P2 Composite Metal Oxide for Sodium Battery Cathodes
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Solution Overview
Problem
Conventional Na-containing transition metal oxides used as positive electrode materials for sodium secondary batteries have limitations in delivering high initial charge and reversible charge-discharge capacities, making them unsuitable for practical applications.
Innovation Solution
A composite metal oxide with a specific composition represented by the formula NaxMeyO2, where Me is Fe, Mn, or Ni, and x satisfies 0.8<x≦1.0 and y satisfies 0.95≦y<1.05, with a P2 structure, is developed, along with a production method involving mixing Na and Me compounds, calcination, and reduction treatment to enhance Na content and maintain the P2 structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional Na-containing transition metal oxides are used as positive electrode materials, then the battery can be manufactured with existing materials, but the initial charge and reversible charge-discharge capacities are insufficient for practical applications
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition parameters (x and y values) of the Na-containing transition metal oxide to achieve optimal charge capacity. By setting x between 0.6 and 1.0 and y between 0.95 and 1.05, the invention optimizes the electrochemical performance parameters to resolve the contradiction between capacity and practical applicability
Solution Approach 2:
The patent uses composite materials by combining Na with transition metals (Fe, Mn, Ni) in specific ratios to create a composite oxide with enhanced properties. This composite approach allows the material to achieve both high charge capacity and reliable practical performance by leveraging the synergistic effects of different metal elements
2Quantity of substance
If the Na content is increased to improve charge capacity, then the initial charge capacity improves, but the crystal structure stability may be compromised
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing specific ranges for composition parameters (x: 0.6-1.0, y: 0.95-1.05) that simultaneously optimize Na content for high capacity and maintain crystal structure stability. This precise parameter control allows the material to achieve both goals without compromise
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 metal oxide exhibits higher initial charge and reversible charge-discharge capacities, surpassing conventional materials, and enables the production of sodium secondary batteries with improved capacity characteristics.
Implementation Method 1
In sodium secondary batteries, sodium ions are used as carrier ions
Implementation Method 2
the resulting battery can exhibit better capacity characteristics than those of conventional batteries, such as a high initial charge capacity in addition to a high reversible charge-discharge capacity
Implementation Method 3
calcination, and reduction treatment to enhance Na content and maintain the P2 structure
Data Source
AI summary
An object of the present invention or a problem to be solved by the present invention is to provide, as a material for use as a positive electrode of a sodium secondary battery, a novel material that allows the resulting battery to have capacity characteristics superior to those of conventional batteries. The composite metal oxide of the present invention has a composition represented by the general formula NaxMeyO2, where Me is at least one selected from the group consisting of Fe, Mn, and Ni, x satisfies 0.8<x≦1.0, and y satisfies 0.95≦y<1.05, and consists of a P2 structure. The sodium secondary battery of the present invention includes: a positive electrode (13) containing the composite metal oxide of the present invention; a negative electrode (16) containing a material capable of absorbing and desorbing Na ions; and an electrolyte containing Na ions and anions.