Zirconium-Coated Cathode Particles to Prevent Cracking in Li-Ion Cells
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Solution Overview
Problem
Conventional positive electrode active materials for lithium secondary batteries suffer from cracking and fine powder generation due to volume changes during lithium ion intercalation and deintercalation, leading to reduced conductivity and capacity, and existing coatings do not adequately prevent these issues while maintaining capacity.
Innovation Solution
A method of forming a zirconium-containing coating film on the surface and inner interfaces of lithium transition metal oxide particles by mixing a zirconium-containing raw material with a sintering aid and heat-treating the mixture, creating a zirconium-containing coating layer that stabilizes the particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional doping or coating methods are used to improve physical properties, then thermal stability is improved, but cracks and fine powder generation are not adequately prevented
Solution Approach 1:
The patent applies local quality by using a core-shell structure where the core maintains high nickel content (LiNi0.8Co0.1Mn0.1O2) for capacity while the shell provides protective coating. The coating is applied locally at the particle surface and interfaces to prevent cracks without affecting the bulk composition, thereby maintaining thermal stability while preventing crack propagation and fine powder generation.
Solution Approach 2:
The patent employs composite materials by combining LiNi0.8Co0.1Mn0.1O2 with coating materials such as aluminum oxide, aluminum hydroxide, or boehmite. This composite structure provides both the high capacity of the nickel-rich core and the protective properties of the coating shell, preventing crack formation and fine powder generation while maintaining thermal stability.
2Stability of the object's composition
If non-transition metal elements are doped into the lattice to improve physical properties, then thermal stability is improved, but capacity properties are deteriorated due to substitution at transition metal sites
Solution Approach 1:
The patent applies local quality by concentrating the stabilizing elements (Al, Mn, Co) in the coating shell rather than doping them throughout the bulk lattice. This allows the core to maintain high nickel content (0.8) for maximum capacity while the shell provides thermal stability, avoiding capacity deterioration that would result from bulk doping.
Solution Approach 2:
The coating shell acts as an intermediary layer between the high-capacity LiNi0.8Co0.1Mn0.1O2 core and the external environment. This shell provides thermal stability and mechanical protection without requiring substitution of transition metal sites in the bulk lattice, thereby preserving capacity properties while improving stability.
3Quantity of substance
If lithium nickel composite metal oxide is used to achieve high reversible capacity, then capacity properties are improved, but thermal stability is reduced making the material susceptible to decomposition
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the core (LiNi0.8Co0.1Mn0.1O2) provides high reversible capacity (200 mAh/g) while the shell provides thermal stability. The shell is composed of materials like aluminum oxide, aluminum hydroxide, or boehmite that resist thermal decomposition, thereby protecting the nickel-rich core from degradation while preserving its high capacity.
Solution Approach 2:
The patent employs composite materials by combining LiNi0.8Co0.1Mn0.1O2 with thermally stable coating materials. This composite structure allows the material to achieve both high reversible capacity from the nickel-rich core and thermal stability from the protective shell, preventing decomposition even at elevated temperatures.
4Use of energy by moving object
If volume change is accommodated during charging/discharging, then lithium ion intercalation is enabled, but cracks form at particle interfaces reducing conductivity
Solution Approach 1:
The patent applies local quality by providing a protective coating at the particle surface and interfaces where cracks would form during volume changes. This coating accommodates the mechanical stress from lithium ion intercalation-induced volume changes while maintaining particle integrity and interfacial contact, thereby preserving conductivity without compromising lithium ion insertion/extraction capability.
Solution Approach 2:
The patent employs beforehand cushioning by applying a protective coating shell before the particle undergoes volume changes during charging/discharging. This pre-applied shell acts as a cushion that absorbs and distributes mechanical stress, preventing crack formation at interfaces and maintaining conductivity throughout the battery's cycle life.
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 zirconium coating effectively prevents cracking and fine powder formation, maintaining the capacity and lifespan of the positive electrode active material, while minimizing capacity reduction.
Implementation Method 1
heat treating the mixture to form a zirconium-containing coating film on the surface of the lithium transition metal oxide secondary particle and at the interface between the primary particles present inside the secondary particle
Data Source
Figure 1(A)~2
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Figure 5
AI summary
The present invention relates to a positive electrode active material containing a lithium transition metal oxide in the form of a secondary particle in which primary particles are aggregated, wherein a zirconium-containing coating film is formed on the surface of the lithium transition metal oxide secondary particle and at the interface between the primary particles present inside the secondary particle, and a production method thereof.