What Is Aluminum Sulfide?
Aluminum sulfide is a compound of aluminum and sulfur with the chemical formula Al2S3.
Its molar mass is 150.2 g/mol. Its crystal structure is known to have multiple types of crystal structures, but it mainly has a hexagonal close-packed structure, with sulfur atoms located in the center.
It is generally a gray powdery solid. It has a density of 2.32 g/cm2 and sinks in water, but it is so reactive with water that it decomposes and does not precipitate as aluminum sulfide when left to stand.
The CAS number, which is a unique chemical number, is 1302-81-4.
Uses of Aluminum Sulfide
1. Supercapacitors
Aluminum sulfide is used to produce nano-network structures for the high capacitance and energy density of supercapacitors. Supercapacitors are a type of secondary battery, such as lithium-ion batteries and alkaline batteries, which are devices capable of storing large amounts of energy.
By using aluminum sulfide for the battery electrodes to create nano-network structures, specific surface area and conductivity can be improved to achieve high capacitance and energy density.
2. Battery Active Material
Aluminum sulfide is used as an active material in high-energy-density lithium secondary batteries. Aluminum Sulfide has an initial discharge capacity of approximately 1,170 mAh/g, which is equivalent to 62% of the theoretical capacity of sulfur.
The use of aluminum sulfide as a positive electrode material for rechargeable batteries is expected to improve cycle life and safety while maintaining high electric capacity.
3. Thermal Discharge Type Explosive
Aluminum sulfide is also used as a key component of thermal discharge explosives. Aluminum sulfide can also be used in the manufacture of smoke screens and light-emitting projectiles, since combustion produces aluminum oxide and hydrogen sulfide.
4. Aluminum Smelting and Refining
Aluminum sulfide is produced by adding sulfur to aluminum and heating it. Aluminum can be refined by reacting it with aluminum hydroxide.
Aluminum sulfide is also used as a raw material for medical applications, ceramics, chemical products, and as a water treatment agent. However, it is very sensitive to water and must be handled with care.
Properties of Aluminum Sulfide
Aluminum sulfide has the highest melting point of all sulfides, melting at temperatures above 1,050℃. For this reason, it is often used in reactions at high temperatures and can be used in aluminum smelting and as a raw material for ceramics and glass.
It also sublimates when the temperature is raised to 1,500°C. Aluminum sulfide is virtually insoluble in water. However, under acidic conditions, it undergoes hydrolysis and decomposes into aluminum hydroxide and hydrogen sulfide, which reacts with strong acids.
Its hardness is relatively high, and it is used in applications such as abrasives and friction materials. On the other hand, because of its tendency to decompose at elevated temperatures, this compound is used with carbon and silicon as a reducing agent in steelmaking and other industrial applications.
Other Information on Aluminum Sulfide
1. Safety of Aluminum Sulfide
Hydrogen sulfide has a strong rotten egg odor, is toxic to living organisms, and is flammable and combustible. It is also a skin irritant, a strong eye irritant, and a respiratory tract irritant.
Appropriate protective equipment should be worn when handling. In the unlikely event of contact with skin or eyes, or inhalation of the powder, it is recommended to rinse with large amounts of water and seek medical attention immediately.
2. The Aluminum Sulfide Market
The global market for aluminum sulfide continues to grow due to the increasing demand for water treatment and other applications. The global aluminum sulfide market size is projected to increase by US$1.67 billion during the period 2022-2026, growing at a CAGR of 3.8% during the forecast period.