bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of Li Metal Anode in DMSO-Based Electrolytes Via Optimization of Salt-Solvent Coordination for Li-O2 Batteries
Authors: Liu Bin , Xu Wu , Yan Pengfei , Kim Sun Tai , Engelhard Mark H , Sun Xiuliang , Mei Donghai , Cho Jaephil , Wang Chongmin , Zhang Ji-Guang
Published: February 2020

Stabilization of Li Metal Anode in DMSO-Based Electrolytes via Optimization of Salt-Solvent Coordination for Li-O2 Batteries

Bin Liu,† Wu Xu,†,* Pengfei Yan,‡ Sun Tai Kim,∥ Mark H. Engelhard,‡ Xiuliang Sun,§ Donghai Mei,§ Jaephil Cho,∥ Chong-Min Wang,‡ Ji-Guang Zhang†,*

† Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, United States

‡ Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, United States

§ Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99354, United States

∥ Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan, 689-798, South Korea.

*E-mails: jiguang.zhang@pnnl.gov; wu.xu@pnnl.gov

The conventional DMSO-based electrolyte (1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in DMSO) is unstable against the Li metal anode and therefore cannot be used directly in practical Li-O2 batteries. Here, we demonstrate that a highly concentrated electrolyte based on LiTFSI in DMSO (with a molar ratio of 1:3) can greatly improve the stability of the Li metal anode against DMSO and significantly improve the cycling stability of Li-O2 batteries. This highly concentrated electrolyte contains no free DMSO solvent molecules, but only complexes of (TFSI–)a-Li+-(DMSO)b (where a+b=4), and thus enhances their stability with Li metal anodes. In addition, such salt-solvent complexes have higher Gibbs activation energy barriers than the free DMSO solvent molecules, indicating improved stability of the electrolyte against the attack of superoxide radical anions. Therefore, the stability of this highly concentrated electrolyte at both Li metal anodes and carbon-based air electrodes has been greatly enhanced, resulting in improved cyclic stability of Li-O2 batteries. The fundamental stability of the electrolyte with free-solvent against the chemical and electrochemical reactions can also be used to enhance the stability of other electrochemical systems.

Acknowledgement

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, of the U. S. Department of Energy (DOE) as part of Battery Materials Research (BMR) program.

Figure 1
XPS Comparative Analysis of the Chevrel Phase Mo6S8 and the Analogous Mo6Se8 during Mg Insertion
Authors: Richard Julien , Colin Jean-Francois , Benayad Anass , Martinet Sebastien
Published: February 2020

Since the earlier works in 2000 by Aurbach et al
1, magnesium-ion batteries emerged as an alternative to lithium-ion batteries thanks to many advantages: magnesium is the 5th most abundant metal in the earth crust, its divalent character and its ionic radius similar to lithium ionic radius gives it a volumetric capacity higher than lithium (3833 Ah/L and 2046 Ah/L respectively). Eventually the absence of dendritic growth on metallic magnesium is a plus in term of security.

Several cathode materials were proposed for Mg-ions battery, nevertheless the reference positive electrode material in Mg-Ion technology remained the Chevrel Phase with the formula Mo6S8. The Chevrel phase, synthesized by R. Chevrel et al
2 in 1974, was described as an octahedral cluster of molybdenum located in a cube of sulfur that forms a Mo6S8 pattern. Structural analysis3 (X-Ray Diffraction) showed the existence of 12 insertions sites localized inside a cube of sulfur surrounded by Mo6S8 clusters.

The electrochemistry highlighted 2 types of insertion sites able to host Mg2+ at different potentials.

Mg trapping into the Chevrel Phase was also noticed but curiously this phenomenom doesn’t occur in the analogous phase Mo6Se8
4 thanks to the lower ionicity of Se compared to S.

The anionic framework plays a major role in the redox process during Mg insertion, this study is a comparative analysis of Mo6S8 and analogous Mo6Se8 using electrochemistry and X-ray Photoemission Spectroscopy to get a direct observation of the redox mecanism during charge/discharge of the material.

We performed ex situ XPS core peak analyses on Mo6S8 and Mo6Se8 analogous electrodes at different states of charge to probe the molybdenum, the sulfur and the selenium oxydation states and the environment (polarized or metallic) of inserted magnesium ions.

These results will be discussed based on a step-by-step XPS study before and after cycling, and will be correlated with the electrochemical performances.

References:

(1) D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich & E. Levi, Nature vol 407 (2000) 724

(2) R. Chevrel et al, Mat. Res. BuLl. Vol. 9, pp. 1487-1498, 1974.

(3) R. Chevrel, M. Sergent Superconductivity in Ternary Compounds I
Volume 32 of the series Topics in Current Physics pp 25-86

(4) M.D. Levi et al, Solid State Ionics
Volume 176, Issues 19–22, June 2005, Pages 1695–1699
The Anode - Magnesium Monocarborane Interface for Metal Deposition and Dissolution
Authors: Arthur Timothy S , Singh Nikhilendra , Glans Anders , Liu Yi-Sheng , Guo Jinghua , Kisslinger Kim , Li Jing , Stach Eric A. , Alsem Daan Hein , Salmon Norman , Tutusaus Oscar , Suto Koji , Takechi Kensuke , Mohtadi Rana
Published: February 2020

The future of green mobility depends on continued research into alternative energy storage such as batteries, fuel cells and super-capacitors. However, to exceed the demands of current hybrid, plug-in hybrid and electric vehicles, new battery systems with high energy density are required. Magnesium (Mg) is an attractive alternative to current lithium-ion technologies because of the transfer of 2 electrons per magnesium-ion, higher volumetric capacity of magnesium metal compared to lithium metal (3833 mAh/cm3 Mg vs 2061 mAh/cm3 Li), and greater natural abundance [1]. Many challenges must be met to promote magnesium batteries as a practical candidate for the next generation of batteries. One of the pivotal issues is a complete understanding of the Mg deposition and dissolution interface.

