bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction of Csi As Multi-Functional Redox Mediator for Enhanced Li-Air Batteries
Authors: Park Yong Joon , Lee Chan Kyu
Published: February 2020

Recently, Li-air batteries have attracted enormous research attention as a promising next-generation energy-storage system because of their high theoretical energy density. However, they still face several obstacles that must be overcome before practical application becomes feasible. The basic reaction of the non-aqueous Li-air batteries is the formation of Li2O2 during the discharging process and its dissociation during the charging process on the surface of air electrode. One of the major issues is that the dissociation of solid and electrical insulating Li2O2 is relatively slow and inefficient. This feature of non-aqueous Li-air batteries results in undesirable electrochemical properties, such as large over-potential, low rate-capability, and limited cyclic performance. Moreover, the instability of the Li metal anode is another major issue surrounding Li-air batteries. The chief problem associated with using the Li metal anode concerns the dendritic growth and low coulombic efficiency that occur during cycling. In this study, we introduce CsI as a new redox mediator in order to enhance Li-air batteries. The CsI dissolved in the electrolyte will be ionized to Cs+ and I−. The Cs+ ions can then attach at sharp morphological spots on the Li metal surface, and electrostatically repel the incoming Li+ ions, which can suppress the growth of Li dendrites. At the same time, the I− ions in the electrolyte can react with Li2O2 on the surface of the air electrode and act as a redox mediator, which can facilitate the dissolution of Li2O2. In this way, our new redox mediator can act as an electron-hole transfer agent at the cathode as well as an electrostatic shied for the suppression of dendritic growth at the anode.
Ab-Initio Calculations of Transition Metal Doping in Li2FePO4F Polymorphs
Authors: Patel Shane , Kim Soo , Wolverton Christopher
Published: February 2020

Lithium ion batteries have been widely used in commercial electronics since the 1990s, and with the growth of the electric vehicle market and the need to store renewable energy from intermittent sources, the demand for lithium ion batteries will continue to expand. In an effort to improve the safety, life-time, and energy density of these battery systems, there is a demand to search for alternative cathode materials. Density Functional Theory (DFT) is a powerful computational method that can be used to efficiently screening for cathode materials with desired properties [1].

Materials in the Li2-xMPO4F family, in which the M sites are occupied by a transition metal (M = Fe, Co, Ni, etc.), have been proposed as alternative cathodes to replace traditional cathode materials, such as LiCoO2. Depending on synthesis pathways, materials in this family can take three distinct structures, one in the triclinic space group P1 [2], and  two with orthogonal space groups, Pbcn and Pnma [3,4], all of which permit multi-dimensional lithium transport. This, in combination with the wide range of transition metals that may occupy or be doped into the M sites, make the family potentially rich with cathode structures that operate within a desired voltage range. In addition, materials within this family are interesting due to the presence of two lithium ions per formula unit, compared to the single lithium ion present per formula unit in the olivine LiMPO4.  However, extracting lithium ions from the standard Li2FePO4F past LiFePO4F requires a voltage of roughly 5 V, regardless of the polymorph [5]. By changing the redox active transition metal species, the operating voltage for lithium extraction can be tuned.

We use DFT to perform first principles calculations of  Li2-xMPO4F structures with both M sites fully filled with single transition metal species, and structures with transition metal doping in the form of Li2-xMI
1-yMII
yPO4F. From our calculations, we determine ground state phase stability as a function of M, as well as structural, energetic, and electrochemical properties.

References

[1] M.M. Thackeray, C. Wolverton, E. D. Isaacs, Energy Environ. Sci. 5. 7854-7863 (2012).

[2] T.N. Ramesh, K. T. Lee, B.L. Ellis, and L. F. Nazar, Electrochem. Solid-State Lett. 13. A43-A47 (2010)

[3] B.L. Ellis, W. R. M. Makahnouk, Y. Makimura, K. Toghill, and L.F. Nazar, Nat Mater. 6. 749-753 (2007).

[4] N. R. Khasanova, O.A. Drozhzhin, D. A. Storozhilova, C. Delmas, E.V. Antipov, Chem. Mater. 24‎. 4271-4273 (2012).

[5] F. Yang, W. Sun, Y. Li,H. Yuan,Z. Dong,H. Li, J. Tian,Y. Zheng, and J. Zhang, RSC Adv., 4. 51095-50201 (2014).
What Is the Rate-Limiting Transport Factor in LiNi0.8Co0.15Al0.05O2 (NCA)?
Authors: Wen Bohua , Tsai Ping-chun , Chiang Yet-Ming
Published: February 2020

LiNi0.8Co0.15Al0.05O2 (NCA) has been widely used as cathode in commercialized lithium-ion batteries (LIBs), but its fundamental electrokinetic properties such as interfacial and bulk transport, are poorly understood. In our previous study, diffusivity and conductivity of bulk NCA at different states of charge (SOC) have been investigated using dense single-phase pellets1. Based on that, we further attempt to understand the electrochemical charge-transfer kinetics at NCA/liquid electrolyte interface, and find out the rate-limiting transport factor of NCA cathode in LIBs.

