Engineering topics
Publications and source records attributed to Platt, Heather A. S..
A solid electrolyte material comprises Li, T, X and A wherein T is at least one of P, As, Si, Ge, Al, and B; X is one or more halogens or N; A is one or more of S and Se. The solid electrolyte material has peaks at 17.8°±0.75° and 19.2°±0.75° in X-ray diffraction measurement with Cu-Kα(1,2)=1.5418 Å and may include glass ceramic and/or mixed crystalline phases.
A solid electrolyte material comprises Li, T, X and A wherein T is at least one of P, As, Si, Ge, Al, and B; X is one or more halogens or N; A is one or more of S and Se. The solid electrolyte material has peaks at 17.8°±0.75° and 19.2°±0.75° in X-ray diffraction measurement with Cu-Kα(1,2)=1.5418 Å and may include glass ceramic and/or mixed crystalline phases.
All-solid lithium batteries are an attractive next-generation technology that use ion-conducting solids such as ..beta..-Li3PS4 (LPS) to enable use of a lithium metal anode, which increases theoretical capacity and widens the stable voltage window over traditional lithium-ion systems. These ion-conductive solids also provide increased safety by replacing flammable liquid electrolytes. Although solid-state electrolytes are significantly more stable and dendrite-resistant than traditional liquid electrolytes, lithium anodes in all-solid systems may nevertheless grow dendrites under high stress or repeated cycling, leading to short circuits and premature battery breakdown. For this reason, we study the formation and propagation of Li metal features within solid electrolytes using synchrotron-based X-ray tomography with in-situ current-voltage cycling supported by our custom sample platform. Our results demonstrate the ability of this technique to delineate different layers of the Li/LPS/Li structure with spatial resolution approaching 1 um. At this resolution, we are able to detect expansion of voids, especially in early stages of cycling. This expansion of voids is observed throughout the volume of the symmetric cells and visually resembles propagation of cracks resulting from interactions between the Li metal and pre-existing voids in the LPS electrolyte.
Alternative solution-based techniques such as aerosol jet printing offer the dual benefits of contactless pattern deposition and high material utilization. We have used aerosol jet printing to investigate non-contact printed Al metal ink as a replacement for screen printed Al back contacts on wafer Si solar cells. This particle-based ink can be prepared at high loadings of 60 weight % metal, which enables rapid deposition of 1 - 10 um thick lines. Al lines printed on Si wafers and heated between 550 and 800 degrees C form low resistance contacts suitable for current extraction. The effectiveness of these printed Al back contacts has further been demonstrated by incorporating them into a series of 21 cm 2 crystalline Si solar cells that produced a champion power conversion efficiencyof 13%.
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