Artificial Graphite Coating Viscosity for Stable Fast-Charging Anodes
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Solution Overview
Problem
Current lithium secondary batteries face challenges in high temperature performance and fast charging characteristics due to changes in electrode structure and internal pore volume during the rolling process, which affects their cycle-life and energy density, especially when using carbon-based negative electrode active materials.
Innovation Solution
A negative electrode active material for lithium secondary batteries is manufactured using a method that involves preparing artificial graphite, forming a carbonizing coating layer with a liquid coating material of specific viscosity, and carbonizing it at controlled temperatures, eliminating the need for an assembly process and ensuring excellent electrode adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If artificial graphite is used as negative electrode active material, then cycle-life is improved, but high temperature performance deteriorates due to electrode structure changes during rolling
Solution Approach 1:
The patent applies a coating layer to the artificial graphite particles before electrode rolling, performing protective action in advance. This preliminary coating prevents structure changes and pore volume increase during the rolling process, thereby maintaining high temperature performance while preserving the long cycle-life benefit of artificial graphite
Solution Approach 2:
The patent modifies the physical and chemical parameters of the artificial graphite surface by applying a coating layer with specific properties (viscosity 300-25000 mPa·s at 35°C, fixed carbon content 15-60 wt%). This parameter change protects the graphite structure during rolling, preventing deterioration of high temperature performance
2Strength
If liquid coating material is applied to artificial graphite, then electrode adhesion is improved, but processing complexity increases
Solution Approach 1:
The patent applies coating material locally to the artificial graphite particles rather than treating the entire electrode. This localized application improves adhesion at the particle level without requiring complex overall processing, as the coating is applied directly to particles before electrode assembly
Solution Approach 2:
The patent extracts the coating application step from the overall electrode manufacturing process and applies it directly to particles in a separate, simplified operation. This extraction allows adhesion improvement without integrating complex coating equipment into the main production line
3Stability of the object's composition
If viscosity of liquid coating material is increased, then coating stability is improved, but coating uniformity deteriorates
Solution Approach 1:
The patent identifies and controls the viscosity parameter of the liquid coating material, specifying a range of 300-25000 mPa·s at 35°C. This parameter optimization balances coating stability (preventing settling) with coating uniformity (ensuring even distribution), resolving the contradiction between these two requirements
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 approach enhances the high temperature characteristics and fast charging capabilities of lithium secondary batteries by maintaining structural stability and reducing the number of processing steps, resulting in improved energy density and cycle-life without contamination issues.
Implementation Method 1
carbonizing it at controlled temperatures
Data Source
AI summary
It is related to a manufacturing method of negative electrode active material for lithium secondary battery, comprising: preparing an artificial graphite; forming a coating layer covering the artificial graphite by mixing the artificial graphite and a liquid coating material; and carbonizing the artificial graphite on which the coating layer is formed; wherein, the liquid coating material has a viscosity of 300 to 25000 mPa s at 35° C.; a negative electrode active material according to the method; and a lithium secondary battery including the same.