bluuebunny/crossref_metadata_2025 huggingface dataset:
Layered-to-Spinel Phase Transformations Inhibited By ALD Coatings on NMC Cathodes to Mitigate Voltage Fade in Lithium-Ion Cells
Authors: Dahlberg Kevin , Mohanty Debasish , Lee Myongjai , Anderson Erik , Mahajan Vishal , Stanley Joel , King David M , Wood David L , Albano Fabio
Published: February 2020

Low cost, high energy and long cycle life Lithium-ion batteries are the technology of choice widespread implementation of high-performance electric vehicles (EVs). In spite of the strides technology has made, current high energy density solutions suffer from well understood and catastrophic degradation mechanisms that have prevented to full fruition of lithium- and manganese-rich NMC cathode materials. Capacity, power, and voltage fade, excessive SEI growth, electrolyte oxidation, cathode dissolution, structural degradation, and phase transformations are only few of the mechanisms that have been identified. Layered-to-spinel phase transformations at high voltages (~4.8 V), are a main contributor to voltage fade in LMR-NMC-based batteries. Here we show that TiO2 and Al2O3 atomic layer deposition (ALD) coatings applied to NMC powder, conformally coating active material particle surfaces, create a cathode artificial SEI layer which alters and slows the chemical pathways for nucleation and propagation of layered-to-spinel phase transformations at high voltages. XRD, TEM, and magnetic susceptibility characterization of active materials before cycling and at end of cycle life in 95x64 mm pouch cells (~2.5Ah) showed decreased extent of phase transformation with coated NMC compared to uncoated. XALT Energy’s integrated cell design and manufacturing makes 95x64 mm cell performance representative of large format (216x216 mm) production EV cells, demonstrating the validity and scalability of this approach.
Effect of Crosslinking of Guar Gum As a Bio-Derivative Binder for Negative Electrodes of Lithium-Ion Batteries
Authors: Choi In-Yeong , Lee Ji-Eun , Oh Eun-Suok
Published: February 2020

Nowadays, large-sized lithium-ion batteries (LIB) for electric vehicles (EV) and energy storage systems (ESS) require extraordinary long-cycled, high-powered, and high-capacity, when compared to small-sized LIBs for mobile devices. In addition, it is also necessary to actively respond to environmental problems by applying green materials.

From our previous results, guar gum binders, branched polysaccharides, facilitated the transport of lithium ions in Li4Ti5O12(LTO) electrodes than conventional carboxymethyl cellulose (CMC) binders, linear polysaccharide, even though their adhesive strength were not as strong as CMC[1]. Unlike polyvinylidene fluoride (PVdF), guar gum binder was soluble in water, thus allowing the LIB manufacturing process to be environmentally friendly.

In this study, we investigate the effect of crosslinking of the guar gum binder on their mechanical properties in the LTO electrodes. To evaluate the effect of these crosslinking, a variety of physical and electrochemical characterization are applied.

Reference

1. Bo-Ram Lee, So-Jin Kim and Eun-Suok Oh, Journal of the Electrochemical Society, 161, A2128-A2132  (2014)
High Performance Pillared Vanadium Oxide Xerogel Cathode for Lithium Ion Batteries
Authors: Hawthorne Krista L , Tung Siu on , Mainero James , Ding Yi , Thompson Levi T
Published: February 2020

Lithium ion batteries commonly utilize layered oxide materials as the cathode, where lithium is intercalated and deintercalated between the layers in the crystal structure during cycling. The repeated lithium insertion and extraction can cause stress on the material, leading to fracture. Additionally, the extent of lithiation may cause phase changes in the layered structure that are sometimes irreversible. These changes to the material cause capacity loss and reduce the battery cycle life. This research focuses on nanostructuring layered oxides to enhance their cyclability and power capabilities. In particular, vanadium oxide xerogels were modified by adding pillaring molecules between the layers to increase the interlayer spacing. Vanadium oxide xerogels possess attractive capacities but suffer from significant capacity fade due to distortion of the crystal structure. We hypothesize that the pillars will enhance thermal and mechanical stability by reducing the strain on the structure and increasing lithium ion mobility, thereby increasing the cycle life and high rate capacities.

Aluminum Keggin ions were used as pillaring agents for the vanadium oxide xerogels. X-ray diffraction showed an interlayer spacing increase from 1.14 to 1.32 nm after pillaring, consistent with the size of the keggin ions (~1.3 nm), while still maintaining the layered V2O5 xerogel crystalline structure (Figure 1). Elemental analysis indicated an aluminum loading of 9 wt% in the pillared material. The pillared materials also demonstrate increased thermal stability and rate capabilities during cycling in coin cells, with capacities over 60% higher than those of the unpillared V2O5 xerogel. Additionally, the pillared materials retained more capacity during cycling at C/2. Pillaring the layered vanadium oxide xerogels improved both capacity retention and battery lifetime.

Figure 1.  Diffraction patterns for V2O5 xerogel (a), pillared V2O5 xerogel (b), and pillared V2O5 xerogel after heat treatment in either air (c) or nitrogen (d). The dotted line is intended as a guide for the eye.