Recently, advances in electrolyte synthesis has encouraged continued research into high energy density materials for magnesium batteries. Our group introduced a new family of electrolytes for Mg battery based on anions incorporating the B-H motif [2]. Among them, magnesium borohydrides (Mg(BH4)2) provides a segue between classic electrolytes based on Grignard reagents and the new electrolytes, such as magnesium monocarborane (MMC), which stands out as the first simple-salt magnesium compound stable to Mg metal, providing high anodic stability, non-corrosive electrochemistry, and chemically robustness [3]. However, the mechanism of deposition and dissolution of magnesium remains a complex process.

Operando electrochemical cells coupled with spectroscopic and microscopic tools are powerful techniques to understand the dynamic processes in batteries. Previously, we have used Operando electrochemical/X-ray absorption to identify the active species in organohaloaluminate electroltyes [4-5], and here we extend that research for (Mg(BH4)2) electrolytes. In combination with electrochemical impedance spectroscopy, we identify the presence of an active interphase required for magnesium deposition and dissolution. For MMC, we have determined that magnesium deposition and dissolution to be able to sustain high-current (10 mA/cm2), high-charge (5 mAh) and cold temperature (0oC) without the presence of magnesium dendrites. We utilize electron microscopy and X-ray photoelectron spectroscopy to elucidate the chemistry and mechanism of the promising anode / electrolyte interphase.

[1] Muldoon, J.; Buccur, C.; Gregory, T. Chem. Rev.
2014, 114, 11683.

[2] Tutusaus O.; Mohtadi, R.; ChemElectroChem
2015, 2, 51.

[3] Tutusaus, O.; Mohtadi, R.; Arthur, T.S.; Mizuno, F.; Nelson, E.G.; Sevryugina, Y.V. Angew. Chem. Int. Ed.
2015, 54, 7900.

[4] Arthur et al., Electrochem. Comm., 2012,
24, 43.
Dynamic Pulse Charging Equalization Scheme for Series Connected Cells Using Matlab/Simulink
Authors: Stephens Jamal Frederon , Morris Larry , Moss Pedro L. , Weatherspoon Mark H
Published: February 2020

Pulse charging has shown some very appealing advantages that can maintain the battery’s optimal performance during cycling. It has been shown that pulse charging can reduce the build-up of film at the solid electrolyte interface (SEI), allowing ions to flow back into the electrolyte, provide shorter equalization cycles, and allows more of an efficient charge after each short relaxation period than the conventional constant current charge method [1]. Some pulse charging strategies use a high voltage pulse with a relaxation period, this can result in an unexpected variation of charge current which can lead to performance loss in the cell and error in state-of-charge (SOC) estimation [2,3]. In this study, we propose a current pulse charge topology that can charge and equalize a series connected battery string.

Methodology

This system uses a dc-dc converter mainly to maintain a constant current in each cell, 2N low resistance solid state switches are used to control the pulse current with short relaxation periods for each cell as shown in figure 1. Where N is the number of cells. During the charging process, the individual batteries in series are connected to the power and ground bus via a microcontroller to be charge one at a time. This configuration provides a means of isolation or bypassing capabilities for each cell in the stack without the need of a solid-state transformer (SST). The pulses are precisely controlled by varying the duty cycle for a specific switching period which is based on the average current represented by equation (1).

Equation (1)

Iavg is the average current, T is the period of the pulse and i(τ) is the pulse current induced in battery. The duration for each pulse is given by equation (2).

 Equation (2)

Using this approach, constant-current/constant-voltage can also be achieved by using pulse charging simply by varying the duty cycle. Furthermore, this approach allows each battery to receive its own independent charge and increasing the equalization rate for the pack itself. Figure (1)

References

[1] Beh, Hui Zhi, Grant A. Covic, and John T. Boys. "Effects of Pulse and DC Charging on Lithium Iron Phosphate (LiFePO4) Batteries." IEEE 315.(2013): 315-20. Print.

[2] Yin, Meng Di, Jeonghun Cho, and Daejin Park. "Pulsed-Based Fast Battery IoT Charger Using Dynamic Frequency and Duty Control Techniques Based on Multi-Sensing of Polarization Curve." Energies (2016): 1-20. Print

[3] Li, Jun, Edward Murphy, Jack Winnick, and Paul A. Kohl. "The Effects of Pulse Charging on Cycling Characteristics of Commercial Lithium-ion Batteries." Journal of Power Source (2001): 302-09. Print.

Figure 1
High Performance GeO2 Inverse Opal Anode Materials for Long Cycle Life Li-Ion Batteries
Authors: McNulty David , O'Dwyer Colm
Published: February 2020

With the rapid and ever increasing growth in portable electronics, such as smartphones and tablet computers, and the growing need for safer and longer range electric and hybrid powered vehicles, there has never been a more prevalent demand for light weight, high performance batteries with high power and energy densities. Commercial Li-ion batteries are just about keeping up with advancements in electronics. However, the limited performance of today’s commercial batteries is common knowledge, with the majority of hand held electronic devices requiring charging every day. Identifying and preparing battery materials which are capable of high performance, fast charging, and stable, safe capacity retention during operation would significantly advance portable device power technology.

