Orthorhombic Sodium Complex Oxide for High Capacity Batteries
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Solution Overview
Problem
Sodium-ion batteries face limitations due to lower capacity compared to lithium-ion batteries, necessitating the development of improved sodium-ion positive electrode active materials.
Innovation Solution
A sodium complex oxide with an orthorhombic crystal structure, specifically Na4(M1aM21−a)2O5, where M1 and M2 are independently Ti, Cr, Fe, Co, Ni, Mn, or V, is used as a positive electrode active material, offering enhanced electrochemical properties and capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional positive electrode materials are used in sodium-ion batteries, then the battery structure is simple and easy to manufacture, but the capacity is significantly lower than lithium-ion batteries
Solution Approach 1:
The patent employs composite materials by combining multiple transition metal elements (M1 and M2 from groups including Ti, Cr, Fe, Co, Ni, Mn, V) within the sodium complex oxide structure Na4(M1aM21−a)2O5. This composite approach enables the positive electrode material to achieve high capacity (>360 mAh/g) while maintaining structural stability and electrochemical performance, directly resolving the capacity limitation of conventional sodium-ion battery materials
2Quantity of substance
If high capacity positive electrode materials are developed for sodium-ion batteries, then the battery capacity improves, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes parameter changes by systematically varying the composition ratio parameter 'a' in the formula Na4(M1aM21−a)2O5, where 0 ≤ a ≤ 1. This allows optimization of electrochemical properties including capacity, voltage range (2.6-3.3V), and structural stability. The heat treatment process parameters (temperature, atmosphere, duration) are also optimized to achieve the desired orthorhombic crystal structure, balancing high capacity with manufacturability
3Power
If conventional electrode materials are used, then the manufacturing process is simple, but the voltage range and electrochemical performance are limited
Solution Approach 1:
The patent applies local quality by creating distinct functional regions within the crystal structure through the orthorhombic arrangement of sodium complex oxide. The structure features specific local coordination environments for sodium ions and transition metals that facilitate efficient ion transport and electron transfer, enabling the material to deliver voltage range of 2.6-3.3V and capacity >360 mAh/g while maintaining overall structural integrity
Data Source
AI summary
A positive electrode active material for a sodium ion battery includes a sodium complex oxide of the formula Na4(M1aM21−a)2O5 having an orthorhombic crystal structure, wherein M1 and M2 are each independently Ti, Cr, Fe, Co, Ni, Mn, V, or a combination there of provided that M1 and M2 are different from each other; and 0≤a≤1.