UltraBattery is a trademark of the lead-acid battery technology commercialized by Furukawa Battery Co. Ltd. UltraBattery has thin carbon layers on spongy lead active material for negative plates. The original idea that combines ultracapacitor technology with lead–acid battery technology in a single cell with a common electrolyte came from Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO).
Introduction
Research conducted by independent laboratories, such as the United States's Sandia National Laboratories, the Advanced Lead-Acid Battery Consortium (ALABC), the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and commercial tests by East Penn Manufacturing, Furukawa Battery and Ecoult indicate that in comparison with conventional valve regulated lead acid (VRLA) batteries, UltraBattery technology has higher energy efficiencies, a longer lifetime and superior charge acceptance under partial state of charge (SoC) conditions.
Combining the two technologies in one battery cell means that UltraBattery works very efficiently compared with conventional lead acid technologies largely due to the fact that it can be operated for long periods in a partial state of charge (pSoC), whereas conventional lead acid batteries are more typically designed for high SoC use (i.e. when the battery is close to fully charged). Operating in the partial SoC range extends the battery's life chiefly by reducing sulfation and by reducing time spent operating at very high and very low states of charge, where various side reactions tend to cause deterioration. A conventional VRLA battery tends to deteriorate quickly when operated in this partial SoC range.
History The original idea of UltraBattery came from CSIRO.
The development of UltraBattery was funded by the Australian government. Japanese company Furukawa Battery Co., Ltd also contributed to the development of UltraBattery technology, and the Japanese government funded part of its development through the New Energy and Industrial Technology Development Organization (NEDO).
In 2007, East Penn Manufacturing obtained a global head license to manufacture and commercialize UltraBattery technology for motive and automotive applications (in various territories) and for stationary energy storage applications (globally, outside Japan and Thailand, where Furukawa Battery is the head license holder).
The United States Department of Energy has also funded UltraBattery for research into grid-scale stationary energy storage applications. In 2007, CSIRO formed a subsidiary company, Ecoult, to address this market. Ecoult also received support from the Australian Government to further the development of Ultrabattery. In May 2010, US battery manufacturer East Penn Manufacturing acquired Ecoult from CSIRO.
In March 2013, the Australian Government announced further funding through the Australian Renewable Energy Agency's Emerging Renewables Program to further develop UltraBattery technology as cost-effective energy storage for residential and commercial renewable energy systems.
Storage principle Energy storage principle of UltraBattery is same as conventional lead-acid battery. The carbon layers on the negative electrode act as reaction sites for reduction of Pb2+ ions to Pb(0) and storage sites of Pb2+ ions.
Hard sulfation
During normal lead–acid battery operation, lead sulfate crystals grow on the negative electrode during discharging and dissolve again during charging. The formation of these crystals is called sulfation. Over time sulfation can become permanent, as some crystals grow and resist being dissolved. This is particularly the case when the battery is forced to perform at very high rates of discharge, which tends to promote lead sulfate crystal growth on the surface of the electrode. At moderate rates of discharge, the lead sulfate crystals grow throughout the cross section of the electrode plate (which has a sponge-like consistency) since the electrolyte (dilute sulfuric acid) is drawn diffused through the body of the electrode to allow the reaction can take place throughout the plate.
But at very fast rates of discharge, the acid already inside the body of the plate is used up quickly and fresh acid cannot diffuse through the electrode in time to continue the reaction. Hence the reaction is favored toward the outer wall of the electrode, where crystals may form in a dense mat, rather than in dispersed clumps throughout the plate. This mat of crystals further impedes electrolyte transfer. The crystals then grow larger, and because the larger crystals have a large volume compared to their surface area it becomes difficult to remove them chemically during charging, particularly as the concentration of the sulfuric acid in the electrolyte is likely to be high (since only limited lead sulfate has been created on the surface of the plate) and lead sulfate is less soluble in concentrated sulfuric acid (above about 10% concentration by weight) than it is in dilute sulfuric acid.
This condition is sometimes termed the “hard” sulfation of the battery electrode. Hard sulfation increases the battery's impedance (since the lead sulfate crystals tend to insulate the electrode from the electrolyte) and decreases its power, capacity and efficiency due to increased undesirable side reactions, some of which occur inside the negative plate due to charging taking place with low availability of lead sulfate (inside the plate body). One undesirable effect is the production of hydrogen inside the plate, further reducing the efficiency of the reaction. “Hard” sulfation is generally irreversible since the side reactions tend to dominate as more and more energy is pushed into the battery.
