1. Region of maximum conductivity 1% 88% 2%31% 54% 64% 1% Fraction crystallinity Solid polymer electrolytes for lithium ion batteries Janna K. Maranas, Pennsylvania State Univ University Park, DMR 0706402 Batteries and fuel cells require an electrolyte through which ionic species diffuse. For batteries in cell phones and laptop computers, the diffusing species is lithium, and the electrolyte is a liquid mixture. Replacement of this electrolyte with a polymer has many advantages, yet lithium conductivity in solid polymer electrolytes [SPE] is insufficient for device applications. The polymer used in SPEs has up to three crystalline phases at room temperature, combined with more liquid-like regions, where transport of the lithium ions is assumed to occur. We use a specific sample treatment that isolates of one the crystal phases. We find that the presence of this crystal phase is not directly related with conductivity, challenging current thinking. In the Figure, we show features of the isolated crystalline phase overlaid with the region of maximum conductivity. Within this region, the conductivity is constant although the fraction of crystallinity grows. This result suggests a different approach to designing SPEs where crystalline regions are incorporated, and perhaps even manipulated to increase conductivity. Features of crystals in a solid polymer electrolyte for lithium batteries, as a function of lithium content. Black regions are the polymer crystals, organized into layers called lamellae, with the spacing given on the y axis. These crystals are separated by a non-crystalline layer [yellow], and occupy the fraction of the sample indicated in red. The blue shaded area indicates the region over which maximum lithium conductivity is maintained.

2. One technique used to obtain the results on the previous slide is neutron scattering, a powerful method for obtaining structural and dynamic information on the nanoscale. These experiments are performed at various neutron scattering facilities, in which the US has invested significantly. One way to broaden the impact of using the method as a research tool is reaching established researchers who may not be familiar with the technique. This year we organized a short course in dynamic neutron scattering. Solid polymer electrolytes for lithium ion batteries Janna K. Maranas, Pennsylvania State Univ University Park, DMR 0706402 Instruments used for dynamic neutron scattering at the NIST Center for Neutron Research. These instruments are supported by NSF via the Center for High Resolution Scattering [CHRNS] DMR-0454672 Teaching and training the next generation of scientists receives high importance in our group. In addition to exposing graduate students to neutron scattering in combination with molecular simulation, we hosted two undergraduate summer students this year, who now understand the importance of research and the unique role of neutrons as a research tool. Two undergraduate researchers, Ryan Bradley and Onajite Shemi [left and middle] studied protein and polymer dynamics with Prof. Maranas [right] this summer.