Coated Nickel Cathode Material to Limit Agglomeration Loss
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Solution Overview
Problem
Lithium secondary batteries with high energy density face safety concerns and reduced lifespan due to particle agglomeration and low discharge capacity when using single-crystal cathode active materials, which are exacerbated by high-temperature heat treatment processes.
Innovation Solution
A cathode active material comprising nickel-based lithium metal oxide monolithic particles with a cobalt compound-containing coating layer and molybdenum doping, where the particles are between 1 μm to 4 μm in size, and the cobalt compound coating layer is between 0.1 mol% to 5.0 mol% of the total material, with a thickness of 1 nm to 50 nm, is used to enhance discharge capacity and charge/discharge efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If single-crystal cathode active material is used to reduce particle agglomeration and improve lifespan, then structural stability is improved, but discharge capacity and charge/discharge efficiency decrease
Solution Approach 1:
The patent creates a composite structure combining single-crystal core particles with polycrystalline coating layers. The single-crystal core (LiNi0.8Co0.1Mn0.1O2) provides structural stability and prevents particle agglomeration, while the polycrystalline coating layer (containing Li2SiO3, Li3PO4, and amorphous carbon) enhances discharge capacity and charge/discharge efficiency. This composite approach resolves the contradiction by allowing each material type to contribute its advantageous properties.
Solution Approach 2:
The patent applies different crystal structures and material compositions to different regions of the cathode active material. The core region maintains single-crystal structure for structural stability, while the surface coating region uses polycrystalline structure with specific phases (Li2SiO3, Li3PO4, amorphous carbon) to enhance electrochemical performance. This local differentiation allows simultaneous achievement of both structural stability and high discharge capacity.
2Stability of the object's composition
If high-temperature heat treatment is applied to achieve single crystallization, then structural stability is improved, but productivity decreases due to particle agglomeration
Solution Approach 1:
The patent performs preliminary surface coating treatment before the high-temperature heat treatment process. By pre-coating the nickel-based lithium metal oxide particles with lithium hydroxide, silicon oxide, phosphorus compounds, and carbon-containing compounds, the surface is protected against agglomeration during subsequent high-temperature treatment. This preliminary action enables successful single crystallization while maintaining particle dispersibility and productivity.
Solution Approach 2:
The patent introduces intermediate coating substances (lithium hydroxide, silicon oxide, phosphorus compounds, carbon-containing compounds) that act as mediators during the heat treatment process. These intermediates prevent direct particle-to-particle contact and agglomeration while allowing the single-crystal structure to form. The coating layers serve as protective intermediaries that enable high-temperature treatment without productivity loss.
3Use of energy by moving object
If high energy density is pursued in lithium secondary batteries, then energy density is improved, but safety and lifespan are reduced
Solution Approach 1:
The patent applies thin film coating layers (comprising Li2SiO3, Li3PO4, and amorphous carbon) on the surface of the single-crystal cathode active material particles. These thin film coatings act as protective shells that enhance safety by preventing harmful reactions between the high-energy nickel-based cathode material and the electrolyte, while maintaining high energy density. The coatings provide thermal and chemical stability without significantly increasing particle size.
Solution Approach 2:
The patent creates a composite cathode material combining high-energy nickel-based lithium metal oxide (LiNi0.8Co0.1Mn0.1O2) with protective coating materials (Li2SiO3, Li3PO4, amorphous carbon). This composite structure enables the battery to achieve high energy density from the nickel-rich core while the protective coating phases ensure safety and extended lifespan by preventing degradation and thermal runaway.
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 proposed cathode active material improves the structural stability and dispersibility of lithium secondary batteries, reducing particle agglomeration and surface defects, thereby enhancing safety, capacity, and charge/discharge efficiency while maintaining suitable phase stability and electrochemical characteristics.
Implementation Method 1
the nickel-based lithium metal oxide monolithic particles are doped with molybdenum
Implementation Method 2
a cobalt compound-containing coating layer on surfaces of the nickel-based lithium metal oxide monolithic particles
Implementation Method 3
heat treatment at high temperatures for single crystallization
Data Source
AI summary
A cathode active material, a method of preparing the same, and a lithium secondary battery including a cathode including the same are provided. The cathode active material includes nickel-based lithium metal oxide monolithic particles, the nickel-based lithium metal oxide monolithic particles having an average size of about 1 μm to about 4 μm, and a cobalt compound-containing coating layer on surfaces of the nickel-based lithium metal oxide monolithic particles, wherein the nickel-based lithium metal oxide monolithic particles are doped with molybdenum.