Sodium-Ion Cathode Composite Oxide for High Capacity and Voltage
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Solution Overview
Problem
Existing sodium ion secondary batteries do not meet the required energy density levels due to insufficient discharge capacity and average operating voltage, necessitating an improvement in positive electrode active materials.
Innovation Solution
A composite oxide positive electrode active material with a specific composition (Na a Ni b Mn c Ti d O e ) and crystalline structure (space group R-3m) is developed, featuring a peak intensity ratio of 003 reflection to 104 reflection greater than 1.00, facilitating smooth sodium ion insertion and high discharge capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional positive electrode active materials are used, then the battery can operate, but the discharge capacity and average operating voltage are insufficient to meet required energy density levels
Solution Approach 1:
The patent applies parameter changes by precisely controlling the compositional parameters (a, b, c, d, e) of the composite oxide Na a Ni b Mn c Ti d O e to optimize both discharge capacity and average operating voltage. The specific stoichiometric ratios and crystalline structure parameters are tuned to achieve high energy density while maintaining electrochemical performance.
Solution Approach 2:
The patent employs composite materials by creating a multi-element composite oxide containing Na, Ni, Mn, and Ti in specific ratios. This composite structure combines the advantages of each element: Na for ion conduction, Ni for high voltage, Mn for capacity, and Ti for structural stability, thereby simultaneously achieving high discharge capacity and average operating voltage.
2Use of energy by moving object
If lithium ion secondary batteries are used to achieve high energy density, then performance requirements are met, but stable supply becomes problematic due to lithium's rare metal status and uneven production distribution
Solution Approach 1:
The patent substitutes expensive and geographically constrained lithium with abundant and widely distributed sodium. While sodium-ion batteries may have different lifecycle characteristics, this substitution ensures reliable and stable material supply by eliminating dependence on lithium's uneven global production distribution and price volatility.
Solution Approach 2:
The patent changes the fundamental parameter of the battery system from lithium-ion to sodium-ion chemistry. This involves adjusting all related parameters including electrode compositions, electrolyte formulations, and operating conditions to accommodate sodium's different ionic radius and electrochemical properties, thereby achieving high energy density with a reliably supplied material.
3Quantity of substance
If the peak intensity ratio of 003 reflection to 104 reflection is increased to facilitate smooth sodium ion insertion, then discharge capacity improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent establishes specific parameter ranges for the compositional ratios (a, b, c, d, e) that directly control the crystalline structure and resulting XRD peak intensity ratio. By defining precise stoichiometric relationships, the patent makes it easier to achieve the required peak intensity ratio through conventional manufacturing processes, reducing the actual precision burden despite the theoretical sensitivity.
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 new positive electrode active material achieves a large discharge capacity and high average operating voltage in sodium ion secondary batteries, enhancing energy density.
Implementation Method 1
facilitating smooth sodium ion insertion and high discharge capacity
Data Source
Figure 1~2
AI summary
An object of the present invention is to provide a positive electrode active material for a sodium ion secondary battery which has a large discharge capacity and a high average operating voltage in the sodium ion secondary battery to be obtained. The positive electrode active material for a sodium ion secondary battery according to the present invention is a positive electrode active material for a sodium ion secondary battery, the material including a composite oxide represented by particular Formula (1), a crystalline structure of the composite oxide belongs to a space group R-3m, and in a diffraction chart obtained by performing X-ray diffraction measurement, a ratio of a peak strength of 003 reflection of the composite oxide to a peak strength of 104 reflection of the composite oxide is not less than 1.00.