Printed electronics has received attention in recent years as a technology for the realization of ultra-low-cost electronic systems, and also for the realization of electronics on flexible substrates. Proposed applications include RFID tags and embedded sensors. Given the interest in low-cost tags and sensors, there has been an upsurge in interest in printed batteries. Unfortunately, the cost of integrating conventional batteries into such systems is unacceptably high. What is needed, therefore, is a printed battery technology that is implementable at low cost and meets the performance needs of these applications. Conventional printed alkaline batteries do not provide the energy density required, while lithium cells are too expensive to integrate due their strong oxygen sensitivity. A battery technology that addresses these tradeoffs is required. In this work, the investigators are developing a novel printed battery technology based on a Zn/Ag-based silver oxide chemistry. Nanoparticle inks of the various metals and metal oxides required to fabricate a Zn/Ag battery are synthesized and printed using gravure printing and pneumatic dispensing. A printable cellulosic / polymer KOH electrolyte is printed as an electrolyte / separator layer. Based on promising initial results, extensive optimization of materials and printing processes are being used to realize a primary cell with energy density on par with state of the art lithium cells, but with the manufacturability and low cost of more conventional alkaline cells. The entire cell is printed on plastic, thus enabling direct integration into low-cost printed electronic systems.
In this project, we have developed a novel printed battery based on a silver-zinc chemistry. Numerous applications require small form-factor batteries, including various sensing and tagging applications. Conventional thin film lithium batteries suffer from drawbacks in this regard, since lithium is highly oxygen sensitive. As a result, lithium cells have to be processed in inert environments, are susceptible to explosion, and have to be encapsulated carefully. In particular, for small cells, this results in degraded energy density, since a significant fraction of the cell is encapsulation. In this project, to address these shortcomings, we have developed a novel printed silver zinc battery. Silver zinc is attractive since it is air-stable and delivers high energy density. We have developed materials and processes to realize all the components of a printed silver zinc battery, and have printed these to realize a cell with energy density higher than the best reported thin film lithium cells. All layers have been developed to be solution-processable and printable, thus allowing for realization of a very low-cost cell architecture. The overall cell shows good energy density in an air-stable configuration, and is fully-printed. This makes it attractive for a wide range of applications requiring small form-factor, energy-dense batteries such as numerous evolving sensing and smart tagging applications.
