Core-Shell Lithium Manganese Oxide Cathode Coating
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Solution Overview
Problem
Existing methods for surface coating spinel LiMn2O4 to enhance cycling stability in lithium-ion batteries result in non-uniform and discontinuous coating layers, leading to unsatisfactory performance at elevated temperatures.
Innovation Solution
A process involving heat-treatment of spinel LiMxMn2-xO4 particles with P2O5 to form a continuous and uniform lithium manganese phosphate shell layer, reducing the contact area with the electrolyte and preventing Mn dissolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sol-gel method or precipitation method is used for surface coating, then the spinel surface is coated with metal oxide particles, but the coating layer is not uniform and continuous
Solution Approach 1:
The invention changes the chemical parameters of the coating process by using phosphoric acid treatment instead of sol-gel or precipitation methods. The phosphoric acid concentration (0.1-10 M) and treatment temperature (20-100°C) are optimized to achieve uniform and continuous coating layers, resolving the contradiction between coating uniformity and cycling stability improvement.
Solution Approach 2:
The invention utilizes phase transition during the heat treatment process (calcination at 400-900°C) where the phosphoric acid-treated surface undergoes chemical transformation to form a uniform lithium phosphate coating layer. This phase transition ensures continuous coverage that prevents Mn dissolution while maintaining structural integrity.
2Object-affected harmful factors
If isolated nano-sized metal oxide particles are attached on spinel surface, then some coating effect is achieved, but the cycling performance improvement is not satisfactory
Solution Approach 1:
The invention applies local quality by creating a uniform phosphoric acid treatment layer across the entire spinel surface, ensuring consistent protection against Mn dissolution. The localized chemical reaction between phosphoric acid and spinel surface creates a continuous protective barrier rather than isolated particles, significantly improving cycling performance.
Solution Approach 2:
The invention creates a composite structure by combining spinel LiMn2O4 with a uniform lithium phosphate coating layer formed through phosphoric acid treatment. This composite material structure provides both the electrochemical activity of spinel and the protective properties of the phosphate coating, effectively preventing Mn dissolution and improving cycling stability.
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 core-shell structured lithiated manganese oxide exhibits significantly improved cycling stability and capacity retention at elevated temperatures, with a capacity retention of about 82% after 200 cycles at 60°C compared to 50% for untreated samples.
Implementation Method 1
heat-treatment of spinel LiMxMn2-xO4 particles with P2O5 to form a continuous and uniform lithium manganese phosphate shell layer
Implementation Method 2
heat-treatment of spinel LiMxMn2-xO4 particles with P2O5
Data Source
Figure 1~3
Figure 4
AI summary
The invention relates to a process for preparing a core-shell structured lithiated manganese oxide, comprising the steps of providing spinel LiMxMn2-xO4 particles, where M is one or more metal ions selected from the group consisting of Li, Mg, Cr, Al, Co, Ni, Zn, Cu, and La, and 0<=x<1, as core particles, and subjecting the spinel particles to a heat-treatment with a reactive chemical reagent in the form of liquid or gas to form a shell layer on the surface of the core particles, and to the prepared core-shell structured lithiated manganese oxide, and its use as a cathode material for a lithium ion battery