Continuous novelty as the basis for creative advance in rapidly developing different form-factor microelectronic devices requires seamless integrability of batteries. Thus, in the past decade, along with developments in battery materials, the focus has been shifting more and more towards innovative fabrication processes, unconventional configurations, and designs with multi-functional components.We present here, for the first time, a novel concept and feasibility study of a 3D-microbattery printed by fused-filament fabrication (FFF). The reversible electrochemical cycling of 3D printed lithium iron phosphate (LFP) and lithium titanate (LTO) composite polymer electrodes vs. the lithium metal anode has been demonstrated in cells containing conventional non-aqueous and ionic-liquid electrolytes. We believe that by using comprehensively structured interlaced electrode networks it would be possible not only to fabricate free form-factor batteries but also to alleviate the continuous volume changes occurring during charge and discharge.

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Printed secondary batteries have market potential in two main fields -highly customized personal electronic devices, and smallscale battery production. While many different technologies may be utilized to produce a printed battery, drop-on-demand (DoD) dispensing has the advantage of being highly tailor-made, notably with the ability to produce both very thin and thick batteries. We report the cathode printing protocols, morphology and electrochemical properties of patterned electrodes. Our electrode inks are aqueous, with obvious environmental and processing benefits. We chose to study the lithium iron phosphate (LFP) cathode because of its excellent electrochemical performance. DoD-printed LFP cathodes exhibit close to theoretical capacity value, highrate capability and close to 100% coulombic efficiency. The similarity of the voltage profiles, electrochemical performance and impedance components of the AC spectra of lithium cells with printed LFP cathodes to those of commercial electrodes, indicates that printing does not alter the charge/discharge mechanism of active electrode material.

Here, we studied for the first time the kinetics of the chemical reactions between oxide-free silicon and electrolytes and the composition and morphology of the surface film formed during these reactions. We found that the kinetics of these reactions is swift; a few nm passivating film is formed during a few milliseconds and a complete passivation takes place in about 30 seconds. XPS study show a passivating film consisting of large organic molecules or polymers containing C-O, C=O, C-F x and O-C-F moieties, SiF x , SiO x F y , some SiO 2 and small amounts of LiF. Containing only traces of Li, it cannot serve as an SEI and may lead to lesser uniformity of the SEI formed on top of it.

It has long been recognized that silicon, with a gravimetric capacity of nearly 11 times that of graphite, better safety and abundance, is the most obvious choice for the next-generation anode for lithium batteries. Silicon particles, in the anode, are covered by a thin oxide film which stops, or significantly slows, the reaction with oxygen in the air. During cell assembly, the silicon anode may react spontaneously with the electrolyte. The goal of this work was to study the spontaneous reaction between oxide-covered silicon with lithium-battery electrolytes, the kinetics of the reactions and the composition and impedance of the film formed. The passivating film has a very high impedance, it consists of polymers containing C-O, C=O, C-F x and O-C-F moieties, SiF x , SiO x F y , some SiO 2 and LiF. It was concluded that cells containing silicon anodes should be charged as soon as possible after electrolyte-filling to create a less resistive and more stable SEI that will slow further reaction of the silicon anode with the electrolyte.

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The focus on shifting towards miniaturized products coupled with the booming demand for consumer electronics are some of the key-driving factors behind the flexible-battery market. In the development of innovative power sources, freeing from design limitation along with the synthesis of reliable electrochemical materials with well-tuned features, is considered to be the most important technical prerequisite. In the current research we present for the first time, a unique, single-step method for the preparation of a membrane-electrode assembly for flexible-batteries application. Concurrent electrophoretic deposition (EPD) of positive and negative battery electrodes (LFP and LTO) on opposite sides of a commercial nanoporous membrane (Celgard 2325) results in the formation of a three-layer-battery structure. The cell comprising this electrophoretically deposited structure ran for more than 150 cycles with 125-140mAh/g capacity, which approaches the theoretical value of lithium iron phosphate. The electrodes can be deposited either cathodically or anodically by replacing the interchangeable charging agents, like polyethyleneimine and polyacrylic acid. These polyelectrolytes, when adsorbed on the particles of the active material, serve also as the binders. The simultaneous EPD, which we developed, can be used for the simple and low-cost manufacturing of a variety of cathode and anode materials on nanoporous polymer- and ceramic ion-conducting membranes for energy storage devices

The increasing demand for multifunctional portable/wearable electronic devices, including wireless sensors and implantable medical devices is continuously growing. Such devices need rechargeable batteries with dimensions on the scale of 1–10 mm3 (few to tens mm2 footprint area of substrate) including all the components and all the associated packing. Thus, in the past decade, along with the developments in battery materials, the focus has been shifting more and more towards innovative fabrication processes, unconventional configurations, and designs with multi-functional components. 3D printing technologies enable a well-controlled creation of functional materials with three-dimensional architectures, representing a promising approach for fabrication of next-generation electrochemical energy storage (EES) devices with high performance due to a higher electrode/electrolyte interfacial area. In this work, we demonstrate a novel design and a novel approach of 3D printing of batteries of different shapes and size by using filaments composed of active electrode materials bound with polymers. The electrodes were printed by fused-filament fabrication (FFF) method. We demonstrated a reversible electrochemical cycling of 3D printed lithium iron phosphate (LFP) and lithium titanate (LTO) composite polymer electrodes vs. lithium metal anode with high performance and capacity in cells containing both conventional non-aqueous and ionic-liquid electrolytes. In addition, the development and fabrication of a novel 3D-printed solid-state or quasi-solid electrolyte by FFF has been accomplished. The electrolytes are composed primarily of polyethylene oxide (PEO) and polyethylene glycol (PEG) which are known ionic conductors, and polylactic acid (PLA) for enhanced mechanical properties and high temperature durability. Our research introduces novel thick-layer 3D batteries, thus reducing cost related to high mass loading per battery footprint of smart 3D structures with the help of low-cost fabrication method. References [1] H. Ragones et al. "Towards smart free form-factor 3D printable batteries." Sustainable Energy & Fuels 2.7 (2018): 1542-1549. [2] H Ragones et al. On the Road to a Multi-Coaxial-Cable Battery: Development of a Novel 3D-Printed Composite Solid Electrolyte Journal of The Electrochemical Society 2019 ,167 (7), 070503.