bluuebunny/crossref_metadata_2025 huggingface dataset:
Doped Li2CuO2 Cathode for Li Ion Batteries
Authors: Ramos-Sánchez Guadalupe , Romero-Ibarra Issis , Vazquez-Arenas J. , Galvan Marcelo Enrique , González I.
Published: February 2020

Li ion batteries is one of the emerging technologies that might have a broad use in electric and hybrid vehicles; however, it is of primordial importance to formulate high capacity electrodes obtained from readily available sources. Lithium cuprates have been studied for more than twenty years, the reason being is the high theoretical capacity (490 mAh/g) which is much higher than that  of the largely used cathode materials LiCoO2 and LiFePO4. The structural transitions from Li2CuO2 to CuO2 upon delithiation (charging) and then to LiCuO2 and Li2CuO2 upon discharge are very dramatic leading to loss capacity on the very first charging cycle. To the date no reports have been published on the maximum capacity that can be reached with Li2CuO2 as function of electrode preparation variables, the potential window for charge/discharge and C-rate. The determination of the maximum capacity at several conditions is of primordial importance in order to propose possible niche applications and alternative routes to improve the reversibility of the system. We have found that the preparation under inert atmosphere is of primordial importance in order to enhance the capacity, since the mixing, coating and drying under air atmosphere accelerate the transformation of Li2CuO2 to LiO2 and CuO2i n the lapse of minutes. Moreover the electrode calendaring  process (usually carried out on air) diminishes  the maximum capacity on the first cycle and leads to the reduction to the capacity up to 20 mAh/g during the first ten cycles at a C/15 rate and in the range of 1.5-4.3 V (Li+/Li0). On the other hand if the calendaring process is replaced by pressing at 6 ton/cm2 the capacity after ten cycles is as high as 150 mAh/g at C/15. However, in order to obtain stable capacity up to 100 cyles, the operation potentials  should be diminished  from 1.5-4.3 V to 2.2-3.8 V (Li+/Li0), in this situation 100 mAh/g are obtained after 100 cycles suffering no affectation on the structural stability of the material. Further modification on the synthesis by Co, Mg and Fe doping are being under study, preliminary results indicate that the insertion of the ions between the layer of Li2CuO2 improve the reversibility, enhancing the capacity up to 10% of the value of maximum value obtained with pure Li2CuO2.
Battery Electrode Fabrication via Powder Based Additive Manufacturing
Authors: Wang Yan , Zheng Zhangfeng , Pan Heng , Ludwig Brandon
Published: February 2020

Lithium ion battery electrodes were manufactured using a new, completely dry powder painting process. The solvents used for conventional slurry-cast electrodes have been completely removed. Thermal activation time has been greatly reduced due to the time and resource demanding solvent evaporation process needed with slurry-cast electrode manufacturing being replaced by a hot rolling process. It has been found that thermal activation time to induce mechanical bonding of the thermoplastic polymer to the remaining active electrode particles is only a few seconds. Removing the solvent and drying process allows large-scale Li-ion battery production to be more economically viable in markets such as automotive energy storage systems. By understanding the surface energies of various powders which govern the powder mixing and binder distribution, bonding tests of the dry-deposited particles onto the current collector show that the bonding strength is greater than slurry-cast electrodes, 127.14 kPa as compared to 84.29 kPa. Electrochemical tests show that the new electrodes outperform conventional slurry processed electrodes, which is due to different binder distribution. Based on Argonne Cost Model, the dry processed electrode could save ~15% of the battery cost.

Figure 1
Battery Cost Reduction through Design of a Multi-Chemistry Pack
Authors: Aryanpour Masoud , Ashcraft Robert , Miara Lincoln J.
Published: February 2020

In recent years, there has been an enormous drive to develop fully or hybrid electric cars by taking advantage of novel secondary batteries, and in particular, of Li-based battery technologies. Realization of a fully electric vehicle (EV), nonetheless, requires overcoming big challenges that demand much larger energy densities, simultaneously with much higher rate (power) capabilities [1].

  Current efforts try to address those challenges by focusing on two main roadmaps: 1) Materials, that is, optimizing current or inventing new chemistries [2, 3], and 2) Battery Management and mathematical modeling [4, 5], that is, optimizing the usage of current chemistries through various strategies that would adapt charge/discharge cycling properties.

  In addition, there are prior or current works that try to take advantage of different available chemistries, which although promising, lack a clear roadmap for fully utilizing available technologies.

   Hereby, we introduce a clear roadmap/method for 1) determining the areas of benefit of, and 2) designing of a “multi-chemistry battery pack” that would perform better than any “single-chemistry packs”. In simple terms, we show how to determine when a multi-chemistry pack can beat its constituent single-chemistries, and how to design/utilize different chemistries in hybrid pack whenever the hybrid combination is more beneficial.

REFERENCES

[1] By panel reporters of National Research Council, “Overcoming Barriers to Deployment of Plug-in Electric Vehicles”, The (U.S.) National Academies of Sciences, Engineering, and Medicine, 2015.