From Butler-Volmer equation, exchange current density jo
can be utilized to evaluate the kinetics at solid/electrolyte interface. Thus, we applied two methods - electrochemical impedance spectroscopy (EIS) and potentiostatic intermittent titration technique (PITT) to study the exchange current density of NCA at different SOC using the same dense bulk pellets2. Primary results of these measurements are shown in Fig. 1. Exchange current density from PITT is found to decrease with increasing SOC, whose value is nearly 102smaller at high SOC (70 %) than that of pristine NCA. However, EIS results show discrepancy above 50 % SOC.

Based on the PITT results from bulk pellets, relative contributions of bulk and interfacial transport of the particles can be modeled using Biot numbers Λ and time constant analysis. Fixing the acceptable overpotential as 0.1 V, the rate of bulk diffusion and interfacial reaction of the 5.6 um commercial spherical NCA particles are plotted as Fig. 2. With increasing SOC, the maximum C-rate decreases by almost 102 and Λ is of order 100 indicating the mixed-control kinetics. In other words, the interfacial reaction clearly becomes the rate-limiting kinetic step and thus determine the rate-performance of NCA.

This work was supported as part of the North East Center for Chemical Energy Storage (NECCES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0012583.

References:

[1]. R. Amin, D.B. Ravnsbaek, Y.-M. Chiang, J. Electrochem. Soc. 2015, 162, A1163-A1169.

[2]. J. Li, X. Xiao, F. Yang, M. W. Verbrugge, Y.-T. Cheng, J. Phys. Chem. C. 2012, 116, 1472–1478.

Figure 1
Interfacial Strength of Cathode Materials By Laser- Spallation Measurments
Authors: Seyed Faraji Leila , Keller Michael Wade , Teeter Dale
Published: February 2020

The adhesion of anode and electrode materials to such substrates as current collectors and solid electrolytes is an important area of research.  Many potential anode and cathode materials such as SnO2 and sulfur expand as much as 300% with the intercalation of lithium.  Thus understanding adhesion mechanisms can result in better functioning electrode systems and could allow new electrode materials to be used.  Recently, a procedure for producing nano-scale batteries using a nano-porous alumina membrane has been developed.  This battery structure consists of thin film anodes and cathodes deposited on top of the electrolyte-filled nanoporous membrane.  At the moment, the interfacial strength of the anode/substrate and the cathode/substrate bond has not been studied and this battery configuration presents an ideal system for adhesion studies.  In the present work, the strength of this adhesion is investigated using the novel method of laser spallation.  This approach allows for the investigation of the interface adhesion  strength without the complication of mechanical loading techniques. For the experiments presented, a model substrate loaded by laser spallation and the interfacial strength of the substrate-cathode bond is investigated as a function of cycling history and processing parameters. Understanding the role of process parameters like deposition condition and design parameters such as substrate thickness and film thickness, on mechanical performance of the layer is essential in optimizing manufacturing.
High Rate Performance of Ti Doped LiFePO4 Cathodes for Lithium Ion Battery
Authors: Kim Sungjin , Mathew Vinod , Gim Jihyeon , Song Jinju , Jo Jeonggeun , Vu Thi Trang , Kim Seokhun , Kim Jaekook
Published: February 2020

A Li-ion battery cathode with target stoichiometry LiTi0.08Fe0.92PO4 was prepared by doping excess amount of Ti4+ into the olivine structure using solid-state reaction at 700 °C. X-ray diffraction (XRD) results of the prepared sample confirmed the presence of a major olivine phase in addition to few impurity phases including the ion-conducting NASICON-type Li3Fe2(PO)4 and Li2TiFe(PO4)3 phases. Further, the calculated lattice parameter values appear to confirm Ti-doping in LiFePO4. Electron microscopy and particle distribution studies revealed a slight increase in the average particle-sizes in addition to fragmented particles and the presence of surface carbon coating on the sample particles. EDX mapping studies revealed a fair distribution of Ti4+ ions in the prepared sample. When examined as a cathode in a non-aqueous lithium cell at room temperature, LiTi0.08Fe0.92PO4 delivered high specific capacities and good capacity retentions (≤ 2% capacity loss after 50 cycles). Besides, the cathode delivered impressive rate capabilities as specific capacities of 160 and 110 mAhg-1 at 0.1 and 11.4 C, respectively, were retained. Although the average particle-size was slightly higher, the presence of ion-conducting NASICON-type species appear to contribute to the enhanced electrical conductivity and hence to the cathode performance of LiTi0.08Fe0.92PO4.
Carbon Nanotubes Doped with Silicon for Use in the Anode of Lithium Ion Batteries
Authors: Zeferino González Isaias , Gauvin Raynald , Miki Yoshida Mario , Verde Gómez Ysmael
Published: February 2020

