Composite Graphite Material for Secondary Battery Expansion Control
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Solution Overview
Problem
Secondary batteries experience volume expansion during cycling, leading to increased internal stress and reduced service life and safety performance, which is a concern for the growing market of new energy vehicles.
Innovation Solution
A composite graphite material with a core coated to achieve a Zeta potential of at least 20 mV in deionized water, enhancing hydrophilicity and stability, is used in the negative electrode plate to improve cohesion and bonding forces, thereby reducing volume expansion and enhancing cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If graphite core material is used in secondary batteries, then high energy density is achieved, but volume expansion during cycling occurs leading to increased internal stress and reduced service life
Solution Approach 1:
The patent applies composite materials by coating the graphite core material with a specific coating layer that modifies the surface properties. This composite structure maintains the high energy density of graphite while the coating layer prevents volume expansion during cycling, thereby resolving the contradiction between energy density and service life.
Solution Approach 2:
The patent changes the surface parameter of graphite by controlling the Zeta potential to be at least 20 mV in deionized water at pH 7. This parameter change improves hydrophilicity and dispersion uniformity, leading to better bonding with the binder and reduced volume expansion, thus extending service life while maintaining energy density.
2Use of energy by moving object
If graphite core material is used in secondary batteries, then high energy density is achieved, but volume expansion during cycling occurs leading to increased internal stress and reduced safety performance
Solution Approach 1:
The composite structure of coated graphite particles reduces internal stress during cycling by preventing volume expansion. The coating layer acts as a buffer that accommodates dimensional changes, thereby maintaining safety performance while preserving the high energy density of graphite.
Solution Approach 2:
By modifying the surface charge density to achieve a Zeta potential of at least 20 mV, the patent improves the interaction between graphite particles and the binder. This reduces internal stress during cycling and enhances safety performance without compromising energy density.
3Stability of the object's composition
If graphite surface is coated to achieve Zeta potential of at least 20 mV, then hydrophilicity and dispersion uniformity are improved, but manufacturing complexity increases
Solution Approach 1:
The patent focuses on controlling a single key parameter (Zeta potential) to achieve the desired dispersion uniformity and hydrophilicity. By targeting this specific parameter, the manufacturing process remains relatively simple while achieving significant improvements in slurry stability and electrode performance.
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 composite graphite material effectively reduces cyclic expansion, improves energy density, and enhances the safety and performance of secondary batteries by maintaining structural integrity and reducing internal stress.
Implementation Method 1
the composite graphite material has an absolute value K of Zeta potential of at least 20 mV in deionized water with a pH of 7
Implementation Method 2
The composite graphite material has good hydrophilicity, so its dispersion uniformity and stability in the aqueous slurry is higher
Implementation Method 3
The negative electrode plate prepared by the slurry has higher cohesion and bonding force
Data Source
AI summary
The present application discloses a composite graphite material, a secondary battery, an apparatus and a preparation method thereof. The composite graphite material includes a core material and a coating layer coating at least a part of the surface of the core material, the core material including graphite; wherein the absolute value K of zeta potential of the composite graphite material in deionized water with a pH of 7 is at least 20 mV. The use of the composite graphite material provided by the present application can improve the cohesion and bonding force of the negative electrode plate, thereby reducing the cyclic expansion of the secondary battery.