Carbon Nitride-Coated Anode Material for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Current rechargeable lithium batteries face challenges in achieving rapid charging times and maintaining cycle-life characteristics due to high interface resistance and lithium metal precipitation on the surface of carbon materials, which hinders the widespread adoption of electric vehicles.
Innovation Solution
A negative active material is developed, comprising a carbon material core with carbon nitride on its surface, which promotes lithium ion intercalation and reduces interface resistance, achieved through a process involving mixing, acid removal, and heat-treatment under an inert atmosphere, enhancing the battery's fast charging and cycle-life capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional carbon materials are used as negative active material, then the battery structure is simple and manufacturing is easy, but interface resistance is high and lithium metal precipitation occurs on the surface
Solution Approach 1:
The patent applies composite materials by combining carbon material core with carbon nitride coating layer. The carbon nitride layer (containing C3N4, CN, C2N, C3N, C2N2, C2N3, C5N, or C5N2) is formed on the surface of the carbon material through heat treatment of precursors like urea, melamine, dicyanamide, thiourea, or cyanamide. This composite structure reduces interface resistance and prevents lithium metal precipitation while maintaining the base carbon material's properties.
2Use of energy by moving object
If high energy density is pursued to increase driving range, then energy storage capacity improves, but charging time increases
Solution Approach 1:
The patent changes the surface chemical parameters of the carbon material by introducing carbon nitride compounds. The carbon nitride layer modifies the surface chemistry and electronic structure, enabling faster lithium ion intercalation kinetics. This allows the battery to maintain high energy density while achieving rapid charging capabilities, as the modified surface facilitates quicker ion transport without compromising storage capacity.
3Productivity
If carbon nitride is added to the negative active material, then fast charging capability and cycle-life characteristics improve, but manufacturing process complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating carbon nitride precursors (such as urea, melamine, dicyanamide, thiourea, or cyanamide) into the carbon material mixture before heat treatment. The precursors are mixed with the carbon material and acid, then undergo heat treatment to form the carbon nitride coating in advance. This preliminary incorporation simplifies the manufacturing process compared to post-coating methods, as the functional layer is formed during the standard heat treatment step rather than requiring additional coating equipment and processes.
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 carbon nitride-coated carbon material core significantly improves high-rate charging and cycle-life characteristics by reducing interface resistance and preventing lithium metal precipitation, leading to enhanced performance in rechargeable lithium batteries.
Implementation Method 1
carbon nitride on a surface of the core... promotes lithium ion intercalation
Implementation Method 2
promotes lithium ion intercalation and reduces interface resistance
Implementation Method 3
heat-treating the mixture... The carbon nitride may be derived from a precursor including urea, melamine, dicyanamide, thiourea, cyanamide, or a combination thereof. The preliminarily heat-treatment may be performed at about 200° C. to about 700° C.
Data Source
AI summary
A negative active material and a rechargeable lithium battery including the same, the negative active material including a core including a carbon material; and a carbon nitride on a surface of the core, and the rechargeable lithium battery including a negative electrode including the negative active material; a positive electrode; and an electrolyte.