Germanium based anode materials have attracted a lot of attention due to the high theoretical capacity of Ge (1384 mAh/g) with various nanostructures such as nanowires, nanotubes and nanoparticles being investigated as anode materials. (1-3) However the cost of preparing pure Ge nanostructures can be quite high due to the use of expensive anhydrous precursors such as diphenylgermane and the need to perform synthesis under an inert atmosphere. These factors would also impede scaling up the synthesis of these materials for industrial applications. To circumvent these issues we are investigating the electrochemical performance of GeO2 with an inverse opal (IO) morphology, which can be prepared in air using cheaper precursors.

In this work we detail the preparation of GeO2 IOs with application as anode materials for Li-ion batteries. The IO samples are initially structurally characterised via electron microscopy, electron diffraction and X-ray diffraction. We demonstrate the electrochemical evaluation of our GeO2 IO samples with cyclic voltammetry, rate capability testing and long cycle life (>1000 cycles) galvanostatic testing. Previous reports on the electrochemical performance of GeO2 as an anode material have indicated that the capacity values obtained from the oxide are lower than those obtained from pure Ge. However, we demonstrate that by preparing a highly ordered, porous, three dimensionally interconnected network of GeO2 in the form of an IO, we can obtain capacity values which are comparable to the highest values previously reported for pure Ge.

Acknowledgements

This work was also supported by Science Foundation Ireland (SFI) through an SFI Technology Innovation and Development Award under contract no. 13/TIDA/E2761. This publication has also emanated from research supported in part by a research grant from SFI under Grant Number 14/IA/2581.

References

1. T. Kennedy, E. Mullane, H. Geaney, M. Osiak, C. O’Dwyer and K. M. Ryan, Nano Lett., 14, 716 (2014).

2. L.-F. Cui, R. Ruffo, C. K. Chan, H. Peng and Y. Cui, Nano Lett., 9, 491 (2009).

3. D.-J. Xue, S. Xin, Y. Yan, K.-C. Jiang, Y.-X. Yin, Y.-G. Guo and L.-J. Wan, ‎J. Am. Chem. Soc., 134, 2512 (2012).
The Role of Porosity-Graded Electrode in Mitigating Performance Degradation of High Voltage Lithium-Ion Battery
Authors: Guan Pengjian , Liu Lin
Published: February 2020

LiNi0.5Mn1.5O4 (LNMO) is one of the most potential candidates as cathode material for lithium-ion batteries (LIBs) due to the high operating voltage (4.7 V vs. Li) and high specific energy (650Wh·kg-1). However, severe accelerated performance degradations as well as electrolyte decomposition, especially at the interface between electrode and electrolyte, hinder the implementation of the LNMO. The degradations can cause capacity fade and reduce the battery life time. In this work, porosity-graded electrodes are designed to mitigate the LNMO degradation. The LNMO was synthetized by solid-state reaction. X-ray powder diffraction (XRD) experiment was applied to confirm the crystal structure of the LNMO. Scanning electron microscope (SEM) experiment was used to observe the porosities and confirm the elements in the electrode. A double-layered electrode with different porosities was fabricated in this experiment. The increase in porosity can improve the conductivity and diffusivity of lithium-ions through the electrode. In addition, solid electrolyte interphase (SEI) growth is location dependent due to its growth related to the electron current flow and Li+ diffusion. Therefore, SEI formation can be varied and controlled when the porosity is different inside the electrode. The testing results showed, comparing with single layer electrode, the porosity-graded electrode reduced the capacity fade about 8.285% for full cell and 5.290% for half-cell.
Evaluation of the Mechano-Electrochemical Behavior of Soft 75Li2s-25P2S5 Solid Electrolyte Against Metallic Lithium
Authors: Garcia-Mendez Regina , Arthur Timothy S , Sakamoto Jeff
Published: February 2020

As all-solid state batteries have garnered significant attention due to their potential to enable high-energy applications, the presence of only solid materials within the battery pack calls attention to the importance of mechanical properties during operation in an Electric Vehicle. Moreover, the mechanical integrity of the battery pack and its correlation to the electrochemical behavior observed becomes vital to determine the system’s performance and lifetime. Therefore, an understanding of the mechano-electrochemical behavior of all-solid state batteries is required to realize their potential benefits. In this work, the mechanical behavior of Li2S-P2S5 was investigated in Li-Li symmetric cells. Ultrasonic testing and galvanostatic cycling measurements were used to characterize the mechanical and electrochemical response of Li2S-P2S5 upon cycling. The evolution of the cell potential and AC impedance spectra was monitored and correlated to the change in mechanical properties observed during cycling. The electrolyte was considered isotropic and the change in elastic constants (Young’s Modulus and Shear Modulus) was evaluated as a function of current density, charge passed and amount of lithium passed. This approach can provide insight into the fracture, degradation and stability of solid electrolytes for use in all-solid state batteries.
Advanced Silicon Anode Enabled By Simple Pouring of Bifunctional Gel Polymer
Authors: Song Jiangxuan , Zhang Li
Published: February 2020

Electrode structure deterioration and unstable solid-electrolyte-interphase (SEI) are crucial issues hindering the application of silicon anode in high energy lithium-ion batteries.[1-3] Here, we report a simple way to construct a stable silicon anode enabled by pouring branched polyurethane gel that comprise ion-conductive ethylene oxide (EO) soft segment into electrode. This tough gel conformably coated on the electrode components and strongly bonded them together through the chemical bonding and hydrogen bonding, forming a robust electrode. Additionally, it provides mechanical and chemical protection while Li+ transport, behaving as an artificial SEI layer. The harness of bifunctional gel polymer lead to a significant improvement of electrochemical performance with an capacity retention of 90% within 150 cycles and achieve a high areal capacity over 4 mAh/cm2 when micro-sized silicon-based materials was evaluated.