The lithium ion battery is an attractive and environmental friendly energy source because of its large versatile applications ranging from portable electronics systems to support renewable energy sources. In addition, lithium ion batteries have the highest energy density among others known chemical batteries and are the most promising technology for portable applications. However, to satisfy such applications is essential to improve some components of lithium ion battery. One of the main challenges is to increase their electrochemical performance by improving the storage of lithium ions in the anode electrode. Graphite has been the most successful materials for the anode electrode, which has reached a specific capacity of 372 mAh g-1. However, those materials have reached its storage capacity limit. Thus, alternative supports which can provide higher capacity than graphite are needed. Carbon nanotubes (CNT) can be a promissory alternative material, especially those that are doped with heteroatoms. The physical and chemical properties of CNT are modified by the dopant atoms intrusion in the carbon lattice that improve the electrical conductivity, morphology and the structure of carbon. The present study shows the synthesis and characterization of silicon doped carbon nanotubes (Si-CNT). Si-CNTs were synthesized by a modified chemical vapor deposition using toluene as carbon source and ferrocene as metal catalyst for the nanotubes growth. Triphenylsilane were used as silicon doping. The effects of various parameters including furnace temperature and silicon concentration were investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X ray diffraction (XRD) and Raman spectroscopy. The results showed that the morphological and physical properties of Si-CNT, such as lengths, diameter, defects, and wall thickness, changed in comparison to those of undoped CNT. According to the Raman results the doped nanotubes showed major defect in the structure; this phenomenon can be explained by the integration of the silicon atoms in the structure of the nanotubes, which increase the order of the graphitic network. On the other hand, the elemental atomic composition analysis using SEM by energy-dispersive x-ray spectroscopy (SEM-EDS) showed that silicon is presented with Si content of 0.25±0.09 at. %. The Si-CNT properties and its evaluation as anode materials in lithium ion batteries are discussed.
Electrochemical Properties of Hard Carbon Materials As Anode Materials for Sodium-Ion Battery
Authors: Kim Dae Sik , Park Eunjun , Yoo Hyundong , Kim Hansu
Published: February 2020

Sodium ion battery has gained much attention as an alternative power source to replace lithium ion battery in order to address recent concerns on the limited resources of lithium and its localized reserves in the earth. However, graphite, currently used anode electrode material in lithium ion battery, cannot be used for sodium ion battery because of insufficient interlayer distance between graphene layers for the intercalation of sodium ions. Instead, various carbon materials which have disordered structure have been investigated as anode materials for sodium ion battery. In this presentation, the electrochemical performances of hard carbon materials and their modified forms by mechanical milling and mild oxidation were investigated as sodium ion storage materials for sodium ion battery with respect to structural and surface modifications of hard carbon.
Novel Titanates As Anode Materials for Sodium Ion Batteries
Authors: Ma Xuetian , Chen Hailong
Published: February 2020

Low cost electrochemical energy storage is very much desired for electric grid and transportation. Concerns on cost and availability of lithium are raised for lithium ion battery (LIB) and other Li-chemistry based energy storage technologies, such as Li-Air and Li-S systems. Sodium ion battery (SIB) is considered as an alternative technology, due to the potentially low cost and abundance of sodium[1]. Yet many key components, including cathode, anode, electrolyte, still require further improvement.

Hard carbon and Sn alloys have shown good performance as anode for SIBs. Intercalation anodes are also desired owing to relatively small volume changes during cycling. Some titanates, such as Na2Ti3O7 and Na2Ti6O13 have been reported to have high performance. In this work, we report several new titanate compounds as promising anode material for sodium ion batteries. The compounds are synthesized through solid state reactions. Powder X-ray diffraction (XRD) and refinement were applied to identify and confirm the crystal structure. Electron microscopy was used to study the morphology of the compound and to compare the products with different synthesize treatments. The electrochemical tests showed that ~80 mAh/g reversible capacity can be achieved with good retention for one of the titanates, as shown in Figure 1, for cycling at C/10 rate between 0.01-2.5V. Ex situ and in situ XRD are used to study the structural changes during cycling. The results demonstrated a topological intercalation with small lattice volume change. The influence of synthesis conditions, including temperature, ball mill rate and carbon coating amount were also investigated.

Figure caption:  Figure 1. The electrochemical cycling voltage curves of the titanate at C/10 rate between 0.01 and 2.5V.

[1] S.P.Ong, G. Ceder, Energy Environ. Sci.,2011,4,3680-3688

Figure 1
Stability of Li Metal Anode in Li-S Batteries
Authors: Cao Ruiguo , Chen Junzheng , Engelhard Mark H , Han Keesung , Xu Wu , Zhang Ji-Guang
Published: February 2020

Because of its high energy density and promising potential to revolutionize the future electric energy storage systems, the technology of Li-S batteries has attracted significant interests in recent years. With the significant progresses made on the development of cathode materials in lithium-sulfur (Li-S) batteries, the stability of anode in Li-S batteries has become one of the more urgent challenges in order to reach the long-term stability of Li-S batteries.

Lithium metal is the preferential option for the anode material in Li-S batteries because of its high specific capacity. However, lithium polysulfides formed during discharge and charge processes may migrate from cathode to anode side to react with the lithium metal, so called shuttle problem, leading to limited cycle life and poor Coulombic efficiency of Li-S batteries. A passivation layer is easily formed on the metallic Li anode surface because of the presence of polysulfides and electrolyte additives, which is supposed to corrode Li anode and result in failure of the Li-S battery. Various strategies used to minimize the corrosion of Li anode and to reduce its impedance increase have been developed, including electrolyte additives, polymer electrolytes and interlayers. Recently, concentrated electrolytes were demonstrated to offer lower solubility of polysulfides and could lead to more stable cycling stability in Li-S batteries. Concentrated electrolytes tend to reduce the solubility of lithium polysulfides due to the lack of available solvent to partially solvate the Li+ cations. Coordinating anions also affect the solubility of lithium polysulfides through interacting with the Li+ cations with different solvation strength. In this presentation, the failure mechanism and the stability of anode/electrolyte interface in Li-S batteries with highly concentrated electrolyte will be reported.
Insights into Electrochemical Sodium Metal Deposition As Probed with in Situ 23na NMR
Authors: Bayley Paul M. , Trease Nicole M. , Grey Clare P.
Published: February 2020

