Composite Cathode 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 nickel-rich composite oxide with larger average particle size, both formed from secondary particles of aggregated primary particles, is used to enhance lithium-ion diffusion and electronic conductivity, with a specific ratio and content balance to optimize battery performance.
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 enhanced
Solution Approach 1:
The patent uses a composite positive electrode active material consisting of two types of lithium-(transition metal) composite oxides with different compositions. The first type has formula Li1+a1Nix1Mny1M1z1O2 with 0.13≤a1≤0.33, 0≤x1≤0.3, 0.47≤y1≤0.67, and the second type has formula Li1+a2Nix2Mnym2M2z2O2 with -0.1≤a2≤0.1, 0.6≤x2≤1. This composite structure allows simultaneous enhancement of volumetric energy density and input-output properties by combining materials with complementary characteristics.
2Ease of manufacture
If larger particle size active material is used, then the manufacturing is easier, but the lithium-ion diffusion distance increases reducing input-output properties
Solution Approach 1:
The patent applies different particle size characteristics to different components of the composite active material. The first lithium-(transition metal) composite oxide has a controlled particle size distribution optimized for lithium-ion diffusion, while the second type provides structural stability. This local optimization of particle size for different material components resolves the contradiction between ease of manufacture and lithium-ion diffusion rate.
3Quantity of substance
If nickel content is increased to enhance capacity, then the energy density improves, but the structural stability and safety deteriorate
Solution Approach 1:
The patent creates a composite positive electrode active material where the first lithium-(transition metal) composite oxide with controlled nickel content (0≤x1≤0.3) provides high specific capacity, while the second lithium-(transition metal) composite oxide with high nickel content (0.6≤x2≤1) but different structural characteristics provides overall structural stability. This composite approach allows the battery to achieve high energy density while maintaining reliability and safety.
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 proposed active material design results in a secondary battery with improved volumetric energy density and input-output properties by reducing lithium-ion diffusion distance and enhancing electronic conductivity.
Implementation Method 1
enhance lithium-ion diffusion and electronic conductivity, with a specific ratio and content balance to optimize battery performance
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.