[2] J.-M. Tarascon and M. Armand, “review article Issues and challenges facing rechargeable lithium batteries”, Nature, 414, 359-367, 2001

[3] J.B. Goodenough and Y.S. Kim, “Challenges for Rechargeable Li Batteries”, Chemistry of Materials, 22 (3), 587–603, 2010

[4] M.F.M. Sabri, K.A. Danapalasingam, and M.F. Rahmat, “A review on hybrid electric vehicles architecture and energy management strategies”, Renewable and Sustainable Energy Reviews, 53, 1433-1442, 2016

[5] A. Fotohi, D.J. Auger, K. Propp, S. Longo, and M. Wild, “A review on electric vehicle battery modelling: From Lithium-ion toward Lithium–Sulphur”, Renewable and Sustainable Energy Reviews, 56, 1008–1021, 2016
Evaluation of Different Separators By Using 18650 Li-Ion Cells
Authors: Song Wen feng , Zhang Ya li , Deng Zhong yi , Carlson Steve A
Published: February 2020

Safety and performance characteristics are mainly correlated with electrode materials, electrolytes and separators.  The presentation will outline many key functions that the separator serves in lithium-ion batteries and describes a separator design – specifically, AlOOH-based nanocomposite membranes – which addresses several critical safety concerns for high performance lithium-ion batteries.

      Boehmite(γ-AlOOH) separator, polypropylene(PP) separator and boehmite-PP separator 18650 Li-ion cells have been made, The safety performance of the different separator 18650 Li-ion cells have been investigated, especially by nail penetration which is well known to be the most difficult safety test for high energy density including NMC/NMA positive material 18650 cells and passing this test is critical for  xEV applications in China.

     The preliminary results show that the cycling performance of boehmite separator cells was better than the other two kinds of separator cells.   Cells using boehmite separator showed improved nail penetration performance compared with PP separator cells, which may be attributed to the excellent thermal stability of the boehmite separator.  More safety test results and cycling performance data of all three different separator cells will be further discussed in this presentation.
Investigation into State-of-Health Impedance Diagnostic for 26650 4P1S Battery Packs
Authors: Huhman Brett , Heinzel John M , Mili Lamine , Love Corey T
Published: February 2020

State-of-Health (SOH) is a critical parameter for determining the safe operating area (SOA) of a battery cell and battery packs to avoid abuse and prevent failure and accidents. A set of experiments was performed to generate aging data on LiFePO4 batteries discharged with a specific load profile, with an emphasis on measuring changes in the 1 kHz – 0.1 Hz electrochemical impedance spectra (EIS). A parallel set of experiments was performed to identify a frequency range where the impedance response appears to be independent of the state of charge of the cell. Four 26650 cells were placed in a 4P1S array and discharged in parallel at 10 C (26 A) with the aforementioned load profile for a significant number of cycles to age the cells. Individual cell EIS measurements were taken, as well as measurements of the array as a whole. It is expected that deviations in the frequency-independent impedance response reflect SOH changes that may signal premature cell death. This work will discuss experimental results to date.
Hybridizing Organic and Solid State Single-Ion Conductors: Thermotropic Ionic Liquid Crystals for Lithium Battery Electrolytes
Authors: Bresser Dominic , Leclere Mélody , Bernard Laurent , Rannou Patrice , Mendil-Jakani Hakima , Lyonnard Sandrine , Picard Lionel
Published: February 2020

The continuously increasing importance of lithium-ion batteries for the transportation sector does and will require also substantial enhancements of their energy and power density as well as their safety. As the latter aspect is mainly determined by the currently utilized liquid organic electrolytes, comprising LiPF6 as conducting salt, extensive research efforts are directed towards the development and optimization of alternative (solid) electrolytes.1–3 In addition to a suitable ionic conductivity, these new electrolyte systems have to fulfill a series of other requirements, most importantly, a sufficient electrochemical stability, beneficial interfacial properties, enhanced thermal stability, and, preferably, flexibility as well as single-ion conductivity to avoid the necessity of using LiPF6 and detrimental cell polarization. The two electrolyte systems, which are currently considered most promising to realize safer lithium-based batteries, are basically solid ceramic and polymer-based electrolytes.1–3 However, while the former frequently suffer electrode/electrolyte interfacial instability and thus rapid capacity fading (apart from its intrinsic rigidity), the latter commonly face challenges regarding their thermal stability and large cell polarization due to the necessity of adding a conducting salt to the polymer matrix.

In an attempt to combine the beneficial characteristics of these two systems, we designed and synthesized a completely new electrolyte system: single-ion conducting thermotropic liquid crystals (TILCs, Figure 1). These TILCs reveal self-assembling, homeotropically aligned, lamellar nanostructures, providing confined ionic nanochannels for reversible lithium ion transport across suitable electrode/electrolyte interfaces. Herein, we will report their extended characterization as lithium battery electrolytes with a particular focus on the structure to transport interplay, highlighting the importance of large-scale facility experiments (structure and dynamics) to finally unveil and understand the ion transport mechanism on the molecular and sub-molecular level.

Figure 1. General chemical formula of TILCs.