Sodium batteries have seen a resurgence of interest from researchers in recent years, owing to numerous favourable properties including cost and abundance. Here we examine the feasibility of studying this battery chemistry with in situ NMR, focussing on Na metal anodes. Quantification of the NMR signal indicates that Na metal deposits with a morphology associated with an extremely high surface area, the deposits continually accumulating, even in the case of galvanostatic cycling. Two regimes for the electrochemical cycling of Na metal are apparent that have implications for the use of Na anodes: at low currents, the Na deposits are partially removed on reversing the current, while at high currents there is essentially no removal of the deposits in the initial stages. At longer times, high currents show a significantly greater accumulation of deposits during cycling, again indicating a much lower efficiency of removal of these structures when the current is reversed.
Prediction of the Lithiation Process of Transition Metal Oxides (Co3O4 and NiO) for Lithium-Ion Batteries from First Principles
Authors: Yao Zhenpeng , Kim Soo , Aykol Muratahan , Li Qianqian , Wu Jinsong , Dravid Vinayak , Wolverton Chris
Published: February 2020

To study the important role played by metastable phases during electrode’s charging and discharging cycling, we simulated the lithiation process of the Co3O4 and NiO using DFT calculations. The studies are started with creating supercells for Co3O4 and NiO. Li-ions were put into the unoccupied interstitial sites for a series of stoichiometries (LixMaOb, x = 0.5, 1.0, 1.5... and M=Co, Ni). For Co3O4, to investigate the energetic influence of the Co migration, initial structures are created with Cos moved from tetrahedral sites to the octahedral sites. For each composition, all the geometrically different derivative structures were generated and selected to be relaxed in DFT. Convex hulls are built with all formation energies of different stoichiometries. Voltage profiles are calculated using the energetics of the phases on the hull. Six and two metastable phases are identified for Co3O4 and NiO. Structures evolution predicted for Co3O4 are confirmed with the former experimental studies. The simulated voltage profiles resulted from the prediction of the metastable phases fit much better with the experimental measurements. The results indicate that the lithiation process of Co3O4 and NiO occur through a series of metastable phases.

Acknowledgements

Z.Y., Q.L., J.W., V.D., and C.W. were supported as part of the Center for Electrochemical Energy Science (CEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of the Science, Basic Energy Science. S.K. was supported by Northwestern-Argonne Institute of Science and Engineering (NAISE). M.A. was supported by the Dow Chemical Company. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract DE-AC02-05CH11231.
Materials Design Guidelines for All-Solid-State Batteries
Authors: Wang Yan Eric , Richards William Davidson , Miara Lincoln J. , Kim Jae Chul , Ceder Gerbrand
Published: February 2020

All-solid-state batteries with non-flammable solid-state electrolytes have significant advantages over Li-ion or Na-ion batteries with liquid electrolytes. In this poster we will present our recent advances in understanding the fundamental relationship between crystal structure and ionic transport in fast Li-ion conductors [1]. We find that the topology of the sites along the lithium hopping path, and the volume per anion, largely control the activation energy for Li motion.  This topology is more favorable in compounds where the anions form a bcc lattice than in the typical close-packed fcc and hcp anion arrangements, explaining why most compounds are not fast-ion conductors.  Furthermore, an accurate and efficient first-principles computational methodology has been developed to evaluate thermodynamic stability of the solid-state electrolyte against battery electrodes [2]. These findings not only provide valuable insights towards the understanding of materials behaviors in discovered ionic conductors, but also serve as design principles for new Li and Na conducting materials and all-solid-state batteries. We will also report a few novel Li and Na ionic conductors that are predicted based on our design principles and experimentally confirmed by our collaborators.

[1] Y. Wang, et al., “Design principles for solid-state lithium superionic conductors,” Nat. Mater., 14, 1026-1031, (2015).

[2] W. Richards, et al., “Interface stability in solid-state batteries”, Chem. Mater., 28, 266-273, (2016).
A Multiple Particles Model for Super Lithium Ion Capacitor
Authors: Cheng Yun , Li Jie , Jia Ming , Tang Yiwei , Du Shuanglong
Published: February 2020

Super lithium ion capacitor (SLIC) is a hybrid energy storage system containing functionalities derived from lithium ion batteries and electric double-layer capacitors. The energy storage in the electric double layer plays an important role and depends on the microstructure of the electrodes and the interfacial morphology at the electrolyte/electrodes interfaces. Although numerical models based on the real structure of electrodes by 3D microstructure reconstruction technique can help us to understand the influences of microstructure on the energy storage performance of SLIC, these models are time assuming.

