Manganese-Rich LNMO Cathode for High-Voltage Capacity Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium secondary batteries with lithium nickel manganese composite oxide as a positive electrode active material face challenges in maintaining capacity when kept at high upper limit voltages, specifically at 5.0 V, leading to reduced energy efficiency.
Innovation Solution
A lithium nickel manganese composite oxide with a manganese-rich surface layer and a specific composition (LixNiyMnzO2, where x is 0.95≤x≤1.1, y is 0.45≤y≤0.5, z is 0.45≤z≤0.5, and y=z) is developed, which prevents the formation of LiMn6 and maintains a Mn/Ni ratio of 1.0 to 1.5, ensuring a high capacity even at 4.8 V.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a lithium nickel manganese composite oxide is simply synthesized to increase battery capacity, then the upper limit voltage must be kept at 5.0 V, but this leads to reduced energy efficiency and capacity loss after aging
Solution Approach 1:
The patent applies local quality by creating a manganese-rich surface layer on the lithium nickel manganese composite oxide particles. This surface layer has a different composition (higher Mn/Ni ratio of 1.0-1.5) than the bulk material, providing localized protection at the particle surface while maintaining the high-capacity bulk composition. This resolves the contradiction by enabling high capacity utilization without requiring excessive voltage, thus preserving energy efficiency.
2Quantity of substance
If the upper limit voltage is increased to 5.0 V to maximize capacity, then more lithium can be extracted, but the battery undergoes capacity degradation after keeping (aging)
Solution Approach 1:
The patent applies preliminary action by forming a protective manganese-rich surface layer on the composite oxide particles before they are assembled into the battery. This pre-formed surface layer prevents harmful reactions between lithium and manganese during subsequent cycling and aging, allowing the battery to operate at optimal voltage (4.8 V) without suffering from capacity degradation. The surface layer is created in advance through controlled synthesis conditions (950-1150°C heating treatment).
Data Source
AI summary
The present invention relates to a lithium nickel manganese composite oxide which includes secondary particles in which a plurality of primary particles are aggregated with each other, and is represented by General Formula (1): LixNiyMnzO2 (in Formula (1), x is 0.95≤x≤1.1, y is 0.45≤y≤0.5, z is 0.45≤z≤0.5, and y=z is satisfied), wherein Li contained in a transition metal layer does not form LiMn6, wherein the lithium nickel manganese composite oxide has a manganese-rich layer from a surface of the secondary particles toward an inside of the secondary particles, wherein a ratio of a number of Mn atoms to a number of Ni atoms (Mn/Ni ratio) in the manganese-rich layer is 1.0 or more and 1.5 or less, and wherein the lithium nickel manganese composite oxide has a space group R-3m, an a-axis lattice constant of 2.87 Å to 2.90 Å, and a c-axis lattice constant of 14.28 Å to 14.32 Å.