from May 2008 ABT

meeting report

25th International Battery

Seminar & Exhibition

Ft. Lauderdale, FL USA

March 17-20, 2008

Originated by Dr. Sumner P. "Shep" Wolsky and Dr. Nicola Marincic, the International Battery Seminar and Exhibit is now organized by Dr. Wolsky and Dr. A. Harry Taylor and administered by Tom DeVita. Concurrently, the 12th International Battery Materials Recycling Seminar was held at the same location.

The Battery Seminar was highly successful with presentations on a variety of timely topics and more than 450 attendees, 40 exhibitors and five additional sponsors. It opened with two tutorials.

The first was given by Yoshio Nishi of The Sony Research Center and was entitled The Past and the Present of Lithium-ion Secondary Batteries and What Lies Ahead. Nishi reviewed the history of battery technology from ancient times to the present and why, out of a possible 110 million combinations of active materials, only about 30 are currently available. Nishi also reviewed the development of lithium-ion battery technology from the introduction of the first 1.1Ah 18650 cell using lithium cobalt oxide (LCO) and coke in 1991 to the present 2.6Ah cells employing LCO and graphite anodes.

New cathode and anode materials were discussed, including the use of a Sn-Co-C alloy in Sony’s Nexelion cells. The increase in safety-related recalls as cell capacity has increased was pointed out and factors affecting safety were reviewed in detail. The development of lithium-polymer batteries (LPB) was discussed and the need for gel electrolytes with a low vapor pressure was emphasized. The emergence of direct methanol fuel cells (DMFCs) as a competitor for lithium-ion and the advantages of hybrid fuel cell-battery systems were pointed out.

The second tutorial, Worldwide Market Update on NiMH, Li-ion and Polymer Batteries for Portable Applications and HEVs, was given by Hideo Takeshita of the Institute for Information Technology of Japan. This presentation was Takeshita’s annual marketing update by market segment, cell technology and manufacturers. Particular emphasis this year was placed on batteries for HEVs, PHEVs and full EVs.

The Monday afternoon session was devoted to "Lithium-Ion Battery Safety." The first talk was presented by Dan Halberstein of the USDOT on his agency’s Lithium Battery Public Awareness Initiative to prevent accidents during air travel caused by passenger ignorance of the dangers of carrying loose batteries, the use of counterfeit batteries and unsafe charging procedures. More information is available on the DOT website at http://safetravel.dot.gov.

The next presentation, Lithium-ion Battery Safety Overview, was given by Brian Barnett of TIAX LLC. Safety-related incidents with lithium-ion occur in only one of 5-10 million cells produced and typically are caused by internal short circuits. TIAX has employed Finite Element Analysis to model the rapid temperature rise in 18650 cells and finds that threshold levels of power and energy exist above which catastrophic failures occur.

Celina Mikolajczak of Exponent Inc. then spoke on Lithium-ion Battery Cell Failure Analysis, detailing the causes of Li-ion failures and the analysis procedures developed by Exponent. The observations which lead to identifiable causes of failure were described and pictures of these phenomena were shown.

David Freeman of Texas Instruments presented a talk on Battery and Charge Management: Past, Present and Future. He detailed the development of charging procedures for secondary battery technologies to the current lithium-ion system which employs a constant current to a voltage limit, followed by a taper charge to a current limit. Specific procedures required for cell phones and notebook computers were detailed, future trends to increase safety and optimize run-time through power management were described and circuit diagrams to achieve these objectives were shown.

Next was a panel discussion on lithium battery safety with presentations by representatives of Intel, USDOT, PRBA, FAA and the Airline Pilots Association (ALPA). Kamal Shah of Intel is the chairman of the Mobile PC Extended Life Working Group (www.eblwg.org). There are an estimated 2 billion cells installed in notebook computers, and safety-related incidents have increased as the capacity of 18650 cells has increased with internal short circuits being the principle cause of these incidents and subsequent recalls. He outlined key safety precautions and mentioned industry initiatives being undertaken such as the IEEE 1625 standard which takes a systems approach and is being updated for publication in May 2008. Others include the mobile PC EBL Working Group (vide supra), IEC 62133, UL 1642 and UL 2054.

