Composite Positive Electrode Coating for High-Nickel Cycle Life
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Solution Overview
Problem
High-nickel ternary positive electrode materials in lithium-ion batteries face challenges with cycle life due to reactions with the electrolyte and uneven surface modification, and conventional binder selection affects performance, leading to decreased capacity retention and high-rate charge/discharge issues.
Innovation Solution
A composite electrode is created using a dry mechanofusion method to pre-coat conductive carbon on high-nickel NCM positive electrode materials, enhancing surface hydrophobicity and facilitating uniform coating with Li-Nafion polymer material, which replaces conventional binders, improving coating performance and maintaining particle morphology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inorganic metal oxides are used to modify the surface of high-nickel material, then surface protection is improved, but manufacturing complexity and cost increase due to additional heat treatment procedures
Solution Approach 1:
The patent replaces the conventional liquid-phase coating method requiring heat treatment with a dry-process mechanofusion method using high-energy mixing. This mechanical approach directly coats conductive carbon and Li-Nafion polymer on the high-nickel NCM surface without solvents or thermal processing, eliminating the complex heat treatment step while achieving uniform surface modification and protection.
2Manufacturing precision
If conventional liquid phase method is used to coat metal oxides, then surface coating is achieved, but manufacturing cost and process complexity increase due to solvent selection and recycle requirements
Solution Approach 1:
The patent extracts and eliminates the solvent system from the conventional liquid-phase coating process. By using a dry-process mechanofusion method with high-energy mixing, the invention achieves surface coating without any solvents, thereby removing all associated costs and complexities of solvent selection, application, and recycle while maintaining uniform coating quality.
Solution Approach 2:
The dry-process mechanofusion method allows the coating materials (conductive carbon and Li-Nafion polymer) to self-adhere and uniformly distribute on the high-nickel NCM surface through mechanical energy input alone, without requiring external solvent mediation or complex processing steps.
3Power
If high-nickel content is increased to improve power density, then power density increases, but cycle life decreases due to negative reactions with electrolyte
Solution Approach 1:
The patent creates a composite structure by coating high-nickel NCM particles with conductive carbon and Li-Nafion polymer materials. This composite approach maintains the high power density of the high-nickel core while the coating layers provide protective functions: conductive carbon ensures electrical conductivity and Li-Nafion polymer provides chemical stability and electrolyte resistance, thereby extending cycle life without sacrificing power density.
Solution Approach 2:
The patent applies different functional materials to different aspects of the high-nickel NCM surface: conductive carbon addresses electrical conductivity requirements while Li-Nafion polymer addresses chemical stability and electrolyte resistance. This localized functional differentiation allows the high-nickel material to maintain its high power density while the surface coating provides the necessary protection for long cycle life.
4Ease of manufacture
If conventional binder is used in secondary battery process, then electrode assembly is achieved, but capacity retention rate decreases under high rate charge/discharge conditions
Solution Approach 1:
The patent changes the chemical and physical parameters of the binder material by selecting Li-Nafion polymer, which possesses superior ion-conducting properties compared to conventional binders. This parameter change in material selection enables efficient ion transport during high-rate charge/discharge, maintaining capacity retention rate while still achieving proper electrode assembly and binding functionality.
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 enhances high-rate charge/discharge performance and capacity retention by ensuring uniform Li-Nafion polymer coating, improving cycle life and reducing manufacturing costs without the need for additional solvents or heat treatments.
Implementation Method 1
The conductive carbon is pre-coated on the surface of the high-nickel NCM positive electrode material through a dry mechanofusion method to improve the surface hydrophobicity
Implementation Method 2
improve the coating performance of the lithiated Nafion (Li-Nafion) polymer material in the subsequent process, so that the original spherical secondary particle morphology of the high-nickel NCM positive electrode material is maintained effectively
Implementation Method 3
An appropriate amount of conductive carbon can be coated on the surface of the high-nickel NCM positive electrode material through the dry mechanofusion process, it helps to improve the hydrophobicity of the surface of the positive electrode material
Implementation Method 4
by pre-treating the surface with the conductive carbon, it facilitates the Li-Nafion polymer material as the functional coating to be more uniformly coated on the surface of the high-nickel positive electrode material
Data Source
AI summary
A composite electrode and a preparation method thereof are disclosed. The composite electrode includes a composite positive electrode material layer coated on a carrying surface of an electrode plate. The composite positive electrode material layer includes plural positive electrode material particles, a first conductive carbon and a Li-Nafion polymer material. The positive electrode material particles are composed of ternary materials. The first conductive carbon is pre-coated on surfaces of the positive electrode material particles by dry mechanical mixing. A weight percent of the first conductive carbon relative to the positive electrode material particles is ranged from 1 wt. % to 5.5 wt. %. The Li-Nafion polymer material covers the surfaces of the positive electrode material particles and is bonded among the surfaces of the positive electrode material particles. A weight percent of the Li-Nafion polymer material relative to the positive electrode material particles is ranged from 10 wt. % to 20 wt. %.