Figure 1
Lithium Iron Phosphate Nanosheet Nests As Cathode Material for Li-Ion Batteries
Authors: Wainright Robert John , Ramasamy Ramaraja P.
Published: February 2020

Nano Electrochemistry Laboratory, College of Engineering, The University of Georgia, Athens, GA 30602.

Lithium-ion batteries are the current state-of-the-art energy storage technology for advanced electric vehicles and portable power applications due to their high energy density. The need for low cost lithium ion batteries has driven the development of inexpensive LiFePO4 cathodes, which offer a relatively high specific capacity (170 mAh·g-1) and relatively high discharge potential plateau (3.45 V) at a fraction of the cost of other materials. In additional to the low electrical conductivity, one of the major drawbacks of this material is the inherently slow lithium diffusion. Unlike spinel or layered structures, the olivine structure of LiFePO4 allows lithium diffusion in only one direction and therefore severely limits the intercalation rate due to slow solid-state diffusion. This limitation could be overcome by de-sizing the material in the < 010 >, the direction of diffusion. This can be achieved by synthesizing LiFePO4 nanosheet nests (LFP-NSN) using a directed growth method adapted and modified from a synthesis procedure reported earlier.1 Figure 1 shows the scanning electron microscopy (SEM) image of the LFP-NSN synthesized by our modified procedure.  Figure 2 shows the X-ray diffraction (XRD) pattern of the synthesized LFP-NSN, which compares well with the XRD pattern of orthorhombic, olivine-type LiFePO4 from the library.  For battery testing, the synthesized structures were mixed in a ratio 80:10:10 of LFP-NSN: Super C carbon: poly(vinylidine fluoride) in N-methyl pyrrolidone to form a slurry that was cast on aluminum foil to be used as the cathode in CR2032 lithium ion coin cells for testing and evaluation.

Fig. 1: a) SEM image and b) XRD pattern (black) with LiFePO4 characteristic peaks identified in red of LFP-NSN synthesized by a solvothermal reaction.

Acknowledgements:

The authors would like to thank Dr. Tina Salguero and Dr. Zhengwei Pan for their help in this project.

* Corresponding Author: rama@uga.edu

Reference:

1. Y. Zhao, L. Peng, B. Liu and G. Yu, Single-Crystalline LiFePO4 Nanosheets for High-Rate Li-Ion Batteries. Nano letters
2014,
14, 2849-2853.

Figure 1
High Capacity Hybrid Si-SWCNT Anode Structures for Li-Ion Batteries
Authors: Bobrenok Oleg , Kosolapov Andrew , Shchukin Victor , Sharafutdinov Ravel , Predtechensky Mikhail , Tikhonov Konstantin , Notman Konstantin
Published: February 2020

In this presentation we describe structure, synthesis routes and electrochemical performance of hybrid Si-SWCNT composites developed by our team. We have investigated several approaches to the design of the silicon anodes to accommodate volumetric changes during charge and discharge of Si active material. Mass-produced single wall carbon nanotubes (SWCNTs) were used as a structural component in the 3D electrode matrix to provide mechanical support and conductivity path to deposited Si nano-beads. In other structures, layers of  SWCNT acted as a cushion accommodating volumetric changes of Si layers. Initial capacity of 2500mAh/g was achieved with good capacity retention up to 300 cycles. Advantages and shortcomings of several Si-SWCNT anode designs will be discussed.
Ternary Type I Silicon Clathrates for Lithium-Ion Battery Anodes
Authors: Li Ying , Chan Candace K.
Published: February 2020

Silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba8AlySi46-y as the anode material for lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li (~1 Li/Si) into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from large volume changes. The electrochemical reactions are proposed to occur as single phase reactions at approximately 0.2 and 0.4 V vs. Li/Li+ during lithiation and delithiation, respectively, distinct from diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g-1 at a 5 mA g-1 rate were observed for silicon clathrate with composition Ba8Al8.54Si37.46, corresponding to ~1.18 Li/Si. These results show that silicon clathrates could be promising durable anodes for lithium-ion batteries. Changing the composition of the clathrate, namely replacing the Ba guest atom and Al framework substitution with other metals, was found to have a strong effect on the number of Li reversible inserted into the structure. The cycling performance of the clathrate electrodes in different liquid and solid electrolytes will also be presented.

Reference:

Y. Li, R. Raghavan, N.A. Wagner, S.K. Davidowski, L. Baggetto, R. Zhao, Q. Cheng, J.L. Yarger, G.M. Veith, C. Ellis-Terrell, M.A. Miller, K.S. Chan, C.K. Chan, Advanced Science, DOI: 0.1002/advs.201500057, (2015).
Mineral-Inspired, Nanostructured Polyanion Materials for Rechargeable Battery Electrodes
Authors: Zhao Ran , Li Ying , Chan Candace K.
Published: February 2020

Polyanion materials are promising candidates for new rechargeable battery electrodes due to their good capacity, operation voltage, safety characteristics, as well as low cost. A family of materials based on metal hydroxysulfate or hydroxyphosphate naturally occurring minerals offers the possibility for improved performance as cathode materials due to the following characteristics: (1) open framework or layered structures that can facilitate fast Li+ insertion, (2)  flexibility in alkali and transition metal cation incorporation as observed in nature, which can allow for the design of solid-solutions to enhance structural stability, capacity, and reaction potentials, and (3) possibility for multi-electron redox reactions, which can result in capacities >200 mAh/g. This presentation will introduce our investigation into nanostructured brochantite and jarosite minerals for use as electrodes in Li-ion and Na-ion batteries.

