Prussian Blue Analogue (PBA)-Zn aqueous batteries are attractive because of the high potential of PBA against Zn (~1.7 V), relative safety of the system, and high rate capability. But, despite the long cycle life of PBA half-cells, full PBA-Zn battery systems studied thus far have typically reported only up to 100 cycles and suffer significant capacity fade beyond that. In this work we demonstrate that the loss in capacity retention and cycle life is a combined effect of Zn 2+ ion poisoning at the PBA cathode, as well as dendrite formation in the zinc anode. We address both these issues via the use of a dual ion (Na + as the primary charge carrier) electrolyte and hyper-dendritic Zinc (HD Zn) as the anode. The copper hexacyanoferrate (CuHcf) vs. HD Zn system with Na + ion electrolyte demonstrated herein exhibits 90% (83%) capacity retention after 300 (500) cycles at a 5C rate and a 3% reduction in usable capacity from 1C to 5C. Detailed characterization is done using in situ synchrotron energy-dispersive XRD (EDXRD), conventional XRD, XPS, SEM, TEM, and electrochemical techniques.

This study investigates the evolution of material and electrochemical properties in commercial lithium-ion batteries during cycling. Results indicate that as-received batteries undergo a post-formation break-in period, which is signified by an initial, rapid evolution of the battery's properties before stabilizing. Break-in corresponds to non-chemical crosstalk, whereby physical changes in the negative electrode affect the electrochemical performance of the positive electrode. These findings demonstrate how interplay between components during early cycles can affect the future battery performance.

In this work we build upon acoustic-electrochemical correlations to investigate the relationships between sound wave structure and chemo-mechanical properties of a pouch cell battery. Cell thickness imaging and wave detection...

Safety of lithium ion batteries (LIBs) has been a primary concern since their first appearance in commercialized products [1]. Abusive conditions such as over-charging/discharging, overheating, and internal short circuit lead to gas evolution and mechanical expansion in LIBs, and result in transformations to electrode morphology [2]. These changes potentially negatively impact electrochemical performance and even the safety characteristics of LIBs [3]. Here, we studied the use of an in-house transmission X-ray microscope (TXM) to visualize mechanical expansion and degradation of electrode stacks during the abusive cycling of LIBs [3, 4]. We also characterized the capacity fade of LIBs with Electrochemical-Acoustic Time-of-Flight (EAToF) [5] and electrochemical impedance spectroscopic (EIS) measurements.

Flexible, wearable electronics are starting to reach mass consumer markets but an adequate solution to power these devices remains a challenge. The size constraints in traditional mobile devices impose a premium on high energy density batteries to capitalize on limited space. These energetically dense systems often require bulky, rigid casings for robust protection against fire and chemical hazards. Thus we target energy storage in textiles, where size constraints are less stringent, battery real estate is scalable to requirements, and safer materials may be used. We demonstrate a zinc/Prussian blue analog battery on a thread/fiber architecture that can be woven into clothing/textiles. First, we show a cell that consists of a copper hexacyanoferrate (CuHcf) cathode dyed or coated on to conductive carbon fibers and a counter zinc electrode, suspended in a sodium-rich agarose hydrogel electrolyte at neutral pH. Agarose is a seaweed based gel known to conduct ions such as Na+. We introduce sodium salt loaded agarose gels as a potential high rate battery electrolyte.  Preliminary charge/discharge tests of the 1.7 V cells in a flooded 2 cell setup show an initial specific discharge capacity of 51 mAhr/g of CuHcf, and 43 mAhr/g after 25 cycles. Further optimization is likely to improve cycle life significantly. Next, we demonstrate simple woven structures with CuHcf and Zn coated threads with Agarose/Na+ electrolyte as a proof of concept towards realizing wearable and washable electronics. We characterize the physical properties of the fiber electrodes and gel electrolyte with SEM, stress loading, and washing with sodium salt based laundry detergents. A range of electrochemical characterization is performed on the woven structures to analyze their cycle life, energy and coulombic efficiencies and specific capacities.

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In recent years Prussian Blue Analogues (PBA) have attracted a lot of interest as a battery material due to their relative safety to skin contact and exceptionally high cyclability. Their open cage structure allow a variety of ions to shuttle in and out and thus store energy. This can be done very rapidly as there is no phase change associated with this process, which makes them stable for over thousands of cycles.(Pasta et al. 2012) Recent developments in this field show the use of zinc to act as the anode, which can exhibit a PBA vs. Zn cell potential as high as 1.7 V. But the performance of such a system reported thus far show less than 10% cycle life as that of  highly reversible PBA half cells. (Zhang et al. 2014) In this work we demonstrate a high potential aqueous Sodium ion battery with high cycle life, to achieve as much as 500 cycles with over 80% cell capacity retention, which is five times of the maximum reported in literature. (Trócoli and La Mantia 2015)The high potential of Zn and high reversibility of Na+ ion cycling in Copper Hexacyanoferrate lattice is exploited in making a considerable improvement over previous Zn/ Zinc Hexacyanoferrate system. We validate the hypothesis that the slow kinetics of zinc intercalation compared to sodium in Hexacyanoferrates enables preferential intercalation of sodium ions and hence reduce zinc poisoning. We further show the use of Hyper Dendritic Zinc (HD Zn) to improve capacity retention and overall kinetics of the system. Prussian Blue has been used as a fabric dye for over 80 years. The relative safety of the dual ion PBA/HD Zn system that we demonstrate helps us step closer to realizing batteries on fibers woven integrated with wearable electronics.

Integrating energy storage into clothing would enable wearable electronics of a more comfortable form factor and weight distribution compared to traditional rigid cells. Work on LTO vs LCO systems by previous groups have demonstrated the material system’s ability to be flexed or produced with scalable methods. In this work we report a low-cost automated fabrication setup to produce flexible LTO/LCO batteries on carbon fiber substrates. The modular thread-coating system reported here takes advantage of cheap Arduino microcontrollers and 3D printed structures for a highly customizable design allowing for rapid prototyping of different material systems. In this particular setup, a stepper motor pulls a fiber through a series of 3D-printed stages where the fiber substrate is subjected to slurry deposition, washing, heating or packaging to produce a functional LTO/LCO battery. The modular system serves as a useful intermediary between initial lab scale research— in which artisanal manual skills are often required from the researcher— and the industrial production process— in which automation and high throughput are paramount. The modular intermediary allows one to mimic mass production at a lab scale to identify challenges and solutions to scaling up a battery architecture for wide use.