Technology Marketing Summary
Rechargeable metallic sodium batteries have application in large-scale energy storage applications such as electric power generation and distribution, in motive applications such as electric vehicles, hybrids, and plug-in hybrids, and for aerospace applications such as powering satellites. So far, two sodium-based battery technologies have shown particular commercial promise: sodium-sulfur and sodium-nickel chloride, both referred to as sodium-beta batteries. Sodium-β battery technologies are potentially superior to the best lithium-ion (Li-ion) technologies, but cells must be operated at a temperature of 270-350 C to maintain active electrode materials in the molten state; and this has limited their attractiveness for commercial applications such as electric vehicles. The temperature requirement also impairs battery performance, since approximately 10% of the cell’s energy is spent in maintaining the battery at its operating temperature. LLNL research into next-generation energy storage systems and materials has led to the design of an improved sodium-beta battery that operates at ambient temperatures and can be manufactured from abundant, readily available materials.Description
Researchers at Lawrence Livermore National Laboratory have modeled a high-performance, rechargeable sodium-beta battery that is expected to provide twice the specific energy of the best Li-ion system without the high-temperature operating requirements of conventional sodium-beta systems. The improved battery design employs a low-melting Na alloy as the anode that cycles between Na-rich and Na-lean alloy compositions. The Na-based alloy anode has been designed so that the other alloying elements are electrochemically stable at potentials where Na is oxidized and reduced. Various low-melting alloy systems have also been identified for fabrication of the cathode. A battery of this design is anticipated to have a specific energy greater than 400 Wh/kg, and an expected life of 4500 charge-discharge cycles. Also, like conventional Na-beta cells, a battery of this improved design would not generate gaseous products in the event of an overcharge.
The most popular power source for all-electric vehicles (EVs), hybrids and plug-ins (HEVs/PHEVs) is presently the high-temperature sodium-nickel chloride (ZEBRA) system. Although robust, ZEBRA batteries are limited to a range of 120–180 miles, and the battery must be heated after four hours of inactivity. LLNL’s improved, low-temperature design for a Na-B battery overcomes those drawbacks. Additionally, ZEBRA batteries require a double-walled, Dewar-style battery case to reduce conductive heat loss. Because it operates at ambient temperature, the LLNL design does not demand this elaborate casework, and the result is significant savings in mass, weight, and cost of battery production.Benefits
Applications and Industries
- Designs can be made fully operational at ambient/room temperature and lower with no performance degradation
- Ambient temperature operation results in significant energy efficiencies compared to conventional sodium-beta batteries
- Expected life is 4,500 charge–discharge cycles, twice as long as the best Li-ion batteries
- No gaseous products are formed or released in the event of an overcharge
- The design can be readily modified or re-formed to meet specific application requirements; embodiments may be cylindrical or tubular, for example.
- Electrodes may be formed of various low-melting material combinations that best suit a targeted application.
Patents and Patent Applications
- Motive applications: powering EVs, HEVs, and PHEVs including automobiles, buses, delivery vans, transport trucks, and other vehicles.
- Marine applications: deep-sea rescue submersibles and exploration–research vehicles; stand-by power for long-distance submarines and a variety of sea-surface vessels.
- Stationary uninterruptible power supplies (UPSs) for server farms, load-leveling, peak-shaving, grid storage, drilling and oil production downhole equipment.
- Lighter and better-performing power supplies for satellites.
|Title and Abstract
Low temperature sodium-beta battery
A battery that will operate at ambient temperature or lower includes an enclosure, a current collector within the enclosure, an anode that will operate at ambient temperature or lower within the enclosure, a cathode that will operate at ambient temperature or lower within the enclosure, and a separator and electrolyte within the enclosure between the anode and the cathode. The anode is a sodium eutectic anode that will operate at ambient temperature or lower and is made of a material that is in a liquid state at ambient temperature or lower. The cathode is a low melting ion liquid cathode that will operate at ambient temperature or lower and is made of a material that is in a liquid state at ambient temperature or lower.
Lawrence Livermore National Laboratory
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