Positive Electrode Active Material for Energy Density and Rate Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing positive electrode materials in non-aqueous electrolyte secondary batteries face challenges in achieving enhanced volumetric energy density and good input-output properties.
Innovation Solution
A positive electrode active material comprising a first lithium-rich composite oxide with smaller average particle size and a second lithium-rich composite oxide with larger average particle size, both formed from secondary particles of aggregated primary particles, with specific compositional ratios and content ratios, along with the inclusion of carbon nanotubes to enhance conductivity and reduce oxidative degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single type of lithium-(transition metal) composite oxide is used as positive electrode active material, then the battery structure is simple, but the volumetric energy density and input-output properties cannot be simultaneously optimized
Solution Approach 1:
The patent uses a composite of two lithium-(transition metal) composite oxides with different compositions and particle sizes. The first oxide has formula Li1+a1-x1-y1-z1M1a1M2x1O3 and the second has Li1+a2-x2-y2-z2M1a2M2x2O3, creating a composite material that combines high capacity with good conductivity and stable structure, simultaneously achieving high volumetric energy density and good input-output properties
Solution Approach 2:
The patent segments the positive electrode active material into two distinct oxide components with different functions. The first oxide (with 0.13≤a1≤0.33) provides high lithium content and capacity, while the second oxide (with -0.1≤a2≤0.1) provides structural stability and conductivity. This segmentation allows each component to optimize its specific function, resolving the contradiction between energy density and input-output properties
2Productivity
If only one particle size of active material is used, then the electrode structure is simple, but both volumetric energy density and input-output properties cannot be optimized
Solution Approach 1:
The patent applies local quality by using different particle sizes for different functional requirements. The first oxide has smaller particle size (D150) for high surface area and good lithium-ion diffusion, while the second oxide has larger particle size (D250) for high packing density and volumetric energy density. Each particle size region serves its specific function, optimizing both input-output properties and energy density
Solution Approach 2:
The patent changes the particle size parameter between the two oxide types. By controlling the average particle size D150 of the first oxide and D250 of the second oxide, the patent optimizes the balance between surface area (affecting lithium-ion diffusion and input-output properties) and packing density (affecting volumetric energy density), resolving the contradiction through parameter optimization
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 a secondary battery with improved volumetric energy density and good input-output properties by optimizing lithium-ion diffusion and electronic conductivity.
Implementation Method 1
the positive electrode active material layer further includes carbon nanotubes
Implementation Method 2
optimizing lithium-ion diffusion
Data Source
AI summary
A positive electrode active material comprises a first active material represented by a formula (I) and a second active material represented by a formula (II). The formula (I) and the formula (II) are as specified in the claims. Each of the first active material and the second active material is secondary particles each consisting of 50 or more primary particles aggregated together. An average particle size (D150) of the first active material is smaller than an average particle size (D250) of the second active material.