References

[1] C.-M. Park, J.-H. Kim, H. Kim, H.-J. Sohn, Chem. Soc. Rev.
2010, 39, 3115.

[2] J. Song, M. Zhou, R. Yi, T. Xu, M. L. Gordin, D. Tang, Z. Yu, M. Regula, D. Wang, Adv. Funct. Mater.
2014, 24, 5904.

[3] J. Song, Z. Yu, M. L. Gordin, D. Wang, Nano Lett.
2016, 16, 864.
Multifunctional SnO2/3D Graphene Composites for Lithium-Ion and Sodium-Ion Batteries
Authors: Lee Jung-In , Song Junhua , Cha Younghwan , Lin Yuehe , Song Min-Kyu
Published: February 2020

Although both Li-ion batteries (LIBs) and Na-ion batteries (NIBs) were investigated in the similar era (1980’s), LIBs are a current technology of choice for portable electronics and electric vehicle applications due to NIBs’ lower gravimetric/volumetric energy density. Recently, NIBs have gained another momentum for grid-scale energy storage systems (ESS) where the weight and volume limitations are relatively low. The most important requirements of EES would be the cost, reliability and long service life, while the high-energy density would be still viewed as an advantage. While looking slightly similar, Li and Na metals (and their cations) have distinct physical and chemical properties. It would be interesting to develop the multifunctional materials which can be used as effective electrode materials for both batteries.

SnO2 is an attractive material due to high theoretical capacity (for both LIBs and NIBs), low cost, abundance and ease of synthesis. But there are many drawbacks that need to be overcome for SnO2 to be applied to actual batteries. Various technical issues include the large volume expansion during discharge/charge process in batteries, the formation of unstable solid electrolyte interface (SEI), and the aggregation of Sn particles during battery operation, all of which can lead to the rapid capacity fading of batteries.

In this work, ultra-fine SnO2 nanoparticles dispersed within unique 3D-graphene structure (SnO2/3D GS) were synthesized by easy and simple hydrothermal process. These 3D-graphene structure could accommodate large volume change, prevent aggregation of Sn, and provide much facile electron transfer during battery operation. The SnO2/3D GS material exhibited outstanding electrochemical performances as anodes for both LIBs and NIBs. The structure-property-performance relation was investigated by various methods including SEM, TEM, EIS, CV, and XRD. The focus was on comparative studies of the internal resistance and diffusivity of Li-ions and Na-ions in SnO2/3D GS composites. Furthermore, the direct conversion from SnO2 to amorphous Sn during discharge/charge of 1st cycle in LIBs and NIBs was monitored by in-situ XRD.

Figure 1
Ultrafine TiO2 and Nb2O5 Nanoparticles on Reduced Graphene Oxide As Anode Materials for Lithium and Sodium Ion Batteries
Authors: Yan Litao , Luo Hongmei
Published: February 2020

The potential practical application of electric vehicles and large-scale energy storage system, have prompted extensive research in the development of electrode materials with high performance and high rate capability. Ultrafine TiO2 and Nb2O5 nanocrystals/reduced graphene oxide (TiO2/rGO and Nb2O5/rGO) were prepared by controllable hydrolysis and followed by thermal treatment. First, hydrolysis of titanium or niobium precursor formed amorphous hydroxide thin layer on graphene oxide (GO). After annealing at 450 °C under forming gas, amorphous hydroxide layer converted to TiO2 or Nb2O5 nanocrystals with particle size of around 5 nm or 3 nm, respectively, and GO reduced to rGO with enhanced conductivity. TiO2/rGO and Nb2O5/rGO were demonstrated as promising anode materials for high performance lithium ion batteries and sodium ion batteries. The architecture of ultrafine TiO2 or Nb2O5 nanocrystals anchored on highly conductive rGO network and can not only enhance charge transfer and buffer the volume change during lithiation/delithiation or sodiation/desodiation processes, but also provide more active surface area for lithium or sodium ion storage, resulting in superior rate and cycle performance. Ex situ XPS analysis revealed that the sodium ion storage mechanism in Nb2O5 could be accompanied with Nb5+/Nb4+ redox reaction and the ultrafine Nb2O5 NCs provide more surface area to accomplish the redox reaction.
New Insights into Parasitic Reactions in Non-Aqueous Alkaline-O2 Batteries
Authors: Mahne Nika , Schafzahl Bettina , Leypold Christian , Kramer Denis , Slugovc Christian , Wilkening Martin , Borisov Sergey M. , Freunberger Stefan A
Published: February 2020

Non-aqueous lithium-oxygen batteries depend critically on the reversible formation and on the decomposition of lithium oxides on cycling [1-3]. The discharge reaction in the cathode of nonaqueous Li-O2 batteries involves the reduction of O2 and the formation of solid Li2O2. The process is reverse on charge. True reversibility of the cathode reaction in the Li-O2 battery requires a set of qualities to obey the stoichiometry and to match each other during discharge and subsequent charge. These are 1) e-/O2 = 2 both on discharge and charge, 2) to produce/consume exactly one mole of Li2O2 and one mole of O2 per 2e- and on discharge/charge, 3) absence of any other gas evolution, e.g. CO2, or generation of solid products other than Li2O2 during discharge and charge, 4) O2 consumed during discharge matches the amount released on subsequent charge.

