Nickel-Based Positive Active Material for Lithium Batteries
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Solution Overview
Problem
Current rechargeable lithium batteries face challenges in achieving high performance and large capacity due to limitations in the properties of negative active materials, and there is a need for improved positive active materials that balance specific surface area and average particle diameter to enhance capacity and power characteristics while minimizing resistance.
Innovation Solution
A positive active material for rechargeable lithium batteries is developed, comprising secondary particles of agglomerated primary nickel-based compound particles with a specific surface area ranging from 0.4 to 2.0 m2/g and average particle diameters between 5.5 μm to 13 μm, coated with a metal oxide layer, prepared through a process involving spray-drying and heat-treatment, which includes a transition element composite precursor mixed with a lithium salt and coated with a metal oxide layer to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the specific surface area of the positive active material is increased to enhance capacity, then the power characteristics improve, but the resistance increases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the specific surface area within 0.2-2.0 m²/g and average particle diameter within 5-15 μm ranges. By optimizing these physical parameters of the nickel-based compound particles, the invention achieves a balance between capacity (related to surface area) and resistance (affected by particle size), resolving the technical contradiction between these two opposing requirements.
2Power
If the average particle diameter is decreased to improve power characteristics, then the capacity increases, but the manufacturing complexity increases
Solution Approach 1:
The patent employs parameter changes by设定ing the average particle diameter within a specific range of 5-15 μm. This parameter optimization enables improved power characteristics while maintaining manufacturability, as extremely fine particles would require complex manufacturing processes. The specified range represents an optimal balance between performance and manufacturing feasibility.
3Stability of the object's composition
If the nickel-based compound particles are agglomerated to form secondary particles, then the structural stability improves, but the lithium mobility may be affected
Solution Approach 1:
The patent resolves this contradiction by controlling the specific surface area and particle diameter parameters. By maintaining the specific surface area within 0.2-2.0 m²/g and particle diameter within 5-15 μm, the agglomerated secondary particle structure provides structural stability while preserving sufficient lithium mobility. The parameter optimization ensures that the agglomeration does not excessively hinder lithium ion transport.
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 results in improved capacity and power characteristics, reduced resistance, and enhanced lithium mobility, making the positive active material suitable for high-power batteries while maintaining structural stability and electrochemical excellence.
Implementation Method 1
spray-drying the transition element composite precursor under a pressure greater than 0.5 MPa and less than or equal to 1.0 MPa to prepare a porous transition element composite precursor
Implementation Method 2
heat-treating the mixture
Data Source
AI summary
A positive active material for a rechargeable lithium battery is a secondary particle formed of an assembly of primary particles of a nickel-based compound. The positive active material has an average particle diameter ranging from 5.5 μm to 7.5 μm and a specific surface area ranging from 0.40 m2/g to 2.0 m2/g. When the positive active material has an average particle diameter ranging from 11 μm to 13 μm, the positive active material has a specific surface area ranging from 0.15 m2/g to 1.0 m2/g. A rechargeable lithium battery includes the positive active material.