References

1. B. Scrosati and J. Garche, J. Power Sources, 195, 2419–2430 (2010).

2. J. Kalhoff, G. G. Eshetu, D. Bresser, and S. Passerini, ChemSusChem, 8, 2154–2175 (2015).

3. Y. Wang and W.-H. Zhong, ChemElectroChem, 2, 22–36 (2015).

Figure 1
Recent Developments in Garnet-Type Solid State Electrolyte Thin-Films Grown By CO2-Laser Assisted Chemical Vapor Deposition
Authors: Loho Christoph , Djenadic Ruzica , Clemens Oliver , Hahn Horst
Published: February 2020

The research on solid state electrolytes (SSE) is motivated by their excellent safety properties, their potential for battery miniaturization, and their possibility to enhance the energy density of the battery. However, their often low Li-ion conductivity compared to liquid electrolytes is a drawback. In this respect garnet-type Li7La3Zr2O12 (LLZO) attracted much attention, since it combines features such as a very good electrochemical stability over a wide potential range as well as against lithium metal and a reasonably high Li-ion conductivity of around 10-6 S·cm-1 in tetragonal and 10-4 S·cm-1 in cubic modification.[1]

Regarding fabrication, chemical vapor deposition (CVD) is a suitable method to grow functional thin-films for Li-ion batteries, since it allows for a homogeneous growth over large areas with high deposition rates and a very high purity.[2] Despite these advantages, reports on CVD grown thin-films for Li-ion battery application are rare. One reason may be that with conventional CVD precursor delivery systems it is often difficult to achieve the correct composition of complex, multicomponent materials such as typically used for Li-ion batteries. Recently, our group established a novel CVD precursor delivery system applying CO2-laser flash evaporation of solid precursors (LA-CVD) and demonstrated its applicability for Li-ion battery research.[3]

In this contribution we report on the latest progress in LLZO thin-film deposition using LA-CVD. The detailed characterization includes results on microstructure, phase composition and electrochemical performance. Thin-films that are dense, free of cracks and mainly consist of tetragonal LLZO show a Li-ion conductivity of about 10-6 S·cm-1, probed with impedance spectroscopy. This compares with lithium phosphorus oxynitride (LiPON), which is a glassy solid electrolyte typically used in current all-solid-state cells. To further improve the Li-ion conductivity of the LLZO thin-films two approaches are followed up: one is to increase the bulk conductivity by stabilization of the cubic LLZO phase via doping. The second is to reduce the grain boundary contribution by tuning the morphology of the thin-films.

References:

[1] R. Murugan, V. Thangadurai, W. Weppner, Angew. Chem. Int. Ed.
2007, 46, 7778-7781.

[2] M. L. Hitchman, K. F. Jensen, Chemical Vapor Deposition: Principles and Applications, Academic Press, London 1993.

[3] C. Loho, A. J. Darbandi, R. Djenadic, O. Clemens, H. Hahn, Chem. Vap.
Deposition
2014, 20, 152-160.
Investigation of Na Removal/Insertion Mechanism in Na1.86Fe3(PO4) 3 Cathode Material
Authors: Essehli Rachid , Ben Yahia Hamdi , Maher Kenza , Moulay Tahar Sougrati , Abouimrane Ali , Park Jin-Bum , Sun Yang-Kook , Almaadeed Mariam , Belharouak Ilias
Published: February 2020

In recent years, sodium batteries have raised interest as cheap rechargeable batteries for large format rechargeable battery applications such as the grid storage. A number of promising cathode materials has already been tested, however their electrochemical performances remain below their lithium counterpart cathodes. Complete structural and electrochemical investigations are needed to improve the characteristics of existing sodium electrode materials, design and synthesis of new ones with improved battery performance. Phosphate based materials are considered as promising cathode materials for sodium batteries due to their low cost and the variety of structural arrangements. In addition, it is predicted that phosphate cathode materials are thermally and electrochemically stable due to the presence of strong P-O bonds. The alluaudite-type structure, with the general formula AA’BB’2(PO4)3 (A and A’ = Li, Na; B is a large six coordinated cation; B’ is a small six coordinated cation), has been intensively studied as electrode materials for LIBs and/or NIBs. In the present work, we report on the synthesis, characterization and electrochemical performance of a new Na1.86Fe3(PO4)3 alluaudite-type structure compound. The material delivers ~ 109 mAhg-1 as a reversible capacity at ~ 3 V with a small capacity fade during cycling. The refinement of the structure by the Rietveld method and results of Mössbauer experiments indicate the presence of sodium deficiency and a Fe2+/Fe3+ ratio below 2/1 in the pristine material. Detailed study on the mechanism of sodium removal/insertion will be presented using X-ray, galvanometric cycling, cyclic voltammetry and Mössbauer techniques.
Reversible Na-Ion Uptake in Si Nanoparticles
Authors: Xu Yaolin , Swaans Ellie , Borsa Dana M. , Mulder Fokko M.
Published: February 2020

Na ion batteries attract significant research interest since they provide potentially high energy density while using low cost and abundant sodium as the active ion. Si has been extensively investigated for its operation as anode in lithium based batteries since it has a high theoretical lithiation capacity up to Li4.4Si. However, the sodium analogue with successful reversible electrochemical sodiation of Si has not been reported yet. Si sodiation is anticipated to be different with respect to phase behaviour, insertion voltages and kinetic barriers when compared to Li ion, for instance because of the difference in ionic radius of Na+ (0.97 Å) and Li+(0.68 Å). From thermal synthesis of Na-Si materials it is known that NaSi is the most Na rich phase for Na-Si binary compounds, which would enable a sizeable capacity of 954 mAh/g.

