implementation Method 1
configured to maintain electrical and ionic conductivity while accommodating mechanical expansion and contraction
Implementation Method 2
electronic conductive material which interconnects the cores of the core-shell particles
Implementation Method 3
shells made from an ionic conductive material...configured to maintain electrical and ionic conductivity
Data Source
AI summary
Core-shell particles, composite anode material, anodes made therefrom, lithium ion cells and methods are provided, which enable production of fast charging lithium ion batteries. The composite anode material has core-shell particles which are configured to receive and release lithium ions at their cores and to have shells that are configured to allow for core expansion upon lithiation. The cores of the core-shell particles are connected to the respective shells by conductive material such as carbon fibers, which may form a network throughout the anode material and possibly interconnect cores of many core-shell particles to enhance the electrical conductivity of the anode. Ionic conductive material and possibly mechanical elements may be incorporated in the core-shell particles to enhance ionic conductivity and mechanical robustness toward expansion and contraction of the cores during lithiation and de-lithiation.