bluuebunny/crossref_metadata_2025 huggingface dataset:
Fabrication of LiCoO2/Li2s-P2S5 Composite Cathode By Electrostatic Slurry Spray Deposition for All-Solid-State Lithium Ion Batteries
Authors: Park Chan Hwi , Son Seung Hyeon , Choi Lak Young , Lee Se Wook , Shin Dongwook
Published: February 2020

The requirements of large scale lithium ion batteries such as electric vehicles (EV) and energy storage systems (ESS) have been attention. However, lithium ion batteries using liquid electrolytes have been badly reported of safety issues by its flammability. To resolve this issue, all-solid-state lithium ion batteries have been considered for candidate of next generation lithium ion batteries. The key material to realize all-solid-state lithium ion batteries is solid electrolytes with high conductivity and safety.

The ionic conductivity of solid electrolytes are currently attracting great attention. Several types of sulfide based electrolytes have been shown favorable lithium ion conductivities of 10-3-10-2 S/cm, which are comparable to those of liquid electrolytes, have been reported. In addition, those have several advantages of single Li ion conduction, good electrochemical stability over wide potential range.

However, all-solid-state cell has obstacle that is energy density of composite electrode lower than battery system using liquid electrolytes. It is difficult to make composite cathode with solid electrolytes for developing all-solid-state cells, that was required the continuous lithium ion and electron conducting paths. Inorganic solid electrolytes had lower contact area with active materials than liquid electrolytes, it was caused restrict ionic paths with active materials, and low electrochemical performance. In a large number of articles on all-solid-state lithium ion batteries using sulfide based electrolytes, composite electrodes were prepared by dry mixing. However, it is very difficult to control the particle mixture by dry mixing, it was caused low electrochemical performance. To conclude, an effective method for homogeneously mixed composite electrodes can improve the electrochemical performance of the all-solid-state lithium ion batteries.

In the present study, the LiCoO2/Li2S-P2S5 electrolyte composite cathodes were successfully fabricated by using the ESSD method for archive homogeneous thick film composite electrodes. The ESSD (Electrostatic Slurry Spray Deposition) process is unique method for thick film fabrication. The ESSD technique uses electrical energy to atomize and spray solutions. The ESSD technique is a method of spraying the slurry containing prepared powders. Dense film without any cracks and agglomeration can be easily fabricated by ESSD.

The composite cathodes were produced with differential cathode material / solid electrolyte ratio. Solid electrolytes were synthesized by mechanical milling method. In the deposited composite cathode thick films, all components homogeneously mixed, which were investigated by SEM and EDX. In addition, we made all-solid-state lithium ion batteries with composite cathode / solid electrolyte / In structure by uniaxial cold pressing method, which were successfully tested.
Lithium Garnet Based All-Solid-State Batteries By Spark Plasma Sintering
Authors: Hodkinson Jack
Published: February 2020

Solid state electrolytes (SSEs) have a wider electrochemical and thermal stability window than either liquid or polymer electrolytes, making them a desirable component of high voltage lithium ion batteries. The superior thermal stability of SSEs reduces the need for added coolant in a multi-cell battery allowing for more efficient stacking. The SSE also provides structural stability, lending itself to smaller and inherently safer batteries.

Recently LISICON sulfates, perovskites and garnets have been investigated because they exhibit a highly mobile sub-lattice of lithium. Among these the lithium garnet Li7La3Zr2O12 is a suitable candidates for use as a SSE as it is stable against lithium metal. Room temperature ionic conductivities as high as 1.3 S/cm have been reported for the cubic phase of this material, however the thermodynamically stable tetragonal phase has an ionic conductivity orders of magnitude bellow the cubic phase. Higher conductivity values and stabilization of the cubic phase may be obtained by chemical substitution. The strategy adopted in this study is the substitution of Li for Al, Ga, In, and Sc; La for Ca, Sr, Ba and the lanthanide series; and Zr for Hf and Ta. The lithium occupation and local environment will be studied in these structures to give insight into the phase transition from the cubic to the tetragonal phase. Preliminary PXRD results have confirmed the cubic phase can be stabilized by substitution of 25% of Zr for Ta.

