Core-Shell Lithium Metal Oxide Cathodes for Stable High-Nickel Cycling
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Solution Overview
Problem
Current lithium-ion battery cathode materials with high nickel and reduced cobalt content face challenges in cycle life and phase stability, making it difficult to commercialize stable and efficient battery systems while addressing social and manufacturing concerns related to cobalt usage.
Innovation Solution
A three-stage process is employed to create stabilized lithium metal oxide cathode materials with a core-shell structure, where the core is composed of nickel-containing lithium metal oxide and coated with a different composition, allowing metal ions to penetrate and form concentric regions, enhancing stability and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If cobalt content is reduced and nickel content is increased in layered NMC electrodes, then battery capacity is improved, but cycle life and phase stability deteriorate
Solution Approach 1:
The patent applies local quality by creating a compositional gradient within the NMC particles, where the core region has high nickel content (0.6-0.8) for high capacity, while the surface region has lower nickel content (0.3-0.5) and higher cobalt content for stability. This spatial variation in composition allows different regions to fulfill different functions: the core provides capacity while the surface provides structural stability during cycling.
Solution Approach 2:
The patent creates a composite structure with distinct core and shell regions. The core consists of high-nickel NMC material (LiNixMnyCozO2 where x=0.6-0.8) for high capacity, while the shell consists of lower-nickel, higher-cobalt NMC material (LiNixMnymCozO2 where x=0.3-0.5) for structural stability. This composite architecture combines the advantages of both high-capacity and stable materials.
2Quantity of substance
If cobalt content is reduced and nickel content is increased in layered NMC electrodes, then battery capacity is improved, but phase stability deteriorates
Solution Approach 1:
The patent applies local quality by creating a compositional gradient within the NMC particles, where the core region has high nickel content (0.6-0.8) for high capacity, while the surface region has lower nickel content (0.3-0.5) and higher cobalt content for stability. This spatial variation in composition allows different regions to fulfill different functions: the core provides capacity while the surface provides structural stability during cycling.
Solution Approach 2:
The patent creates a composite structure with distinct core and shell regions. The core consists of high-nickel NMC material (LiNixMnymCozO2 where x=0.6-0.8) for high capacity, while the shell consists of lower-nickel, higher-cobalt NMC material (LiNixMnymCozO2 where x=0.3-0.5) for structural stability. This composite architecture combines the advantages of both high-capacity and stable materials.
3Stability of the object's composition
If batch coprecipitation process is used to create compositional gradients, then phase stability is improved, but manufacturing complexity increases
Solution Approach 1:
The patent segments the coprecipitation process into two distinct stages: (1) a continuous coprecipitation stage to form the core particles with high nickel content, and (2) a second continuous coprecipitation stage to form the surface coating with lower nickel and higher cobalt content. This segmentation allows each stage to be optimized independently while maintaining continuous operation, avoiding the complexity of batch processing.
Solution Approach 2:
The patent changes process parameters between the two coprecipitation stages to achieve different compositions. In the first stage, the feed solution has a high nickel content ratio, while in the second stage, the feed solution has a lower nickel content ratio and higher cobalt content. This parameter change approach allows continuous production of gradient materials without complex batch processing.
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 process results in improved cycling stability, capacity, and thermal stability of lithium-ion batteries, addressing the limitations of conventional high-nickel NMC materials by maintaining structural integrity and performance.
Implementation Method 1
During the coating stage, some of the metal ions from the coating composition penetrate into the cores of the particles
Implementation Method 2
a three stage process involving coprecipitating precursor metal hydroxide (MOH) core particles
Implementation Method 3
coprecipitating a MOH coating with a different metal hydroxide composition (e.g., an MOH comprising Mn in combination with Co and/or another metal ion) on the core particles
Implementation Method 4
and then calcining the resulting coated precursor particles with lithium hydroxide to form the stabilized LMO material
Data Source
AI summary
A stabilized lithium metal oxide cathode material comprises microparticles of lithium metal oxide in which individual particles thereof a core of lithium metal oxide and a coating of a different lithium metal oxide surrounding the core. There is an interface layer between the cores and the coatings in which there are gradients of metal ions in the direction of coating to core. The materials are made by a three stage process involving coprecipitating precursor metal hydroxide core particles at a controlled pH; coprecipitating a different metal hydroxide coating on the particles without controlling the pH; and then calcining the resulting coated precursor particles with lithium hydroxide to form the stabilized lithium metal oxide material.