Vanadium Oxide Cathode Particles With Controlled Crystal Length
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Solution Overview
Problem
Magnesium and lithium ion secondary batteries using vanadium oxide as a positive electrode active material face issues with battery capacity and cycle retention due to excessive growth of vanadium oxide crystals, leading to increased ion migration resistance and reduced rate characteristics.
Innovation Solution
A method to produce vanadium oxide crystals with a maximum length of 5 μm or less by precipitating them from a nucleation material in an acidic solution, using nucleation materials like titanium compounds, iron compounds, or graphite, and firing at specific temperatures to enhance yield and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If vanadium oxide is precipitated at high temperature (60°C or higher), then gelatinization is suppressed and crystal formation is improved, but rod-like crystals grow excessively leading to increased ion migration resistance
Solution Approach 1:
The patent changes the precipitation temperature parameter to a specific range (50-70°C) to optimize crystal morphology. By controlling the temperature within this range, the patent achieves a balance between preventing gelatinization and suppressing excessive crystal growth, thereby resolving the contradiction between crystal structure stability and crystal size control.
2Reliability
If vanadium oxide crystals grow excessively, then battery capacity decreases and cycle retention worsens, but controlling crystal growth reduces yield
Solution Approach 1:
The patent optimizes multiple parameters including precipitation temperature (50-70°C), pH value (2-4), and precipitation time (1-10 hours) to control crystal growth. By carefully adjusting these parameters, the patent achieves high yield (over 90%) while maintaining crystals with maximum length of 5 μm or less, thus improving both cycle retention and production yield simultaneously.
Solution Approach 2:
The patent employs a controlled precipitation process where the formation of nuclei is promoted first, then crystal growth is regulated through controlled addition of vanadium compound solution. This feedback-controlled approach ensures that crystals grow to the desired size range while maximizing yield, resolving the contradiction between reliability and productivity.
3Speed
If rod-like crystals are formed, then rate characteristics deteriorate, but preventing crystal growth reduces material efficiency
Solution Approach 1:
The patent changes the precipitation conditions to produce short, thick crystals rather than long rod-like crystals. By controlling temperature (50-70°C), pH (2-4), and precipitation time (1-10 hours), the patent achieves crystals with maximum length of 5 μm or less, which significantly improves ion insertion speed while maintaining high material utilization efficiency through high yield production.
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 approach results in high-yield vanadium oxide particles with improved battery capacity, cycle retention, and rate characteristics for both magnesium and lithium ion secondary batteries by controlling crystal growth and facilitating easier ion insertion and desorption.
Implementation Method 1
precipitating them from a nucleation material in an acidic solution
Implementation Method 2
precipitating a crystal of vanadium oxide
Implementation Method 3
firing at specific temperatures to enhance yield and performance
Data Source
AI summary
The invention discloses a positive electrode active material for a magnesium secondary battery or lithium ion secondary battery, including: a particle including a nucleus and a crystal of vanadium oxide grown from the nucleus as a starting point and having a maximum length of 5 μm or less in the major axis direction.