Typically these measures deviate more or less significantly from the ideal due to parasitic reactions, whose source has not been entirely identified. Irreversible parasitic reactions have predominantly been ascribed to the reactivity of reduced oxygen species, e.g., superoxide with cell components [4-6]. These species, however, cannot fully explain these observed side reactions. Only better knowledge of parasitic reactions will allow inhibiting them and reaching towards fully reversible cell reactions.

We will discuss recent insights into irreversible parasitic reactions during cycling of a Li-O2 battery, that have so far been overlooked, their detection via newly developed methods and strategies to suppress them effectively [7]. Awareness of these reactions in non-aqueous Li-O2batteries gives a rationale for future research towards achieving highly reversible cell operation.

References

[1] P.G. Bruce; S.A. Freunberger; L.J. Hardwick; J.-M. Tarascon; Nature Mater. 11 (2012) 19.

[2] A.C. Luntz, B.D. McCloskey, Chem. Rev. 114 (2014) 11721.

[3] Y.-C. Lu; B.M. Gallant; D.G. Kwabi et al.; Energy Environ. Sci. 6 (2013) 750.

[4] S.A. Freunberger, Y. Chen, N.E. Drewett, L.J. Hardwick, F. Bardé, P.G. Bruce, Angew. Chem. Int. Ed., 50 (2011) 8609.

[5] M.M. Ottakam Thotiyl, S.A. Freunberger, Z. Peng, Y. Chen, Z. Liu, P.G. Bruce, Nature Mater.12 (2013) 1050.

[6] B.D. McCloskey, A. Valery, A.C. Luntz, et al., J. Phys. Chem. Lett.(2013) 2989.

[7]N. Mahne et al., submitted.
Strategy for Metal Anode Protection in Advanced Energy Storage Systems
Authors: Lin Chuan-Fu , Noked Malachi , Kozen Alex C , Luo Wei , Hu Liangbing , Lee Sang Bok , Rubloff Gary W
Published: February 2020

To meet the demand for higher capacity longer life batteries in a “next-generation batteries” technology, anodes with substantially higher energy density than current graphite are needed. One class - metal anodes (particularly Li, Na) - offers far higher energy density, but to date their utilization has been impeded by their high surface reactivity (especially to the organic electrolyte) and tendency to form dendrites (a shorting and safety hazard).

We have used atomic layer deposition (ALD) to create highly controlled, thin ceramic type coatings as an artificial solid electrolyte interphases (SEIs) to protect these anode surfaces by preventing dendrite formation and electrolyte decomposition. The ultrathin Al2O3 protective coating on Na stabilizes the Na-electrolyte interface and extends its cycle life under high current density (i.e., high power) cycling conditions. We have also developed a hybrid (elastomer + ceramic-type) protective coating on Li metal by combining ALD ceramic (LiPON) and electrochemical deposition of a polymeric elastomer. The hybrid layer achieves high Li conductivity while suppressing corrosion and due to electrolyte breakdown. The elastomer component provides mechanical flexibility to accommodate volume change both may play roles in the observed mitigation of dendrite growth at high current density.

These results demonstrate promise for achieving high energy density anodes with significantly enhanced chemical stability, electrochemical cyclability, and dendrite protection as needed for a viable beyond Li or Na ion battery technology.
Tuning Solution Chemistry for Compositional Control of Multicomponent Lithium-Ion Battery Materials
Authors: Koenig Gary , Dong Hongxu
Published: February 2020

A common route to synthesize lithium-ion battery active materials in the literature is to precipitate transition metals with a desired stoichiometry and then perform a calcination to produce the final active material. While this approach has produced many high performance materials, depending on the details of the solution conditions used during precipitation the stoichiometry of the precipitate can deviate from the stoichiometry of the feed. This stoichiometry deviation is largely ignored; however, a few groups have attempted to address this discrepancy with solution equilibrium models to rationally approach compositional control in the final active material. In this talk, we will present results that show the extent of the deviation of the precipitate stoichiometry from the feed stoichiometry across a number of solution conditions and compare experimental results to equilibrium calculations for one co-precipitation process. In addition, we will show initial results for the rate of precipitation of different transition metals in solution and the potential impact on the resulting final material.
Atomistic Simulation Studies of Lithiated and Sodiated TiO2 nanospheres
Authors: Ngoepe Phuti E , Kgatwane Kenneth M , Matshaba Malili G , Sayle Dean C
Published: February 2020

Sodium-ion batteries (SIBs) are considered to be a promising low-cost alternative to common lithium-ion batteries. Several electrochemical studies have been carried out on anode nanomaterials of TiO2 and good cyclability and high rate capability has been reported for Li-ion batteries [1]. Recently, its possible application in Na-ion batteries has put it forward as a promising candidate [2,3]. Simulated armorphization and recrystallization technique has been employed to generate nano-architectures of TiO2 [4].

Herein, we present a detailed simulated synthesis for nanospheres of lithiated and sodiated TiO2 where amorphous precursors were crystallised. Mixed polymorphs consisting mainly of brookite, rutile were observed from microstructures and XRDs. Crystallised nanospheres were lithiated and sodiated up to high concentrations to imitate the charging process and related volume expansions were predicted. Structural aspects were deduced from radial distribution functions and differences associated with lithiation and sodiation are quite obvious. Calculated XRDs are generated and compared with experimental results where available. Microstructures of the resulting models are analysed and a wealth of crystallographic defects (i.e. grain boundaries and point defects) were captured and their resulting influence on Li-ion and Na-ion transport are discussed.

 References

[1] J. Wei, J.X. Liu, Y.C. Dang, K. Xu, Y.A. Zhou, Adv. Mater. Res. (2013), 750−752, 301.