In this respect, we develop a Multiple Particles Model based on Single Particle Model issued by Ralph E. White. This moel is characteristiced with multiple active materials. Using this model, some electrochemical properties under galvanostatic charge/discharge behavior as well as AC-impedance behavior and rapid current pulses are in real time obtained.
Structural, Compositional and Electrochemical Control of Integrated Layered-Layered-Spinel Cathodes
Authors: Park Joong Sun , Croy Jason R. , Lee Eungje , Blauwkamp Joel D. , Thackeray Michael M.
Published: February 2020

A concerted effort is being made at Argonne National Laboratory to stabilize high capacity ‘layered-layered’ xLi2MnO3•(1-x)LiMO2 electrodes, in which M is typically Mn, Ni and Co, when cycled to high potentials.  The strategy being adopted is to marginally reduce the lithium content in ‘layered-layered’ structures in order to induce the formation of a spinel component, thereby introducing stabilizing transition metal ion pillars in the lithium layers of structurally-integrated ‘layered-layered-spinel’ (1-y)[xLi2MnO3•(1-x)LiMO2]•yLi0.5MO2 electrodes. This approach, which follows earlier related work on the composite ‘layered-spinel’ system, xLi2MnO3•(1-x)LiMn2-zLizO4 (0≤z≤0.33) [1], has yielded positive results with improvements in first-cycle efficiency, discharge capacity, and cycling stability being reported, particularly when targeting 5-15% of spinel in the electrode structure [2, 3].

In this presentation, the results of structural studies of ‘layered-layered-spinel’ materials using a combination of X-ray and neutron diffraction, transmission electron microscopy techniques, coupled to complementary electrochemical data, will be reported.  One of the major goals of the study is to determine at what value of y do the transition metal ions start to drop into the lithium layers for any given system and composition, and to what extent can a lithium deficiency in the ‘layered-layered’ structure be compensated by changes in the oxidation state of the M cations while keeping the layered configuration intact.

References

C. S. Johnson, N. Li, J. T. Vaughey, S. A. Hackney, M. M. Thackeray, Electrochem. Commun., 7, 528 (2005).

D. Kim, G. Sandi, J. R. Croy, K. G. Gallagher, S.-H. Kang, E. Lee, M. D. Slater, C. S. Johnson, M. M. Thackeray, J. Electrochem. Soc., 160, A31 (2013).

B. R. Long, J. R. Croy, J. S. Park, J. Wen, D. J. Miller, M. M. Thackeray, J. Electrochem. Soc, 161, A2160 (2014).

Acknowledgment

Support for this work from the Office of Vehicle Technologies of the U.S. Department of Energy, in particular, Tien Duong, David Howell and Peter Faguy, is gratefully acknowledged.

The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.
Role of Graphene Coating in Improving the Low Temperature Performance of Li-Rich Li(Li0.125Mn0.375Ni0.5)O2 for Lithium-Ion Batteries
Authors: Dong Li , Hua Lai
Published: February 2020

Li-rich Li(Li0.125Mn0.375Ni0.5)O2 was prepared by a carbonate co-precipitation method and modified with graphene. The effects of graphene on the surface structure, morphology and low-temperature electrochemical properties of Li(Li0.125Mn0.375Ni0.5)O2 are investigated. The electrochemical performance results show that the charge-discharge capacities and voltages platform are lowered with the reducing temperature, however, cathode materials surface modified by graphene exhibit higher specific discharge capacity and slower voltage fading rate. The electrochemical impedance spectroscopy (EIS) results indicate that the improvement of low temperature electrochemical performance of Li(Li0.125Mn0.375Ni0.5)O2 modified by graphene is originated from the stable interface and higher conductivity.
Preparation and Preliminary Electrochemical Characteristics of Cooking Oil Based Nano Carbons As Electrode Materials for Lithium Ion Batteries
Authors: Arie Arenst Andreas , Kristianto Hans , Lee Joong Kee , Halim Martin
Published: February 2020

In the past decades, the development of nano- carbon materials with well-defined characteristics such as fullerenes, nanotubes and graphene have been a very active area of research. Carbon nanospheres (CNSs) are other class of nanostructured carbon materials, and have shown good prospects for application as alternative LIB anodes. CNSs possess some remarkable characteristics such as high specific capacity and good rate capability as anode materials in LIB. Those specific characteristics are attributed to a combination of several factors, including a short diffusion paths for Li+ ions; good porosity and high surface area. In this study, carbon nanospheres (CNSs) were synthesized by thermal assisted pyrolysis process using palm oil as carbon precursors, Fe-catalyst and activated carbon support. Prior to the synthesis of carbon nanospheres, Fe-catalyst on carbon supports was prepared by deposition precipitation by varying the amount of catalyst (10%, 20% and 30% w with respect to the mass of carbon support). The effect of catalyst amount on the morphology and structural characteristics of carbon products was investigated by x-ray diffraction (XRD), Raman spectroscopy and transmission electron microscope (TEM). The study indicated that structural properties are changed when a Fe catalyst amount is increased from 10 to 30 wt%. The stable cycle performances of carbon products were demonstrated when they are utilized as anode materials in lithium ion batteries. However, it can be observed that the highest specific capacity was shown by the carbon samples produced at the highest content of Fe catalyst.
Constructing Well-Designed Conductive Network for Lithium-Ion Battery LiNixCoyMnzO2-Type Cathodes
Authors: Cho Inseong , Choi Jaecheol , Kim Kyuman , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Ternary transient metal component systems of Li-Ni-Co-Mn-O (NCM; LiNixMnyCozO2 with x + y + z = 1) have advantages of high energy density, lower toxicity, lower cost, and high safety performances. But, NCMs suffer from poor rate capability and cycling performance under high rate charge/discharge conditions due to their low electric conductivities. Constructing well-dispersed conductive network is an important approach to overcome the inherent limits in the performance of the active materials. A variety of carbon materials such as carbon black (Super-P), carbon nanotubes, vapor-grown carbon fibers (VGCFs) have been studied as conductive agents.[1,2] Herein, the effect of different types of conductive agents on the cathode performance of lithium ion batteries is investigated in more detail. Three types of cathode materials (LiCoO2, LiFePO4, LiNi0.6Co0.2Mn0.2O2) which are containing different ratios of VGCFs and Super-P are used.  Pillar-like morphology of the VGCF makes them to efficiently connect to the active materials and therefore, when we use the electrodes composed of primary particles, these achieve the highest electric conductivity for LiCoO2 (1.721 S cm−1) and LiFePO4 (1.23 S cm−1). On the contrary, for LiNi0.6Co0.2Mn0.2O2, consisted of micro-sized secondary particles made up of nano-sized primary particles, a mixture of two kinds of conductive additives shows synergistically improved electric conductivity (1.403 S cm−1). Well-dispersed powdery Super-P can helps electron transfer over the constituent primary particles. For all the studied cathodes, the cathode with a higher electrical conductivity shows improved result for the both cycle performance and rate capability.