The structure of these garnets will be characterized by NMR and diffraction techniques. To avoid Li volatilization and the formation of undesirable reaction products, the garnets will be consolidated by spark plasma sintering. The ionic conductivities will be determined by pulsed field gradient NMR and impedance spectroscopy. Half cells will be assembled by sintering a layered composition of the electrolyte and active material. The half cells will be cycled against lithium and the electrolyte/electrode interface will be characterized by microscopy techniques. Compatible electrode materials will be determined in this way and an entire solid state cell will be assembled by spark plasma sintering. These cells will be characterized by impedance spectroscopy and an analysis of their charge discharge behavior will be performed.
Lattice Dynamics and Thermal Transport in Superionic Conducting Li7La3Zr2O12 Garnet
Authors: Wang Shanyu , Qiu Wujie , Duan Bo , Zhang Wenqing , Yang Jihui
Published: February 2020

Highly conductive solid electrolytes (SE) that are stable in contact with Li and cathodes are required for all solid state battery or high energy Li-S and Li-air batteries. With the advantages of high conductivity (>10-4 S/cm) and excellent stability, Li-stuffed garnet Li7La3Zr2O12 has emerged as one of most promising SEs for Li batteries. Even though the Li ionic dynamics in garnet have been studied extensively, the couplings between Li transport and the vibrations of framework atoms, namely phonons, have seldom been studied, and the controversies in Li transport mechanism and superionic transition have not been settled. In this study, we synthesized phase-pure tetragonal and cubic Li7La3Zr2O12 using a solid state reaction method, and systematically studied their thermal conduction, lattice dynamics, and phase transition. Cubic phase, stabilized by 0.3 mol aluminum, shows much lower thermal conductivity k than that of tetragonal phase, e. g. 1.7 vs. 4.3 W/m-K at 70 K and 1.4 vs. 2.4 W/m-K at 300 K. More specifically, k of cubic phase is almost temperature independent and approaches the amorphous limit, indicating very strong phonon scattering; while the tetragonal phase shows a decreased k with increasing temperature, typical of crystalline solids with the Umklapp processes dominating phonon scatterings. By examining the lattice dynamics and velocity auto–correlation function (VAF) in the cubic phase, we found a high frequency hopping mechanism of Li rather than a liquid-like diffusion mechanism, and Li atoms predominantly contribute to the low energy lattice excitations. This indicates that Li atoms ‘rattle’ intensively in their equilibrium position before hopping to another sites, and the ‘rattling-like’ mode strongly correlate with lattice phonons to block their transport. Moreover, the Li-framework couplings also cause the instability of Li atoms in their positions and promote the hopping responsible for the high ionic conductivity. Our study provides additional understanding of ionic transport mechanism in garnet and insights into thermal management of all solid state batteries.
Facile Chemistry Towards All Solid State Polymer Electrolytes and Lithium Ion Batteries
Authors: Liu Zhihong , Cui Yanyan , Cui Zili , Chai Jingchao , Wang Qingfu , Cui Guanglei
Published: February 2020

Abstract: All solid state lithium batteries have been attracted intensive attention due to higher energy density and higher safety characteristics. Compared with inorganic solid state batteries, all solid polymer electrolyte lithium batteries possess advantages of readily processability and lower electrolyte/electrode interfacial impedance. These unique characteristics endow it a very promising power sources for large format application. However, the conventional fabrication for the solid polymer lithium battery involved a prefab solid polymer membrane laminated by the cathodes and anodes sheets. Herein an in situ polymerization process is developed to prepare all solid polymer electrolyte during the battery assembly. Some liquid precursors, such as epoxy compounds, are injected into battery and then catalyzed by LiFP6salt into all solid polymer electrolyte. In situ polymerization results in even lower electrolyte/electrode interfacial resistance, greatly improving the battery rate capability and cycling performance. These facile chemistry demonstrates a manufacturing innovation for all-solid-state polymer electrolyte batteries with cost-effectiveness and high performance.