[2] K.T. Kim, G. Ali, K.Y. Chung, C.S. Yoon, H. Yashiro, Y-K. Sun, J. Lu, K. Amine, and S-T. Myung, Nano Lett. (2014), 14, 416.

[3] L. Wu, D. Bresser, D. Buchholz, G.A. Giffin, C.R. Castro, A. Ochel , and S. Passerini, Adv. Energy. Mater. (2015), 5, 1401142

[4] M.G. Matshaba, D.C. Sayle, T.X.T. Sayle and P.E. Ngoepe, J. Phys. Chem. C, (2016), 120, 14001.
Structural and Chemical Evolution of Li-Excess Li2IrO3 during Electrochemical Cycling
Authors: Li Liang , Lee Eungje , Park Joong Sun , Castro Fernando , Yao Zhenpeng , Fister Timothy T , Freeland John W , Wolverton Christopher , Dravid Vinayak , Thackeray Michael M. , Chan Maria K. Y.
Published: February 2020

The family of Li-excess layered Li2TMO3 (TM=Mn, Ru, Ir, etc.) compounds has recently drawn considerable attention in the pursuit of improved capacity of Li-ion batteries. Many studies have unambiguously demonstrated the extra capacity of Li2TMO3 associated with oxygen redox behavior.1,2 Unlike Li2MnO3, which suffers from severe structural degradation and capacity fading upon cycling, Li2IrO3 shows negligible structural change and much improved reversibility,3 and thus serves as a model system to understand the structural response of Li-excess cathodes to Li extraction, as well the exact role of oxygen in compensating Li+ loss.

In this study, we employed various experimental techniques as well as first-principles density functional theory (DFT) to investigate the structural and electronic evolution of Li2IrO3 upon electrochemical cycling. It is found that Li2IrO3 undergoes phase transition and slight capacity fading at each cycle. All the thermodynamically stable phases of Li2-xIrO3 (0≤x<2) are identified through a complete structural screening based on electrostatic energy and DFT calculations, and compared with Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) experiments. Core Level Spectroscopy is adopted to probe the changes in the oxygen electronic structure at various (de)lithiation stages, and corresponding oxygen K-edge spectra are simulated based on first-principles calculations. The cationic/anionic charge compensation mechanism of Li2IrO3 upon delithiation, as well as its resistance to O2 loss are discussed based on the spectroscopic observations.

Reference:

1. D. Seo, J. Lee, A. Urban, and R. Malik, Nat. Chem., 8, 692–697 (2016)

2. M. Saubanere, E. McCalla, J.M. Tarascon, and M.L. Doublet, Energy Environ. Sci., 984–991 (2016)

3. E. McCalla et al., Science, 350, 1516–1521 (2015)
Supercapacitor Aging and Diagnosis
Authors: El Mejdoubi Asmae , Chaoui Hicham , Gualous Hamid
Published: February 2020

The lifetime of an energy storage component is the time required to fail. The failure is defined as the lack of ability of a component to fulfill it's specified function. One of its characteristics will be out of the specification. For example the capacitance will be below its specified limit value, or the series resistance will be above its specified value, the component will be leaking, or will be opened.

This paper is about supercapacitor aging and diagnosis. At the first, supercapacitor aging according to the temperature and to the voltage is presented. Experimental tests are realized at constant temperature when the supercapacitors are polarized at the maximum voltage. To quantify the supercapacitor aging, the equivalent series resistance and the equivalent capacitance are measured. To lead to the determination of the supercapacitor lifetime, Arrhenius law, that describes the effect of temperature on the velocity of a chemical reaction, is considered.

The second part of this paper presents an online diagnosis method for supercapacitors’ aging problem. The proposed strategy capitalizes on the capabilities of the sliding mode for the design of a sliding mode observer. Therefore, online parameters’ estimation is achieved, which yields State-of-Health (SoH) prediction. Unlike other methods such as electrochemical impedance spectroscopy, where estimation is performed offline and requires interruption of the system’s operation, this paper presents an online diagnosis method. Moreover, only voltage and current measurements are required. The effectiveness of the proposed online observer is shown through a set of experiments. Results highlight its good performance in parameters estimation with robustness to current’s nonlinearities.
Electrodeposition of MnO2-Based Nanomaterials As Carbon-Free and Binder-Free Cathodes for Li-O2 Battery
Authors: Deng Zhaofeng , Li Chi-Ying Vanessa , Chan Kwong-Yu
Published: February 2020

Carbon based nanomaterials have been widely used as cathode materials for Li-O2 batteries because of their high conductivity, large surface area, and good ORR catalytic activity. However, instability of carbon under Li-O2 operation poses problems. During recharge, carbon can decompose to form lithium carbonate at high charging potential1, but also react chemically with the discharge product Li2O2
2. Metal oxides, like MnO2 and RuO2, have been investigated as cathode catalysts in Li-O2 batteries3. In this study, MnO2 nanostructure is electrodeposited on stainless steel mesh and applied as a carbon-free and binder-free cathode for non-aqueous Li-O2 battery. To maintain good adhesion and electrical contact between deposited layer and the substrate, the mesh is pre-treated. Benefiting from enhanced electronic contact and large surface area of MnO2, the electrochemical performance is improved. Material characterization and electrochemical impedance spectroscopy (EIS) technique are also utilized to systematically study the electrochemical processes of these carbon-free MnO2-based electrodes.