Next came Bob Richard of USDOT which is concerned primarily with safety incidents during transportation because there have been about 90 such incidents since 1991 involving batteries or devices using batteries. Of these, 27% involved lithium batteries with external or internal short circuits accounting for 68% of the incidents. Initiatives being taken by DOT include increased public awareness, publication of proposed rule making and working with stakeholders to update an eight-point battery safety plan that was to be issued in April 2008. The talk concluded with many photos of the batteries involved in safety-related incidents and an analysis of those types plus new NTSB recommendations and current enforcement issues. For further information, call the DOT Hazardous Materials Info Line at (800) 467-4922.

George Kerchner of PRBA spoke on industry initiatives to work with government and industry groups to improve battery safety which resulted in a DOT safety advisory issued on March 26, 2007. As a result of two International Civil Aviation Organization meetings in 2007, new, more stringent regulations on the shipment of lithium metal and lithium-ion batteries are being promulgated and will become effective on January 1, 2009. Due to an incident on a ship in 2005, Germany has proposed that NiMH batteries be shipped as Class 9 dangerous goods. Additional requirements may be required for large format lithium batteries under the United Nations test protocols.

Chris Bonati of the FAA discussed the need for improved quality control since there is no cleanliness standard under ISO-9000. He also emphasized the need to keep batteries in the cabin of passenger aircraft.

Mark Rogers of ALPA discussed the pilot’s role in dangerous goods transport. Pilots must accept shipment of dangerous goods and are the last link in the safety chain. ALPA is very concerned about recent lithium-ion battery fires on aircraft. Once ignited, the cells erupt multiple times and Halon 1301 has no effect on the fire, although it is effective against lithium metal battery fires. He discussed recent incidents and the NTSB recommendations to carry lithium-ion batteries in the passenger cabin and lithium metal batteries in fire-resistant containers and/or limited quantities. He also discussed reducing the cabin fire potential on passenger aircraft and addressing the risk on cargo flights through proper packaging, testing, labeling, and notification procedures. ALPA believes lithium/lithium-ion batteries should be fully regulated. The presentations by the panel were followed by a question and answer session with the seminar attendees.

The Tuesday morning session was devoted to "Advanced Materials for Performance and Safety." A featured talk was given by Prof. Jeff Dahn of Dalhousie University, Nova Scotia, Canada and was entitled Sn-Co-C: It Works, But Many Mysteries Remain. The anode material Sn-Co-C is used in Sony’s Nexelion cells, avoids the high irreversible capacity loss associated with tin oxides and may be prepared by sputtering or mechanical attriting. Dahn and co-workers find that Sn30Co30C40 produces stable cycling performance and consists of a nanostructured Sn-Co intermetallic phase in a carbon matrix. The alloy Sn30Fe30C40 has also been studied as a lower-cost material. The mystery involves the question of why the sputtered phase produced higher capacity per unit weight and volume than the attrited material.

A presentation on anode materials entitled Tailored Reactive Binders for Si-Based Anodes with Improved Cycling was given by Martin Winter of the University of Muenster, Germany. He discussed the use of various binder materials with Si-C anodes to accommodate the large volume change which occurs on cycling. The use of carboxymethylcellulose with Si-C produced ester linkages between the binder and active material and the use of nanosilicon produce the best results.

Mark Obrovac of 3M Co. then spoke on Alloy Anode Materials for Li-Ion Batteries. He outlined the requirements for a practical anode material in Li-ion batteries. Silicon has the highest specific capacity but a volume expansion of 280%. When the volume expansion is considered, there is little difference between potential anode materials such as: Al, Bi, Si, Sn and Pb. 3M has found that the binder type is a major factor in cycling performance with these anode materials. 3M has developed a proprietary binder which provides 110% volume expansion with 11% irreversible capacity loss. When coupled with the 1/1/1 MNC cathode, it provides a rate capability comparable to graphite with twice the specific energy and energy density of that anode material.

