Integrated By Design: An Investigation into Solid-State Battery Processing & the Elucidation of Reaction Mechanisms

Among the portable electronics market, Li-ion batteries remain the preferred choice for many applications, due to their high specific energy. However, current battery technologies have flaws associated with both their chemistries, manufacturing methods and architecture. Battery and device architectures are regularly kept as separate entities during product design, and only put together in the final design, unnecessarily increasing device footprint, costs and weight. Herein, we explore an alternative approach to these limitations, by developing an integrated battery antenna system. The three main components of the battery: the cathode, the electrolyte and the anode are investigated with an aim to design an all-solid-state flexible, wearable, body conformable antenna battery system.

Li2FeSiO4 is explored as a high capacity, environmentally benign cathode material. Utilizing in-operando XAS and ex-situ XRS to explore the origin of the materials' additional capacity associated with the removal of >1Li+ per unit formula. It is found that oxygen contributes, reversibly, as a charge compensation mechanism to the additional capacity.

A PEGDA based solid polymer electrolyte membrane (PEM) is explored as a high performance, high conductivity, flexible, stretchable and thermally stable alternative to liquid electrolytes. The PEM is found to be stable up to 4.7V vs Li/Li+ and yield a conductivity of 1.4x10-3Scm-1, which places it securely into the "superionic" region. For the first time, this system has been applied to a full-cell configuration, yielding strong

cycling performance throughout, with full-cell capacities reaching as high as 151mAhg-1at room temperature.

PEDOT:PSS is a mixed conductive polymer, assessed as a potential anode material. The material was deposited using three different techniques:(I) tape casting (II) spray-coating (III) inkjet printing. It was found that cycling performance was heavily dependent on the manufacturing technique employed. Inkjet printed, binder free films exhibited the greatest performance with capacities stable across all 50 cycles tested.

Finally, the PEDOT:PSS anode was incorporated into an on-body electronic device - an RFID antenna, utilizing the antenna architecture as a dual purpose component. The antenna powered by the integrated battery exhibited strong performance characteristics, matching those of a commercial coin cell battery.