Positive Electrode Active Material Balancing Density and Cycle Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Sodium ion batteries suffer from low energy density and poor cycle performance due to limitations in the filling rate and toughness of the positive electrode active material, which affects the stability and integrity of the material structure during electrochemical processes.
Innovation Solution
The cross-section filling rate of the positive electrode active material is set between 75% to 99%, with a compression resilience ranging from 3% to 10%, and the ratio of filling rate to resilience is maintained between 8≤α/ε≤30, enhancing the material's densification, resilience, and toughness to improve ion content and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the filling rate of the positive electrode active material is increased to improve energy density, then the gravimetric capacity increases, but the structural stability and integrity deteriorate
Solution Approach 1:
The patent applies parameter changes by optimizing the filling rate to a specific range (75%-99%) and controlling the compression resilience within 3%-10%, with their ratio maintained between 8≤α/ε≤30. This precise parameter control allows the material to achieve high ion content while maintaining structural integrity during electrochemical cycling.
Solution Approach 2:
The patent employs composite materials through element doping and surface coating modifications to enhance both the filling rate and structural stability simultaneously. The composite structure allows the material to achieve high density while the dopants and coatings provide structural reinforcement to prevent pulverization.
2Reliability
If the compression resilience is increased to improve toughness and structural integrity, then the cycle performance improves, but the actual compression density decreases
Solution Approach 1:
The patent resolves this contradiction by establishing an optimal parameter range where compression resilience is controlled at 3%-10% rather than maximized. By maintaining the ratio relationship between filling rate and compression resilience (8≤α/ε≤30), the material achieves sufficient toughness for good cycle performance while preserving high compression density for energy density.
3Quantity of substance
If the filling rate is increased to improve gravimetric capacity, then the ion content increases, but the material toughness decreases leading to pulverization
Solution Approach 1:
The patent uses parameter changes to define the optimal filling rate range of 75%-99% and controls compression resilience at 3%-10%. This balanced parameter control ensures high ion content while maintaining sufficient material toughness to prevent pulverization during electrochemical processes.
Solution Approach 2:
The patent applies composite material strategies through doping and surface coating to enhance material toughness while maintaining high filling rate. The composite structure provides reinforcement that prevents pulverization even at high compression densities.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A positive electrode active material, a positive electrode, a sodium ion battery, a battery assembly, and an electric system are disclosed. The positive electrode active material meets the following conditions. The cross-section filling rate α of the positive electrode active material ranges from 75% to 99%; the compression resilience ε of the positive electrode active material ranges from 3% to 10%, where the compression resilience ε=1- (post-recovery compaction density/maximum compaction density); and the cross-section filling rate α and the compression resilience ε of the positive electrode active material meet 8≤α/ε≤30. The positive electrode active material provided in the present disclosure has high energy density and good cycle performance.