The electrochemical properties of brochantite, Cu4(OH)6SO4, a natural mineral and patina constituent on the Statue of Liberty, were investigated. Nanostructured brochantite was synthesized using precipitation and microwave-assisted hydrothermal reactions and evaluated in half-cells with Li metal counter electrodes. Reversible capacities >400 mAh/g corresponding to the 2 electron reduction of Cu2+ and discharge potential of 1.8 V versus Li/Li+ were observed in brochantite with a nanoplate morphology.

The electrochemical properties of the jarosite and V3+ jarosite analogue compounds, MN3(SO4)2(OH)6, where M=K, Na and N=Fe, V, were also investigated. A common industrial mining waste byproduct and naturally occurring mineral on Earth and Mars, the jarosite structure can accommodate many different cations and may serve as a good starting point for developing cathodes for batteries beyond Li-ion. Microstructured jarosites were synthesized using microwave-assisted hydrothermal reaction and the electrochemical characteristic were evaluated in half-cells with Li and Na metal.

Detailed characterization using X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy was performed to better understand the structural changes and reaction mechanisms in both brochantite and jarosite systems.

Reference:

R. Zhao, T. Yang, M.A. Miller, C.K. Chan, Nano Lett., 13, 6055 – 6063 (2013).
Operando high-Energy Synchrotron X-Ray Diffraction and Modeling of Alpha-MnO2 Battery Materials upon Heat Treatment
Authors: Yang Zhenzhen , Chan Maria K. Y. , Ren Yang , Johnson Christopher , Thackeray Michael M.
Published: February 2020

Hybrid Li-ion/Lithium-O2 batteries offer extremely attractive theoretical energy densities and therefore represent a rapidly emerging area of research. Our research has focused on developing dual-functioning metal oxides electrode/electrocatalyst materials that can lower the charge hysteresis and potentially impact the nature of the discharge products. Specifically we have synthesized and characterized the transition metal oxide, α–MnO2, which has a hollandite-type structure with relatively large, one-dimensional (1-D) ‘2x2’ tunnels formed by the connection of octahedral [MnO6] units, operates as a superior electrode/catalyst in hybrid Li-ion/Li-O2 cells. α–MnO2 generally contains 2~3% of lattice water in the crystal structure, which stabilizes the structure and dramatically influences not only electrochemical properties but also other properties such as density and electronic conductivity. The water can be removed from α-MnO2 framework by heat treatment without degradation of the structure, and then partially replaced by Li2O. The Li2O-doped alpha-MnO2 electrodes, stabilize the structure and provide higher capacities on cycling than the parent material. However, the structure changes of hydrated and dehydrated MnO2 related with electrochemical properties has not been clarified yet.  Herein we report operando temperature-resolved high energy X-ray diffraction experiments performed on alpha-MnO2 electrodes. The data provides evidence that the crystal structure of α-MnO2 undergoes reversible changes in lattice parameters and strain during heating and cooling. Insights into reversible changes of tunnel structure of MnO2 with H2O/H3O+, as determined by first principles density functional theory calculations, are used to provide a possible explanation for some of the observed results. With the help of the proposed technique, we are expecting to understand the water removal and insertion into MnO­2 and generate knowledge on how to improve the sustainability in the practical usage of α-MnO2 as Li and oxides capture medium for hybrid Li-ion/Li-O2 cells.
(Invited) Ti-Substituted Li[Li0.26Mn0.6-X
Ti
x
Ni0.07Co0.07]O2 Layered Cathode Material with Improved Structural Stability and Suppressed Voltage Fading
Authors: Yu Zhaoxin , Shang Shunli , Mousharraf Adnan , Liu Zi-Kui , Wang Donghai
Published: February 2020