Jerry Barker, a consultant to Valence Technology, then spoke on Phosphates for Lithium-Ion Batteries: Materials, Synthesis and Future Opportunities. Valence has developed low-cost routes to produce olivene phosphate materials using carbothermal reduction which produces a residual conductive network in the phosphate active materials. Valence has produced a variety of phosphates by this route. A LiFeMgPO4 material when cycled against a graphite anode gives excellent performance with little capacity loss. Sodium- ion and hybrid lithium-sodium ion cells have also been demonstrated.

The final talk on Tuesday morning was given by Christian Masquelier of the University of Picardie, France, on New Compositions, New Mechanisms of Li Extraction in LiFePO4-Based Electrodes. He discussed new routes to produce nanosized LFP materials which show higher specific capacities compared to microsized particles and require no coating or doping.

For the first time in the 25-year history of the seminar, two parallel sessions were held Tuesday afternoon and Wednesday morning. Selected presentations were covered during this period. In addition to the Battery Materials session, the second session covered Large Format Systems.

The first talk in the latter session was given by Christophe Pillot of Avicenne Development, France, on Electric and Hybrid Vehicle Trends and Their Impact on the Battery Market. He gave data on the portable rechargeable battery market from 1994 to 2007 with projections to 2015. Batteries for HEVs claimed 9% of this market in 2007 and have led to a recapture of market share for Ni/MH with more than 530,000 HEVs sold. Two-thirds of the units were sold in the U.S. and Toyota had 79% of the overall market. The HEV market is smaller in Europe because of lower taxes on diesel fuel than gasoline, resulting in more diesel vehicles. The cost of Ni/MH and Li-ion batteries for HEVs are projected to be comparable in 2015 but concerns about safety have delayed the introduction of Li-ion in HEVs, with first sales projected for 2009. The Li-ion market for HEVs is projected to reach 35% of the $2.5 billion HEV battery market by 2015.

Mark Verbrugge of GM Research and Development then reported on Electrochemical Energy Storage Systems and Range-Extending Electric Vehicles. This talk dealt with GM’s plans to introduce HEVs, PHEVs and EVs in the future. An analysis of a high-energy battery with a supercapacitor in parallel indicates this is an attractive system for use in range-extending electric vehicles (PHEVs). This would require a battery capable of 5K deep cycles before replacement and a cost of $0.25/Farad for the supercapacitor and $0.50/Wh for the battery. A specific energy of 120Ah/kg and a specific power of 750W/kg are also required for the energy storage system.

Ted Miller of Ford presented a talk on Energy Storage The Key Enabler in Future Automotive Technology. Ni/MH technology has been successful in both cylindrical and prismatic designs and is well suited for HEV applications. Li-ion technology has also been developed in cylindrical and prismatic designs and provides potential weight, volume and long-term cost advantages. Safety considerations have led to design improvements. Remaining technical challenges for HEV use include improved low temperature performance and increased specific power with adequate energy retention. The USABC price goal for an EV battery in 1991 was $100/kWhr when gasoline cost $1.10/gal. In May 2007, gasoline costs $3.27/gal. so the resultant battery price may be $300/kWhr and the threshold may have been reached which makes battery energy storage a viable option. If another market for stationary energy storage with similar requirements as EVs can be developed, then the cost of Li-ion batteries should reach the $300/kWhr price target.

A talk on High-Power Li-Ion Batteries was given by Andrew Chu of A123 Systems which includes T/J Technologies and a Chinese manufacturing operation. A123 uses a doped LiFePO4 (LFP) cathode nanomaterial in developing the power tool market and believes the HEV market has similar technical requirements. A123 believes the choice of cathode material is the most important factor in Li-ion safety and their cells vent mildly, with ignition, when tested on an ARC at a rate of 10C/min. Testing of LFP cells at Argonne National Laboratory on a hybrid pulse power test has given 300,000 cycles at 60% state-of-charge (SoC) at both 30C and 45C. A123 is working with GM on their technology for both PHEV and extended-range EV (ER-EV) vehicles.