Anticipating that nanoscaling is of advantage for the kinetics of ion insertion and extraction, we studied Si particles with much reduced size (~ 20 nm) containing a large fraction of amorphous Si. The nano particles were obtained from Expanding Thermal Plasma Chemical Vapour Deposition (ETPCVD) of silane. The materials consist of aggregated individual nano particles with a very thin silicon oxide layer that forms after contact with air. The work presented here reports, to our knowledge for the first time, reversible electrochemical Na ion uptake in these Si based materials for a significant capacity. The desodiation capacity is stable around 260 mAh/g, while the initial sodiation shows a large irreversible Na loss attributed to SEI formation. The experiments show that during Na insertion a two phase equilibrium may be present between NaSi and Si:        x Na + Si  ->  x NaSi + (1-x) Si, where the NaSi becomes amorphous. For desodiation a sloping voltage profile is observed indicative of a solid solution behaviour. Therefore we propose that desodiation occurs as NaSi ->  Na1-xSi + x Na, where the Na1-xSi  phase remains amorphous. After 100 cycles all Si has been transformed to amorphous phases, and no crystalline nano Si particles remain.

In conclusion, nanoparticles containing both amorphous and crystalline Si, produced by ETPCVD, demonstrate an excellent reversible capacity of 279 mAh/g for Si at 10 mA/g and a capacity retention of 248 mA/g after 100 cycles at 20 mA/g. Significant reversible capacities can be achieved at high dis-/charge rates as well. Nanoscaling benefits the Na insertion and extraction kinetics in Si although reversible Na uptake and release for the full theoretical capacity has not been reached. Initial amorphous and crystalline Si are performing an equally active role in the electrochemical sodiation. Coexistence of Si and NaSi may occur during Na insertion into amorphous Si and on the surface of the Si crystallites; while a solid solution desodiation reaction is evidenced when Na is being extracted.

Y. Xu, E. Swaans, S. Basak, H. W. Zandbergen, D. M. Borsa, F. M. Mulder, Adv. Energy Mater. 2015, doi 10.1002/aenm.201501436 early view

Figure 1
Highly Reversible Aqueous Zn/MnO2 Energy Storage System from Chemical Conversion Reactions
Authors: Pan Huilin , Shao Yuyan , Yan Pengfei , Cheng Yingwen , Han Keesung , Nie Zimin , Wang Chongming , Yang Jihui , Li Xiaolin , Mueller Karl T , Liu Jun
Published: February 2020

Rechargeable aqueous batteries are highly desirable for large scale energy storage due to their low cost and high safety. Lead acid batteries are low cost aqueous systems and much easy to scale up for stationary applications. Nevertheless the use of lead causes significant environmental concern besides the low energy density and limited life span, even though lead-acid batteries still account for more than half of the global battery market. An alternative, low cost and high safety aqueous energy storage system is highly desirable. Herein, we demonstrated a highly reversible chemical conversion reaction mechanism of Zn/MnO2 systems in optimized mild aqueous electrolytes. This conversion reaction provides an operating voltage of 1.44 V, high capacity of 285 mAh g-1 (MnO2), excellent rate, and capacity retention of 92% over 5000 cycles. Zn metal anode also shows high reversibility. The highly reversible and stable chemistry in aqueous Zn/MnO2 batteries opens new opportunities and can be a viable alternate to the widely used lead acid batteries.
Robust Electron-Donating Organic Compounds for Non-Aqueous Redox Flow Batteries
Authors: Odom Susan A , Kaur Aman Preet , Casselman Matthew D , Elliott Corrine F , Attanayake Harsha A , Parkin S R , Risko Chad
Published: February 2020

The development of robust electro-active materials is critical for a variety of electrochemical energy storage applications. Phenothiazines, phenoxazines, carbazoles, and triphenylamines are among some of the numerous electron-donating aromatic compounds that have been studied for numerous applications in organic electronics, photovoltaics, and electrochemically-mediated synthesis.  Their use as electrolyte components and electrode materials has only been studied by a few groups, yet these materials are easy to functionalize, enabling tuning their electronic properties, solubility, and stability. My research group initially explored derivatives of these compounds as redox shuttles for overcharge protection of lithium-ion batteries. With systematic variations in structure, our efforts combining analytical techniques with density functional theory calculations have enabled us to identify decomposition products and to predict reasonable mechanisms that lead to failure in neutral and oxidized states. Our development of robust derivatives that survived for thousands of hours of overcharge was a result of the design rules that came from these studies. Recently we have expanded our use of these compounds as catholyte components for non-aqueous redox flow batteries. In one to three steps from commercially available materials, we have prepared highly soluble phenothiazine derivatives (solubility of 1-2 M in organic electrolytes) that can serve as one- and/or two-electron donors with long lifetimes in the charged states.  This presentation will focus on the synthesis, spectroscopic, and electrochemical analysis of these materials as electron donors for redox flow batteries.
Metallic Lithium Anode Protect By Gel Electrolyte in Lithium-Sulfur Batteries
Authors: Zhong Hai , Xu Zhibin , Sang Lin , Ding Fei
Published: February 2020

Lithium metal is an ideal battery anode. However, dendrite growth and limited coulombic efﬁciency during cycling have prevented its practical application in rechargeable batteries.[i]Herein, we report a gel electrolyte which have a highly effective to reducing the corrosion and suppressing the formation of lithium dendrites.

