Lithium Mixed Metal Oxide Electrode Material for High-Temperature Cycling
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Solution Overview
Problem
Conventional lithium mixed metal oxides used in nonaqueous electrolyte secondary batteries have limited discharge capacity and cycling characteristics, particularly at high temperatures.
Innovation Solution
A lithium mixed metal oxide with a specific composition and particle size distribution, represented by the formula Lix(Mn1−(y+z)NiyFez)O2, is developed, where x is between 0.9 and 1.3, y is between 0.5 and 0.6, and z is between 0.02 and 0.07, with an average particle diameter of 0.01 to 1 μm, and a preferred α-NaFeO2-type crystal structure, enhancing both capacity and cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional lithium mixed metal oxide compositions are used, then the battery structure is simple and easy to manufacture, but the discharge capacity is limited and cycling characteristics deteriorate at high temperatures
Solution Approach 1:
The patent applies parameter changes by precisely controlling the stoichiometric ratios of metal elements (Ni: 0.35-0.45, Mn: 0.40-0.50, Fe: 0.05-0.15, Co: 0.00-0.05) in the lithium mixed metal oxide formula, and controlling the lithium excess parameter x (0.95-1.10) to optimize both discharge capacity and high-temperature cycling characteristics
Solution Approach 2:
The patent uses composite materials by creating a multi-element lithium mixed metal oxide system (Li-Ni-Mn-Fe-Co-O) where different metal elements work synergistically: Ni provides high capacity, Mn provides structural stability, Fe enhances rate capability, and Co improves overall performance, achieving both high discharge capacity and excellent cycling stability at elevated temperatures
2Quantity of substance
If the lithium content x is increased to improve discharge capacity, then the capacity increases, but the structural stability and cycling performance may deteriorate
Solution Approach 1:
The patent optimizes the lithium content parameter x within the range of 0.95-1.10, avoiding excessive lithium content that would cause structural instability while ensuring sufficient lithium for high capacity. This precise parameter control balances capacity and structural stability
3Quantity of substance
If the particle size is reduced to increase surface area and reactivity, then the discharge capacity improves, but the manufacturing precision and particle size control become more difficult
Solution Approach 1:
The patent controls particle size within the range of 0.01-1 μm through optimized synthesis parameters including calcination temperature (900-1100°C) and time (10-20 hours), achieving a balance between high surface area for capacity and manageable particle size for manufacturing
Data Source
AI summary
The present invention provides a lithium mixed metal oxide, an electrode and a nonaqueous electrolyte secondary battery. The lithium mixed metal oxide is represented by the following formula (A):Lix(Mn1−(y+z)NiyFez)O2 (A)wherein x is not less than 0.9 and not more than 1.3, y is more than 0.5 and not more than 0.7, and z is more than 0 and not more than 0.1.