From solid state to lithium ion based ones, batteries have taken long strides over the decades. But the best is yet to come.
Once electricity is generated it has to be used instantaneously by an electricity consuming device, else it will be lost otherwise. Hence need for energy storage, is essential to balance supply and demand varying from time to time.
Energy storage systems can be classified into the following categories -
- Solid State Batteries - a range of electrochemical storage solutions, including advanced chemistry batteries and capacitors
- Flow Batteries - batteries where the energy is stored directly in the electrolyte solution for longer cycle life, and quick response times
- Flywheels - mechanical devices that harness rotational energy to deliver instantaneous electricity
- Compressed Air Energy Storage - utilising compressed air to create a potent energy reserve
- Thermal - capturing heat and cold to create energy on demand The most common among the above is the Solid State Battery.
Solid State batteries
There are two types of electrochemical energy storage systems: Chemical storage, here batteries store energy as chemical energy in their active materials and Capacitive storage, here electrochemical capacitors store energy as charge. Certain available electrochemical storage technologies fall short of projected day-to-day requirements, as for example, for electric vehicles, in terms of their energy and power densities, and even in terms of the time they take to get recharged. Electrochemical batteries include Secondary batteries such as Lead Acid, Nickel Cadmium, Nickel Metal Hydride, Lithium ion, Sodium Sulphur among others.
Hundreds of different types of batteries are announced, but most of them remain in the laboratory as very few technologies goes into production. Battery is mostly a chemical process and very few master the art of production.
Recent breakthroughs Recycled Vanadium
A US-based company has developed an exclusive process for producing high-performance flow batteries with recycled vanadium from mining slag, oil field sludge, fly ash and other forms of environmental waste. Other manufacturers of vanadium flow batteries build their devices with virgin vanadium extracted from mining. It must then be processed to a 99% plus level of purity.
A Canadian company has developed a creative energy storage solution that costs much less than most of the traditional battery technologies. It is also believed to last twice as long. They achieve their method by storing energy as compressed air that is housed underwater inside giant storage balloons. This idea is extremely efficient in energy storage and is also a zero-emissions solution. Located off the shore of Toronto Island, a grouping of their underwater balloons is submerged under the water. These balloons are then connected to a power facility through piping. The facility´s purpose is to store excess energy from the Canadian power grid when it is off-peak time. They convert excess electrical energy into compressed air which is then pumped into the submerged balloons. It then stays inside the underwater balloons until it is needed by Toronto consumers during peak energy hours. Once it is time to utilise this energy source, there is a conversion of the compressed air back into electricity. By utilising the natural pressure of the lake to expel the air out of the balloons, it is driven towards a designated turbine. The turbine is then used to generate electricity, which is then pushed back onto the electric grid. This set-up can also be utilised for storage of energy from alternative energy sources such as solar or even wind power.
This again will allow them to store excess energy during peak generation times.
Electric Gel In another case, researchers at The University of Texas have developed a self-healing gel that appears to be able to repair electronic circuits. Previously designed materials have always relied on light or heat to repair. This gel that can repair, as well as connect the circuits, has created a unique opportunity to advance the development of batteries as electricity storage devices. The innovative application as an energy storage unit is where it holds tremendous potential. Scientists were able to achieve about 10 times the conductivity of previous materials used for creating our conventional rechargeable batteries.
Latest Commercialised technology
The buzzword in energy storage today worldwide is lithium. Lithium ion batteries are made up of one or more generating compartments called cells. Each cell is composed of three components: a positive electrode, negative electrode, and a chemical called an electrolyte in between them. The positive electrode is made from chemical compound named lithium cobalt oxide (LiCoO2) or lithium iron phosphate (LiFePO4). The negative electrode is made up of carbon (graphite) and the electrolyte varies from one type of battery to another.
Battery safety is a matter of crucial importance to the lithium battery industry. When phosphate is used as cathode material in a lithium iron phosphate battery, we get very safe battery. Phosphates can withstand high temperatures, and hence they are extremely stable in overcharge or short circuit conditions. Phosphates are not prone to thermal runway and will not burn even though abuse occurs.
Therefore, lithium ion batteries made by phosphate as cathode are very safe as compared to other lithium ion batteries. Batteries made from LiFePo4 technology have good shelf life, long cycle life (~3000 cycles at 100% DoD or 12 years) and are maintenance-free. LiFePo4 batteries are environment friendly as compared to other lithium-based chemistries. LiFePo4 batteries can work in temperature range of -20C to 70C. LiFePo4 technology does not contain heavy metals and does not have the memory effect like nickel cadmium and nickel metal hydride batteries.
Given the above benefits, LiFePO4 has become the latest battery chemistry to be commercialised and is steadily gaining popularity worldwide and replacing traditional lead acid and other lithium-based chemistries. Although, relatively more expensive than lead acid and lithium ion, LiFePO4 batteries have a lower Levelized Cost of Storage (LCOS) when compared to the other chemistries.