Electro-polymerization method was adopted to synthesize the Gel electrolyte, because it doesn’t need any other catalysts for polymerization, and it can be used directly without any further purify. LiTFSI was chosen as the lithium salt for saturation, and DOL monomer as the solvent for electropolymerisation. Figure 1a-c are typical photographs of the electrolyte with different forms which corresponding the prepared steps. It can be seen that the saturation electrolyte (LiTFSI/DOL) kept the characteristics of the liquid with its low viscosity (Figure 1a). After electro-induced polymerisation for several hours, the viscosity of the as-prepared electrolyte increased significantly compared to that of the saturation electrolyte, but it could slowly flow down the bottle wall when inverted (Figure 1b). Further self-polymerisation of the as-prepared electrolyte for more than two weeks at room-temperature produced a transparent solid polymer electrolyte which was immobile upon inversion of its container (Figure 1c).

Figure 2 show the typical scanning electron microscopy images (SEM) of metallic lithium anodes after long cycling experiments in Li-S cells. From these images, both of lithium anode with TEGDME and PIS electrolyte had an obvious change compared with fresh lithium, but the PIS electrolyte shows much the lower damage level of metallic lithium anode compared with the TEGDME.

The morphology of metallic lithium anodes which demonstrates that the gel electrolyte system can effectively inhibit the polysulfide diffusion, thus it can be reducing the corrosion. And also the ultrahigh lithium salt concentration and high viscosity can suppress the formation of lithium dendrites, and decrease the solubility of lithium polysulfide due to the common ion effect.

 

[i] J. F. Qian, W. A. Henderson,W. Xu, P. Bhattacharya, M. Engelhard, O. Borodin and J. G. Zhang. Nature Communications, 2015, 6, 6362.

Figure 1
Investigating the Factors for the Low Cycle Life of Sodium Oxygen Batteries
Authors: Bi Xuanxuan , Ren Xiaodi , Lu Jun , Amine Khalil , Wu Yiying
Published: February 2020

Metal air (oxygen) batteries have recently attracted extensive research attentions due to the high theoretical energy density. Compared to lithium oxygen batteries, sodium oxygen batteries have much lower charging overpotentials which may offer longer cyclability and higher energy efficiency without losing much energy density (~1100 Wh kg-1 vs. ~3460 Wh kg-1). However, the short cycle lives of sodium oxygen batteries greatly limit their applications in transportations or energy storage systems. The main reasons for the short cycling life of sodium oxygen batteries were primarily ascribed as the accumulation of by-product during discharge and charge processes and/or electrolyte degradation. However, in our studies, issues from the anode such as sodium dendrite formation and side reactions were ascribed to the major reasons for the short circuit of sodium oxygen batteries. By employing a sodium ion exchange Nafion membrane in separators, largely improved cyclability of sodium oxygen batteries was achieved by suppressing the penetration of dendrites formed during the charging process. After solving the deadly short circuit of sodium oxygen batteries by Nafion’s physically preventing effect, cycle lives of 118 cycles in dimethoxyethane (DME) based electrolytes and 80 cycles in bis(2-methoxyethyl) ether (diglyme) based electrolytes were achieved with a current density of 0.16 mA cm-2. The components of SEI layer on the sodium anode and by-product in the air electrode were identified. The sodium anode went through severe degradation process. It is proved that oxygen crossover was another factor to cause the failure of sodium oxygen batteries. These results highlight the significance of solving dendrite penetration and blocking oxygen crossover in sodium oxygen batteries and paved the way for further improving the performance and cyclability of batteries.

Figure 1
Mesoporous Carbon Nanocube Architecture for High-Performance Lithium-Oxygen Batteries
Authors: Sun Bing , Wang Guoxiu
Published: February 2020

One of the major challenges to develop high-performance lithium–oxygen (Li–O2) battery is to find effective cathode catalysts and design porous architecture for the promotion of both oxygen reduction reactions and oxygen evolution reactions. Herein, the synthesis of mesoporous carbon nanocubes as a new cathode nanoarchitecture for Li–O2 batteries is reported. The oxygen electrodes made of mesoporous carbon nanocubes contain numerously hierarchical mesopores and macropores, which can facilitate oxygen diffusion and electrolyte impregnation throughout the electrode, and provide sufficient spaces to accommodate insoluble discharge products. When they are applied as cathode catalysts, the Li–O2 cells deliver discharge capacities of 26 100 mA h g-1 at 200 mA g-1, which is much higher than that of commercial carbon black catalysts. Furthermore, the mesoporous nanocube architecture can also serve as a conductive host structure for other highly efficient catalysts. For instance, the Ru functionalized mesoporous carbon nanocubes show excellent catalytic activities toward oxygen evolution reactions. Li–O2 batteries with Ru functionalized mesoporous carbon nanocube catalysts demonstrate a high charge/discharge electrical energy efficiency of 86.2% at 200 mA g-1 under voltage limitation and a good cycling performance up to 120 cycles at 400 mA g-1 with the curtaining capacity of 1000 mA h g-1.
Novel Lithium-Ion Cell for Operation at Very Low Temperatures
Authors: Farmakis Filippos , Elmasides Costas , Georgoulas Nikolaos , Balomenou Stella , Tsiplakides Dimitrios , Nestoridi Maria
Published: February 2020