The Lithium ion batteries (LIBs) with intercalated cathodes, such as LiCoO2 and LiFePO4, have achieved great success in portable electronic devices. However, they are unsatisfied for the stationary grid storage and electrical vehicles due to their low specific capacity (<160 mAh/g). Recently, Lithium- and Manganese-rich layered oxide cathode has attracted great interest due to its high theoretical specific capacity (~ 240 mAh/g) and high working voltage. However, its real practical application is highly hindered by its poor structure stability and severe voltage fading, which is caused by Mn ion migrating to adjacent lithium ion layers, forming spinel structure. Here, we report Titanium (Ti) substituted Li- and Mn-rich cathode material (Li[Li0.26Mn0.6-xTixNi0.07Co0.07]O2) through a facile co-precipitation approach. Ti substitution greatly extends the cathode’s cycling life and weakens the voltage fading. Taking the advantage of first-principles analyses of the cohesive energy, phonon force constants, and charge density of these materials, it indicates that Ti substitution increases the stability of the layered structure and prevents Mn ions migration from transitional metal layer to adjacent lithium ion layer. Taking the facile preparation process and much enhanced electrochemical performance into account, it would be of significant interest for scalable fabrication for rechargeable lithium battery.
Biwedge Octahedron-Shaped Li-Excess Nickel-Manganese Oxide Cathode Showing Remarkably Suppressed Potential Fade
Authors: Wu Nae-Lih , Chen Wen-Chin , Wu Hung-Chun
Published: February 2020

Li-ion batteries (LIBs) are foreseen to play a very important role in energy storage for the next decade. Research for advanced Li-ion secondary batteries has been following the direction toward higher energy and power densities. Various cathode materials, such as LiCoO2, LiMn0.33Ni0.33Co0.33O2, spinel LiMn2O4,olivine LiFePO4, and Li1+x(M,Mn)1-xOy, having different or similar lattice structures have been developed. Among these materials, the class of layered Li-rich Mn-transition metal oxides (Li1+x(M,Mn)1-xOy) has lately drawn escalated attention due to their potential high capacities beyond 200 mAh/g. In these oxides, the excess Li ion gives rise to the presence of inter-grown Li2MnO3 slabs within Li(M,Mn)O2 matrix to form a layered “composite” structure. These Li2MnO3 slabs may be transformed to electrochemical active MnO2 layers by removal of Li+ upon charging above 4.5 V (versus Li/Li+) and stabilizing the layered structure under high depth of lithiation/de-lithiation during the charge/discharge cycles. During charge and discharge process,  the layered composite suffers from the well known phenomena of potential fade. The potential fade has been attributable to the migration of the transition metal ions, notably manganese and nickel, into the lithium layers, causing slow transformation to a spinel-like domain within the crystal lattice. The fade results in gradual loss in energy capacity of the electrode.

In this study, a biwedge octahedron-shaped Li1+x(M,Mn)1-xOy powder has been synthesized via a oxalate-based precipitation process followed by high-temperature calcination. The resulting powder shows a large aspect ratio with a width near 10 μm and a thickness of a couple of μm. The large width allows for high powder tap density, while the small thickness enables fast charging-discharging kinetics. More importantly, in either full-cell or half-cell testing, the resulting oxide electrode showed essentially no potential fade after several hundred cycles. The synthesis process and the material and electrochemical characterization results will be presented.

 

Figure 1
Micron-Sized a-Silicon-Fe-Cu Ternary Composite Anode Material for High Energy Libs
Authors: Chae Sujong , Cho Jaephil
Published: February 2020

To realize the high energy LIBs, extensive studies for silicon anodes have been widely carried out for recent years in order to succeed in commercialization through overcoming its intrinsic problems of low coulombic efficiency and severe capacity degradation upon cycling as results of large volume expansion, low conductivity and lithium diffusivity. Herein, we suggested a sophisticated structure of silicon-based ternary alloy composite with a scalable series of processes by synthesizing high density micron-sized secondary particles comprising of metal silicide and amorphous silicon primary particles (~100 nm). This silicon-based ternary alloy composite, whose reversible specific capacity is 1300 mAh/g with 85% coulombic efficiency at 1st cycle, shows not only great cycling stability with 84% retention at 0.5 C after 100th cycles but also high rate capability with 91% of capacities retention at 7C (vs. 0.2C). These remarkable electrochemical properties come from a-silicon characteristics and formation of either Fe-Si or Cu-Si alloys with reactions of a-Si, leading to improve the structural integrity with porosity. This silicon-based ternary alloy composite have also succeeded in increasing the tap density as high as 0.8 g/cm3. Furthermore, the electrode was swollen only 42% after 100th cycles. In these regards, the silicon-based ternary alloy composite will contribute to the progress of practical use of silicon anode for next generation LIBs.
Identification of Multiple Failure Mechanisms in Si-Based Electrodes for Li-Ion Batteries
Authors: Beattie Shane D , Loveridge Melanie , Polzin Bryant J , Lain Michael J , Rubio Irene
Published: February 2020

Identification of multiple failure mechanisms in Si-based electrodes for Li-ion batteries

Silicon (Si) electrodes are often studied as an alternative to graphite for negative electrodes in Lithium-ion (Li-ion) battery technology due to their high theoretical specific and volumetric capacity (3579 mAh/g and 2190 mAh/cm3respectively).  Although encouraging theoretically, practical silicon electrodes exhibit relatively low cycle efficiency, causing capacity to drop quickly as a function of cycle number. There are numerous factors which conspire to reduce cycle life in silicon electrodes.  Eight of the most important factors to consider are:

1)                  Evolution of the voltage profile to higher charge voltages as a function of capacity/cycle number and the effect on cycle efficiency  (Figure 1)

2)                  Large expansion during lithiation (up to 280%)

3)                  Delamination from the current collector as a function of cycle number (Figure 2)

4)                  Instability of the Solid Electrode Interphase (SEI) due to large volume expansion

5)                  Instability of the electrolyte with lithiated silicon (Figure 3)

6)                  Excessive gassing due to electrolyte decomposition

7)                  Continued growth of electrode thickness as a function of cycle number

8)                  High porosity and therefore low volumetric energy density

This communication will present data exemplifying each of the failure mechanisms above.

