Lithium-Ion Battery + Nano-technology ___________________________ ? An Overview of the battery technology that powers our mobile society. Bryan Lamble Energy Law, Spring 2008 Battery History and Basics The modern battery was developed by Italian physicist Alessandro Volta in 1800. Ingredients: Zinc, Saltwater paper, and Silver An electrochemical reaction. The “Voltaic Pile” The Voltaic Pile Battery Chemistry 101 Electrochemical reaction - a chemical reaction between elements which creates electrons. Oxidation occurs on the metals (“electrodes”), which creates the electrons. Electrons are transferred down the pile via the saltwater paper (the “electrolyte”). A charge is introduced at one pole, which builds as it moves down the pile. Primary vs. Secondary Batteries Primary batteries are disposable because their electrochemical reaction cannot be reversed. Secondary batteries are rechargeable, because their electrochemical reaction can be reversed by applying a certain voltage to the battery in the opposite direction of the discharge. Standard Modern Batteries Zinc-Carbon: used in all inexpensive AA, C and D dry-cell batteries. The electrodes are zinc and carbon, with an acidic paste between them that serves as the electrolyte. (disposable) Alkaline: used in common Duracell and Energizer batteries, the electrodes are zinc and manganeseoxide, with an alkaline electrolyte. (disposable) Lead-Acid: used in cars, the electrodes are lead and lead-oxide, with an acidic electrolyte. (rechargeable) Battery types (cont’d) Nickel-cadmium: (NiCd)  rechargeable,  “memory effect” Nickel-metal hydride: (NiMH)  rechargeable  no “memory effect” Lithium-Ion: (Li-Ion)  rechargeable  no “memory effect” Recharge-ability & the “memory effect” Recharge-ability: basically, when the direction of electron discharge (negative to positive) is reversed, restoring power. the Memory Effect: (generally) When a battery is repeatedly recharged before it has discharged more than half of its power, it will “forget” its original power capacity. Cadmium crystals are the culprit! (NiCd) Lithium Periodic Table Symbol: Li Atomic Weight: 3 (light!) Like sodium and potassium, an alkali metal. (Group 1 – #s 1 through 7) Highly reactive, with a high energy density. Used to treat manic-depression because it is particularly effective at calming a person in a “manic” state. The Periodic Table  Lithium (Ion) Battery Development In the 1970’s, Lithium metal was used but its instability rendered it unsafe and impractical. Lithium-cobalt oxide and graphite are now used as the lithium-Ion-moving electrodes. The Lithium-Ion battery has a slightly lower energy density than Lithium metal, but is much safer. Introduced by Sony in 1991. Advantages of Using Li-Ion Batteries POWER – High energy density means greater power in a smaller package. 160% greater than NiMH 220% greater than NiCd HIGHER VOLTAGE – a strong current allows it to power complex mechanical devices. LONG SHELF-LIFE – only 5% discharge loss per month.  10% for NiMH, 20% for NiCd Disadvantages of Li-Ion EXPENSIVE -- 40% more than NiCd. DELICATE -- battery temp must be monitored from within (which raises the price), and sealed particularly well. REGULATIONS -- when shipping Li-Ion batteries in bulk (which also raises the price). Class 9 miscellaneous hazardous material UN Manual of Tests and Criteria (III, 38.3) Environmental Impact of Li-Ion Batteries Rechargeable batteries are often recyclable. Oxidized Lithium is non-toxic, and can be extracted from the battery, neutralized, and used as feedstock for new Li-Ion batteries. The Intersection “In terms of weight and size, batteries have become one of the limiting factors in the development of electronic devices.” http://www.nanowerk.com/spotlight/spotid=5210.php “The problem with...lithium batteries is that none of the existing electrode materials alone can deliver all the required performance characteristics including high capacity, higher operating voltage, and long cycle life. Consequently, researchers are trying to optimize available electrode materials by designing new composite structures on the nanoscale.” “Nano”-Science and -Technology The attempt to manufacture and control objects at the atomic and molecular level (i.e. 100 nanometers or smaller). 