Double Coated Graphite Anode for PC Electrolyte Stability
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Solution Overview
Problem
Lithium secondary batteries face issues with side reactions and poor cycle properties due to exposure of graphite edge planes, especially with PC-containing electrolyte liquids, leading to reduced output and stability.
Innovation Solution
A negative electrode active material with a graphite core coated with a first layer of amorphous carbon and a second layer of nitrogen-doped fine carbon particles, where the layers bind through electrostatic attraction, enhancing conductivity and suppressing side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If natural graphite is mechanically globularized or mixed with other graphite, then filling density and initial capacity are improved, but graphite surface cracks occur and side reaction with electrolyte liquid increases
Solution Approach 1:
A coating layer is formed on the graphite particle surface before battery assembly to prevent surface cracking and side reactions during subsequent charging-discharging cycles. The coating layer acts as a protective barrier that is applied in advance to mitigate harmful effects that would otherwise occur during battery operation.
2Power
If artificial graphite is used, then output property is improved, but vulnerability to PC-containing electrolyte liquid increases and cycle property declines
Solution Approach 1:
The invention uses a composite coating structure consisting of amorphous carbon material and nitrogen-doped fine carbon particles. This composite material combines the advantages of different carbon types to provide both high output property and excellent resistance to PC-containing electrolyte liquid, thereby maintaining good cycle property while preserving power performance.
3Quantity of substance
If plate-shaped natural graphite is compressed and oriented, then filling density is improved, but electrolyte liquid immersion becomes difficult and high rate charge-discharge property deteriorates
Solution Approach 1:
The coating layer is applied to graphite particles before electrode manufacturing and battery assembly. This preliminary coating prevents surface cracking that would otherwise occur during compression, maintaining both high filling density and good high-rate charge-discharge properties by preserving the integrity of the graphite surface while allowing dense packing.
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 double coating layer effectively prevents side reactions with electrolyte liquids, reducing OCV drop and enhancing the high-rate properties of lithium secondary batteries, while maintaining excellent cycle and output performance.
Implementation Method 1
a first coating layer including an amorphous carbon material formed on the core; and a second coating layer including nitrogen-doped fine carbon particles formed on the first coating layer, wherein the first coating layer and the second coating layer bind to each other by electrostatic attraction
Data Source
AI summary
The present invention relates to a negative electrode active material having a double coating layer of a first coating layer and a second coating layer, which has an excellent output property, effectively suppresses a side reaction with an electrolyte liquid, particularly a PC-containing electrolyte liquid, and has excellent electric conductivity, a method for manufacturing the same, a negative electrode including the same, and a lithium secondary battery including the negative electrode. The negative electrode active material according to the present invention is capable of effectively preventing a side reaction with an electrolyte liquid, particularly a PC-containing electrolyte liquid, and is capable of improving electric conductivity, and as a result, enhancing a rate determining property by reducing an OCV drop of a lithium secondary battery including the negative electrode active material, and enhancing a high rate property.