The next presentation, Large Li-ion Single Cells for Emerging Applications, was given by George Thomas of Tianjin Lishen Battery Co. Lishen manufactures LFP cells in 5Ah and 11Ah sizes and spinel lithium manganese oxide cells in 11Ah and 50Ah sizes, all in prismatic designs. The production rate in 2007 was 240 million cells per year and will increase to 306 million cells per year in 2008, including prismatic, cylindrical and polymer cells. Lishen defines large cells as 5Ah or higher and is developing these products for two-wheel EVs and four-wheel HEVs, PHEVs, EVs and stationary back-up power markets. High-energy LFP cells have provided 1400 cycles at the 1-C discharge rate and have passed a variety of safety tests with acceptable results. The Lishen 5Ah LFP cell delivers 70% of its rated capacity at the 25-C discharge rate and has also passed many safety tests. Lishen’s 11Ah prismatic manganese spinel cell is stated to be 40% cheaper than cobalt or NMC cells and to provide a safer product with better low-temperature performance. The manganese-spinel technology still suffers from reduced cycle life at high temperatures.

The final talk in the Large Format Systems session on Tuesday afternoon was given by Ivan Exnar of High Power Lithium (HPL) in Switzerland on High Performance Lithium Manganese Phosphate Synthesized by a Polyol Method. HPL believes that the lithium manganese phosphate material is preferable to other olivine compounds for batteries because it combines a higher voltage (4.1V) than iron with low cost. Using diethylene glycol as a chelating agent for manganese, they produce LMP nano-particles with carbon to produce the required conductivity. Processes to produce electrodes with this material have been developed and the electrodes tested in Swagelok cells. At a C/5 rate, 200 cycles have been obtained. Mixed metal phosphates of 90% Mn and 10% Fe have also been produced by this process to provide a SoC indicator from the two plateaus of the discharge curve. Using LMP and lithiated titanium oxide (LTO), a 2.5V cell has been produced which is stated to be very safe.

The final presentation in the Advanced Materials Session was given by John Zhang of Polypore Inc. on Li-ion Safety, Regulations and Separators. Celgard is a division of Polypore and this talk centered on possible causes of internal short circuits and the reactions which may cause them. Ni particles have been used to carry out internal shorts using the Battery Association of Japan’s (BAJ’s) test protocol on several low-capacity spiral-wound Li-ion cells. The reaction of cobalt active material with lithiated carbon produces the most heat followed by the reaction of aluminum (Al) with lithiated carbon and aluminum with carbon. The reaction of Al with Cu was the safest. The methods suggested to prevent internal shorts were to use a stronger separator, removing stress points on the separator and improved processes.

The first talk in the Large Format Session on Wednesday morning was given by Sankar Das Gupta of Electrovaya in Canada. He spoke on Superpolymer Battery Systems for Large Format Applications. Electrovaya uses LFP-based cells with a specific energy of 120-130Ah/kg and an energy density of 220-230Ahr/liter. Doped manganese cells (not spinel based) produce 170-210Wh/kg and 400-450Whr/liter. Cells have been scaled up to 1.5kWhr battery modules and employ an intelligent battery management system (iBMs). These modules have been employed on several demonstration PHEVs which ran more than 100 miles on battery power. Demonstration EVs are also under development.

Florence Fusalba of CEA-Liten in France then spoke on Bipolar Li-ion Cells for HEV Applications. This organization employs phosphates and high-energy spinels as positive electrodes and lithiuated titanates and Si-C composites as negatives in conjunction with polymer electrolytes and ionic liquids as electrolytes in a bipolar configuration. The bipolar LFP-LTO cell is said to provide long cycle life with high-rate charge acceptance at low cost but with reduced energy density. Greater than 11,000 HEV test macrocycles have been obtained with these materials. A bipolar stack of 13 cells has been developed using Al as the bipolar plate. A HEV pack of 10 modules in parallel provides 24V, 7Ah, and 150Whrs. CEA states that the intercell electrolyte leakage problem has been solved for this design.

