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Growing to meet the challenge…. Development of a CFx D Cell for Man Portable Applications Joint Service Power Expo May 2 – 5, 2005. Introduction. EPEPC has been a manufacturer of high capacity lithium batteries for over fifteen years
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Growing to meet the challenge… Development of a CFx D Cell for Man Portable Applications Joint Service Power Expo May 2 – 5, 2005
Introduction • EPEPC has been a manufacturer of high capacity lithium batteries for over fifteen years • The first production contracts were for Li/SO2 batteries followed by the development and manufacturing of Li/MnO2 batteries • The evolution of the chemistries from a liquid to a solid cathode leads the way into the higher performance Li/CFx batteries, very high specific energy and energy density
Introduction • Lithium carbon mono-fluoride is the lightest and safest lithium battery, the enhanced safety can lead to simpler battery design • However, CFx has always been a low rate system, unable to meet the requirements of the US Military • The goal of the recent program is to develop a CFx D cell which will be close to the same weight as the SO2 D cell with twice the capacity and can be discharged at 2A and perform at -20oF, as required of Military batteries • If the goal can be achieved the user will be able to dramatically reduce the number of batteries taken to the field. Carry more water, food and ammunition increasing deployment duration if required
Li/CFx Electrical Performance • Discharged D cells (LC-3355) at 2A at room temperature (I), at 2A at -20oF (L) and at 2A at 131oF, five minutes on and five minutes rest (H test condition) • In addition tested the cell at the BA-5347 power protocol at both I and L test conditions • Finally, EPEPC built and tested the BA-5347 batteries with CFx D cells and compared the results to those obtained from BA-5347 batteries constructed with Li/MnO2 D cells
Li/CFx CFx D cell discharged at 2A, Room Temperature BA-5590 requirement is 3.4 hours
Li/CFx Room Temperature Performance at 2A Three Cell Lots Under real usage the battery would last even longer
Li/CFx Electrical Performance Comparison of Lithium Battery Chemistries at 20oC and 2A
Li/CFx CFx D Cell Discharged at 2A, -20oF
Li/CFx Low Temperature (-20oF) Performance of CFx D Cells Discharged at 2A
Li/CFx CFx D Cell Discharged at BA-5347 Specification, Room Temperature
Li/CFx CFx D Cell Discharged at BA-5347 Specification, Low Temperature
Li/CFx CFx D Cell Discharged at BA-5347 Specification
Li/CFx BA-5347 Batteries built with CFx D cells • Several BA-5347 batteries were built with CFx D cells • Batteries were tested according to the L, I and H test protocols, which are constant power and not constant current • Batteries were also manufactured with EPEPC LiMnO2 D cells and the batteries discharged under identical conditions for comparison
Li/CFx BA-5347 Batteries built with CFx D cells – L Test (-20oF)
Li/CFx BA-5347 Batteries built with CFx D cells – I Test (70oF)
Li/CFx Comparison of BA-5347 Batteries made with CFx or MnO2 D cells * Voltage delay noted
Li/CFx Other Electrical Testing – CFx D cell • Elevated temperature storage (131oF) shows a self-discharge rate of approximately 1%/year, micro-calorimetry techniques gave a self-discharge value of 0.6%/year • The self-discharge results prove that all material changes have not resulted in any corrosion issues • EPEPC has completed all the cell testing for the new Transportation Requirements, T1 to T5, T6 and T8 (forced over discharge) • Forced Over Discharge - Discharged the cells at 2A to a 2.0V endpoint and then carried out a separate FOD test at 2A for a further 7.82 hours or 15.6-Ah
Li/CFx CFx D cell – Storage and Self-Discharge Data Baseline Data
Li/CFx CFx D cell – Storage and Self-Discharge Data Storage Results
Li/CFx CFx D cell – Temperature and Voltage profile - FOD
Li/CFx Conclusions – CFx D cell • Capacity of the D cell at 2A at all temperatures superior to Li/SO2 and Li/MnO2 • No voltage delay noted for high temperature or room temperature • Maximum temperature recorded on the top of the BA-5347 battery was 67oC at end of life under 2A intermittent discharge at 55oC • Self-discharge results are very good, corrosion is not an issue
Li/CFx Conclusions – CFx D cell (continued) • Capacity at -20oF of cells either single or two in a BA-5347 box is higher than room temperature performance for both Li/SO2 and Li/MnO2 • Discharge time under the BA-5347 test protocol of the CFx D cell is approximately 150% of Li/MnO2 • Capacity in a multi-cell battery may be even greater due to self heating • Limited voltage delay measured at low temperature only, more work on low temperature voltage delay may still be required
Li/CFx Conclusions – CFx BA-5347 Battery • Since this application is constant power and not constant current the run time is the best measure of performance • Voltage delay of the BA-5347 at -20oF is excessive but the battery does deliver the required power • The BA-5347 test results show that the CFx variant exhibits 50% higher energy density (Wh/l) and almost 100% increase in specific energy (Wh/kg) over the MnO2 battery
Li/CFx Conclusions – CFx BA-5347 Battery • Fifty percent longer service life at 20% lower weight • Therefore, the user can carry two batteries and not three. The same run time with batteries weighing 504g versus three batteries weighing 888g • The end user can carry less batteries and more other supplies such as water or food • The reduced battery weight will allow for a longer mission times
Li/CFx Conclusions – CFx Battery – Next Steps • The next goal of the CFx development will be the evaluation of the D cell in the BA-5590 form factor • Voltage delay issue may not be present due to five cells in a string as opposed to two in the BA-5347 • Thermal issues in this battery must be evaluated • The CFx battery will be 7.3% heavier but deliver two times the capacity of the SO2 BA-5590. One battery weighing 1030g versus two batteries weighing 1920g
Li/CFx Conclusions – CFx Battery – Next Steps • EPEPC could deliver the BA-5590A/U with the CFx D cell • This battery will be equipped with the SOCI technology • Will use EPEPC’s experience with the BA-5590A/U, the SO2 variant with a SOCI
Recent Developments - SOCI EPEPC BA-5590A/U with SOCI
Author Contact Information Author Contact Information Gregg C. Bruce Director of Product Development EaglePicher Energy Products 13136 – 82A Avenue Surrey, BC Canada, V3W 9Y6 (604) 543-4354 Gregg.bruce@eaglepicher.com