Positive Electrode Active Material With Dual Particle Sizes
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Solution Overview
Problem
Existing rechargeable lithium batteries face challenges in achieving high energy density, low-temperature capacity, average voltage, and lifespan, as well as a strong binding force for the current collector.
Innovation Solution
A positive electrode active material comprising a mixture of first and second particles, each represented by specific lithium-based compounds with controlled particle sizes and compositions, is prepared through a spray drying and calcining process, enhancing the binding force and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single particle size is used for the positive electrode active material, then the manufacturing process is simple, but the battery performance (low-temperature capacity, energy density, lifespan) is insufficient
Solution Approach 1:
The positive electrode active material is segmented into two distinct particle size ranges: first particles with 0.5-2 μm diameter and second particles with 2-5 μm diameter. This segmentation allows each particle size to contribute differently to battery performance, with smaller particles providing better low-temperature capacity and larger particles contributing to energy density, thereby resolving the contradiction between simplified manufacturing and enhanced battery performance.
Solution Approach 2:
Different regions of the electrode are populated with different particle sizes to optimize local performance characteristics. The first particles (0.5-2 μm) are distributed to enhance low-temperature capacity where rapid ion transport is needed, while second particles (2-5 μm) are positioned to maximize energy density in regions where capacity is the priority. This local quality differentiation resolves the contradiction by allowing each particle size to perform its specialized function.
2Use of energy by moving object
If the particle size is increased to improve energy density, then the energy density increases, but the low-temperature capacity and binding force decrease
Solution Approach 1:
The particle population is segmented into two size groups with specific diameter ranges: 0.5-2 μm for first particles and 2-5 μm for second particles. This segmentation ensures that smaller particles are available to maintain low-temperature capacity and binding force, while larger particles contribute to energy density, thereby resolving the contradiction between these competing performance metrics.
Solution Approach 2:
The positive electrode active material forms a composite system combining two particle size types with complementary properties. The first particles (0.5-2 μm) provide enhanced low-temperature performance and binding characteristics, while the second particles (2-5 μm) contribute to higher energy density. This composite approach resolves the contradiction by integrating the advantages of both particle size ranges into a single electrode material system.
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 low-temperature capacity, energy density, average voltage, and lifespan of the rechargeable lithium battery, with a stronger binding force to the current collector.
Implementation Method 1
drying the first mixture through spray drying
Implementation Method 2
calcining the dried first mixture
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A rechargeable lithium battery includes a positive electrode active material, the positive electrode active material including a first particle containing a compound represented by Formula 1 and having a first average particle diameter, and a second particle containing a compound represented by Formula 2 and having a second average particle diameter larger than the first average particle diameter. Each of the first particle and the second particle has a form of a sphere-shaped secondary particle, and an amount of the first particle is greater than an amount of the second particle. A detailed description of Chemical Formulae 1 and 2 is given in this description.