Titanium-Doped Li-Ni-Mn Cathode Material for Thermal Stability
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Solution Overview
Problem
Existing lithium ion secondary batteries face challenges in achieving both high battery capacity and thermal stability, particularly with high nickel ratios, and existing methods for enhancing thermal stability often compromise battery performance or are difficult to scale industrially.
Innovation Solution
A positive electrode active material composed of lithium-nickel-manganese composite oxide with specific elemental ratios and a hexagonal layered structure, incorporating titanium and controlled firing conditions, followed by water-washing and drying, to ensure titanium is solid-solved within the particles, enhancing thermal stability while maintaining high capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the nickel ratio is increased to enlarge battery capacity, then battery capacity is improved, but thermal stability decreases
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the central core region contains high nickel content (0.6-0.8) for high capacity, while the outer shell region has reduced nickel content (0.3-0.6) and includes thermal stability enhancing elements (manganese 0.2-0.5, cobalt 0.1-0.3). This spatial differentiation allows simultaneous achievement of high battery capacity from the nickel-rich core and high thermal stability from the nickel-reduced, thermally stable shell.
Solution Approach 2:
The patent employs composite materials by combining multiple metal elements (nickel, manganese, cobalt, and optionally aluminum, titanium, or vanadium) in a core-shell structured lithium-metal composite oxide. The composite structure integrates the high capacity advantage of nickel-rich materials with the thermal stability advantage of manganese and cobalt containing materials, achieving synergistic performance.
2Reliability
If a heterogeneous element such as niobium is added to improve thermal stability, then thermal stability is improved, but battery characteristics such as discharge capacity may be compromised
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of metal elements within specific ranges (nickel 0.3-0.6, manganese 0.2-0.5, cobalt 0.1-0.3) and the ratio between core and shell regions (0.3-0.8). This quantitative optimization ensures that thermal stability is enhanced through manganese and cobalt while maintaining high discharge capacity through sufficient nickel content and optimized core-shell structure.
3Reliability
If coating methods are used to enhance thermal stability, then thermal stability is improved, but the processes become cumbersome and difficult to scale industrially
Solution Approach 1:
The patent merges the thermal stability enhancement function directly into the active material synthesis process itself, rather than using separate coating steps. The core-shell structured lithium-metal composite oxide is produced in a single firing process from mixed metal oxides or hydroxides, integrating structure formation and compositional optimization into one manufacturable step, thereby ensuring industrial scalability.
4Quantity of substance
If high nickel ratio materials are used, then battery capacity is improved, but oxygen release occurs compromising safety
Solution Approach 1:
The patent applies local quality by concentrating the high nickel content (0.6-0.8) in the core region where it contributes to capacity without direct oxygen release risk, while placing nickel-reduced (0.3-0.6), manganese and cobalt-enriched material in the outer shell region that acts as a protective barrier against oxygen release during thermal events.
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 solution provides a lithium ion secondary battery with both excellent battery capacity and high thermal stability, suitable for industrial-scale production, by suppressing oxygen release and maintaining high nickel ratios.
Implementation Method 1
incorporating titanium and controlled firing conditions, followed by water-washing and drying, to ensure titanium is solid-solved within the particles
Implementation Method 2
Lithium ion secondary batteries using a layered or spinel type lithium-metal composite oxide as a positive electrode material can provide a high voltage of 4 V-class
Implementation Method 3
followed by water-washing and drying, to ensure titanium is solid-solved within the particles
Implementation Method 4
followed by water-washing and drying, to ensure titanium is solid-solved within the particles
Data Source
AI summary
A positive electrode active material for a lithium ion secondary battery, in which the lithium-nickel-manganese composite oxide has a hexagonal layered structure, a mole number ratio of elements is represented as Li:Ni:Mn:M:Ti=a:(1-x-y-z):x:y:z, provided that 0.97≤a≤1.25, 0.035≤x≤0.15, 0≤y≤0.15, and 0.01≤z≤0.05, a ratio of a total amount of peak intensities of most intense peaks of a titanium compound to a (003) diffraction peak intensity that is the most intense peak of the hexagonal layered structure is 0.2 or less, a crystallite diameter at (003) plane is 80 nm or more and less than 160 nm, and a specific surface area is 0.7 m2/g or more and 4.0 m2/g or less.