Porous Carbon Core Coating for Li-Ion Electrode Swelling Control
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Solution Overview
Problem
Lithium-ion batteries face issues with mechanical degradation due to volumetric changes in electrode materials during charging and discharging, leading to swelling, surface cracking, and the formation of the solid-electrolyte interphase (SEI), which reduces cycle life and performance.
Innovation Solution
The development of composite materials with a carbon-based core coated by a layer that is permeable to metal ions but impermeable to liquids, preventing electrolyte penetration and mitigating swelling, thereby enhancing the structural support and electrochemical stability of the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-capacity electrode materials are used to increase battery capacity, then energy density is improved, but volumetric changes during cycling cause mechanical degradation and reduced reliability
Solution Approach 1:
The patent uses a composite material structure consisting of a porous core (accommodating volume expansion) and a permeable coating layer (allowing ion transport while preventing electrolyte penetration). This composite structure enables high-capacity electrode materials to maintain structural integrity and reliability during cycling by decoupling the functions of capacity storage and mechanical stability.
Solution Approach 2:
The patent applies different properties to different parts of the electrode material: the porous core provides volumetric flexibility and expansion space, while the permeable coating layer provides selective transport properties. This local differentiation of material properties allows the electrode to simultaneously achieve high capacity and maintained reliability during cycling.
2Duration of action of moving object
If electrode materials undergo volumetric changes during charging and discharging, then battery functionality is enabled, but mechanical stress causes surface cracking and pulverization
Solution Approach 1:
The patent segments the electrode material into a porous core and a coating layer, where the porous core accommodates volumetric changes through its open-cell structure while the coating layer maintains structural integrity. This segmentation allows the electrode to undergo repeated cycling without pulverization by distributing mechanical stress across different structural components.
Solution Approach 2:
The patent employs a flexible porous coating layer that can accommodate volumetric changes while maintaining structural continuity. This flexible shell structure prevents surface cracking by allowing controlled deformation during charge-discharge cycling, thereby preserving electrode strength and integrity over extended cycling.
3Object-generated harmful factors
If a coating layer is applied to prevent electrolyte penetration, then SEI formation is reduced, but ion transport may be hindered
Solution Approach 1:
The patent uses a porous coating layer with controlled porosity that allows metal ion transport while preventing bulk electrolyte penetration. The porous structure provides ion conduction pathways through the coating layer, ensuring that ion transport efficiency is maintained while still reducing harmful SEI formation by blocking electrolyte contact with the electrode surface.
Solution Approach 2:
The permeable coating layer acts as an intermediary between the electrode core and the electrolyte, selectively allowing metal ions to pass through while preventing electrolyte molecules from reaching the electrode surface. This intermediary function simultaneously reduces SEI formation and maintains ion transport efficiency by providing a controlled interface for ion exchange.
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 solution improves the cycling stability and lifespan of lithium-ion batteries by inhibiting volume expansion and reducing SEI formation, resulting in improved capacity and performance.
Implementation Method 1
the coating is (i) substantially permeable to at least one type of metal ions or metal atoms, and (ii) substantially impermeable to liquid molecules
Implementation Method 2
lithium ions move via diffusion and migration from one electrode to the other through the electrolyte and separator
Data Source
AI summary
Provided herein are composite materials for use in an electrical energy storage system (e.g., high-capacity batteries) and methods for preparing the same. The composite materials of the present disclosure comprise a carbon-based core having a porous exterior surface and a coating on at least a portion of the porous exterior surface of the core. Such coatings are made from a material that is (i) substantially permeable to at least one type of metal ions or metal atoms, and (ii) substantially impermeable to liquids