References

[1] M.M.O.Thotiyl, S. A. Freunberger, Z. Peng, and P. G. Bruce, J. Am. Chem. Soc., 135, 494 (2013)

[2] B. D. McCloskey, A. Speidel, R. Scheffler, D. C. Miller, V. Viswanathan, J. S. Hummelshøj, J. K. Nørskov, and A. C. Luntz, J. Phys. Chem. Lett., 3, 997 (2012)

[3] Z. Ma, X. Yuan, L. Li, Z.F. Ma, D.P. Wilkinson, L. Zhang, and J. Zhang, Energy Environ. Sci., 8, 2144 (2015)

Acknowledgements

This project is financially supported by HKU Seed Fund for Basic Research (Project No.: 201605159011), and University Development Fund for Clean Energy and Environment.
Sub-Micrometer Active Material Particle Synthesis for Solid Dispersion Lithium-Ion Redox Flow Batteries
Authors: Qi Zhaoxiang , Koenig Gary
Published: February 2020

Solid dispersion lithium-ion redox flow batteries incorporate carbon-free lithium-ion active materials in a flow battery geometry, taking advantage of both the flexibility of a redox flow battery and the high energy density of lithium-ion active materials. This promising technology, however, needs sub-micrometer or nanometer sized active material particles to form well-dispersed fluids. These small particles are also desirable for achieving high rate capability and round trip energy efficiency in conventional battery cells. While many methods have been reported in literature to produce sub-micrometer sized battery particles, often these processes are challenging to scale up for large quantity production. In this poster, we will describe a highly scalable process to produce high performance sub-micrometer battery active materials with an initial demonstration cathode chemistry, LiCoO2. The LiCoO2 produced with this method exhibited excellent electrochemical performance as lithium-ion battery cathode active materials, including high discharge capacity, rate capability, and coulombic efficiency. The LiCoO2 material also performed well as the cathode material dispersed in the electrolyte for solid dispersion lithium-ion redox flow battery applications.
The High Performance Silicon Anodes Including New Water Based Binder in Lithium Ion Batteries
Authors: Kim Soo Jung , Kim Nam Seon , Han Sang Wook , Choi Kwang Sik
Published: February 2020

Silicon based negative active material has very high charge capacity and is widely applied to a high capacity battery. However, the silicon based negative active material may expand by about 300% to about 400% during charge and discharge.

Recently much attention has been devoted developing functional binders that can improve adhesion on silicon particle and accommodate substantial volume change during the charge/discharge process to maintain the electrode structure.

The binders for silicon electrodes hold stiff polymeric backbones as like carboxymethyl cellulose (CMC), poly(acrylic acid), and alginate show better electrochemical performance than commercial binders. Despite promising progress, the current research on polymer binders for silicon is still far from the practical application where high mass loading is necessary for the high areal capacity.

Here we report high performance silicon anodes using new water based binder including inorganic binder. This polymer matrix is compatible with lithium ion slurry manufacturing process, and can maintain both electric conductivity and mechanical integrity during the battery operation which results in good stability, rate capability, and cycle-life characteristics at high mass loading (>4.5 mg/cm2).
Comparative Studies on Interfacial Kinetics of Ordered and Disordered Spinel LiNi0.5Mn1.5O4
Authors: Amin Md Ruhul
Published: February 2020

The charge-discharge behavior of LiNi0.5Mn1.5O4, having both the ordered and disordered spinel structures, had been investigated by several research groups [1–5]. However, there are discrepancies with regard to the suitability of the disordered or ordered spinel for better battery performance [3–5]. It is also not clearly understood whether the rate performance of the material is limited by bulk transport properties or interfacial charge transfer reaction kinetics. The purpose of the present work is to elucidate the role of the electrochemical charge transfer kinetics at the electrode/electrolyte interface of Li1-xNi0.5Mn1.5O4 in determining the rate performance of the spinel cathode. The measurements have been carried out on additive free sintered dense plate in order to exclude any extrinsic effect. The exchange current density at the electrode/electrolyte interface is found to be continuously increased with increasing the degree of delithiation for ordered phase (~0.21-6.5mA/cm2) at (x=0.01-0.60), in contrast the disordered phase exhibits gradually decrease of exchange current density in the initial delithiation at the 4V plateau regime (x=0.01-0.04) and again monotonously increases (0.65-6.8mA/cm2) with further delithiation at (x=0.04-0.60). The ionic diffusivity of ordered and disordered phase is found to be ~5x10-10cm2s-1 and ~10-9cm2s-1, respectively, and does not vary much with the degree of delithiation. From the obtained results it appears that the chemical diffusivity during electrochemical use is limited by lithium transport, but is fast enough over the entire state-of-charge range to allow charge/discharge of micron-scale particles at practical C-rates.

 

References

K. Amine, H. Tukamoto, H. Yasuda and Y. Fujita, J. Electrochem. Soc., 143, 1607 (1996).

Q. M. Zhong, A. Bonakdarpour, M. J. Zhang, Y. Gao and J. R. Dahn, J. Electrochem. Soc., 144, 205 (1997).

H. F. Xiang, X. Zhang, Q. Y.Jin, C. P. Zhang, C. H. Chen and X. W. Ge, J. Power Sources, 183, 355 (2008).

H. M. Wu, I. Belharouak, H. Deng, A. Abouimrane, Y. K. Sun and K. Amine, J. Electrochem. Soc., 156, A1047 (2009).

J. Hassoun, S. Panero, P. Reale and B. Scrosati, Adv. Mater., 21, 4807 (2009).
Investigating the Polysulfides Reactions on the Conducting MagnéLi-Phase Ti4O7 By Means of First Principles Simulations
Authors: Kachmar Ali , Cuisinier Marine , Abouimrane Ali , Belharouak Ilias
Published: February 2020

