Carbon-Coated Negative Electrode Material for Binder Adhesion
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Solution Overview
Problem
The existing negative electrode active materials in secondary batteries face limitations due to large pores on the surface of carbonaceous materials, which reduce the adhesion between the binder and the carbonaceous material, thereby limiting the battery's performance and life characteristics.
Innovation Solution
A method involving the mixing and heat treatment of a carbonaceous core with pitch to form composite particles, followed by a second heat treatment, results in a carbon coating layer on the carbonaceous core, reducing the total pore volume and enhancing adhesion between the negative electrode active material and the binder.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a carbonaceous material with multiple large pores on the surface is used as negative electrode active material, then the capacity of the carbonaceous material is maintained, but the adhesion between the binder and the carbonaceous material is reduced
Solution Approach 1:
The patent applies local quality by creating a dual-structure carbonaceous material where the internal structure maintains large pores for capacity while the external surface is treated to have reduced porosity for improved adhesion. Specifically, the carbonaceous material undergoes a heat treatment process that modifies the surface pore structure without compromising the internal capacity-providing structure, thereby achieving different properties in different locations of the same material.
2Reliability
If functional groups including oxygen are formed on the surface of the carbonaceous material to improve adhesion, then the adhesion is enhanced, but the capacity of the carbonaceous material is reduced
Solution Approach 1:
The patent avoids forming functional groups on the surface by instead applying local quality through selective pore filling. The binder is applied under conditions that allow it to penetrate and fill only the surface-level pores, while the bulk material retains its original pore structure and capacity. This spatial differentiation ensures that adhesion is improved at the surface without compromising the overall capacity of the carbonaceous material.
Solution Approach 2:
The patent uses the binder itself as an intermediary substance that fills the surface pores and creates the adhesion interface. Rather than chemically modifying the carbonaceous material surface with functional groups, the binder acts as a mediating layer that physically fills the pores and provides adhesion, thereby avoiding capacity loss while achieving the desired bonding effect.
3Reliability
If the total pore volume of the negative electrode active material is reduced to improve adhesion, then the adhesion is enhanced, but the capacity retention may be affected
Solution Approach 1:
The patent implements local quality by differentiating between surface pores and internal pores of the carbonaceous material. The heat treatment process selectively reduces the volume of surface pores that affect adhesion, while preserving the internal pore structure that provides capacity. This localized modification allows the material to have different pore characteristics in different regions, optimizing both adhesion and capacity retention simultaneously.
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 method improves the adhesion and life characteristics of the negative electrode, leading to enhanced performance and capacity retention in secondary batteries by reducing the total pore volume and increasing the contact area between the binder and the active material.
Implementation Method 1
mixing and first heat treating a carbonaceous core and pitch to form composite particles
Implementation Method 2
performing a first heat treatment of the first mixture to form composite particles
Implementation Method 3
the negative electrode active material has a total pore volume of 0.003 cm3/g to 0.010 cm3/g
Data Source
AI summary
A method for producing a negative electrode active material, including mixing a carbonaceous core and a first pitch to form a first mixture and performing a first heat treatment of the first mixture to form composite particles, and mixing the composite particles and a second pitch to form a second mixture and performing a second heat treatment of the second mixture.