The manufacturing and the electrochemical performance at very low temperatures of novel lithium-ion cell will be presented.
Electrocatalysis Approach to Lithium Polysulfides Redox Chemistry
Authors: Arava Leela mohana reddy
Published: February 2020

Stabilizing polysulfide-shuttle process while ensuring high sulfur loading holds the key to realize high theoretical energy density (2500 Wh/kg) of lithium-sulfur (Li-S) batteries. Though several carbon based porous materials have been used as host structures for sulfur and its intermediate polysulfides, the week adsorption of polysulfides on carbon surface and its poor reaction kinetics limits them from practical application. Here, we preset a novel ‘electcatalysis’ approach to stabilize polysulfide shuttle process and also enhance its red-ox kinetics. Nature of electrocatalyst, pore-size distribution, concentration of polysulfides, temperature of the cell etc., on electrochemical properties will be discussed. 1, 2 We reveal substantial improvement in electrochemical properties such as specific capacity, rate capability, coulombic efficiency etc. and corroborate our findings with systematic experimental studies. Interaction between electrocatalyst and polysulfides has been evaluated by conducting X-ray photoelectron spectroscopy and electron microscopy studies at various electrochemical conditions. Thus, introducing a catalyst in the Li−S system will open a new avenue for improving electrochemical performance.

1.         Al Salem, H.; Babu, G.; V. Rao, C.; Arava, L. M. R. Journal of the American Chemical Society
2015,137, (36), 11542-11545.

2.         Babu, G.; Ababtain, K.; Ng, K. Y. S.; Arava, L. M. R. Scientific Reports
2015,5, 8763.
The Li Ion Diffusion Kinetics Study of Beta LiVOPO4 As Cathode Material for Lithium Ion Batteries
Authors: Ryu Kwang-Sun , Park Da jeong
Published: February 2020

Lithium vanadyl phosphate (LiVOPO4) is an attractive cathode for lithium ion batteries with a high operating voltage 4.0V in phosphate poly-anion cathode materials and good theoretical capacity of 166mAh/g. LiVOPO4 exist mainly in two different crystallographic phases, one is orthorhombic β-LiVOPO4 another is triclinic α-LiVOPO4. Among these phases, β-LiVOPO4 is widely studied in view of lithium ion intercalation, and it shows better electrochemical performance than α-LiVOPO4. K. Nagamine et al. presented that the orthorhombic crystals have a three-dimensional Li ion pathway consisting of interconnected VO6 octahedral and PO4 tetrahedral units that consequently create channels for Li+ion movement. However, the main defects such as poor electrical conductivity and low lithium ionic conductivity are drawback for its application in lithium ion batteries. To improve the poor electrical conductivity, many researches have been studied by carbon coating and composite method.

While, the studies are extremely rate to enhance lithium ion conductivity and lithium ion diffusion coefficient technique. In this study, we have investigated that the diffusion coefficient of lithium ion in β-LiVOPO4 by SSCV (slow scan cyclic voltammetry), EIS (Electrochemical impedance spectroscopy), GITT (Galvanostatic intermittent titration technique) and PITT (Potentiostatic intermittent titration technique) to compare lithium diffusion value according to four techniques. And we have optimized diffusion technique in β-LiVOPO4. The synthesis of β-LiVOPO4 was carried out by sol-gel method. Firstly, oxalic acid and V2O5 in stoichiometric ratio were dissolved in deionized water with magnetic stirring at 70°C. After a clear blue solution formed, a mixture of stoichiometric NH4H2PO4 and LiNO3 was added to the solution while stirring for 4h and the green gel formed. Finally, the dried gel was decomposed at 300°C for 4h and the obtained product was sintered at 500 °C for 4h in air. As a result, SSCV, GITT, PITT techniques relatively indicated similar lithium ion diffusion coefficient value. But, low lithium ion diffusion coefficient value was obtained by EIS technique. Due to the accuracy for calculating needed. The chemical diffusion coefficient of EIS depends on the fitting of experimental impedance with an equivalent circuit model. While, the GITT and PITT techniques were obtained under deviation from equilibrium conditions. Because the between current and voltage and time more exactly reflected the diffusion property. So, among the four techniques, GITT and PITT were more reliable in β-LiVOPO4 cathode material.
Computational Insights to the Layered-to-Spinel Structural Transformation in Ni-Rich Lithiated Transition Metals Oxide Materials (LiNixCoyMnzO2)
Authors: Dixit Mudit , Schipper Florian , Markovsky Boris , Aurbach Doron , Major Dan Thomas
Published: February 2020

