Battery sodium-sulfur is a type of salt liquid battery made of liquid sodium (Na) and sulfur (S). This type of battery has a high energy density, high filling/discharging efficiency and long cycle life, and is made from inexpensive materials. The operating temperature is 300 to 350 Â ° C and highly corrosive properties of sodium polysulfides, especially making it suitable for stationary energy storage applications. Cells become more economical with increasing size.
Video Sodium-sulfur battery
Construction
Typical batteries have a dense electrolyte membrane between the anode and the cathode, compared to a liquid metal battery in which the anode, cathode and membrane are liquids.
A cell is usually made in a cylindrical configuration. The entire cell is covered by a protected steel casing, usually by chromium and molybdenum, from corrosion on the inside. This outer container serves as a positive electrode, while liquid sodium serves as a negative electrode. The container is sealed at the top with an airtight alumina cap. An important part of the cell is the presence of a BASE (beta-alumina solid electrolyte) membrane, which selectively performs Na . In commercial applications cells are arranged in blocks for better heat conservation and are encased in a vacuum-insulated box.
Maps Sodium-sulfur battery
Operation
During the release phase, the liquid element sodium at the core acts as anode, which means that Na donates electrons to an external circuit. Sodium is separated by a beta-alumina solid-electrolyte cylinder (BASE) from a liquid sulfur container, made of an inert metal that acts as a cathode. Sulfur is absorbed in carbon sponges. BASIC is a good sodium ion conductor, but a poor electron conductor, and thus avoids its own expenditure. When sodium releases the electrons, the Na ion migrates to the sulfur container. The electrons move the electric current through the liquid sodium to the contact, through the electrical load and back to the sulfur container. Here, other electrons react with sulfur to form S n 2 - , sodium polysulfide. The disposal process can be represented as follows:
- 2 Na 4 S -> Na 2 S 4 (E cell ~ 2 V)
When the cell is released, the sodium level drops. During the charging phase the reverse process proceeds. Upon walking, the heat generated by the charging and discharging cycle is sufficient to maintain the operating temperature and usually no external source is required.
Security
Pure sodium presents a danger, because it spontaneously burns contact with air and moisture, so the system must be protected from water and the oxidizing atmosphere.
Fire incident Factory of Tsukuba 2011
On September 21, 2011, NSK-made NaS batteries to store electricity installed in Tsukuba, Japan, burning plants. After the incident, NGK temporarily halts the production of NaS batteries.
Development
United States
Ford Motor Company pioneered batteries in the 1960s to power an early model electric car.
In 2009, lower temperatures, compact electrode versions were being developed in Utah by Ceramatec. They use the NASICON membrane to allow the operation at 90 ° C with all the remaining solid components.
In 2014 researchers identified a liquid sodium-cesium alloy that operates at 150 ° C, and produces 420 milliampere-hours per gram. The material is fully coated ("wetted") electrolyte. After 100 charge/discharge cycles, the test battery maintains approximately 97% of its initial storage capacity. Lower operating temperatures allow the use of polymer external casing that is cheaper than steel, offsetting some of the increased costs associated with cesium use.
Japanese
The NaS battery is one of four types of batteries selected as candidates for intensive research by MITI as part of the "Moon Light Project" in 1980. The project seeks to develop durable electrical storage devices that meet the criteria shown below in project 10 years.
- 1,000Ã, class kW
- 8 hours of charging/8 hours of discharge at rated load
- Efficiency 70% or better
- Lifetime 1,500 cycles or better
The other three are increased lead-acid, redox flow (vanadium type), and zinc-bromide battery.
A consortium formed by TEPCO (Tokyo Electric Power Co.) and NGK (NGK Insulators Ltd.) expressed their interest in researching NaS batteries in 1983, and has been a key driver behind this type of development ever since. TEPCO selects NaS batteries because all its component elements (sodium, sulfur, and ceramic) are abundant in Japan. The first large-scale trial was conducted at TEPCO's Tsunashima substation between 1993 and 1996, using a 3 x 2 MW, 6.6 kV battery bank. Based on the findings of this trial, an improved battery module was developed and made commercially available in 2000. The commercial NaS battery bank offers:
- Capacity: 25-250 kW per bank
- Efficiency 87%
- Lifetime 2,500 cycles at 100% discharge (DOD), or 4,500 cycles at 80% DOD
A demonstration project using NaS batteries at Miura Wind Park Japan Wind Development Co. In Japan.
Japan Wind Development opened a 51 MW wind farm that incorporates a 34 MW sodium sulfur battery system at Futamata in Aomori Prefecture in May 2008.
In 2007, 165 MW capacity was installed in Japan. NGK announced in 2008 plans to expand its NaS plant output from 90 MW per year to 150 MW per year.
In 2010 Xcel Energy announced that it will test a wind farm energy storage battery based on twenty 50 kW sodium-sulfur batteries. Battery weighing 80 tons, 2 semi-trailers is expected to have a capacity of 7.2 MW per hour with the cost and discharge of 1 MW.
In March 2011, Sumitomo Electric Industries and Kyoto University announced that they have developed low temperature liquid sodium ion batteries that can generate power below 100 Â ° C. The battery has twice the Li-ion energy density and costs much lower. Sumitomo Electric Industry CEO Masayoshi Matsumoto indicated that the company plans to start production by 2015. Initial applications are considered to be buildings and buses.
Challenges
The corrosion of the insulators was found to be a problem in harsh chemical environments as they gradually became conductive and increased self-discharge rates. Dendritic-sodium growth can also be a problem.
Apps
Grid and standalone systems
NaS batteries can be used to support the power grid, or for stand-alone renewable power applications. In 2010, Presidio, Texas built the world's largest sodium-sulfur battery, which can deliver 4 MW of power up to eight hours when a single line of cities into the Texas power grid goes down. Under some market conditions, NaS batteries deliver value through arbitrage energy (charging when electricity is overflow/cheap, and discharging to the network when electricity is more valuable) and voltage regulation. NaS Batteries are a possible energy storage technology to support renewable energy generation, particularly wind and solar power plants. In the case of wind farms, the battery will store energy during high winds but low power demand. This stored energy can then be removed from the battery during peak load periods. In addition to this shifting power, sodium sulfur batteries can be used to help stabilize the power output of the wind farm during wind fluctuations. This battery type provides an option for energy storage in locations where other storage options are not feasible. For example, pumped hydroelectric facilities require significant space and water resources, while compressed air energy storage (CAES) requires several types of geological features such as salt caves.
Space
Due to its high energy density, NaS batteries have been proposed for aerospace applications. The sodium sulfur cells can be made to qualify space: the actual sodium sulfur cell test flies in the Space Shuttle. The NaS flight experiment shows a battery with a specific energy of 150 W Â · h/kg (3 x density of nickel-hydrogen battery energy), operating at 350 Â ° C. Launched on the STS-87 mission in November 1997, and showed 10 days of experimental surgery.
Transportation and heavy equipment
The first large-scale use of sodium-sulfur batteries was at the Ford "Ecostar" demonstration vehicle, a prototype electric vehicle in 1991. The high operating temperatures of sodium sulfur batteries provide difficulties for the use of electric vehicles. Ecostar never goes into production.
See also
- List of battery types
- Lithium-sulfur batteries
- Battery salt liquid
References
External links
- US Utility Application at American Electric Power
- Sodium-sulfur batteries smooth the wind power variables
- Advanced Energy Storage for Renewable Energy Technology
Source of the article : Wikipedia
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