Sodium Nickel Composite Oxide for High Voltage Batteries
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Solution Overview
Problem
Non-aqueous electrolyte secondary batteries using NaNiO2 as a positive electrode active material suffer from low operating voltage, necessitating a more resource-abundant and cost-effective alternative.
Innovation Solution
A composite oxide with a hexagonal crystal structure, primarily composed of sodium, nickel, and a tetravalent metal, produced by firing a mixture of sodium, nickel, and tetravalent metal compounds in an inert atmosphere, is used as the positive electrode active material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LiCoO2 is used as the positive electrode active material, then the battery performance is good, but the cost is high and resource availability is low
Solution Approach 1:
The invention changes the chemical composition parameters by replacing LiCoO2 with NaNiO2, substituting expensive and scarce cobalt with abundant and cheaper sodium and nickel, while adjusting the crystal structure parameters to achieve the desired electrochemical performance
Solution Approach 2:
The invention uses inexpensive and abundant materials (sodium and nickel compounds) to replace expensive materials (lithium cobalt oxide), making the battery more cost-effective and resource-sustainable
2Quantity of substance
If NaNiO2 is used as the positive electrode active material, then the cost is reduced and resource availability is improved, but the operating voltage is low
Solution Approach 1:
The invention changes the crystal structure parameter from cubic to hexagonal, which fundamentally alters the electrochemical properties and increases the operating voltage from 2.0V to above 2.0V, while maintaining the cost advantages of sodium and nickel-based materials
Solution Approach 2:
The invention uses composite oxide materials with specific hexagonal crystal structures containing sodium, nickel and other elements, combining multiple materials to achieve both low cost and high operating voltage characteristics
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
This approach results in non-aqueous electrolyte secondary batteries with higher operating voltage and improved characteristics, offering a resource-abundant and cost-effective solution.
Implementation Method 1
positive electrode active material for non-aqueous electrolyte secondary batteries which is characterized by comprising a composite oxide mainly containing sodium, nickel and a tetravalent metal and having a hexagonal crystal structure
Implementation Method 2
the positive electrode active material can be obtained by firing a metal compound mixture containing a sodium compound, a nickel compound and a compound of a tetravalent metal in an inert atmosphere
Data Source
AI summary
Disclosed is a positive electrode active material for nonaqueous electrolyte secondary batteries which contains a complex oxide mainly containing sodium, nickel and a tetravalent metal while having a hexagonal structure. This positive electrode active material enables to obtain a nonaqueous electrolyte secondary battery with high operating voltage. The complex oxide is preferably expressed as Na[Na(1/3-2x/3)Ni(x-y)M(2/3-x/3-y)A2y]O2 (wherein M represents one or more tetravalent metals, A represents one or more trivalent metals, 0<x≦0.5, 0≦y<1/6, and x>y).