A significant presentation in the Advanced Materials Session was made by Rachid Yazami of CalTech-CNRS (France) on Nanostructured Carbon Fluoride for High Performance Lithium Batteries. LiCFx batteries feature a very high specific energy of 1700Wh/kg and a very long shelf life. Carbon monofluoride is obtained by fluorinating coke or graphitic carbons and exists as covalent CF and layered CFx materials. Commercial CFx exists with x~1.0 and subfluorinated with x = 0.53 and 0.65 obtained from KS-15 graphite. More recently, subfluorinated carbon nanofibers and multiwall carbon nanotubes (MWNTs) have been produced. Cathodes have been fabricated with 75% CFx, 10% AB carbon and 15% PVDF binder and tested in coin cells with a PE-DME-LiBF4 electrolyte using a Celgard shut-down separator. The CFx materials have been studied by XRD, Raman spectroscopy, high-resolution transmission electron diffraction and C13 NMR. Electrochemical discharge of the coin cells with the various materials has been carried out as a function of rate and temperature. Commercial CFx with x~1.0 gave a very high specific capacity of 800mAh/g compared to a theoretical value of 865mAh/g at room temperature. The subfluorinated graphites gave values around 500mAh/g for x = 0.53 and 600mAh/g for x = 0.65 at low rates.

Yazami went on to say that the partially fluorinated fibers provide up to six times the power capability of the commercial material. Partially fluorinated, 400 micron MWNTs with x = 0.75 provide capacities of 700mAh/g at the 1-C rate and can be discharged above 2V at -40¿C. They also provide discharge capability to +140¿C with a different electrolyte and separator. Specific energies above 1700Ah/kg have been obtained and some reduction of the PVDF binder and possibly the electrolyte may account for this effect.

Bridget Deveney of SAFT presented a talk on Large Format Li-Ion Cells with LiFePO4 Cathode Materials in conjunction with coauthors from the U.S. Army Research Laboratory. SAFT is using LFP obtained from PhosTech for its large cell development using the hardware from its existing NCA Li-ion cells. The VL10Fe 10Ah cell is optimized for high power and provides a specific power of 4375W/kg at 100% SoC. The VL25Fe 25Ah cell is optimized for moderate power (3.5W/kg continuous) and moderate energy (89Ah/kg). Electrode design and electrolyte composition have been optimized to enhance low-temperature performance for military requirements. Cycle life testing of these cells is in progress and life testing has been initiated. The VL10Fe has passed an external short circuit safely and FL25Fe cells on overcharge and slow nail penetration tests vented with smoke but no flames. The remaining challenge with these LFP cells is to improve storage life at high temperature.

Clint Winchester of the Naval Surface Warfare Center, Carderock Division made a presentation on Large Format Li-ion Batteries; Use, Abuse, Testing and Safety Concerns   A U.S. Navy Perspective. It opened with a film showing the adverse effects that can occur when large batteries are subjected to safety tests. The Navy defines "large format" as being cells with capacities of 20Ah or greater and batteries containing cells whose capacity is 400Ah or greater. Safety hazards increase with increased Ah, Wh and component count. Technical means to mitigate these safety concerns were discussed and include redundant safety and battery management systems and an intelligent choice of cell chemistry. Military applications such as UAVs and UUVs require both high power and high energy sources to meet mission requirements and this requires trade-offs between performance, cost and safety. A hazards analysis and systems integration study is required by MIL-STD-882. This requires a variety of test protocols including NAVSEA S9310.

K. M. Abraham, a consultant to Electro Energy Inc., presented a paper on High Power and High Energy Wafer-cell Ni/MH and Li-ion Batteries for Advanced Transportation Applications. This talk focused on the EEI wafer cell first developed for Ni/MH and now being adapted to Li-ion technology. By stacking wafer cells, a quasi-bipolar battery configuration is obtained. Li-ion wafer cells are stated to have a specific energy of 200Ah/kg and an energy density of 500Ah/liter. These cells employ a NCM (1/1/1) cathode and a MCMB anode and have achieved 1000 cycles to 100% DoD. Prototype BB-X590 Army batteries have been built and tested and provide 9.1Ah compared to 7Ah for a BB-2590 using 18650 cells. A cycle life of 500 has been demonstrated at the C/2 charge and discharge rates with periodic cell balancing. A Ragone plot was shown which demonstrates that the EEI wafer cell has a higher power capability than commercial spinel manganese or LFP cells. A 3.6V, 20Ah wafer cell has been developed to serve as a building block for PHEV and HEV batteries and design specifications were shown for each. A specific power of 1kW/kg was given for the PHEV battery and >2kW/kg for the HEV battery.

