Lithium Nickel Complex Oxide Positive Electrode Material
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Solution Overview
Problem
Lithium batteries face challenges in achieving high filling density and thermal stability while maintaining capacity, as conventional positive active materials like LiCoO2 are expensive and unstable, and increasing nickel content in nickel-based complex oxides compromises capacity and thermal stability.
Innovation Solution
A positive active material comprising a mixture of lithium nickel complex oxides with specific particle size distributions and varying nickel atomic percentages, including a first lithium nickel complex oxide with a higher nickel content and a second with a lower nickel content, optimized to enhance filling density and thermal stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the atomic percentage of nickel is increased to increase capacity per unit volume, then capacity is improved, but thermal stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a multi-component system where different lithium nickel complex oxides have different nickel contents tailored to specific roles. The first lithium nickel complex oxide has higher nickel content (0.5≤x1<0.6) for capacity, while the second has lower nickel content (0.3<x2≤0.5) for stability, and they are combined in specific proportions (70-99 wt% first component, 1-30 wt% second component). This spatial and compositional differentiation resolves the contradiction between capacity and thermal stability.
Solution Approach 2:
The patent employs composite materials by combining two distinct lithium nickel complex oxides with different nickel compositions into a single positive active material system. This composite approach allows the higher-nickel component to provide capacity while the lower-nickel component maintains thermal stability, achieving both objectives simultaneously that would be impossible with a single homogeneous material.
2Quantity of substance
If the density of the positive active material is increased to increase capacity per unit volume, then capacity is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent applies parameter changes by optimizing specific ranges for nickel content (x1 and x2), particle size distributions (D10, D50, D90 for each component), and compositional ratios (70-99 wt% first component, 1-30 wt% second component). These controlled parameter variations enable high density and capacity while maintaining manufacturability through defined preparation conditions and particle morphology control.
3Reliability
If LiCoO2 is used as positive active material, then thermal stability is maintained, but cost increases and preparation stability decreases
Solution Approach 1:
The patent replaces expensive LiCoO2 with lithium nickel complex oxides that use more abundant and cheaper nickel-based materials. The lower-nickel-content second lithium nickel complex oxide (0.3<x2≤0.5) specifically provides thermal stability comparable to LiCoO2 while using cheaper nickel-based composition, reducing material cost while maintaining safety.
Solution Approach 2:
The patent creates a composite lithium nickel complex oxide system that replicates the thermal stability of LiCoO2 while using cheaper nickel-based materials. The lower-nickel component provides structural stability and thermal resistance, while the higher-nickel component provides capacity, achieving both performance and cost advantages over conventional LiCoO2.
Data Source
AI summary
A positive active material includes first and second lithium nickel complex oxides. A positive electrode and lithium battery include the positive active material. The positive active material, and the lithium battery including the positive active material have increased filling density, are thermally stable, and have improved capacity.