O6-Type Cathode Active Material for Cobalt-Free High-Capacity Li-Ion Cells
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Solution Overview
Problem
Current positive electrode materials for lithium ion secondary batteries face challenges in achieving high capacity, avoiding capacity degradation due to aging, and reducing costs by minimizing the use of cobalt, a limited mining resource, while maintaining effective performance.
Innovation Solution
A positive electrode active material with an O6-type structure, formulated as Lix[AzBw(Li1/6Ni1/6Mn4/6)1-z-w]O2, where A and B are specific elements, and a preparation method involving mixing oxygen-containing anion compounds of nickel, manganese, and sodium, followed by Na—Li ion exchange, to create a lithium-rich mixed oxide without requiring cobalt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt-containing materials are used to achieve high capacity, then battery capacity is improved, but cost increases and resource sustainability deteriorates due to cobalt being a limited mining resource
Solution Approach 1:
The invention extracts and removes cobalt from the cathode material composition entirely, replacing it with a cobalt-free lithium-rich layered oxide material with formula Lix[AzBw(Li1/6Ni1/6Mn4/6)1-z-w]O2. This extraction eliminates dependency on cobalt while maintaining high capacity through the lithium-rich composition and O6-type structure, thereby resolving the contradiction between capacity and cost/sustainability.
Solution Approach 2:
The invention changes the chemical composition parameters by采用 a lithium-rich formulation with x>1 and a specific ratio of Li:Ni:Mn elements (1:1:4 in the core structure). This parameter change enables achieving high capacity without cobalt, as the excess lithium content and specific stoichiometry provide high lithium-ion storage capacity while using only nickel, manganese, and other non-cobalt metals.
2Quantity of substance
If lithium-rich composition is used to improve capacity, then battery capacity increases, but capacity degradation through aging worsens due to potential spinel structure formation
Solution Approach 1:
The invention applies local quality by creating a core-shell structure where the core contains the lithium-rich layered oxide with formula Lix[AzBw(Li1/6Ni1/6Mn4/6)1-z-w]O2 and the surface is modified with a protective layer. This local differentiation allows the bulk material to maintain high lithium content for capacity while the surface layer prevents degradation and spinel formation, thus resolving the contradiction between high capacity and aging resistance.
Solution Approach 2:
The invention uses composite materials by combining lithium-rich layered oxide with surface modification layers or coating materials. The core material provides high capacity through its lithium-rich composition, while the surface layer or composite structure prevents irreversible spinel transformation and capacity degradation during cycling, thereby achieving both high capacity and long-term stability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The O6-type structure provides improved capacity compared to O3 types, avoids irreversible spinel structure formation, and eliminates the need for cobalt, resulting in enhanced battery performance and sustainability.
Implementation Method 1
carrying out, as a second step, an Na—Li ion exchange through application of a further lithium source to the mixed oxide of sodium, lithium, nickel and manganese prepared in the first step
Data Source
AI summary
A positive electrode active material has O6-type structure having Lix [AzBw(Li1/6Ni1/6Mn4/6)1-z-w]O2, wherein 1≥x>0; z<0.005; when present, A is at least one element chosen from the group consisting of: Mg, Ca, Sr, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Zn and Al; w<0.05; and when present, B is at least one element chosen from the group consisting of: Mg, Ca, Sr, Sc, Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Zn, and Al.