In addition, the use of a Raspberry Pi to collect data for some of the experiments above will be discussed (Figure 3).

Figure 1
A New Design and Fabrication of Si-C Composite for Lithium-Ion Batteries Anodes
Authors: Ogata Ken , Takei Koichi , Lee Byoung-Sun , Lee Kang Hee , Yu Tae-Hwan , Doo Seokgwang
Published: February 2020

For the last few decades, nano-structured silicon anodes are expected to be alternatives to graphitic carbons in rechargeable Li-ion batteries, owing to their extremely high capacities [1,2]. Despite the recent intensive studies with a variety of elaborated nano-Si materials, major use of Si in the anode, i.e. with higher Si wt% in graphite, is still limited. This is due to numerous and entangled issues, the most basic being the complex kinetics and thermodynamics that control the reactions and the huge structural rearrangements, which we have previously elucidated [3]. Based on our previous findings, in this study, we have re-designed and fabricated Si-C composites with scalable methods that can intrinsically overcome the fundamental degradation issues, correlating its electrochemical properties with Li-Si local phase transformations at atomistic scale. Details will be discussed at the conference.

[1] Obrovac, M. N. & Christensen, L, Electrochem. Solid-State Lett. 7, A93–A96 (2004).

[2] Holzapfel, M. et al., Electrochim. Acta 52, 973 (2006)

[3] Ogata, K. Grey, C.P., et al., Nat. Commun. 5, 3217 (2014)
Foldable Paper-Based Lithium-Ion Batteries
Authors: Chan Candace K.
Published: February 2020

One of the most important aspects to enabling paper electronics are suitable and well integrated power sources. A convenient and useful aspect of paper is its ability to be folded into a multitude of shapes, such as those available by applying origami concepts, which can open the door for unprecedented types of paper electronics. Hence, the development of robust batteries that can also be folded is attractive for achieving good integration with paper-based devices. In this talk, I will discuss how paper folding techniques inspired from Japanese origami can be used to compact a Li-ion battery and increase its energy per footprint area. Full cells were prepared using Li4Ti5O12 and LiCoO2 powders deposited onto current collectors consisting of paper coated with carbon nanotubes. Folded cells showed higher areal capacities compared to the planar versions, with a 5 x 5 cell folded using the Miura-ori pattern displaying a ~14X increase in areal energy density. Furthermore, these cells could achieve extremely high levels of deformability, including foldability, bendability and twistability. This strategy represents the fusion of the art of origami, materials science, and functional energy storage devices and provides new opportunities for foldable, flexible and curvilinear electronics with new mechanical characteristics and functionalities.

 

References:

Q. Cheng, Z. Song, T. Ma, B.B. Smith, R. Tang, H. Yu, H. Jiang, C.K. Chan, Nano Lett., 13, 4969-4974 (2013).

Z. Song, T. Ma, R. Tang, Q. Cheng, X. Wang, D. Krishnaraju, R. Panat, C.K. Chan, H. Yu, H. Jiang, Nature Commun., 5, 3140 (2013).
Design, Fabrication and Characterization of Flexible Thin Film Rechargeable Lithium Ion Batteries
Authors: Oukassi Sami , Giroud-Garampon Cédric , Poncet Séverine , Salot Raphaël
Published: February 2020

The advent of fully flexible electronics is considered as a major technological leap forward and has attracted much attention during the last decade. Compared with conventional electronics, flexible electronics are lightweight, bendable and may be wearable or implantable. Hence the rapid and continuous growth in this field has stimulated the research and development of corresponding flexible energy storage systems and more particularly rechargeable lithium ion batteries [1-3].

In this work we developed flexible thin film lithium ion batteries based on all-solid-state materials. The flexible batteries were fabricated using sequential physical vapor deposition techniques. A thin film battery (TFB) architecture consisting of Ti/V2O5/LiPON/Li/encapsulation multilayer was deposited on flexible polyimide substrate. The fabricated flexible TFBs presented an overall thickness of 70µm (figure 1).

The flexible TFBs delivered discharge capacity as high as 0.15mAh (1.5 cm² of cathode area) upon galvanostatic cyling at C/5 rate within 3.8-1.5V voltage range. The capacity decreased during cycling with an average fading rate of 0.25% over 100 cycles (figure 2). Electrochemical impedance spectroscopy (EIS) measurements and modeling analysis revealed a significant and continuous increase of the internal resistance during cycling. Furthermore, it was shown that the internal resistance increase was induced by a progressive decrease of the electrolyte/electrodes contact area. A strong correlation was identified between the variation of electrolyte/electrode contact area and variation of flexible TFB discharge capacity.