1 nanometer = 1 billionth of a meter (10-9) 1 nanometer : 1 meter :: 1 marble : Earth 1 sheet of paper = 100,000 nanometers Nano S & T (cont’d) Nano-science: research of the differing behavioral properties of elements on the nano scale. Conductivity (electric/thermal), strength, magnetism, reflectivity.... Sometimes these properties differ on the nanoscale. Carbon is particularly strong on the nano scale. C60 = “Fullerene,” a.k.a “buckyball” Nano S & T (cont’d) Nano-technology: the use of nanoscale materials in critical dimensions of mechanical devices. Nanotubes -- carbon molecules have greater mechanical strength at less weight per volume. Nanotransistors -- the computer industry’s best technology features microchips with transistors as small as 45nm. Batteries with nanoscale materials deliver more power quickly with less heat. Environmental Impacts and Use of Nanotechnology Smaller scale technology means less resources used and less waste. The EPA recently issued research grants to use nanotechnology to develop new methods of detecting toxins in water. An example of the intersection... From graphite to metallic tin (electrodes), but metallic tin isn’t great either…yet. “...the biggest challenge for employing metallic tin...is that it suffers from huge volume variation during the lithium insertion/extraction cycle, which leads to pulverization of the electrode and very rapid capacity decay." But nanotechnology could offer a solution... The Director of the Institute of Chemistry at the Chinese Academy of Sciences published a paper in February describing the novel carbon nanocomposite above as “a promising [electrode] material for lithium-ion batteries.” Another example... “The storage capacity of a Li-Ion battery is limited by how much lithium can be held in the battery's anode, which is typically made of carbon. Silicon has a much higher capacity than carbon, but also has a drawback.” “Silicon placed in a battery swells as it absorbs positively charged lithium atoms during charging, then shrinks during use as the lithium ion is drawn out of the silicon. This cycle typically causes the silicon to pulverize, degrading the performance of the battery.” The Nano-technology solution... “The lithium is stored in a forest of tiny silicon nanowires, each with a diameter one onethousandth the thickness of a sheet of paper. The nanowires inflate to four times their normal size as they soak up lithium but, unlike other silicon shapes, they do not fracture.” See next slide… • Photos taken by a scanning electron microscope of silicon nanowires before (left) and after (right) absorbing lithium. Both photos were taken at the same magnification. The work is described in “High-performance lithium battery anodes using silicon nanowires,” published online Dec. 16 in Nature Nanotechnology. The Potential of Li-Ion Batteries Electrodes that don’t deteriorate metallic tin with carbon hollow spheres silicon nanowires 2D & 3D battery design “Forested” rods on a thin film electrode “Stacked” rods in a truck bed Nano + Li-Ion = ? Nanotechnology and Li-Ion applications in the commercial sector are apparent... lighter, more powerful batteries increase user mobility and equipment life. DeWalt 36volt cordless power tools Nanotechnology & Li-Ion applications in the residential sector are not so obvious... HVAC system batteries? Micro-generated energy storage? Micro-Generated Energy Storage Li-Ion batteries’ high energy density allows batteries them to power complex machinery. Li-Ion batteries recharge quickly and hold their charge longer, which provides flexibility to the micro-generator. particularly helpful for wind and solar generators! Lightness, and power per volume allow for storage and design flexibility. Finally, an interesting idea... Background: battery research results in annual capacity gains of approximately 6% Moore’s Law: The number of transistors on a computer microchip will double every two years. (40 years of proof!) Idea: If battery technology had developed at the same rate, a heavy duty car battery would be the size of a penny. Links to References http://electronics.howstuffworks.com/battery.htm http://everything2.com/e2node/Lithium%2520ion%2520battery http://www.batteryuniversity.com http://news-service.stanford.edu/news/2008/january9/nanowire010908.html http://www.nano.gov/html/research/industry.html http://en.wikipedia.org/wiki/Buckminster_Fuller http://www.nanowerk.com/spotlight/spotid=5210.php