References

[1] B. Jin et al., Electrochem. Comm., 2008, 10, 1537

[2] I. Cho et al., RSC Adv., 2015, 5, 95073

Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea(NRF-2014H1C1A1066977)
Using Synchrotron Radiation to Study Li-Ion Batteries
Authors: Alfredsson Maria , Mountjoy Gavin , Bras Wim , Brownrigg Alex , Dominko Robert , Bruce Peter G. , Armstrong Anthony Robert , Billaud Juliette Marie , Kelder Eric M.
Published: February 2020

X-Ray Absorption Spectroscopy (XAS) is a powerful tool, which can be used to study the atomic local structure as well as oxidation state during battery cycling. Hence, XAS can be used to provide detailed atomic information for improvement of materials design.

Here we present in situ XAS results for Li2FeSiO4 and Li2.2Fe0.9SiO4, promising cathode materials for lithium-ion batteries. It provides a low cost solution and is considered as a safe electrode material for future electric transportation, as the Si–O bond provides stability similar to the P – O bond in LiFePO4 compounds. In theory, it is possible to remove two Li ions from Li2FeSiO4, by utilizing both Fe+2/Fe+3 and the Fe+3/Fe+4 redox couples and, thus, producing a higher capacity than 166 mAhg-1 for one Li ion. Although capacities greater than 200 mAhg-1 it has yet to be clarified whether it was due to Fe+4 formation or electrolyte degradation.

The aim was to establish the valence and local structure of Fe during charge and discharge. The valence state changes between Fe+2 and Fe+3, with no evidence of Fe+4 before the onset of electrolyte degradation. There is a reversible contraction and extension of the Fe–O bond lengths during cycling while the Fe-Si distance remains constant, which underlines the stability of the Li2FeSiO4 material. The same observations apply to Li2.2Fe0.9SiO4 cathode material indicating that changing the stoichiometry does not provide any additional structural stability.1

 1. A.W. Brownrigg, G. Mountjoy, A.V. Chadwick, M. Alfredsson, W. Bras, J. Billaud, A.R. Armstrong, P.G. Bruce, R. Dominko and E.M. Kelder, J. of Mater. Chem. A, 2015, 3, 7314-7322
Effects of High Energy Ball Milling on Phase Stability of Li7La3Zr2O12
Authors: Jonson Rob A , McGinn Paul J
Published: February 2020

Solid state batteries offer many potential advantages over their liquid electrolyte counterparts including improved safety, wider electrochemical voltage ranges, better chemical compatibility, and the possibility for structural batteries. Among the solid Li-ion electrolyte materials, Li7La3Zr2O12 (LLZO), a garnet structured compound with a relatively high room temperature ionic conductivity (~ 2 x 10-4 S cm-1), has attracted much research interest.

The solid state method is the most common route to synthesize LLZO. Long duration sintering at temperatures of 1200 °C or greater are used to obtain dense bodies of the highly conductive cubic phase of LLZO rather than the lower conductivity tetragonal structure.

The long time and high temperature sintering can also lead to Li loss requiring the LLZO part be covered in sacrificial mother powder. Stabilization of the cubic phase can be achieved through the addition of one or more dopants including Al, Ta and Nb.

LLZO electrolytes are thus energy intensive and materially inefficient to manufacture. Production scalability of LLZO batteries depends on developing methods to reduce sintering temperatures while maintaining desirable properties. High energy ball milling (HEBM) offers a relatively simple means to reduce particle size, improve microstructural homogeneity, and reduce sintering temperatures.

Here we report the effect of HEBM on phase stability in undoped LLZO. It is observed that HEBM is capable of causing undoped LLZO to transform from the tetragonal phase to the cubic phase at low temperatures ( <40oC). It is seen that the HEBM cubic undoped LLZO transforms back into tetragonal LLZO with heating. This transformation is not observed in HEBM (Al,Nb or Ta)-doped LLZO.

