Carbon-Coated Battery Anode Material for Fast Charging and Crack Control
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Solution Overview
Problem
Lithium ion secondary batteries face limitations in high energy density and charging efficiency due to the theoretical capacity of graphite-based negative active materials, which restricts their application, especially in electric vehicles and other fields, and require surface treatment to enhance cycle-life and charging output.
Innovation Solution
A method of coating a base material for the negative active material with a graphitizable carbon coating material having a softening point of 50°C or less, using a dry coating process without solvents, and heat-treating the coated product to form an amorphous carbon layer, which improves charging and discharge characteristics while preventing cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite-based materials are used as negative active materials, then stable cycle-life characteristics and low operation voltage are achieved, but the theoretical capacity is limited to a maximum of 372 mAh/g
Solution Approach 1:
The patent uses composite materials by combining graphite base material with a coating layer formed from graphitizable carbon and binder. This composite structure allows the graphite to provide stable cycle-life characteristics while the coating layer increases the theoretical capacity beyond 372 mAh/g by utilizing additional carbon materials that can intercalate lithium ions.
Solution Approach 2:
The patent changes the parameters of the negative active material by controlling the softening point of the graphitizable carbon (50°C or less) and the residual carbon amount (1 to 5 weight parts per 100 weight parts of base material). These parameter changes enable the material to achieve both improved capacity and maintained stability during cycling.
2Productivity
If surface treatment is applied to negative active materials, then charging output and cycle-life characteristics are improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies the self-service principle by using a binder that simultaneously serves as both the binding agent and the source of the coating layer. The binder contains graphitizable carbon that forms the protective coating during the heating process, eliminating the need for separate coating and binding materials, thus simplifying the manufacturing process while achieving improved charging output and cycle-life characteristics.
3Speed
If a coating layer is formed on the base material, then fast charging/discharge characteristics are improved, but initial efficiency may be reduced
Solution Approach 1:
The patent optimizes the parameters of the coating layer by controlling the softening point of the graphitizable carbon to be 50°C or less and the residual carbon amount to be 1 to 5 weight parts per 100 weight parts of base material. These parameter changes ensure that the coating layer is thin enough to maintain good initial efficiency while still providing the necessary surface treatment to improve fast charging/discharge characteristics.
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 solution enhances the fast charging and discharge capabilities of lithium secondary batteries with improved initial efficiency and reduced crack formation, maintaining battery performance without significant initial efficiency loss, and achieves a specific surface area and capacity of 350 to 380 mAh/g with an Id/Ig Raman spectrum ratio of 0.300 to 0.450.
Implementation Method 1
the softening point is 50° C. or less
Implementation Method 2
heating a product coated with the coating material
Data Source
AI summary
The present disclosure relates to a manufacturing method of a negative active material for a battery, a negative active material manufactured therefrom, and a lithium secondary battery including the negative electrode, including: the steps of coating a base material for a negative active material with a coating material; and heating the obtained coating product; wherein, the coating material is graphitizable carbon, the softening point is 50° C. or less, and the coating material is included so that the residual carbon amount is 1 to 5 parts by weight with respect to 100 parts by weight of the base material for the negative active material.