Composite Cathode Material for Low-Temperature Sodium-Ion Batteries
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Solution Overview
Problem
Sodium-ion batteries exhibit poor low-temperature resistance, deteriorating significantly below 0°C, hindering their practical application in extreme weather conditions and regions with varying temperatures.
Innovation Solution
A positive electrode active material comprising polyanionic material and Na4Fe3(PO4)2P2O7, combined with an ethers electrolytic solution and natural graphite negative electrode, enhances sodium-ion battery performance at low temperatures by improving diffusion coefficient, energy density, and cycle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional positive electrode materials are used in sodium-ion batteries, then the battery structure is simple and manufacturing is easy, but the low-temperature electrochemical performance deteriorates significantly below 0°C
Solution Approach 1:
The patent employs a composite positive electrode material consisting of polyanionic material (such as NaFePO4 or Na3Fe2(PO4)3) combined with Na4Fe3(PO4)2P2O7. This composite structure leverages the advantages of both materials: the polyanionic material provides structural stability and good low-temperature performance, while Na4Fe3(PO4)2P2O7 contributes high capacity. The synergistic combination resolves the technical contradiction by achieving excellent low-temperature electrochemical performance without overly complicating the material system.
Solution Approach 2:
The patent optimizes the mass ratio of Na4Fe3(PO4)2P2O7 in the composite material to be 40%-60% of the total positive electrode active material mass. This parameter optimization balances the low-temperature performance enhancement with the structural simplicity and manufacturing ease, resolving the contradiction between performance improvement and device complexity.
2Adaptability or versatility
If the operating temperature is decreased to below 0°C, then the battery can operate in extreme weather conditions, but the electrochemical performance (capacity, efficiency, and energy/power density) deteriorates significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the positive electrode material by introducing the specific composite of polyanionic material and Na4Fe3(PO4)2P2O7 with optimized ratios. This composition modification enables the battery to maintain high electrochemical performance across a wide temperature range from -40°C to 60°C, resolving the contradiction between expanded operating temperature range and maintained productivity.
Solution Approach 2:
The composite material structure creates different functional regions at the molecular level: the polyanionic material domains provide low-temperature stability while the Na4Fe3(PO4)2P2O7 domains provide high capacity. This local differentiation of material properties within the composite enables the battery to simultaneously achieve wide temperature adaptability and high electrochemical performance.
3Reliability
If the positive electrode active material is optimized for low-temperature performance, then the diffusion coefficient and cycle stability improve, but the manufacturing process becomes more complex
Solution Approach 1:
The patent uses a composite material system where polyanionic material and Na4Fe3(PO4)2P2O7 can be prepared separately using conventional solid-state reaction methods, then mixed and pressed into electrodes. This approach maintains ease of manufacture by using standard battery production techniques while achieving superior cycle stability through the synergistic composite structure.
Solution Approach 2:
The patent segments the positive electrode active material into two distinct components that can be independently synthesized and characterized, then combined in a controlled ratio (40%-60% Na4Fe3(PO4)2P2O7). This segmentation allows each component to be optimized separately using established manufacturing processes, simplifying the overall production while achieving enhanced cycle stability.
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 sodium-ion battery demonstrates excellent low-temperature resistance, maintaining electrochemical performance down to −40°C with improved cycle stability and reduced production costs, suitable for a wide range of service temperatures.
Implementation Method 1
improving diffusion coefficient
Implementation Method 2
electrochemical performance (including capacity, efficiency and energy/power density)
Implementation Method 3
the electrolytic solution includes an ethers electrolytic solution
Data Source
AI summary
The present disclosure provides a positive electrode active material, a sodium-ion battery and a preparation method therefor and an electrical device, relating to the technical field of secondary batteries. The positive electrode active material includes a polyanionic material and Na4Fe3(PO4)2P2O7, a mass of the Na4Fe3(PO4)2P2O7 being 40% to 60% of a mass of the positive electrode active material. In the present disclosure, the polyanionic material and Na4Fe3(PO4)2P2O7 are compounded as the positive electrode active material. The two materials cooperate with each other, so that the positive electrode active material has a high diffusion coefficient of Na+, a high energy density and excellent cycle stability at a low temperature, which is beneficial to improving the low-temperature service performance of the sodium-ion battery.