High-Nickel Cathode Material With Layered Core and Rock-Salt Surface
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Solution Overview
Problem
Lithium nickel cobalt metal oxides with high nickel content face limitations in structural stability and capacity due to nickel oxidation during charge and discharge, leading to reduced thermal stability and battery performance.
Innovation Solution
A lithium transition metal oxide positive electrode active material doped with specific elements like aluminum, titanium, or strontium, containing 60 mol% nickel or more, is developed with a layered center structure and rock-salt surface structure, achieving improved structural and thermal stability through controlled doping and sintering processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high nickel content (60 mol% or more) is used in lithium nickel cobalt metal oxide to increase capacity, then reversible capacity is improved, but structural stability deteriorates due to nickel oxidation during charge and discharge
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the center portion has a layered structure optimized for capacity while the surface portion has a rock-salt structure optimized for stability. This allows different regions of the same particle to have different properties, enabling high nickel content in the core for capacity while maintaining a stable surface for structural integrity.
Solution Approach 2:
The patent uses composite materials by combining two different crystal structures (layered and rock-salt) within the same particle. The layered structure provides high reversible capacity while the rock-salt structure provides structural stability, creating a composite material that exhibits both properties simultaneously.
2Quantity of substance
If high nickel content is used to achieve high reversible capacity, then battery capacity is improved, but thermal stability deteriorates leading to decomposition and safety issues
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the center portion has a layered structure optimized for capacity while the surface portion has a rock-salt structure optimized for stability. This allows different regions of the same particle to have different properties, enabling high nickel content in the core for capacity while maintaining a stable surface for structural integrity.
Solution Approach 2:
The patent converts the harmful effect of nickel oxidation and structural degradation into a benefit by deliberately creating a rock-salt surface structure that is more stable. The surface structure that would normally form as a degradation product is instead intentionally created to protect the high-capacity core from thermal degradation.
3Quantity of substance
If nickel is oxidized from Ni2+ to Ni3+ or Ni4+ during charge and discharge to increase capacity, then reversible capacity is improved, but structural stability is reduced due to rapid oxygen desorption
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the center portion has a layered structure optimized for capacity while the surface portion has a rock-salt structure optimized for stability. This allows different regions of the same particle to have different properties, enabling high nickel content in the core for capacity while maintaining a stable surface for structural integrity.
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 doped lithium transition metal oxide exhibits enhanced capacity, life characteristics, and thermal stability, preventing cracks and side reactions, thus improving battery performance and longevity.
Implementation Method 1
a lithium transition metal oxide which is doped with doping element M2
Implementation Method 2
a lithium transition metal oxide which is doped with doping element M2... and contains nickel in an amount of 60 mol % or more... wherein the lithium transition metal oxide has a single particle form, and includes a center portion having a layered structure and a surface portion having a rock-salt structure
Data Source
AI summary
A positive electrode active material includes a lithium transition metal oxide, which is doped with doping element M2, wherein M2 includes at least one of Al, Ti, Mg, Zr, W, Y, Sr, Co, F, Si, Na, Cu, Fe, Ca, S, or B, and contains nickel in an amount of 60 mol % or more based on a total number of moles of transition metals excluding lithium, wherein the lithium transition metal oxide has a single particle form, and includes a center portion having a layered structure and a surface portion having a rock-salt structure, and the doping element M2 is included in an amount of 3,580 ppm to 7,620 ppm based on a total weight of the positive electrode active material.