 

Keywords:
solid polymer electrolyte, in situ polymerization, solid lithium battery;
Rechargeable Lithium/PMMA-Libob-Tegdme/O2 Battery
Authors: Kufian M.z , Arof A.k
Published: February 2020

In this work, poly(methyl methacrylate) (PMMA) based gel polymer electrolytes (GPEs) have been added with various concentrations of lithium bis(oxalato)borate (LiBOB). Methyl and methoxy functional groups in PMMA reduce the number of potential reaction pathways for Li2O2 attack in PMMA. Tetraethylene glycol dimethyl ether (Tegdme) has been used as solvent. The highest room temperature (RT) conductivity for the GPE with composition 10 wt.% LiBOB – 90 wt. % PMMA is 3.50 x 10-4 S cm-1. The window stability of the highest ionic conductivity is 4.7 V at room temperature. The lithium-air cells with configuration Li/10 wt.% LiBOB – 90 wt. % PMMA/carbon air cathode was tested at 0.05 mA/cm2 and charged from 2.0 V to 4.5 V at room temperature. The discharge capacity of cell ~ 500 mAh/g. The impedance of the cell has been carried out using electrochemical impedance spectroscopy (EIS).
Sodium Intercalation Mechanism into Hard Carbon
Authors: Tsai Ping-chun , Chung Sai-Cheong , Morikawa Yusuke , Nishimura Shinichi , Lin Shih-kang , Yamada Atsuo
Published: February 2020

Sodium-ion battery is attracting much attention as large-scale energy storage devices, because sodium is an earth-abundant element and it is of low cost. Hard carbon is one of the most promising anode material for the sodium-ion battery owing to its large reversible capacity of ca. 300 mAhg–1[1]. However, the reaction mechanism has not been fully elucidated.

Both lithium and sodium can intercalate into hard carbon. Their charge–discharge curves show similar profiles, having a slope and a flat region, therefore the reaction mechanism has been considered to be similar. However, our ab initio calculations and experimental results revealed the clear differences. We built several models of hard carbon with two graphene sheets that have typical point defects (MV, DV, SW). Initially, sodium adsorption onto the point defects occurs well above the sodium plating potential, and induces expansion of interlayer distance of the two graphenes. Then, sodium intercalation into the interlayer space becomes possible[2]. On the other hand, lithium ions intercalate into the interlayer at the slope region followed by the aggregation into nanopores[3].

[1] D. A. Stevens and J. R. Dahn, J. Electrochem. Soc., 147 (4), 1271 (2000)

[2] P. Tsai et al., J. Mater. Chem. A, 3, 9763-9768 (2015)

[3] Park C. W. et al., Carbon, 38, 995-1001(2000)
A Perylene Anhydride Crystal As a Reversible Electrode for K-Ion Batteries
Authors: Xing Zhenyu , Jian Zelang , Luo Wei , Ji Xiulei , Hu Liangbing
Published: February 2020

There is an ever-increasing demand for electrochemical power sources for electronics, electric vehicles and stationary storage, where currently Li-ion batteries (LIBs) dominate the market.  However, the scarcity of lithium minerals causes a serious concern on LIBs’ sustainability in the decades to come, which motivates researchers to look for alternative technologies.  To date, several Earth-abundant metal-ion batteries are under intense scrutiny, including Na-ion batteries (NIBs), Mg-ion batteries (MIBs) and Al-ion batteries (AIBs), where these technologies may provide sustainable solutions.  However, exceedingly little attention has been paid to K-ion batteries (KIBs) despite the fact that potassium is nearly 1000 times more abundant than lithium in Earth’s crust.  For KIBs, besides low cost, another advantage is its excellent adaptability to the existing carbon industry already developed for Li-ion batteries.  Recently, we reported that both graphite and soft carbon can be used as anodes for KIBs with remarkable properties, where such materials exhibit very poor performance in NIBs.  This is a significant advantage for KIBs over NIBs, which makes it very much urgent for the KIB field to develop more suitable cathode materials for a full cell design, where PTCDA is highly promising in filling up this gap.

We demonstrate that PTCDA is a promising cathode for K-ion batteries with a high capacity of about 122 mAh/g at 20 mA/g and moderate rate/cycling performance.  Upon potassiation, PTCDA crystals experience a high level of amorphization, while upon depotassiation, the crystal structure is partially restored, revealed by ex situ XRD and IR.  We will discuss the mechanism for the different performance between KIBs and NIBs.  As shown in Figure 1, greater polarization between the discharge and charge profiles of PTCDA is observed in KIB than in NIB, which may be attributed to larger strain when intercalating of K ions into PTCDA and the associated slower diffusion of K ions.

F
ig. 1. The comparison of galvanostatic charge-discharge potential profiles of the PTCDA electrode in KIBs and NIBs, (a) the first cycle and (b) the second cycle.

We hope to present our results to bring attention to organic crystals that have intrinsic large interstitial sites for applications in Earth-abundant KIBs.  The very different results of PTCDA in KIBs from in NIBs bring insights as well as questions that may attract further attention on this topic.

