By Subra Iyer
February 20, 2009
Commercially introduced in the early 1990s, lithium-ion batteries exhibited an annual market penetration rate of 25%, replacing less energy dense nickel metal hydride batteries. A typical commercial Li-ion battery has a specific energy of about 200Wh/kg, while some more advanced systems reached a specific energy exceeding 275 Wh/kg. Rechargeable lithium-ion batteries are the power source of choice in present-day electronic devices, such as laptop computers, cell phones, smart phones, cameras, and many more. Additionally, they are becoming a viable option for hybrid electric vehicles (HEVs) and plug-in electric hybrid vehicles (PHEVs).
Rechargeable battery technology has long been a critical bottleneck in development of improved portable electronic products for the communications and information sectors. In essence, the battery does not contain enough energy to enable increasingly advanced features or offer consumers longer device lifetime before recharge. The energy density requirements for near-term applications are 3-5 times more than presently achievable by the lithium ion battery pack, thereby limiting the user experience of consumers at large.
Capacity limitations relate to technological barriers for higher lithium intercalation in the anode, typically composed of graphite, and the cathode, typically composed of lithium cobalt oxide. Rate of recharge is also an issue. At rates that allow recharge of the cell in less than one hour, metallic lithium can be plated on the carbon, creating a safety hazard. Novel electrodes and chemistries are required which allow both rapid charge-discharge cycles as well as higher energy densities for extended run time.
Extensive resources around the world are being dedicated to finding new anode and cathode materials to address power and capacity concerns. With respect to power issues, Altair Nanotechnology is exploring lithium titinates as new anodes with high recharge kinetics. A123 Inc. is developing rapid discharge batteries using nanostructured cathodes. While these new chemistries have improved power characteristics, they exhibit relatively low energy storage capacity. Sony Corporation has developed (and recently marketed under the name Nexelium) Sn-Co amorphous alloy anodes. MIT’s Cedar group is reported to be working on amorphous Al-based anodes. 3M Corporation is developing amorphous Si-based anodes.
In comparison, QuantumSphere, Inc. (www.qsinano.com) is investigating lithiated anodes and amorphous alloys with capacities of 700 mAh/g or higher, with fast charge-discharge rates, and would be a substantial improvement over present secondary lithium battery systems for energy storage applications. The approach consists of using nano-scale alloys and amorphous alloys of lithium, capable of high diffusion rates of lithium from and into the alloy matrix, without volumetric expansion or cycling issues, as well as high capacities of lithium absorption and desorption.
There is significant interest in the private sector for high-power sources for portable electronics, especially for laptop computers, cellular phones, personal digital assistants, video cameras, and other electronic equipment with significant power requirements, needing high energy density batteries. In addition, the needs of advanced energy storage technology for renewable energy (like wind power and photovoltaics) and in the automotive sector is increasing rapidly. It is estimated by the National Renewable Energy Laboratory that the solar energy industry itself is currently growing at an annual 25%, with current sales of $4B in solar cell (PV) installations; and improvements are needed in energy storage technology, since grid connection is not always feasible. Recent interest in the automotive sector for hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEV) is a new sector within the energy sector and clearly a sector with enormous market potential.
Product or Technology and Competition
Vertically integrated foreign manufacturers dominate present rechargeable battery technology, production, and supply. Sanyo is the leading manufacturer of the lithium-ion battery, followed by Sony. Close on their heels are Chinese manufacturers, who have the advantage of both lower raw material costs and cheaper labor over the Japanese and Koreans. The successful completion of the project will re-establish U.S. leadership in portable power sources in electronic devices and serve the needs of the nation for mobile power. New high energy-density, high power-density battery chemistries will support Internet-enabled telephony and WiFi-enabled portable computing and its future convergence in broadband communications in the US. The initial target application for QuantumSphere’s products is expected to be niche markets, especially 3G enabled cellular phones and laptop computers. Strategic alliances are being explored with OEMs for development and use of QuantumSphere’s products in their portable systems.
Later target markets include the automotive sector and the energy storage sector for photovoltaics. The energy storage requirements for these two types of vehicles are somewhat different:
- HEVs require energy storage devices that can deliver high power pulses. For HEV applications, the goal is to develop cells that provide peak power of 1000 W/kg or greater, have a cycle life of at least 300,000 shallow cycles, and have a calendar life of 15 years.
- PHEVs require devices that can both store significant energy and deliver high power pulses. PHEVs will require batteries that can deliver significant energy (several kWh) for several thousand discharge cycles from an almost full charge to a lower state of charge. It has been suggested that a PHEV battery would operate in a charge-depleting hybrid mode from about 90% of full charge to about 25% of full charge. Once the battery reaches this lower state of charge, it will function in a manner similar to the battery in an HEV and must be able to sustain 200,000 – 300,000 shallow cycles with a 15 year calendar life.
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