T HE S YNTHESIS AND P ATTERNING OF L ITHIUM I RON P HOSPHATE E LECTRODES FOR A N EW T YPE OF L ITHIUM I ON B ATTERY Anna Putnam, Yong Li, Wei Yen Chih-hung (Alex) Chang School of Chemical, Biological and Environmental Engineering Sponsored by ONAMI and the Army Research Center Special thanks to Hewlett Packard LiFePO 4 Nanoparticle Formation How a Battery Works The following diagrams illustrate the structure of lithium ion batteries and how they charge and discharge. Low Cost Non-toxicity High abundance of iron Excellent thermal stability Non-explosive properties Can be used in cars Better electrochemical performance Has a high specific energy capacity LiCl + H 3 PO 4 + FeCl 2  LiFePO 4 +3HCl (In ethanol) Drop on Demand (ink-jet printing technology) pico-liter chemical delivery systems provide an ideal manufacturing platform for large scale fabrication of devices. Delivery of individual drops by DoD in multiple layers and over large areas makes possible the fabrication of devices with material architectures ranging from the nanometer to meter scales. Donated by Hewlett Packard Works similarly to a micro-pipette Hand held or mountable Ability to program drop quantity, number of nozzles, drop energy, etc. On-board control with USB interface Will work like a printer when coupled with an X-Y stage Will allow larger particles to pass through it preventing clogging Tips are easily replaceable unlike the Dimatix system Zig-zag pattern that occurs while printing with this program H 3 PO 4 + FeCl 2  HFePO 4 + 2HCl (in ethanol) HFePO 4 + LiOH  LiFePO 4 + H 2 O (in water) A Photon Correlation System was used to show that LiFePO 4 forms nanoparticles over time when synthesized according to the above reaction in ethanol. This is a problem because nanoparticles clog printer nozzles. “Dipping” Method of Synthesizing LiFePO 4 A method of resolving the nanoparticle formation issue was developed by first patterning a precursor product, hydrogen iron phosphate, and then dipping it into another reactant in order to form lithium iron phosphate. Project Goal is to Develop New Printing System Transition from Pipette to Printer Why LiFePO 4 instead of Lithium Cobalt? Drop on Demand Technology Simultaneously using a program developed at HP for the TIPS with a program created by a graduate student in Dr. Chang’s lab for the X-Y stage, the TIPS can be made to work like a printer instead of a pipette system. Accomplishments Measuring Thickness of Printed Squares Average Diameter= 1060 nm Size (nm) [log] Model made in Solid Works based on all graduate student needs Platform constructed by purchasing used optical breadboard and getting all other parts machined Demonstrated negative effects of nanoparticle formation Selected formation procedure Explored TIPS operating space specific to formulation Related heating pad set point with actual substrate temperature Measured thickness of printed films as a function of vertical printing speed Acknowledgments: Phil Harding, Manfred Dittrich, Andy Brickman, Changqing Pan, Craig Olbrich,Bill Buckley Squares were printed on silicon at varying vertical speeds. A profilometer was used to measure the thickness of the squares. The above graph shows how thickness increases with decreasing vertical speed. Construction of Printing System First a design was made in Solid Works, then an apparatus was constructed to hold the TIPS over the X-Y stage and be moveable with a sliding mechanism. A heating pad was added, and a study was done to relate heating pad set point with actual substrate temperature.