Figure 1
A Stable Carbon-Free Cathode for Rechargeable Lithium-Oxygen Battery with Long Cycle Performance
Authors: Song Shidong , Yan Pengfei , Liu Bin , Bowden Mark E , Engelhard Mark H , Wang Chongmin , Xu Wu , Zhang Jason
Published: February 2020

Lithium-oxygen (Li-O2) batteries have extremely high theoretical specific capacities and energy densities than Li-ion batteries. It is estimated that a practical Li-O2 battery could provide 3-5 times gravimetric energy density of conventional Li-ion batteries. The cathode active material (oxygen) is not stored in the Li-O2 battery and can be obtained from the environment outside the batteries. However, the cycle performances of these Li-O2 batteries are still limited by the stability of the air electrode and the electrolyte. Carbon-based electrodes are believed to decompose during charge and promote electrolyte decomposition as well. The fabrication of a stable and highly active carbon-free cathode for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) becomes a great challenge at present for the development of rechargeable Li-O2battery.

Recently, some carbon-free cathode materials have been reported, including noble metals,1 oxides,2 and carbides.3 Metal oxides have low conductivities and are mainly utilized at low current densities. Noble metals show outstanding performance but may not be applicable due to the high cost and high density. Carbides can achieve good bi-functional activities for ORR and OER and be with low cost. However, only TiC was reported to achieve high cycle performance as a carbon-free cathode for Li-O2 batteries so far. Here we report the application of a novel material for the carbon-free cathode of Li-O2 batteries. The battery can be stably operated for more than 200 cycles with a stable voltage profile under the capacity-limited condition. With the aid of structure and composition characterizations, the mechanism of discharge and charge process is also investigated. This novel material is very promising for the use as an alternative carbon-free cathode, as well as for studying and exploring the stable electrolyte in rechargeable Li-O2batteries. 

Acknowledgements

This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, the Advanced Battery Materials Research Programs of the U.S. Department of Energy (DOE). The microscopy and spectroscopy measurements were performed at the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory.

References 

Z. Peng, S. A. Freunberger, Y. Chen, P. G. Bruce, A Reversible and Higher-Rate Li-O2 Battery, Science., 337, 563 (2012).

M. M. O. Thotiyl, S. A. Freunberger, Z. Peng, Y. Chen, Z. Liu, P. G. Bruce, A stable cathode for the aprotic Li-O2 battery, Nature Materials, 12, 1050 (2013).

F. Li, D.M. Tang, Y. Chen, D. Golberg, H. Kitaura, T. Zhang, A. Yamada, H. Zhou, Ru/ITO: A Carbon-Free Cathode for Nonaqueous Li-O2 Battery, Nano Lett., 13, 4702 (2013).
A High-Performance Magnesium Rechargeable Battery Enabled By a Mgcl-Ion Storage Mechanism
Authors: Yoo Hyun Deog , Yao Yan
Published: February 2020

Magnesium rechargeable batteries have recently attracted attention because of the large theoretical volumetric capacity, dendrite-free deposition/stripping behaviour, and earth-abundant Mg resources. However, the sluggish diffusion of Mg2+ in host materials has so far limited the choice of cathodes to Chevrel-phase molybdenum chalcogenide that has Mg-ion storage capacity around 100 mAh g–1. Here we show that a high-performance magnesium rechargeable battery enabled by a MgCl-ion storage mechanism using two-dimensional TiS2 with an interlayer spacing expanded up to an unusually large value of 1.86 nm (327% as large as the pristine form) can deliver a high reversible capacity of 270 mAh g–1 and an exceptional rate performance of 100 mAh g-1 at 5C-rate. We anticipate that this discovery will lead to novel mechanisms and material designs for multivalent ion storage, which could open the way to high-energy-density, low-cost and safe batteries.
Probing Polysulfide Shuttle Effect in the Li-S Battery
Authors: Mistry Aashutosh , Chen Chien-Fan , Liu Zhixiao , Mukherjee Partha P.
Published: February 2020

The lithium-sulfur battery is a strong contender among the beyond Li-ion chemistries due to its superior capacity and energy density as compared to the conventional Li-ion cells.