TFBs having the same architecture and the same design were fabricated on two substrates: a flexible polyimide foil and a rigid silicon wafer. Electrochemical characterization showed a clear influence of substrate type on TFBs discharge capacity and internal resistance variations during cycling (figure 3). The electrochemical results variation with substrate type is discussed in terms of differences of TFB multilayer mechanical behaviour during cycling in both configurations.   

References

1-      Y. Hu and X. Sun, J. Mater. Chem. A, 2, 10712 (2014).

2-      L. Li, Z. Wu, S. Yuan, and X. Zhang, Energy Environ. Sci., 7, 2101 (2014)

3-      M. Osiak, H. Geaney, E. Armstrong and C. O'Dwyer, J. Mater. Chem. A, 2, 9433 (2014).

Figure 1
Dually Li Ion/Electron-Conductive Materials for Polymer-Based, Printable Lib Electrodes
Authors: McDonald Michael Blaine , Hammond Paula T
Published: February 2020

Limitations in lithium ion batteries (LIBs) reside foremost in their 1) energy capacity, and 2) size and configuration modulation. Polymer properties are generally attractive for next-generation electronics due to their flexibility, facile tunability with known chemistry, and processability. Specialized polymers, such as conjugated polymers, are electrically conductive, while others, such as poly(ethylene oxide) (PEO), form matrices suitable for Li ion transport. Inert polymers such as poly(ethylene) and poly(propylene) are fabricated to form ordered porous electrode separators (‘Celgard’) that are typically wetted with liquid electrolyte to form lithium polymer batteries. In this work, the desired properties of polymers are bestowed unto LIBs via the modification of these preformed polymer separators, which are used as the skeletons for all-polymer, wet-fabricated LIBs.

First, commercial separators were infiltrated with PEO in place of toxic, flammable solvents to form the solid state electrolyte. For the electrodes, previously, conducting polymers (CPs) have been shown to act as a binding materials to not only adhere active material, but form conductive pathways to bulk charge collectors for Li ion cathodes such as LiFePO4. Herein, the brittle, usually carbon-based scaffolds and binders are removed to form entirely conducting polymer bulk electrodes that are flexible. Active cathode (LiCoO2) and anode (graphite, Si) microparticle materials are incorporated to optimize battery capacity by exploiting excessive polyanion dopant in the commercially available CP suspension PEDOT:PSS as a dispersing agent, yielding “LIB electrode inks” that are printable onto the solid electrolyte support.

Transport of Li ions through the polymer matrix to access active material is systematically investigated both by forming a porous polymer network akin to carbon paper electrodes, and by fabricating composites of PEDOT:PSS with PEO. The mixtures are optimized for electronic conductivity, Li ion conductivity, and capacity through control of the active material content. All-polymer thin LIBs can then be entirely fabricated through wet deposition across the commercial separator scaffold and demonstrate behavior consistent with the current rigid LIB configurations. This novel configuration juxtaposes the all-polymer printed LIB, where dispersions consisting of PEDOT:PSS-PEO and active material as electrodes and a solution-based polymer electrolyte are wet-cast onto a substrate layer-by-layer.
Prussian Blue Analog Batteries on Thread Substrates for Wearable Electronic Applications
Authors: Kim Andrew , Biswas Shaurjo , Gupta Tanya , Steingart Daniel A
Published: February 2020

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.
FlexibleâStretchable Micro Lithium Ion Batteries for Implantable, Wearable and Embedded Electronics
Authors: Hussain Muhammad M. , Kutbee Arwa T
Published: February 2020

Future generation electronics which will be in the form of implantable, wearable and/or embedded format will require reliable power supply. Remote wireless charging or grid power supplied battery or energy harvesting – in any form of power supply, energy storage or battery will play critical role. In that regard, coin cell batteries and/or super capacitors are not suitable due to their bulky profile and toxic materials involved in their manufacturing. From that perspective, rechargeable micro lithium ion batteries (mLIB) are promising option for such energy storage. They offer high operating voltage, long life and high energy capacity. However, one major challenge is to achieve flexible and stretchable battery which is critical physical form for implantable, wearable and/or embedded electronics. In recent years, two routes have been pursued for such flexible mLIB fabrication: (1) exploration of new types of inherently compliant materials for battery electrodes such as carbon nanotube, graphene, carbon grease and slurry mixes of nanomaterials and (2) thinned inorganic thin film based battery. Although nano-scale thin films based mLIBs are reliable from their manufacturing and performance perspective, they are fabricated on rigid substrates. One option is to use exfoliation of a mica substrate to release battery stack – however, mica substrates are unconventional and physical delamination of such substrate is a low throughput/low yield process. In this work we present a soft etch back based flexible mLIB formation process. First we fabricate the battery on bulk mono-crystalline silicon (100) using lithium based thin films including cobalt, phosphorous alloy and then we spin a soft material on top of it. Next we flip the whole system and etch back the silicon using reactive ion etching in sequential manner. Next we spin another soft material on the flipped “chip”. Finally, we remove the first soft material selectively over the thin films present and the second soft material. In this way, we obtain 40 mm thick silicon based mLIB with an enhanced normalized capacity of 146 mAh/cm2 even after 120 cycles of continued operation. Comparison with a traditional rigid battery (fabricated in batch with the flexible one) shows comparable to superior performance.
A Soft Approach for Energy Storage and Mobile Healthcare
Authors: Xu Sheng
Published: February 2020

