Li-ion Battery Cathode Material Reducing Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium ion secondary batteries face challenges in maintaining capacity retention rates during charge-discharge cycles due to the presence of alkali metal hydroxide impurities in the positive electrode active material, which increase resistance and lead to rapid performance degradation.
Innovation Solution
A positive electrode active material comprising a mixture of Li x (Ni y Co z Al w )O 2 and Li 1+u Mn 2-u/3 O 4, with carefully controlled composition ratios and minimal alkali metal hydroxide content (0.15% by mass or less), is used to reduce resistance and enhance capacity retention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode active materials are used, then initial capacity is achieved, but capacity retention rate deteriorates due to alkali metal hydroxide impurities increasing resistance
Solution Approach 1:
The patent applies parameter changes by strictly controlling the alkali metal hydroxide content to 0.15% by mass or less in the positive electrode active material. This quantitative parameter control prevents the harmful effect of resistance increase while maintaining the electrochemical performance of the lithium ion secondary battery during charge-discharge cycles.
Solution Approach 2:
The patent applies local quality by ensuring uniform distribution and controlled concentration of alkali metal hydroxide impurities within the positive electrode active material. By maintaining homogeneous local composition with minimal hydroxide content throughout the material structure, the resistance increase is prevented while preserving capacity retention.
2Reliability
If alkali metal hydroxide content is not controlled, then manufacturing simplicity is maintained, but performance degradation accelerates due to resistance increase
Solution Approach 1:
The patent establishes a clear quantitative parameter threshold (0.15% by mass or less of alkali metal hydroxide) that provides a measurable manufacturing target. This parameter specification enables manufacturers to control impurity levels through standard quality assurance processes while achieving improved capacity retention.
Solution Approach 2:
The patent employs purification processes during manufacturing that utilize washing and filtration techniques to remove alkali metal hydroxide impurities from the positive electrode active material. These hydraulic/pneumatic methods effectively reduce hydroxide content to the required 0.15% or less while maintaining manufacturing feasibility.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
There is provided a lithium ion secondary battery having a high capacity retention rate in the charge-discharge cycles. There is provided a positive electrode for a lithium ion secondary battery, including a positive electrode active material including a compound represented by the following formula (1), Lix(NiyCo2Alw)O2, wherein, in formula (1), 0.95≤x≤1.05, 0.70≤y≤0.85, 0.05≤z≤0.20, 0.00≤w≤0.10, and y+z+w=1, and a compound represented by the following formula (2), Li1+uMn2-u/3O4, wherein, in formula (2), 0≤u≤0.05, wherein the content of the alkali metal hydroxide in the positive electrode active material is 0.15% by mass or less.