Ag2SxSe1-x Cathode Material for Magnesium Battery
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Solution Overview
Problem
Current rechargeable magnesium batteries face limitations due to the need for a cathode material that is stable in electrolytes containing chloride ions, has high capacity, and provides long cycle life, as conventional materials like Mo6S8 have low energy density and are prone to side reactions with chloride ions.
Innovation Solution
A cathode material represented by the chemical formula Ag2SxSe1-x, where x is between 0 and 1, which forms a solid solution of silver sulfide and silver selenide, offering improved electrochemical stability and capacity, and is synthesized through ball milling and heat treatment to create a nanocomposite with carbon black for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cathode materials like Mo6S8 are used, then the battery can operate with current electrolytes, but the energy density is low (128 mAh/g) and cycle life is limited due to side reactions with chloride ions
Solution Approach 1:
The patent changes the chemical composition parameters of the cathode material by incorporating silver (Ag) and controlling the S/Se ratio (where x is between 0 and 1 in Ag2SxSe1-x). This compositional parameter change enables the material to achieve both high capacity (exceeding 500 mAh/g) and excellent cycle stability (retaining 80% capacity after 500 cycles) by optimizing the electronic structure and electrochemical properties of the cathode material.
Solution Approach 2:
The patent creates a composite cathode material Ag2SxSe1-x that combines properties of silver sulfide and silver selenide in a solid solution structure. This composite approach allows the material to simultaneously achieve high capacity, good electrical conductivity, and resistance to chloride ion corrosion, resolving the contradiction between capacity and cycle life by integrating multiple beneficial properties into a single material system.
2Quantity of substance
If high-capacity cathode materials are developed, then the battery capacity increases, but the material becomes more susceptible to side reactions with chloride ions in the electrolyte
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing silver and adjusting the sulfur/selenium ratio in the cathode material. This parameter optimization creates a material with high capacity that simultaneously exhibits resistance to chloride ion attack, as the specific compositional range (Ag2SxSe1-x where 0≤x≤1) provides both high electrochemical activity and chemical stability against electrolyte decomposition.
Solution Approach 2:
The patent converts the potential harm of chloride ion presence into a benefit by designing a cathode material that not only resists chloride ion corrosion but also utilizes the chloride-containing electrolyte environment to maintain structural integrity. The Ag2SxSe1-x material transforms the challenging electrolyte composition into a compatible operating environment that supports both high capacity and long cycle life.
3Quantity of substance
If conventional cathode materials are used, then the battery structure is simple, but the capacity density is significantly lower than Li-ion battery cathodes
Solution Approach 1:
The patent achieves high capacity density (exceeding 500 mAh/g, which is 4 times higher than conventional Mo6S8) by optimizing the compositional parameters of the cathode material. The specific formulation Ag2SxSe1-x with controlled x values allows the material to achieve Li-ion battery level performance while maintaining a relatively simple synthesis process and single-phase structure, thus improving capacity density without proportionally increasing complexity.
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 Ag2SxSe1-x cathode material exhibits higher capacity and longer cycle life compared to conventional materials, with minimal capacity fading after 500 charge/discharge cycles, making it suitable for high-capacity rechargeable magnesium batteries and hybrid batteries.
Implementation Method 1
a rechargeable magnesium battery which uses magnesium metal as a high-capacity capacity and high-safety anode material, while magnesium ions repeat reversible insertion and extraction into/from a cathode
Implementation Method 2
synthesized through ball milling and heat treatment to create a nanocomposite with carbon black for enhanced performance
Implementation Method 3
synthesized through ball milling and heat treatment to create a nanocomposite with carbon black for enhanced performance
Data Source
AI summary
Provided is a cathode material for a rechargeable magnesium battery, represented by the chemical formula of Ag2SxSe1-x (0≤x≤1), a highly stable cathode material and a rechargeable magnesium battery including the same. The cathode material for a rechargeable magnesium battery has a higher discharge capacity and higher discharge voltage as compared to a typical commercially available cathode material, Chevrel phase, and shows excellent stability in an electrolyte for a rechargeable magnesium battery including chloride ions. In addition, after evaluating the cycle life of the cathode material, the cathode material shows an excellent discharge capacity per unit weight after 500 charge/discharge cycles, and thus is useful for a cathode material for a rechargeable magnesium battery.