Ni-rich lithiated transition metal oxides of layered structure (R-3m space group) LiNixCoyMnzO2 (NCMs, x>0.5) represent a family of promising materials for positive electrodes of advanced lithium-ion batteries (LIB). These materials demonstrate reversible capacities around 160 – 190 mAh/g in the potential range of 2.8 – 4.3 V. Despite of the considerable research on improvement of these materials’ performance by lattice doping with cations, the molecular level of understanding the effect of dopants on the electronic structure, voltages, and ion diffusion is very limited. However, the above information is essential for the design of new and efficient positive electrode materials for LIB. For example, atomistic resolution parameters, such as the diffusion of lithium ions within the layers, are responsible for the power of the battery. The electronic structure, on the other hand, dictates the electro-conductivity. Although many studies suggest improved performance of doped NCM cathode materials, the mechanism of the enhanced behavior still remains unclear. In this work, we present the computational study using ab-initio modeling of the role of Zr-doping on the electrochemical performance and structure of LiNi0.6Co0.2Mn0.2O2 (NCM-622) electrode material. We show that how doping influences on the Li+/Ni2+ mixing, charge distribution among transition metals, and lattice constants. In particular, we reveal that Ni+2 ions migration upon Li-deintercalation (charge) can initiate layered-to-spinel structural transformation. We also demonstrate the role of Zr+4 cations on limiting this transformation by investigating the electronic structure and possible Ni+2 migration pathways and mechanisms. In this presentation, the role of other multivalent dopant cations on the structural stability of NCM will be discussed.
First Principles Study on Lithium Transport through Crystalline and Amorphous Materials for Discovery of Battery Coatings
Authors: Lu Zhi , Hao Shiqiang , Yao Zhenpeng , Aykol Muratahan , Morgan Dane , Wolverton Chris
Published: February 2020

A widely used remedy to slow down the degradation of the electrochemical performances of lithium-ion batteries is to apply coating materials on cathode surfaces.[1] Such coatings can serve as physical barriers to inhibit electrode-electrolyte side reactions, and they can also possess an additional functionality such as scavenging the detrimental acids (e.g., the hydrofluoric acid, HF) in electrolytes. Following our previous thermodynamics high-throughput search for functional cathode coatings,[2] we recently further built on our framework for understanding the battery performance improvement associated with coatings by studying and predicting lithium transport through a number of various crystalline and amorphous coating materials using density functional theory (DFT) calculations.

In the current work, we first investigated the Li diffusion in top candidates of crystalline metal oxides from our thermodynamics screening. With the help of MINT (software developed by our group), we found unique Li interstitial sites and corresponding migration pathway in these crystalline metal oxides. After that, DFT based Nudge Elastic Band (NEB) method was applied to calculate the migration barrier and corresponding Li diffusivity for each material was obtained by Kinetic Monte Carlo (KMC) simulation. Since many reports in the literature show coatings are likely to be in an amorphous form, we further studied the Li transport in a variety amorphous oxides and fluorides by methods that combine first principles density functional theory calculations and statistical mechanics.

In above diffusivity calculations, only dilute Li concentrations is taken into account, since at high Li concentration, phase transitions are likely to occur. Knowing that the Li diffusivity can be improved at high Li concentration, we extended our kinetical framework to some Li-contained metal oxides. All these metal oxides, fluorides and Li-contained metal oxides are top coating candidates examined from previous thermodynamic calculations. After all this kinetical calculation of Li transport, a ranking list is predicted and some materials are suggested as good coating materials in terms of Li diffusivity, which is one of the key factors influencing the rate performance of Li ion battery.

This work is one part of a framework for understanding the battery performance improvement associated with coatings and should aid in the future discovery of functional coating materials.

References

[1] Z. Chen, Y. Qin, K. Amine, Y.-K. Sun, J. Mater. Chem. 2010, 20, 7606.

[2] M. Aykol, S. Kirklin, C. Wolverton, Adv. Energy Mater. 2014, 4, 1400690

Acknowledgement

This computational research work was supported by The DOW Chemical Company.
The Effects of Co-Substitution and Al-Doping on the Structural Stability of LiNiO2
Authors: Lee Eunseok , Iddir Hakim , Benedek Roy
Published: February 2020

Developing advanced cathode materials that provide high specific energy and power is essential for the commercialization of Li-ion batteries for electric vehicles. The layered LiNi0.8Co0.15Al0.05O2 (NCA) has received attentions as a promising candidate due to its cheaper material cost than LiCoO2, competitive electrochemical performance, and improved structural stability than LiNiO2. Thorough understanding of the origin of structural instability of Ni-based cathodes and the mechanism of Co-substitution and Al-doping will enable further improvement of Ni-based cathodes and other types of cathode materials as well. In this talk, we present our computational work on the structural stability of NCA, with emphasis on the effect of magnetic ions.

LiNi1-yCoyO2 (NC) was studied first. Atom-spin coupled cluster expansion (CE) based on the density functional theory (DFT) calculations was performed to find stable atom-spin configurations of NC. The cationic mixing was accounted for by assuming that each cationic lattice site can be occupied by any of Li, Co, or Ni. The result predicted three stable configurations at zero temperature: LiNi0.8Co0.2O2, LiNi0.67Co0.33O2, and LiNi0.5Co0.5O2, as well as several more configurations at finite temperature, especially at y < 1/3, which agreed to the experimental observation on the range of solid-solution phase NC. Interestingly, the configurations of solid-solution phase NC had Ni ions in Li-layer (Ni-defects). We also found that that the solid-solution phase NC became less dominant when the Co content increased, which suggested that Co substitution might have suppressed the formation of Ni-defects.

