Graphene-Coated Cathode Layer for Fast-Charging Energy Density
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Solution Overview
Problem
Existing electrochemical devices face challenges in achieving high energy density and fast charge performance without compromising safety and stability, as reducing positive active material particle size decreases compacted density, and optimizing electrolytic solutions and lithium intercalation activity deteriorate high-temperature performance.
Innovation Solution
Incorporating graphene on the surfaces of positive active material particles in the positive active material layer to enhance electronic conductivity, increase compacted density, and reduce polarization, thereby improving charging speed and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the particle diameter of the positive active material is reduced to improve fast charge performance, then the charging speed is improved, but the compacted density of the positive electrode plate decreases, thereby decreasing the energy density of the electrode assembly
Solution Approach 1:
The patent applies composite materials by combining positive active material particles with graphene coating. The graphene layer forms a composite structure on the particle surfaces, providing both fast charge capability through improved conductivity and maintained compacted density through the space-efficient coating approach.
Solution Approach 2:
The patent changes physical parameters by coating the positive active material particles with graphene, which alters the surface properties and electrical conductivity without significantly changing the particle size distribution. This allows optimization of fast charge performance while maintaining the particle diameter and compacted density relationships.
2Speed
If the electrolytic solution is optimized or the lithium intercalation activity of the negative electrode is increased to improve fast charge performance, then the charging speed is improved, but the high-temperature performance deteriorates, adversely affecting safety and stability
Solution Approach 1:
The patent applies local quality by providing graphene coating specifically on the surfaces of positive active material particles. This localized treatment enhances electrical conductivity and lithium ion transport at the particle surfaces where charge transfer occurs, improving fast charge performance without requiring global changes to the electrolyte or negative electrode that would compromise high-temperature stability.
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 addition of graphene increases the compacted density of the positive active material layer, enhances fast charge performance, and improves energy density while maintaining stability and safety.
Implementation Method 1
Incorporating graphene on the surfaces of positive active material particles in the positive active material layer to enhance electronic conductivity
Data Source
AI summary
An electrochemical device includes an electrode assembly. The electrode assembly includes a positive electrode plate. The positive electrode plate includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material and graphene. At least a part of the graphene is disposed on surfaces of particles of the positive active material. The technical solution of this application not only increases a compacted density of the positive active material layer and an energy density of the electrochemical device, but also reduces polarization and increases charging speed of the electrochemical device.