To reduce the likelihood of hard sulfation, conventional VRLA batteries should therefore be discharged at specific rates, determined by various charging algorithms. Furthermore, they must be frequently refreshed and are most suited to operation toward the top end of the SoC (between 80% and 100% charged). While operating in this limited state of charge mitigates permanent sulfation on the negative electrode, battery operation exclusively at or near a full SoC is highly inefficient. The inefficiency is largely due to increases the incidence of side reactions (for instance electrolysis) which dissipate energy.
The presence of the ultracapacitor integrated in the UltraBattery acts to limit the formation of hard sulfation inside the cell. This supports the battery's ability to operate for long periods in a partial SoC where the battery operates more efficiently. Conventional VRLAs are somewhat constrained to operate in the inefficient region toward the top of their charge capacity in order to protect them against damage by sulfation. Research continues into the reasons why the presence of the ultracapacitor reduces sulfation so successfully. Experimental results show that the presence of carbon within VRLA cells has some mitigating effect but the protective effects of the parallel-connected ultracapacitor within the UltraBattery are much more significant. Hund et al., for instance, found that typical VRLA battery failure modes (water loss, negative plate sulfation, and grid corrosion) are all minimized in the UltraBattery. Hund's results also showed that the UltraBattery, used in a high rate partial state of charge application, exhibits reduced gassing, minimized negative plate hard sulfation, enhanced power performance and minimized operating temperature compared with conventional VRLA cells.
Materials used
Sponge lead and carbon layers form the negative electrode.
The electrolyte solution is made up of sulfuric acid and water.
Lead Sulfate is a white crystal or powder. Normal lead acid battery operation sees small lead sulfate crystals growing on the negative electrode during discharging and dissolving back into the electrolyte during charging.
The electrodes are constructed of a lead grid, with a lead-based active material compound – lead oxide – forming the remainder of the positive plate.
Applications
UltraBattery can be used for a range of energy storage applications, such as: In electric vehicle (EVs) batteries To store renewable energy and smooth electricity supply from intermittent energy sources As part of efficient hybrid power systems with fossil-fuel electric generators To provide ancillary services to electrical grids.
UltraBattery is virtually 100 percent recyclable and can be made at existing battery manufacturing facilities.
UltraBattery in hybrid electric vehicles
When used in hybrid electric vehicles, the UltraBattery's ultracapacitor acts as a buffer during high-rate discharging and charging, enabling it to provide and absorb charge rapidly during vehicle acceleration and braking.
Testing of the Ultrabattery's performance in hybrid electric vehicles by Advanced Lead Acid Battery Consortium achieved more than 100,000 miles on a single battery pack without significant degradation. Laboratory results of UltraBattery prototypes show that their capacity, power, available energy, cold cranking and self-discharge meets, or exceeds, all performance targets set for minimum and maximum power-assist hybrid electric vehicles.
UltraBattery in Microgrids
UltraBattery can be used to smooth and shift (i.e. store for later use) renewable energy sources on microgrids to improve predictable power availability. UltraBattery can also be used in standalone microgrid systems, renewables power systems and hybrid microgrids. Standalone microgrid systems combine diesel or other fossil fuels with UltraBattery storage to improve the efficiency of fossil-fuel energy generation. Including energy storage in the system reduces the size of the gen-set (i.e. array of generators) because the batteries can handle peaks in the load. UltraBattery also reduces the fuel consumption of the gen-set, b
Renewables power systems combine UltraBattery technology with the renewable generation source to deliver local power. Hybrid microgrids integrate renewable generation sources with UltraBattery energy storage and fossil-fuel gen-sets to maximize the efficiency of base-load generation. This can greatly reduce the cost of energy compared with diesel-only powered microgrids. They also substantially decrease greenhouse gas emissions. An example of this type of microgrid is the King Island Renewable Energy Integration Project (KIREIP), being undertaken by Hydro Tasmania. This megawatt-scale renewable energy project aims to reduce both the cost of delivering power to the island and carbon pollution.
Multi Purposing of Data Centers
UltraBattery can be used to backup an uninterruptible power supply (UPS). In conventional UPS systems, the batteries sit, essentially unused, until a grid outage event occurs. Because the UltraBattery can provide frequency regulation and related grid services, it can generate revenue for the UPS asset owner at the same time as providing backup power.
Community, Commercial and Applications
For community applications, UltraBattery can be used as back-up in the event of grid outage (see Section 5.1) and for peak shaving. Also known as peak lopping, peak shaving is the ability to charge batteries during off-peak time, and use the power from the batteries during peak times to avoid higher charges for electricity. Another example of a community application is a 300 kW smart grid demonstration system set up by Furukawa Battery in the Maeda Area in Kitakyushu, Japan. This load-levelling application uses 336 UltraBattery cells (1000 Ah, 2 volts). The company has also installed two smart grid demonstrations of UltraBattery peak shifting technology at Kitakyushu Museum of Natural History & Human History.