Positive Electrode Active Material for High Capacity Battery
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Solution Overview
Problem
Current nonaqueous electrolyte secondary batteries, such as lithium ion batteries, face limitations in increasing capacity and suppressing capacity degradation during repetitive charging and discharging, despite the use of mixed lithium composite oxides as positive electrode active materials.
Innovation Solution
The use of first and second lithium composite oxide particles with specific average particle sizes and dibutyl phthalate absorption values, where the first particles have a nickel content of 60 mol% or more and the second particles have a nickel content of 55 mol% or more, both with layered structures, enhances the battery's capacity and resistance to degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two types of lithium composite oxides with different particle properties are mixed, then battery performance is enhanced, but capacity degradation in repetitive charging and discharging is not sufficiently suppressed
Solution Approach 1:
The patent applies parameter changes by precisely controlling particle size (D50 between 3.0-22.0 μm) and dibutyl phthalate absorption values (14-27 mL/100 g) of lithium composite oxide particles. By optimizing these physical parameters within specific ranges, the invention achieves both enhanced battery performance and suppressed capacity degradation, resolving the contradiction between initial performance and long-term durability.
Solution Approach 2:
The patent employs composite materials by mixing two types of lithium composite oxide particles with different particle properties (different particle sizes and DBP absorption values). This composite approach allows the battery to benefit from both fine particles (providing high capacity) and coarse particles (providing structural stability), thereby achieving both high performance and good cycle stability.
2Quantity of substance
If lithium composite oxide particles with specific composition are used, then capacity is increased, but capacity degradation resistance is not sufficiently improved
Solution Approach 1:
The patent changes physical parameters of lithium composite oxide particles, specifically controlling particle size (D50) and dibutyl phthalate absorption value within defined ranges. These parameter optimizations enable the material to achieve high capacity while maintaining structural integrity during cycling, thus improving both capacity and degradation resistance simultaneously.
Solution Approach 2:
The patent applies local quality by creating a distribution of particles with different properties within the electrode. Fine particles (3.0-6.0 μm) provide high capacity regions, while coarser particles (10.0-22.0 μm) provide stable regions. This spatial distribution of different particle qualities allows the battery to achieve both high capacity and good cycle stability.
Data Source
AI summary
Provided is a positive electrode active material capable of increasing capacity of a nonaqueous electrolyte secondary battery and providing the nonaqueous electrolyte secondary battery with high capacity degradation resistance in repetitive charging and discharging. The positive electrode active material disclosed here includes first lithium composite oxide particles having a layered structure and second lithium composite oxide particles having a layered structure. The first lithium composite oxide particles have an average particle size (D50) of 3.0 μm to 6.0 μm. The first lithium composite oxide particles have a dibutyl phthalate absorption value of 15 mL/100 g to 27 mL/100 g. The second lithium composite oxide particles have an average particle size (D50) of 10.0 μm to 22.0 μm. The second lithium composite oxide particles have a dibutyl phthalate absorption value of 14 mL/100 g to 22 mL/100 g.