There have been new developments of new sulfur cathode materials to enhance the cycling stability of (Li-S) batteries. These new sulfur cathodes are based on metal oxides, which are intrinsically polar materials that can strongly interact with polar polysulfides species because the surface doesn’t need modification for interfacial adsorption [1,2]. I will first present the hybrid functional calculations we performed using the Auxiliary Dynamics Matrix Method (ADMM) [3,4] with varying percentages of exact Hartree−Fock exchange (hfx), ranging from 10 to 50% hfx to compute accurately the band gaps, and to determine the stable surface orientations of the Magnéli-phase of Ti4O7, and Anatase TiO2. Relying on the previous results, I will discuss the first principles molecular dynamics simulations [4] we conducted to investigate the interaction mechanisms, and the dynamics properties of the polysulfides Li2Sx  (x=1, 2, 4, 6) on the identified stable surfaces of the Magnéli-phase of Ti4O7, and Anatase TiO2. Finally, I will discuss the role of the explicit solvent molecules in the solubility of the lithium polysulfides at the interfaces of the investigated models.

Reference
s
:

[1] Tao, Xinyong and Wang, Jianguo and Ying, Zhuogao and Cai, Qiuxia and Zheng, Guangyuan and Gan, Yongping and Huang, Hui and Xia, Yang and Liang, Chu and Zhang, Wenkui and Cui, Yi, Nano Letters, 14, 5288-5294, (2014).

[2] Pang, Quan and Kundu, Dipan and Cuisinier, Marine and Nazar, L. F., Nat Commun, 5, 4579, (2015).

[3] Guidon, Manuel and Hutter, Jürg and VandeVondele, Joost, Journal of Chemical Theory and Computation, 6, 2348-2364, (2010).

[4] CP2K, http://www.cp2k.org/
Free-Standing, Binder-Free Titanium Suboxide Nanofiber Based Sulfur Cathodes for Li-S Batteries
Authors: Singh Arvinder , Dillard Caitlin , Kalra Vibha
Published: February 2020

Lithium sulfur batteries, with a high theoretical specific energy of ~2680 Wh/kg, have attracted great attention in the recent years owing to the direct use of sulfur as a cathode, which is cost-effective, environmentally friendly and naturally abundant. However, shuttling of intermediate polysulfides between cathode and anode is one of the major practical limitations for the realization of Li-S batteries. Others include large volume expansion during lithium insertion, low sulfur utilization, and insulating nature of sulfur and lithium disulfide. Over the years, various carbon and inorganic materials (metal oxides, metal-organic frameworks) have been employed as hosts or polysulfide reservoirs to minimize the shuttling effect and improve the conductivity of cathodes in Li-S batteries. Recently, titanium suboxides (TinO2n-1; n>1), with two Ti3+ and (n-2)Ti4+ (3d0) ions, have been utilized as bifunctional sulphur hosts that not only provide good electrical conductivity, but also chemically bind with the intermediate lithium polysulfide preventing their escape. However, formation of titanium suboxides generally requires high temperature processing, which results in highly dense low surface area material reducing the potential polysulfide-host interaction surface.

Here, we report the use of free-standing, binder-free titanium suboxide nanofibers as host material in sulfur cathodes. Titanium suboxide nanofibers are produced by electrospinning titanium isopropoxide solution in presence of polyvinylpyrrolidone and subsequently, heating at 850˚C to create oxygen vacancies through carbothermal reaction. Sulfur impregnation was carried out by rapid melt-diffusion technique to form final sulfur/titanium suboxide cathodes. Lithium-sulfur coin cell batteries were assembled using as-prepared free-standing cathodes (without any current collector and binder) with ~50 wt% sulfur loading (~1.5 mg cm-2) and cycled at C/5 rate (1C = 1675 mAh g-1) after conditioning at C/10 rate. The initial discharge capacity was ~976 mAh g-1 at C/5 rate, which stabilized to an average capacity of ~738 mAh g-1 after three cycles with coulombic efficiency >97%. The conducting titanium suboxide nanofibers allow the effective utilization of sulfur/Li2S during discharging/charging of cells and help to maintain high discharge capacity (~700 mAh g-1) over 100 cycles. The chemical interaction between these inorganic hosts and lithium polysulfide is under investigation and will be discussed in detail. The electrochemical results presented here show the potential of titanium suboxide family (different n values) as foreseeable solution to the shuttling effect for developing high performance Li-S batteries.

Figure 1
Sparingly Solvating Electrolytes for Lis Batteries
Authors: Cheng Lei , Balasubramanian Mahalingam , Lee Chang Wook , Ha Seungbum , Gallagher Kevin G. , Zavadil Kevin R
Published: February 2020

Achieving reversible electrochemistry under lean electrolyte operation is key to moving LiS chemistry to potentially transformational performance.1 The use of electrolytes that are sparingly solvating to Li polysulfide intermediates is a promising approach to decouple electrolyte volume from reaction mechanism, thus creating a pathway towards high energy density LiS batteries that deviates from the current catholyte approach.2In this work, we discuss the design rules for sparingly solvating electrolytes and the unique electrochemistry that arises through the use of this class of electrolytes.

1D. Eroglu, K. R. Zavadil and K. G. Gallagher, J. Electrochem. Soc., 2015, 162, A982.

2L. Cheng, L. A. Curtiss, K. R. Zavadil, A. A. Gewirth, Y. Shao and K. G. Gallagher, ACS Energy Lett., 2016, 1, 503.