Carbon-Coated Amorphous Lithium Additive for Low-Barrier Deintercalation
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Solution Overview
Problem
Existing crystalline lithium-supplementing additives, such as Li2S, have a high activation barrier during the first charging process, making it difficult for lithium ions to deintercalate, resulting in low actual specific capacity.
Innovation Solution
A composite lithium-supplementing additive is developed, comprising a core with an amorphous lithium-supplementing additive and a carbon encapsulation layer. The amorphous additive has lower polarity, reducing the activation barrier, and the encapsulation layer improves conductivity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If crystalline lithium-supplementing additives such as Li2S are used, then the theoretical specific capacity is high (up to 1166 mAh/g), but the activation barrier is high making it difficult for lithium ions to deintercalate during the first charging process
Solution Approach 1:
The patent changes the physical state parameter of the lithium-supplementing additive from crystalline to amorphous form. This parameter change reduces the activation barrier for lithium ion deintercalation while maintaining the high specific capacity, as the amorphous structure allows easier ion transport compared to the ordered crystalline structure.
Solution Approach 2:
The patent creates a composite structure by coating amorphous lithium-supplementing additives with a carbon layer. This composite material combines the high specific capacity of lithium sulfide with the excellent conductivity and stability of carbon, solving both the deintercalation difficulty and stability issues.
2Ease of operation
If the particle size of Li2S is reduced to nanoscale, then the activation barrier is reduced making it easier for lithium ions to escape, but the electronic and ionic conductivity remains poor
Solution Approach 1:
The patent forms a composite structure where amorphous lithium-supplementing additives are coated with carbon material. The carbon coating layer provides excellent electronic and ionic conductivity pathways, compensating for the poor conductivity of the lithium-supplementing additive core while maintaining the low activation barrier benefits of the amorphous nanoscale structure.
Solution Approach 2:
The patent applies different properties to different parts of the additive structure: the core maintains amorphous nanoscale structure for low activation barrier and high ion mobility, while the surface is coated with carbon material for high electronic and ionic conductivity. This local quality differentiation solves the contradiction between deintercalation ease and conductivity.
3Ease of operation
If amorphous lithium-supplementing additives are used, then the activation barrier is reduced and deintercalation efficiency is improved, but the stability and conductivity of the material deteriorates
Solution Approach 1:
The patent creates a core-shell composite structure where the amorphous lithium-supplementing additive core provides low activation barrier and high deintercalation efficiency, while the carbon shell provides structural stability and excellent electronic/ionic conductivity. This composite approach resolves the contradiction between deintercalation efficiency and material stability/conductivity.
Solution Approach 2:
The carbon coating layer acts as an intermediary between the amorphous lithium-supplementing additive and the electrolyte/environment. It mediates the electrical contact and ion transport, providing the conductivity and stability that the amorphous material lacks while allowing the amorphous core to maintain its low activation barrier properties.
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 additive significantly enhances lithium ion deintercalation efficiency, achieving higher specific capacity and improved stability, effectively compensating for lithium loss during the first charge of lithium-ion batteries.
Implementation Method 1
The amorphous lithium-supplementing additive in the core has a lower polarity so that the voltage platform is lower during charging, which can effectively reduce the activation barrier of the lithium-supplementing additive and significantly improve the deintercalation efficiency of lithium ions
Implementation Method 2
The encapsulation layer can not only improve the stability of the lithium-supplementing additive, but also effectively improve the electronic and ionic conductivity of the lithium-supplementing material in the core
Implementation Method 3
also play a role in isolating water and oxygen, thereby improving the stability of the lithium-supplementing additive
Data Source
AI summary
Disclosed is a composite lithium-supplementing additive, a preparation method, and application thereof. The composite lithium-supplementing additive comprises a core containing an amorphous lithium-supplementing additive and an encapsulation layer coated on the outer surface of the core. In the composite lithium-supplementing additive provided in the present application, the activation potential barrier is low, the lithium deintercalation efficiency is high at a relatively low voltage, and the specific capacity of lithium supplement is high. In the composite lithium-supplementing additive provided in the embodiments of the present application, the amorphous lithium-supplementing additive in the core has a smaller polarization, and during charging, the voltage plateau is lower, thus being able to effectively reduce the activation barrier of the lithium-supplementing additive, and markedly improve the deintercalation efficiency of lithium ions, thereby achieving a high specific capacity of lithium compensation in the additive.