Wearable devices that match the soft, curvilinear, and time-dynamic nature of human body is an important trend for future technologies, redefining not only the appearance, but also the design and fabrication of microelectronics. In this talk, I will discuss the strategy to transform materials and devices that are conventionally rigid and brittle into a soft format. Specifically, the mechanical properties of rigid systems can be engineered by breaking down their geometry into small islands and subsequently rebuilding the interconnections with flexible/stretchable conducting filaments. This principle can be illustrated by two examples, which represent the latest progress in stretchable energy storage and mobile healthcare: a wirelessly rechargeable lithium ion battery with a record reversible biaxial stretchability up to 300%, and a soft wearable system capable of multifunctional physiological sensing on skin for health monitoring.
Baseline Si Electrode Fabrication and Performance for the Battery for Advanced Transportation Technologies Program
Authors: Jia Zhe
Published: February 2020

Baseline Si electrodes were developed and characterized based on Si nanomaterials. Si with a designed nanostructure has attracted much attention as potential anode materials for lithium-ion batteries due to its high gravimetric specific capacity. Because of a resulted poor tap density of Si from the electrode while using nano-sized Si and also from including other additives like conductive carbon and binder, it is difficult to maintain a high loading of active materials at the anode side in lithium-ion batteries.

In this report, we aim to investigate how the thickness of Si-based electrode influences the cycling performance, rate performance and impedance. We also discuss the variation of gravimetric, area and volumetric capacity along with increasing of electrode thickness. It is found that with a thinner electrode of 7 mm the volumetric capacity could reach up to 920 mAh cm-3 but a poor area capacity of 0.7 mAh cm-2, while a thicker one of 33 mm enables to provide a high area capacity up to 1.5 mAh cm-2 and gives a volumetric capacity less than 500 mAh cm-3. A cell operated under 0 °C shows a gravimetric capacity of 2000 mAh g-1 after 60 cycles.
Enhanced Performance of TiO2 Based Supercapacitor By MnO2 Modification
Authors: Weng Yu-Ting , Huang Tzu-Yang , Lee Jyh-Fu , Sheu Hwo-Shuenn , Wu Nae-Lih
Published: February 2020

Titanium dioxide (TiO2) has been considered one of the promising candidates in supercapacitors due to its low cost, electrochemical stability, natural abundance, high surface area, low toxicity, and easy preparation in defined nanoscale dimensions. In spite of its outstanding stability over a large operation window, its specific capacitance is substantially lower than those of other pseudocapacitive metal oxides. In this study, we have demonstrated that the specific capacitance of TiO2 can be dramatically improved by surface modification with MnO2. The composite electrode containing 18 wt.% MnO2 exhibits a high specific capacitance of 738 F/g at 2 mV/sec, which is substantially higher than those of both pristine TiO2 and MnO2 electrode, while having an operating potential window of nearly 2 V in an aqueous electrolyte. In addition, the TiO2-MnO2 supercapacitor exhibits 73 % capacitance retention with cycling up to 5000 cycles. In view of the energy storage capacity, DE=1/2 CV2
, this new composite electrode holds great promise for next-generation high-energy supercapacitors.

Figure 1
FeWO4 As Electrode Material for High Volumetric Capacitance Supercapacitors
Authors: Brousse Thierry , Favier Frederic , Goubard Nicolas , Crosnier Olivier , Payen Christophe
Published: February 2020

The volumetric capacitance of supercapacitors is one of the limiting factors of today’s stationary applications. Further research on new materials with improved storage properties is necessary to meet the requirements concerning high-performance energy storage devices while considering a reasonable manufacturing cost and a low environmental impact. In order to meet those requirements, our interest has focused on high-density oxides operating in aqueous electrolytes.

Metal tungstates (M2+WO4) represent an important group of inorganic high-density oxides with excellent functional and electronic properties. Iron tungstate (FeWO4), crystallizes in the wolframite-type structure, characterized by distorted [MO6] and [WO6] octahedra. It is well known for its magnetic, photocatalytic and photoluminescence properties and has recently been studied in lithium-ion batteries but its electrochemical properties in supercapacitors have not yet been reported. FeWO4 has been synthesized via various low-temperature methods (polyol-mediated, hydrothermal synthesis…) in order to obtain high specific surface area nanoparticles which have been characterized and electrochemically tested as supercapacitor electrode materials in aqueous electrolytes. Concomitantly, zinc tungstate was synthesized by the same method. Specific surface area ranging from 10 to 80 m2/g have been achieved.