DFT calculations with HSE06 functional were additionally performed to investigate the mechanism of Co substitution associated with the suppression of Ni-defects formation. The oxidation state of each ion was obtained by analyzing the magnetic moment and agreed well with experimental observations. We found that a Ni-defect tended to be Ni2+ by oxidizing one Ni ion in TM layer to Ni4+ when they formed the nearest neighbor pair.  In this case, the antiferromagnetic spin distribution was possible for all pairs of paramagnetic Ni ions (Ni2+ and Ni3+), which implies the configurations with Ni-defects (Ni ions in Li layer) are thermodynamically more favorable than non-defective configurations where such the antiferromagnetic spin distribution is not possible due to magnetic frustration. When Co is substitued for Ni, the oxidation state of Co is Co3+, which is diamagnetic like Ni4+. Then the antiferromagnetic spin distribution for all paramagnetic ions is also possible even without creating Ni-defects and we will demonstrate that the most ideal case is when y=1/3.

We performed further calculations to find stable NCA configurations by replacing a portion of Co in NC with Al. By comparing NC and NCA, the effect of Al-doping to the structural stability will be also discussed.
Enhanced Cycle Life and Capacity Retention of Ultrathin Film Coated SnO2 Nanoparticles at High Current Densities
Authors: Palaparty Sai Abhishek , Patel Rajankumar L. , Liang Xinhua
Published: February 2020

Tin oxide (SnO2) has a high theoretical capacity (~782 mAh/g) but, it experiences large volume changes during charge and discharge cycles that causes rapid capacity fade, which limits its practical use as an anode material. In an attempt to solve this, we coated these particles with ultrathin conductive metal oxide films that act as artificial solid electrolyte interphase layer, thus stabilizing the SnO2 particles for better longevity of significantly improved performance at high current densities in a practical voltage window. Since there exists a tradeoff between species transport and protection of particles (expecting long life), a film with an optimum thickness was achieved by atomic layer deposition (ALD) on SnO2 particles. The conductive film coated particles exhibit a significant improvement in capacity and cycling performance compared to uncoated samples. With an optimum thickness, an initial capacity of ~ 646 mAh/g was achieved at a high current density of 1,250 mA/g. After 1,000 cycles of charge/discharge at 1,250 mA/g, the coated sample showed a capacity retention of 95% as compared to 24% of the uncoated sample when cycled at room temperature; at 55 ºC, the capacity retention of the coated sample was 97% compared to 34% of the uncoated sample.
C-MEMS Based Micro-Power: From Symmetric to Battery-Type Hybrid Microsupercapacitors
Authors: Agrawal Richa , Wang Chunlei
Published: February 2020

Given the rapid boom in development of miniaturized electronic devices, there has been an ever-increasing demand for high performance rechargeable micro-power devices. At the heart of micro-power are microsupercapacitors, which have great potential as standalone power devices or even replace microbatteries depending upon the application. Carbon microelectromechanical systems (C-MEMS) a technique, in which a patterned photoresist is pyrolyzed in order to produce carbon microelectrode platforms, has been proved to be a powerful approach for fabricating high-performance microsupercapacitors. The as-fabricated carbon electrodes can further be electrochemically activated or even decorated with different nanostructures as such carbon nanotubes, graphene or conducting polymers such as polypyrrole (PPy) in order to further enhance the electrochemical performance of the microsupercapacitors. In general, supercapacitors with identical anode and cathode are referred to as “symmetric” while the ones with different anode and cathode are referred to as “asymmetric” or colloquially as “hybrid”. The latter type of capacitor combining a faradaic type battery electrode and an electrochemical double layer type electrode has gained significant scientific interest in recent years. Intuitively such a capacitor would combine the benefits of the two very disparate electrodes, such as a wide operating potential, high power, high energy along with high cycle longevity. In previous works, our group has mostly focused on integrating nanostructures onto C-MEMS platforms for mostly symmetric microsupercapacitors and at present we are focusing on C-MEMS platforms for hybrid battery-type microsupercapacitors. Detailed works will be presented at the conference.
Synthesis and Electrochemical Performance of Carbon Coated Prelithiated Silicon Nanoparticles As the Anode for Lithium-Ion Batteries
Authors: He Qianran , Ashuri Maziar , Shaw Leon
Published: February 2020

The most widely used method to address the tremendous capacity decay of silicon anodes due to their huge volume change during cycling is to reduce them into nano-scale structures. While various nanostructures have successfully alleviated the unstable volumetric change of silicon anodes, the exponentially increased surface area of these nanostructures bring out irreversible lithium consumption during the SEI formation process which leads to a large first cycle capacity loss. To solve the problem, here we come up with an idea of synthesizing carbon coated prelithiated silicon nanoparticles to serve as the anode. With the prelithiation treatment the lithium consumed in the SEI formation could be compensated, while leaving void space inside the carbon shell to allow silicon particles expand and shrink freely and thus providing stable interfaces between particles during cycles. By this design, the silicon anode will achieve a high first cycle Columbus efficiency and at the same time maintain a good mechanical stability to ensure a long cycle life. Synthesis method of the carbon coated prelithiated silicon nanoparticles will be introduced and the electrochemical performance will be discussed.