However, experimental evidences suggest that even the first discharge capacity is appreciably lower than the theoretical limit. This non-ideality is usually associated with the so-called “polysulfide shuttle effect”. On the cathode side, solid sulfur dissolves in the electrolyte and undergoes successive reduction to different intermediate and reduced-order sulfide ions. Due to the underlying potential and concentration gradients, these negative ions travel toward the anode and chemically oxidize the lithium metal, while being reduced simultaneously. Theoretical capacity is achieved when sulfur undergoes complete electrochemical reduction; hence the above chemical reaction(s) limit the available capacity.

Lithium sulfide (Li2S) is the final discharge product which forms when the ionic product exceeds the solubility limit. This can passivate the surface, block the porous structure and may lead to the reacting species starvation in the cathode.

The shuttle effect is a resultant manifestation of these coupled phenomena. In this work, a computational study is presented in order to quantify the influence of shuttle effect on the Li-S cell capacity. The model correlates concentration evolution and microstructural changes with cell performance. Based on this understanding, electrode modifications such as, cathode coating and microstructure properties are studied in order to fundamentally understand the deleterious influence of the “shuttle effect” on cell performance.

Figure 1
Combined Battery/Supercapacitor Hybridised Energy Storage Systems for Hybrid Electric Vehicles
Authors: Sarwar Wasim , Offer Gregory James , Gopalakrishnan Krishnakumar , Green Nick
Published: February 2020

Automakers are striving to increase electric vehicle driving range without compromising performance and simultaneously reducing charging times. However, this requires an increase of both the energy and power density of the Energy Storage System (ESS); though in battery design these two attributes are generally mutually exclusive therefore a compromise must be made. It is hypothesised that a Hybridised Energy Storage System (HESS) consisting of Supercapacitors (SC) and high energy density batteries in parallel with no DC/DC converter could result in an ESS with improved energy and power density in comparison to an ESS consisting of batteries only.   

To enable automotive engineers to design such systems we have created a toolset (i.e. models) that can accurately reproduce the behaviour of such a HESS, in particular, the interactions between the battery and SC. Further, the tool is valid over a range of conditions known to affect system performance such as temperature. The tools are also validated with experimental data where the individual contributions of the battery and SC can be assessed.

A high-fidelity physically meaningful electrical Equivalent Circuit Model (ECM) of a supercapacitor is combined with a physical pseudo-3D thermal model. Separately, a physics-based battery model is generated and parameterised for an NCA 18650 cell. Model order reduction techniques are used to obtain an acceptable simulation time, resulting in a physics-informed electrical ECM which is subsequently coupled with a high-fidelity thermal model. Both models are individually validated across a range of operating conditions including temperature and current. The validated models are paired and the HESS model is validated over an automotive drive cycle with a particular emphasis placed upon battery current and temperature evolution. The generated toolset demonstrated that a HESS can provide superior performance to a battery only system for particular applications, however power availability limitations can cause highly detrimental effects for incorrectly sized systems, and hence good system design is critical.

Figure 1
Applied Single Particle Measurement Technique for One Si Particle
Authors: Nishikawa Kei , Li Chunyan , Kanamura Kiyoshi
Published: February 2020

Si is very attractive material for next-generation negative electrode of Li batteries, because of very large capacity. However, Si has very large volume change during the lithiation and delithiation. Such large volume change induces very rapid electrode degradation. There are many researches for the restriction and accommodation of the volume change of Si based materials [1]. Also, in-situ TEM observation technique has been utilized to understand the lithiation and delithiation mechanism of nano-sized Si particles [2]. In-situ TEM technique is very powerful technique, however it needs high vacuum condition or no vapor pressure liquid like ionic liquids. It is also very important to find the electrochemical characteristics in actual electrolytes system. Single particle measurement technique is very useful to reveal the intrinsic electrochemical characteristics of a micro-scale particle in commercial Li-ion battery electrolytes. In this study, the single particle measurement technique is used to understand the volume expansion mechanism of a micro-size Si particle in the first lithiation reaction.