HEBM of (Al,Nb or Ta)-doped LLZO with Li3BO3 is also reported. Li3BO3 is added to promote low temperature sintering (< 900C) which greatly reduces Li losses. Li3BO3 is found to be compatible with LLZO. We observe that dopants may also be incorporated into LLZO through Li3BO3 sintering. This is demonstrated by heat treatment of HEBM undoped LLZO with Li3BO3 and Al2O3 additives. LLZO treated this way retains the cubic structure, rather than reverting to the tetragonal phase, indicating that Al has been incorporated into the lattice.
Fluorinated Carbonate As an Additive for High-Voltage Performance Lithium Ion Battery
Authors: Lee Jieun , Im Jinsol , Cho Kuk Young
Published: February 2020

Increase of the operation voltage of lithium ion batteries (LIB) is one important approach to enhance the energy density. Generally, conventional organic electrolytes based on the carbonate solvents show oxidation at about 4.5 V.

This can lead to severe capacity decay during the charge-discharge cycling. Thus it is significant to suppress decomposition of electrolyte and stabilize the cathode.

Here we investigated fluorinated carbonate solvent as an additive for high-voltage performance of LiNi0.5Co0.2Mn0.3O2 cathode LiB. The effects of additive content and electrochemical performances of the LIB were studied.
Investigation of Local Structures and Dynamics of Li and Na Ions in Nasicon-Type Solid Electrolytes by NMR Spectroscopy
Authors: Indris Sylvio , Kaus Maximilian , Scheuermann Marco , Rhode Magnus , Guin Marie , Tietz Frank , Guillon Olivier , Knapp Michael , Ehrenberg Helmut
Published: February 2020

We investigated the local structure and the dynamics of Li and Na ions in the solid electrolytes Li1.2Al0.6Ti1.4(PO4)3, Li1.6Al0.6Ge1.4(PO4)3, and Na3.4Sc2(SiO4)0.4(PO4)2.6 by NMR spectroscopy.

While 27Al MAS NMR spectroscopy reveals the presence of only octahedral [AlO6] environments for Li1.6Al0.6Ge1.4(PO4)3, Li1.2Al0.6Ti1.4(PO4)3 exhibits large amounts of Al located in tetrahedral [AlO4] environments. 31P MAS NMR measurements reveal multiple environments with different Al/Ge next nearest neighbor composition around P and the relative intensities are in good agreement with a statistical arrangement of Ge/Al on the octahedral sites for Li1.6Al0.6Ge1.4(PO4)3. For Li1.2Al0.6Ti1.4(PO4)3, the 31P MAS NMR results indicate the presence of structural disorder. These results are confirmed by X-ray diffraction and Rietveld refinements.

The dynamics of Li ions have been investigated by temperature-dependent static 7Li NMR lineshape analysis and 7Li NMR relaxometry. Jump rates of about 7∙108 s-1 can be estimated for Li1.6Al0.6Ge1.4(PO4)3 at 400 K and the activation barrier for a single Li ion jump is 0.14 eV. A Li diffusion coefficient of 10-11 m2/s and a Li ion conductivity of 3.6 mS/cm can be estimated at 400 K.

For Na3.4Sc2(SiO4)0.4(PO4)2.6, NMR spectroscopy reveals that Si and P are arranged statistically on the tetrahedral sites and Sc is exclusively located on octahedral sites. Temperature-dependent 23Na NMR measurements show a strong increase of the asymmetry of the local environment, consistent with XRD measurements which yield a strongly anisotropic thermal expansion. Jump rates of higher than 5∙103 s-1 can be estimated for the Na ions for temperatures above 300 K.
Permselective Membrane System As Ion Shield for Polysulfides Toward High-Stable Lithium Sulfur Battery
Authors: Huang Jia-Qi , Zhuang Tingzhou , Peng Hong-Jie , Zhang Qiang , Wei Fei
Published: February 2020

Lithium sulfur batteries attract great attention due to their high energy density, while the real applications are still hindered by the rapid capacity degradation. Despite great effort devoted to solving the polysulfide shuttle between the cathode and anode electrodes, it remains as a serious challenge to build high-stable lithium sulfur battery, which related to the diffusion and reaction between polysulfides and the metal lithium anode.

We proposed a strategy of introducing an ion selective membrane to improve the stability and coulombic efficiency of lithium sulfur battery. Generally, porous polymer membrane serves as membranes in batteries to avoid the short circuit between anode and cathode electrodes, which cannot stop the shuttle effect. By the introduction of permselective functional layer, the polysulfide anions can be confined in the cathode side, which would favor the cyclic stability and lower self-discharge performance.

We replace the routine membrane with an ion selective membrane, in which the sulfonate-ended perfluoroalkyl ether groups on the ionic separators are connected by pores or channels that are around several nanometers in sizes. These -SO3
-- groups coated channels allow ion hopping of positive charge species (Li+) but reject hopping of negative ions, such as polysulfide anions (Sn
2-) in this specific case due to the coulombic interactions. Consequently, this cation permselective membrane acts as an electrostatic shield for polysulfide anions, and confines the polysulfides in the cathode side. An ultra-low decay rate of 0.08% per cycle is achieved within the initial 500 cycles for membrane developed in this work, which is less than half that of the routine membranes.

