Lithium Manganate Particles Coating for High-Temperature Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithium manganate materials for non-aqueous electrolyte secondary batteries fail to provide satisfactory high-temperature storage characteristics and output characteristics, despite efforts to improve crystallizability and prevent manganese elution.
Innovation Solution
Lithium manganate particles with a specific composition (Li1+xMn2-x-yY1yO4+Y2) and production process involving surface coating of manganese oxide with elements like Ni, Co, Mg, Fe, Al, or Ti, followed by calcination with a sintering aid like boric acid, result in particles with optimized crystal structure, size, and distribution, enhancing stability and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If lithium manganate particles are used as positive electrode active substance to achieve high voltage and high energy density, then the battery exhibits high energy density, but the charge/discharge cycle characteristics deteriorate due to crystal lattice expansion and contraction causing breakage and Mn dissolution
Solution Approach 1:
The patent applies a coating film on the surface of lithium manganate particles to protect the crystal lattice from expansion and contraction during charge/discharge cycles. This coating acts as a protective shell that prevents lattice breakage and Mn dissolution, thereby improving cycle characteristics while maintaining high energy density
Solution Approach 2:
The patent creates composite lithium manganate particles by incorporating different elements into the crystal structure and applying surface coatings. This composite approach strengthens the crystal lattice, reduces volume change during cycling, and prevents Mn elution, resolving the contradiction between high energy density and cycle stability
2Stability of the object's composition
If calcination temperature is increased to improve crystallinity and reduce Mn elution, then crystal structure stability improves, but particle aggregation increases and surface area decreases
Solution Approach 1:
The patent optimizes calcination parameters including temperature, time, and atmosphere to achieve the desired balance between crystallinity and surface area. By carefully controlling these parameters, the patent produces particles with sufficient crystallinity for stability while maintaining adequate surface area for electrochemical activity
3Productivity
If particle size is reduced to improve packing property and electrochemical activity, then charge/discharge rate improves, but particle strength decreases and Mn elution increases
Solution Approach 1:
The patent applies protective coating films on small particle surfaces to prevent Mn elution and strengthen the particle structure. This allows the use of small particle sizes for high charge/discharge rates while the coating prevents particle degradation and Mn dissolution
Solution Approach 2:
The patent creates composite particles with strengthened crystal structures through element incorporation and surface coating. This composite structure provides the mechanical strength needed for small particles to resist breakage and Mn elution while maintaining high surface area to volume ratio for fast charge/discharge rates
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 resulting lithium manganate particles exhibit improved high-temperature stability and output characteristics, with initial discharge capacity retention and cycle stability significantly enhanced, making them suitable for non-aqueous electrolyte secondary batteries.
Implementation Method 1
a sintering aid having a melting point of not higher than 800°C, in particular, boron oxide, boric acid, lithium borate or ammonium borate, is added to the lithium manganate particles upon calcination of the particles
Implementation Method 2
mixing a manganese compound and a lithium compound at a predetermined ratio and then calcining the resulting mixture at a temperature of 700 to 800°C
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The present invention relates to lithium manganate particles having a primary particle diameter of not less than 1 µm and an average particle diameter (D50) of not less than 2 µm and not more than 10 µm as measured by a particle size distribution meter, and forming particles having substantially a single phase, which have a composition represented by the following chemical formula: Li1+xMn2-x-yY1yO4+Y2 where Y1 is at least one element selected from the group consisting of Ni, Co, Mg, Fe, Al, Cr and Ti; Y2 is at least one element constituting a sintering aid having a melting point of not higher than 800°C, x and y satisfy 0.03 ≤ x ≤ 0.15 and 0.05 ≤ y ≤ 0.20, respectively, and Y2 is present in an amount of 0.1 to 2.5 mol% based on Mn; the Y1 element being dispersed within the respective particles, and an X-ray diffraction intensity ratio of I(400)/I(111) of the particles being not less than 38% and an X-ray diffraction intensity ratio of I(440)/I(111) thereof being not less than 18%. The lithium manganate particles of the present invention have a high output and are excellent in high-temperature stability.