The different oxides have been tested in neutral aqueous based electrolytes (LiNO3 5M). ZnWO4 does not show any sign of electrochemical activity whatever the potential window. FeWO4 exhibits a typical pseudocapacitive behavior i.e. CVs without any redox peaks but typical rectangular shape. The material exhibits very promising properties that seem to be due to Fe2+/Fe3+ surface redox reactions and are closely related to its specific surface area. The synthesis conditions, materials characterizations and electrochemical performance will be detailed in the presentation. For FeWO4 obtained by polyol-mediated synthesis, a high volumetric capacitance of 210 F.cm-3 was measured at 20 mV.s-1 with less than 5% fade over 10 000 cycles. Furthermore, unlike most previously investigated iron based electrodes, a unique pseudocapacitive behavior emphasizes the role of the crystallographic structure.
Capacitive Deionization Process Via Nano-Titanium Carburizing Electrode
Authors: Wang Li , Zhou Yun
Published: February 2020

Capacitive deionization (CDI) technology is an economical and effective electrosorption desalination method. In Capacitive deionization process, the feed solution flows through high adsorption capacity electrodes in which the anions and cations from the salty water are adsorbed on the charged electrodes. Two methods of chemical deposition and high vacuum magnetron sputtering are used for the preparation of nano-titanium carburizing electrode (named C1-TiO2and C2-TiO2). This paper apply the prepared nano-titanium carburizing electrode to the construction of a CDI desalination reactor. This paper focuses the desalination of capacitive deionization (CDI), investigates the influence of electrode material on adsorption capacity. By comparing the adsorption capacity of different kinds of electrode material, combined with physical and chemical characteristic and electrochemical analysis, the paper choose the optimal electrode material for capacitive deionization. The results show that under the same conditions, the adsorption capacity of nano-titanium carburizing electrode named C2-TiO2 up to 9.61mg/g.

In the capacitive deionization process by the selected nano-titanium carburizing electrode, the most optimal processing parameters of CDI in the research are operating voltage of 1.4 V, flow rate of 10 mL/min and plante spaceing of 4 mm. The kinetics analysis demonstrated that the electrosorption of NaCl on electrodes during dealing different concentration of NaCl solutions and different operating voltages followed pseudo-first-order model. The ion electrosorption on the electrodes can be represented by the Langmuir equation. This phenomenon indicating that the monolayer adsorption was primary during the electrosorption process. The experiment of adsorption-desorption in desalination process presented a better reversibility of nano-titanium carburizing.
Quaternized Graphene Oxide-Based Supercapacitor Electrode
Authors: Movil-Cabrera Omar , Staser John A
Published: February 2020

Electrochemical capacitors (supercapacitors) have received considerable attention as promising energy storage devices for applications including transportation, load leveling, and personal electronic devices.  Common features among electrochemical capacitors are high power density and cycle life, and although they may differ with respect to electrode material, most electrochemical capacitors employ some type of high surface area carbon electrode.  With the emergence of graphene (a single atom thick layer of carbon), some recent attention has focused on using this material as a supercapacitor electrode with generally promising results.  In this paper, we present novel quaternized graphene oxide-based supercapacitor electrodes.  We compare these materials to unmodified graphene oxide.  Our results indicate the functionalized graphene oxide materials exhibit higher capacity than unmodified graphene oxide, leading us to conclude that these materials may be suitable for supercapacitor electrodes.  In addition, we show that the functionalized graphene oxide materials exhibit a mix of double-layer and pseudocapacitance, which ultimately could further enhance material capacity.
(Invited) Dynamic Behaviour of Electric Double Layer Capacitors
Authors: Madabattula Ganesh , Kumar Sanjeev
Published: February 2020

Electrical double layer capacitors (EDLCs) store energy by accumulating ions in electrolyte at electrode-electrolyte interface in the form of a double layer (DL) in porous electrodes.  As electrochemical reactions are not involved, EDLCs find use in devices requiring energy at high rates, such as in hybrid electric vehicles, high power electric tools, and emergency power banks.  Highly non-linear decrease in cell voltage with time and decreased availability of stored charge at high discharge rates, observed experimentally, are major technical issues though.  We present here results of our probe into these limitations by requiring a transport model to quantitatively explain a large body of experimental data available on variation of cell voltage with discharge time at different electrolyte concentrations and discharge currents, charge redistribution and voltage recovery of EDLC during relaxation, and other characteristics.  The model utilizes experimentally measured variation of electrolyte conductivity with salt concentration to make predictions for EDLC characteristics.  In order for the model to consistently explain all the known experimental findings, it requires that (i) the double layer capacitance must vary with local potential difference and electrolyte concentration, (ii) it must decrease with an increase in local voltage drop, (iii) it must vary with local salt concentration in the same manner as bulk conductivity does, and (iv) ionic conductivity in pores of carbon electrodes must be an order of magnitude smaller than the reduced conductivity of electrolyte in porous media, as captured by the correlations available in the literature.  While it is known that double layer capacitance in porous media is understood only poorly, to the best of our knowledge, this is the first time that model based probe has clearly and ambiguously brought out unexpected dependence of capacitance on various parameters.