Core-Shell Lithium Nickel Manganate Cathode for Stable High-Voltage Cycling
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Solution Overview
Problem
Spinel-type lithium nickel manganate secondary batteries face issues with high oxygen deficiency, rock-salt phase formation, and poor cycling performance due to high operating temperatures and voltages, leading to manganese ion dissolution and interface impedance problems.
Innovation Solution
A lithium-nickel-manganese-containing composite oxide with a core-shell structure is developed, where the core includes Lix(NiyMn2-y)1-mMmO4 and the shell is composed of lithium aluminum phosphate, reducing oxygen defects and side reactions, and enhancing lithium ion conduction channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If spinel-type lithium nickel manganate is used as positive electrode active material, then high energy density is achieved, but severe side reactions and interface deterioration occur due to high operating voltage
Solution Approach 1:
A lithium aluminum phosphate shell is introduced as an intermediary layer between the spinel-type lithium nickel manganate core and the electrolyte. This shell acts as a protective mediator that reduces direct contact between the high-voltage electrode material and the electrolyte, thereby suppressing side reactions and interface deterioration while maintaining high energy density performance
2Use of energy by moving object
If high operating voltage is used, then high energy density is achieved, but manganese ion dissolution increases leading to poor cycling performance
Solution Approach 1:
A composite core-shell structure is constructed where the core consists of spinel-type lithium nickel manganate (Lix(NiyMn2-y)1-mMmO4) providing high energy density, and the shell consists of lithium aluminum phosphate providing stability. This composite structure combines the high-voltage performance of the spinel material with the protective properties of the phosphate shell, enabling both high energy density and excellent cycling performance
3Use of energy by moving object
If conventional electrolytes are used with high operating voltage, then high energy density is achieved, but severe side reactions occur at the electrode-electrolyte interface
Solution Approach 1:
The lithium aluminum phosphate shell serves as an intermediary barrier between the high-voltage spinel electrode and the conventional electrolyte. This shell is chemically stable at high voltages and prevents direct harmful interactions between the electrolyte and the electrode material, thereby suppressing side reactions, gas production, and interface deterioration while allowing the system to operate at high energy density
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 composite oxide achieves high energy density, improved cycling performance, and reduced gas production in secondary batteries by stabilizing the crystal structure and reducing manganese ion dissolution.
Implementation Method 1
The shell includes lithium aluminum phosphate, and the lithium aluminum phosphate can construct lithium ion conduction channels, avoiding capacity reduction caused by the shell enveloping the surface of the core
Data Source
AI summary
This application provides a lithium-nickel-manganese-containing composite oxide, a preparation method thereof, and a positive electrode plate, secondary battery, and electric apparatus containing the same. The lithium-nickel-manganese-containing composite oxide has a core-shell structure and includes a core and a shell enveloping surface of the core, where the core includes Lix(NiyMn2-y)1-mMmO4. M includes one or more selected from Mg, elements from group IVB to group VIB, elements from group IIIA to group VA, and lanthanide elements, where 0.95≤x≤1.10, 0.40≤y≤0.60, and 0.001≤m≤0.015. The shell includes lithium aluminum phosphate and optionally includes lithium aluminum phosphate and aluminum phosphate.