The Wednesday afternoon session was devoted to Advanced Product Development and the first presentation was given by Kiyoshi Sato of Hitachi Maxell Ltd. on High Power Type Lithium-ion Batteries. Maxell has developed a 1.3Ah 18650PA cell designed for high power with good low-temperature performance. It is capable of 20 Amp continuous discharge to -10¿C and is developing a 26650PA cell of 2.6Ah capacity which will provide a 60 Amp rate capability. These achievements have been obtained through the use of a mixed cathode containing spinel manganese with lithium cobalt oxide as well as mechanical design modifications and an improved low-temperature electrolyte. The 18650PA has passed a variety of safety tests with no resulting fire or explosions.

The next talk was given by Takuda Endo of Sony Corp. on Sony Li-ion Battery Technologies. Sony has already developed a high power Li-ion cell (Fortelion) and a high-capacity, low-voltage design with a hybrid anode (Nexelion). They are now developing a new polymer cell (Apelion) with a capacity improvement for mobile applications and a conventional carbon anode. This cell employs a new polymer electrolyte with a conductivity of 9 milliSiemens at 20¿C. This cell employs a cathode consisting of Co and another unspecified metal and the electrolyte consist of a fluoride polymer containing a carbonate-based solvent with LiPF6 salt. A prismatic cell (5.4 x 34 x 36mm) has a capacity of 0.92Ah and is capable of discharging at the 3-C rate. It provides 500 cycles at the 1-C charge and discharge rates with minimal swelling. Sony has employed a Numerical Simulation method using the Activation Energy (E) and Total Heat Generated (Q) to predict the results of safety tests with various active materials.

John Wozniak of Hewlett-Packard (HP) spoke on The Future of Li-ion Cell Production in China. As a result of recalls by Japanese manufacturers and production problems in South Korea, HP is evaluating cells from Chinese sources. He described the procedures used to evaluate cells and the methods employed to introduce them into the laptop computer market.

Next, M. Ma of Union Suppo Battery Co. (China) spoke on New Battery Development   NiMH Battery. Suppo has introduced a line of Ni/MH cells with reduced self-discharge. Their trade name is "EnerKeep" and they are designed to replace alkaline manganese primary batteries. The AA cells have 89% charge retention on storage for 78 days at 20¿C and employ 4% less cobalt in the alloy. These improvements are achieved through modifications to the MH alloy, an improved electrolyte composition and the use of thicker electrodes.

The next talk was given by Michael Fetcenko of Ovonic Battery Co. on Advanced Materials for Next Generation NiMH Batteries. He emphasized Ovonic’s patent portfolio and the advances that have been made in NiMH technology. NiMH cells are available in sizes from 15mAh button cells to F-size cylindricals and are sold in the charged state. Prismatic cells for HEV use are available up to 250Ah. Current NiMH technology provides 110Ah/kg, 430Ah/liter and a specific power of 2.0kW/kg. Developments occurring in NiMH batteries for HEV use include MH alloys with a 20% capacity enhancement to 370mAh/g with improved HEV cycle life. This is being accomplished by reducing alloy corrosion and pulverization. Improvements in performance by the Ni(OH)2 electrode are also being made. The target is to merge high energy and high power designs while maintaining HEV cycle life. Ovonic is also carrying out R&D on producing hydrogen from renewable biofuels for use in alkaline fuel cells.

