Cathode Coating Uniformity via Ceramic Nanosol Mixing
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Solution Overview
Problem
Lithium secondary batteries face rapid capacity decline and lifespan reduction due to non-uniform coating layers and poor thermal stability of existing positive electrode active materials, especially at high temperatures and high voltages.
Innovation Solution
A method involving the mixing of lithium complex metal oxide particles with a nanosol of ceramic-based ion conductors, followed by heat treatment to form a uniform coating layer, enhancing lithium ion conductivity and structural stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is formed on positive electrode active material particles, then thermal stability and lifespan are improved, but non-uniform coating thickness causes insufficient improvement and capacity decline
Solution Approach 1:
The invention changes the physical state parameter of the coating material from solid powder to sol form (colloidal solution). This parameter change enables the coating material to flow and distribute uniformly over the particle surfaces, solving the uniformity problem while maintaining the protective function that improves lifespan.
Solution Approach 2:
The invention uses a sol as an intermediary medium to deliver the coating material to the particle surfaces. The sol acts as a carrier that ensures uniform distribution and controlled deposition, preventing the non-uniform coating that occurs with direct solid powder application.
2Temperature
If ceramic-based ion conductor is coated on positive electrode active material, then thermal stability is improved, but lithium ion conductivity may be reduced due to coating barriers
Solution Approach 1:
The invention forms a thin film coating of ceramic-based ion conductor through sol processing. The thin film structure provides thermal stability protection while minimizing the barrier effect on lithium ion transport, allowing ions to penetrate through the coating layer effectively.
Solution Approach 2:
The invention changes the coating material from bulk solid ceramic to sol form, which forms a thinner, more porous, and more ion-conductive film after drying and sintering. This parameter change maintains thermal stability while preserving lithium ion conductivity.
3Reliability
If doping materials are used to improve positive electrode active material properties, then thermal stability and capacity are improved, but the extent of improvement is insufficient
Solution Approach 1:
The invention separates the functional requirements into two distinct components: the core positive electrode active material particles and the outer ceramic-based ion conductor coating layer. This segmentation allows each component to be optimized independently, achieving thermal stability without complicating the bulk material composition.
Solution Approach 2:
The invention creates a composite structure with a core-shell configuration, where the core is the positive electrode active material and the shell is the ceramic-based ion conductor coating. This composite approach achieves thermal stability and improved performance without requiring complex doping of the bulk material.
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 approach results in a positive electrode active material with improved lifespan and minimized capacity decline, offering superior performance in lithium secondary batteries by facilitating lithium ion migration and structural integrity.
Implementation Method 1
mixing lithium complex metal oxide particles with a nanosol of a ceramic-based ion conductor and heat treating the resultant to form a coating layer including the ceramic-based ion conductor on the lithium complex metal oxide particles
Implementation Method 2
heat treating the resultant to form a coating layer including the ceramic-based ion conductor on the lithium complex metal oxide particles
Data Source
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AI summary
The present invention provides a cathode active material, a method for manufacturing the same, and a lithium secondary battery comprising the same, the cathode active material being manufactured by a manufacturing method comprising a step of forming a coating layer including a ceramic ion conductor on lithium composite metal oxide particles by mixing the lithium composite metal oxide particles with nano-sol of the ceramic ion conductor and performing heat treatment, wherein the coating layer including the ceramic ion conductor is formed, with a uniform thickness, on the surface of the lithium composite metal oxide particles, so that the cathode active material can minimize capacity reduction and improve life time characteristics when being applied to a secondary battery.