We also proposed a unique lithium-sulfur battery configuration with ultrathin graphene oxide (GO) membrane for high stability. The oxygen electronegative atoms modified GO into a polar plane and the carboxyl groups acted as ion hopping sites of positively charged species (Li+) while rejected the transportation of negatively charged species (Sn
2-) due to the electrostatic interactions. Such electrostatic repulsion and physical inhibition largely decreased the transference of polysulfides across the GO membrane in lithium-sulfur system. By the incorporation of permselective GO membrane, cyclic capacity decay rate is also reduced from 0.49 to 0.23 %/cycle.

Such ion selective membrane is versatile for various electrodes and working conditions, which is promising for the construction of high performance batteries.

References
:

Huang JQ, Zhang Q, Peng HJ, Liu XY, Qian WZ, Wei F, 2014. Ionic shield for polysulfides towards highly-stable lithium–sulfur batteries.
Energy & Environmental Science
2014, 7, 347.

Huang JQ, Zhuang TZ, Zhang Q, Peng HJ, Chen CM, Wei F. Permselective graphene oxide membrane for high-stable and anti-self-discharge lithium-sulfur batteries.
ACS Nano
2015, 9, 3002.
Free-Standing Graphene-Based Papers with Controlled Pore Structures for High-Performance Li-O2 Battery Cathodes
Authors: Kim Do Youb , KIM Dong Wook , Kang Yongku
Published: February 2020

In this presentation, we report the fabrication of free-standing graphene-based paper electrodes with controlled pore structures for high-performance Li–O2 battery cathodes. Firstly, graphene nanoplatelet/graphene oxide (GNP/GO) papers were fabricated using a vacuum-assisted filtration method. The obtained GNP/GP paper electrodes had a highly wrinkled and disordered morphology and were highly flexible, which was attributed to the partial re-aggregation of the GNPs under the holding effect of the GOs during a drying process. Subsequently, the GNP/GO paper could be directly used as a Li–O2 battery cathode without any conducting additives and polymeric binders. The GNP/GO paper electrode showed a much higher discharge capacity (6910 mAh/g at a current density of 200 mA/g) in comparison to the reduced-GO paper and commercially available carbon papers due to its higher Brunauer–Emmett–Teller (BET) surface area and pore volume. However, the GNP/GO paper electrode suffered from huge irreversible volume expansion during discharge due to the formation of relatively large Li2O2 inside the pores. This irreversible volume expansion of the electrode made a Li–O2cell incapable in few cycles (< 20 cycles).

Secondly, in order to solve the volume expansion problem of the electrode, graphene papers with macropores within the paper that can accommodate relatively large discharge product were fabricated by using polystyrene particles as sacrificial templates. The as-prepared macroporous graphene paper (mp-GP) had a large BET surface area (ca. 373 m2/g), a large pore volume (ca. 10.9 cm3/g), and a high porosity (91.6%). Owing to the high surface area and large pore volume, a Li–O2 cell using the mp-GP electrode exhibited a high discharge capacity of ca. 12,200 mAh/g at a current density of 200 mA/g, as well as good rate capability. Moreover, the mp-GP showed good stability up to 100 and 78 cycles at a current density of 500 mA/g and 2000 mA/g respectively, with a limiting capacity of 1000 mAh/g. It was found that formation and decomposition of the discharge product, Li2O2, occured within the macropores, and thus, the mp-GP maintained its original structure without considerable expansion during cycling.
Assessment of All-Solid-State Lithium-Ion Batteries
Authors: Braun Philipp , Ender Moses , Illig Jörg , Ivers-Tiffée Ellen
Published: February 2020

All-solid-state lithium-ion batteries (SLIBs) are considered as promising next generation energy storage system for electric vehicles [1]. However, as this application needs low internal cell resistance even at high charging/discharging currents, a meaningful selection of materials, material combinations and electrode design is absolutely essential. Commonly known prerequisites are (i) high ionic conductivity of the solid electrolyte, (ii) low charge transfer resistance at the electrode/electrolyte interface and (iii) large active surface area between electrolyte and electrode material.

This study aims on guidelines for selecting solid electrolytes and their electrode interfaces, and on determining targets for further SLIB development. A newly developed one-dimensional model for SLIBs is presented, based on a design concept with 3-D structured composite electrodes (see Fig.1). The expected performance is simulated by linking two phase transmission line models [2] for both composite electrodes with an ohmic resistance for the solid electrolyte. Variations of (i) electrical parameters, i.e. ionic and electronic conductivity, (ii) electrochemical parameters, i.e. charge transfer resistance, and (iii) microstructure parameters, i.e. active surface area and composite electrode thickness, indicate the most important material and design parameters for high-performance. Performance potential will be presented for various anorganic solid electrolytes, i.e., glassy types (Phosphates, Oxides and Sulfides (Li7P3S11)) and crystalline types (LISICON, Garnets (Li7La3Zr2O12), Perovskites (Li3xLa2/3-xTiO3)) and diverse electrode designs with different thickness and microstructure properties.

References:

[1] A. L. Robinson and J. Janek, Solid-state batteries enter EV fray, MRS Bulletin, 39, pp 1046-1047, (2014)                                     

[2] J. Illig et al., Modelling Graphite Anodes with Serial and Transmission Line Models, Journal of Power Sources, 282, 335-347, (2015)

Figure 1