Lithium Manganese Oxide Solid Solution for High C-Rate Battery Performance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium manganese oxide-based solid solutions used in rechargeable lithium batteries face challenges in maintaining high discharge capacity at high C-rates due to large secondary particle sizes, leading to low electron conductivity and incomplete lithium ion diffusion, which results in reduced load characteristics.
Innovation Solution
A lithium manganese oxide-based solid solution with secondary particles having a diameter range of 1 μm to 5 μm and a crystallite diameter between 40 nm and 150 nm, along with a specific particle diameter distribution, is used as the positive active material, enhancing the contact area with the electrolyte and conductive material, thereby improving electron conductivity and diffusion rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the secondary particle size of lithium manganese oxide-based solid solution is large, then the discharge capacity is high, but the electron conductivity is low and lithium ion diffusion is incomplete, resulting in poor load characteristics
Solution Approach 1:
The patent applies segmentation by dividing the positive active material into a hierarchical structure of primary particles (50-200 nm) aggregated into secondary particles (1-5 μm). This segmentation increases the surface area for electrolyte contact and shortens lithium ion diffusion paths within secondary particles, improving electron conductivity and load characteristics while maintaining high discharge capacity through the aggregated structure.
2Quantity of substance
If the crystallite diameter is large, then the discharge capacity is high, but the lithium ion diffusion rate decreases, reducing performance at high C-rates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the crystallite diameter within 40-150 nm and the particle size distribution (D50: 1-5 μm, D90 < 8 μm). These parameter optimizations balance the discharge capacity (enhanced by sufficient crystallite size) with lithium ion diffusion rate (improved by limiting crystallite and particle sizes), enabling high performance at both low and high C-rates.
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
This configuration maintains high discharge capacity and enhances load characteristics by ensuring complete lithium ion diffusion even at high discharge rates, thereby improving the battery's performance under high load conditions.
Implementation Method 1
complete lithium ion diffusion even at high discharge rates
Data Source
AI summary
A positive active material for a rechargeable lithium battery is disclosed. The positive material includes including a lithium-manganese oxide-based solid solution including primary particles and secondary particles having a particle diameter (D50) in the range of about 1 μm to about 5 μm, a particle diameter (D90) in the range of less than about 8 μm, and a crystallite diameter of less than or equal to about 150 nm. The positive electrode for a rechargeable lithium battery includes the lithium manganese oxide-based solid solution is also disclosed.