Lithium Secondary Battery Electrode Mix for Balanced Capacity Fade
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries face challenges in maintaining a balanced utilization capacity ratio and lifespan characteristics due to differences in deterioration rates between positive and negative electrodes, which affects energy density and stability.
Innovation Solution
A lithium secondary battery design incorporating a positive electrode with a mixture of active materials, such as layered and spinel-type materials, and a negative electrode with natural graphite and artificial graphite, optimized through specific weight ratios to achieve a balanced R value of 0.1 to 35, ensuring balanced deterioration and improved energy density and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single type of active material is used in each electrode, then the electrode structure is simple, but the utilization capacity ratio between positive and negative electrodes becomes unbalanced due to different deterioration rates
Solution Approach 1:
The patent applies composite materials by combining multiple types of active materials in each electrode. The positive electrode contains a first active material and a second active material, while the negative electrode contains a third active material and a fourth active material. This composite structure allows different materials with varying deterioration rates to complement each other, achieving balanced utilization capacity ratio between electrodes while maintaining reasonable structural complexity.
2Quantity of substance
If high capacity active materials are used to increase energy density, then the energy density improves, but the deterioration rate increases and lifespan decreases
Solution Approach 1:
The patent applies parameter changes by carefully controlling the capacity ratios of different active materials and the overall R value (ratio of positive to negative electrode capacity). By adjusting these parameters within specific ranges, the battery achieves high energy density while the mixed material composition ensures balanced deterioration rates, thereby extending lifespan despite using high capacity materials.
3Adaptability or versatility
If the positive and negative electrodes have different deterioration rates, then each electrode can be optimized for its specific function, but the overall battery performance becomes limited by the electrode with higher deterioration
Solution Approach 1:
The patent applies local quality by assigning different material compositions to different electrodes and even different materials within the same electrode. The positive electrode uses a combination of first and second active materials, while the negative electrode uses a combination of third and fourth active materials. This localized optimization allows each material to contribute its strengths while the overall composition balances deterioration rates, ensuring reliable overall battery performance.
Data Source
AI summary
A lithium secondary battery includes a positive electrode including a first positive electrode active material and a second positive electrode active material and a negative electrode including a first negative electrode active material and a second negative electrode active material. The first positive electrode active material may have a higher specific capacity value than the second positive electrode active material, the first negative electrode active material may have a higher specific capacity value than the second negative electrode active material, and the lithium secondary battery may have an R value of 0.1 to 35 according to Equation 1 below.R=X/Y[Equation 1]In Equation 1, X is a content ratio of a positive electrode active material and Y is a content ratio of a negative electrode active material.