Doped Sodium Vanadium Phosphate for Faster Sodium-Ion Cathode Kinetics
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Solution Overview
Problem
Current sodium ion batteries face limitations due to the low weight capacity density, volume energy density, and poor rate performance of polyanion compounds used as positive materials, which restrict their development and application.
Innovation Solution
A doped sodium vanadium phosphate is developed, incorporating a nitrogen-doped peony-shaped molybdenum oxide to enhance sodium ion binding sites, structural stability, and reduce diffusion paths, achieved through a specific preparation method involving ball-milling and calcination processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyanion compounds are used as positive materials for sodium ion batteries, then cycle stability is improved, but weight capacity density and volume energy density deteriorate
Solution Approach 1:
The patent uses composite materials by combining sodium vanadium phosphate with nitrogen-doped peony-shaped molybdenum oxide. This composite structure allows the material to maintain the cycle stability of polyanion compounds while improving weight capacity density and volume energy density through the synergistic effects of the two materials.
Solution Approach 2:
The patent applies local quality by doping nitrogen into specific sites of the molybdenum oxide structure and creating peony-shaped morphologies with specific surface area characteristics. This localized modification optimizes sodium ion binding sites and diffusion paths without compromising the overall structural stability needed for cycle performance.
2Reliability
If polyanion compounds are used as positive materials for sodium ion batteries, then cycle stability is improved, but rate performance deteriorates
Solution Approach 1:
The nitrogen-doped peony-shaped molybdenum oxide component creates a porous-like structure with increased surface area and shortened diffusion paths. This allows faster sodium ion transport kinetics for improved rate performance while the overall composite structure maintains structural integrity for cycle stability.
Solution Approach 2:
The patent transforms the traditional bulk material structure into a hierarchical structure with specific morphologies (peony-shaped) and doped sites, creating multiple dimensional pathways for sodium ion transport. This dimensional optimization enables faster kinetics without sacrificing structural stability.
3Quantity of substance
If sodium vanadium phosphate is doped with nitrogen-doped peony-shaped molybdenum oxide, then sodium storage sites are increased, but manufacturing complexity increases
Solution Approach 1:
The patent uses preliminary action by pre-synthesizing the nitrogen-doped peony-shaped molybdenum oxide before combining it with sodium vanadium phosphate. This pre-prepared dopant material can be easily incorporated into the final composite through simple mixing and calcination, reducing the overall manufacturing complexity despite the enhanced functionality.
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 doped sodium vanadium phosphate exhibits improved reversible capacity, cyclic stability, and deintercalation rates, leading to enhanced electrochemical performance and increased sodium storage sites, thereby addressing the limitations of existing polyanion compounds.
Implementation Method 1
adding a regulator into a molybdenum-containing solution for reaction
Implementation Method 2
dissolving the peony-shaped molybdenum oxide in a conditioning agent
Implementation Method 3
adding an amine source for standing, centrifuging, washing and heat treatment, thus obtaining the nitrogen-doped peony-shaped molybdenum oxide
Implementation Method 4
mixing a vanadium source, a sodium source, a phosphorus source and the nitrogen-doped peony-shaped molybdenum oxide for ball-milling
Implementation Method 5
calcining the precursor to obtain the doped sodium vanadium phosphate
Data Source
AI summary
A doped sodium vanadium phosphate and a preparation method and application thereof. Preparation steps of a nitrogen-doped peony-shaped molybdenum oxide in raw materials of the doped sodium vanadium phosphate are as follows: adding a regulator into a molybdenum-containing solution for reaction, concentrating and thermal treatment to obtain a peony-shaped molybdenum oxide; and dissolving the peony-shaped molybdenum oxide in a conditioning agent, and adding an amine source for standing, centrifuging, washing and heat treatment, thus obtaining the nitrogen-doped peony-shaped molybdenum oxide.