Physical–Chemical Hybrid Transiency: A Fully Transient Li-Ion Battery Based on Insoluble Active Materials Yuanfen Chen, 1 Reihaneh Jamshidi, 1 Kathryn White, 1 Simge C¸ınar, 1 Emma Gallegos, 1 Nastaran Hashemi, 1 Reza Montazami 1,2 1 Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 2 Ames National Laboratory, Department of Energy, Ames, Iowa 50011, USA Correspondence to: R. Montazami (E - mail: reza@iastate.edu) Received 25 February 2016; accepted 23 May 2016; published online 22 June 2016 DOI: 10.1002/polb.24113 ABSTRACT: Transient Li-ion batteries based on polymeric constitu- ents are presented, exhibiting a twofold increase in the potential and approximately three orders of magnitude faster transiency rate compared to other transient systems reported in the litera- ture. The battery takes advantage of a close variation of the active materials used in conventional Li-ion batteries and can achieve and maintain a potential of >2.5 V. All materials are deposited form polymer-based emulsions and the transiency is achieved through a hybrid approach of redispersion of insoluble, and disso- lution of soluble components in approximately 30 min. The pre- sented proof of concept has paramount potentials in military and hardware security applications. V C 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2021–2027 KEYWORDS: colloids; degradation; hybrid transiency; Li-ion bat- tery; physical–chemical transiency; swelling; transient batteries; transient electronics INTRODUCTION Unlike conventional electronics that are designed to last for extensive periods of time, a key and unique attribute of transient electronics is to operate over a typically short and well-defined period, and undergo fast and, ideally, complete self-deconstruction and vanish when transiency is triggered. Transient electronics have a wide range of potential applica- tions including those in healthcare, biomedical devices, envi- ronmental sensing/monitoring, green electronics, military and homeland security, to name a few examples. In the very recent years, researchers have developed a wide range of transient electronic devices capable of performing a variety of functions and responsive to a variety of triggering mechanisms including exposure to light, 1 heat 2 or solvent (often aqueous). 3–7 What is common among all these reported transient devices is the need for an external power source. The power is either sup- plied by inducting coils from a very close distance, 8 or from external power supplies. 2 To realize autonomous transient electronic devices, similar to conventional ones, a transient battery is essential. Thus far, there has been limited efforts in design and construction of transient batteries, mainly due to the lack of soluble proper materials. Jimbo et al. reported swal- lowable batteries based on Zn and Pt electrodes and ceramic porous separator; maximum potential of 0.42 V and current of 2.41 mA were achieved. 9 More recently, Kim et al. reported edible water activated sodium batteries based on melanin electrodes where a potential of 0.6–1.06 V and current of 5–20 lA, depending on design, was achieved. 10,11 An intrinsically transient battery capable of environmental resorption was first reported by Yin et al. where Mg anode and biodegradable met- als (Fe, W, or Mo) cathodes were used with a transient polymer casing; potentials ranging from 0.45 to 0.75 V (depending on cathode materials) were reported. 12 To date, all reported tran- sient batteries have shortcomings compare to their conven- tional counterparts; uncompetitive potential, current, stability and shelf life are among the top challenges in construction of a practical transient battery that can supply enough power to run a common electric circuit. The low potential and power density in transient batteries are mainly due to the use of non- optimal electrode materials because of their solubility. One other significantly important limitations of transient batteries reported to date is low transiency rate, which is a result of slow chemical reactions between the constituent materials and the solvent. High transiency rates are specially anticipated in military and hardware security applications. To design a transient battery capable of supplying enough power and undergoing fast transiency, new approaches toward the materials and structural design are necessary. Lithium-ion battery technology is a well-established, mature, and commercialized technology; here, we are integrating a variation of this technology with our new approach toward Additional Supporting Information may be found in the online version of this article. V C 2016 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM JOURNAL OF POLYMER SCIENCE, PART B: POLYMER PHYSICS 2016, 54, 2021–2027 2021 JOURNAL OF POLYMER SCIENCE WWW.POLYMERPHYSICS.ORG COMMUNICATION