Rachid Yazami of CalTech-CNRS (France) gave a presentation on Thermodynamics of Battery Materials: Principles and Applications with coauthors from Viaspace Energy. From the first principles of chemical thermodynamics, the derivative of the variation of the open circuit voltage with temperature can be used to calculate the entropy (S) and enthalpy (H) for a reversible electrochemical reaction. Coin cells with a lithium counter electrode and a Celgard separator have been used to determine these parameters for a number of battery materials as a function of their degree of lithiation. An automated apparatus has been developed to determine these thermodynamic parameters for four cells at once as a function of the state of discharge and is being marketed as the BA-1000 by Viaspace. This unit has been used to evaluate both carbon-based anode and lithiated cathode materials. The Entropy of lithium-ion insertion into high-temperature treated cokes has been correlated with the results of Raman spectroscopy on these materials and the degree of staging of Li(I) insertion. A hysteresis effect was observed near x = 0.5 for natural graphite. A phase diagram has been constructed from the data for LiC6 from x = 0.5 to 1.0. The entropy vs. x curve for lithium cobalt oxide shows details not seen in the discharge curve and has also been used to construct a phase diagram. The entropy data for spinel lithiated manganese oxide show differences between the stoichiometric and the lithiated material with x >1.0. This data can be used to calculate the diffusion coefficient for lithium-ion as a function of the degree of lithiation. This entropy method can be used to evaluate electrode materials and to determine the state-of-health of a battery during its cycle life.

The Thursday morning session included papers on "Advanced Product Development" and "Battery Management and Charging." The last paper in the former category was given by Joe Carcone of Powergenix on The Development of a Consumer AA 1.6V Type Rechargeable Nickel Zinc Battery. Powergenix is developing AA and Sub-C sized Ni-Zn cells for use as a replacement for alkaline manganese in consumer products (AA) and for the lawn and garden market (Sub-C). This technology is said to provide more power and to be safer, greener, and cheaper than competitive technologies such as NiCd and NiMH. The Ni-Zn operates at 1.5V vs. 1.2V for its competitors. The Powergenix design is a spiral-wound sealed cell and is electrolyte starved. The AA cell has a capacity of 1.5Ah while the Sub-C cell provides 2.0Ah, and both feature low impedances. The AA cell has provided 220 cycles at 100% DoD. It is being targeted for use in digital cameras because of its high power output and has given 1000 pictures on the relevant ANSI test. Cost of the Powergenix cells was said to be $0.40/Wh.

John Houldsworth of Power Precise, now part of Texas Instruments, presented a talk on Smart Safety for Li-ion Battery Packs. He reviewed the factors which cause safety problems in Li-ion packs and ways to reduce such problems through statistical process control during manufacture, pack manufacturing with proper location of adequate heat sensors and proper design and utilization of the battery management system.

David Nierescher of Micro Power Electronics spoke on Portable Designs for High-power Batteries and Chargers. This paper dealt with the problem of high-rate charging of custom Li-ion battery packs. Since LFP and LMO-spinel packs have lower specific energy than LCO designs, they must be recharged more often and at high rates which generate more heat in the pack. This presentation described electronic and design approaches to mitigate this problem.

Dan Friel, a consultant to Millennium Cell, presented a talk on Fuel Cell and Battery Hybridization for Long Run Applications, describing a hybrid power source designed to employ the best characteristics of batteries and fuel cells. Batteries provide both power and energy and are still practical for many applications. Fuel cells provide energy decoupled from power. A hybrid system has the advantage of providing power from the battery and energy from the fuel cell. This allows the use of smaller batteries, and additional energy can be obtained by replacing the fuel source. An example was provided requiring a complex duty cycle equivalent to 3.5mA continuous drain for one year of remote operation. This amounts to 300Ahrs per year. A hybrid system consisting of a 4.6Ah Li-ion battery being periodically recharged by a 7.5W proton exchange membrane (PEM) fuel cell offers advantages over a primary battery or a Li-ion rechargeable battery in terms of reduced size and weight, a higher E/P ratio and lower total cost.

Anwar Master of the EAC Division of Electrochem Inc. presented a talk on Battery Management for Primary Chemistries. This presentation described the development of a battery management system which is SBS-compliant to provide fuel gauge capability for primary battery packs.

The final talk was given by Vivien Delport of Microchip Technology on Battery Authentication: Simple Solution to Securely Track Battery Originality. This paper described a means to prevent fraudulent duplication of OEM batteries for the aftermarket through the use of an embedded chip and encryption technology.

A CD containing the complete program for the 25th International Battery Seminar is available from Florida Educational Seminars at www.POWERSOURCES.net.