The detailed experimental conditions for the single particle measurement were described elsewhere [3]. After the electrochemical characterization, the lithiated Si particle was picked-up by micro-tweezers in order to transfer the particle to other analytical equipment, for example, SEM, FIB-SEM, TEM and micro-Raman. In this study, the relationship between the volume expansion behavior of a micro-sized Si particle and the morphological and structural variations is focused. Figure 1 shows the drastic volume expansion behavior of a Si particle during the first lithiation and the charging curve. The measured apparent volume expansion ratio is much larger than the theoretical values [3, 4]. The Si powders used in this study is composite of crystalline and amorphous Si, and micro-sized secondary particles are composed of several hundred nm primary particles. Therefore, the Si particle used in this study may have the space inside the secondary particle. Furthermore, Cui et al. have reported the crystalline Si shows the anisotropy volume expansion during the lithiation. Such anisotropy volume expansion may induce the extraordinary apparent volume expansion. In order to reveal the volume expansion of a Si particle, ex-situ SEM, TEM observation was conducted. Fig.2 shows TEM images of cross section of the lithiated Si particle. The images show the lithiated Si is mainly amorphous phase, and only a very small parts remain crystalline Si phase. It is caused by the local electrical disconnection because of very large volume expansion. The TEM observation also shows surface SEI layer composition. The detailed results will be shown in the presentation.

[1] M. Wu, et. al., J. Am. Chem. Soc., 135 (2013) 12048

[2] M. T. McDowell, et al., Nano Lett., 13 (2013) 758-764

[3] K. Nishikawa, et. al., J. Power Sources, 243 (2013) 630

[4] K. Nishikawa, et al., J. Power Sources
302 (2016) 46

Figure 1
Slow Stabilization of Si-Li Alloys Formed during Charge and Discharge Process in a Si-Carbon Mixed Electrode Studied by in-situ Solid-State 7Li Nuclear Magnetic Resonance Spectroscopy
Authors: Arai Juichi , Gotoh Kazuma , Sayama R , Takeda K
Published: February 2020

Silicon has been attracting large interest for a high capacity electrode material used in lithium ion batteries (LIBs) to conquer facing energy density limit (1,2). Recently, some LIBs using negative electrode composed of Si (or SiOx) and carbon are put in market though their cell lives are not excellent. Some of the issues causing the life shortage may come from the rate ununiformity due to their storage structure difference (Li intercalation in carbon and Li-Si alloying in silicon). An Al-laminated half-cell composed of lithium counter electrode and working electrode composed of 20 wt% of Silicon and 80 wt% of graphite for in situ 7Li nuclear magnetic resonance (NMR) measurement were fabricated (3,4). The NMR spectra were measured every 10% of SOC (state of charge) during charge (Li insertion) and every 10% of DOD (depth of discharge) during discharge (Li extraction). Peak attributed to Li-Si alloy appeared at 8 ppm from SOC 20% and shifted to higher magnetic field associated with SOC increase and reached -13 ppm at SOC 100%. The peak shifted reversibly to lower field during discharge (Fig. 2). The peak grew with charge SOC increase and reversibly shrunk with discharge DOD. The relaxation change after stooping the charge and discharge is investigating. X-ray diffraction (XRD) of charged electrode sample and electrochemical impedance spectroscopy (EIS) are also examined.
Important Roles of Crystallinity in Voltage Fade of Li- and Mn-Rich Cathodes Exemplified By Li2Ru0.5Mn0.5O3 Studies
Authors: Yang Xiao-Qing , Hu Enyuan , Lyu Yingchun , Han Lili , Bai Jianming , Dooryhee Eric , Yu Xiqian , Li Hong , Xin Huolin L.
Published: February 2020

Abstract: Li- and Mn-rich cathode materials have been considered as promising candidates for application of lithium-ion batteries in vehicles due to their high capacity and high energy density (capacity around 250 mAh/g). However, these materials suffer from a serious problem of voltage fade. The average discharge voltage keeps decreasing as the cycling goes on and results in decreased energy output after limited cycles. In order to solve this problem, many efforts have been put in to understand the origin of such phenomenon, mostly from structural and chemical points of view. In this work, the important roles of crystallinity, or the microstructure of the cathode material  in voltage fade are studied. The study is carried out on Li2Ru0.5Mn0.5O3 as an example. The material is electrochemically prelithiated to around Li3.2Ru0.5Mn0.5O3 first and then delithiated to Li2Ru0.5Mn0.5O3 . It is shown that even though the crystal structure mostly remains the same, the crystallinity is severely damaged by breaking the sub-micro domains into very fine nano-sized domains. Such loss of crystallinity causes much more significant voltage fade in the following cycling compared with those normally cycled samples. The more severe voltage fade caused by low crystallinity can be attributed to the accelerated oxygen loss due to the increased defects and surface area of the prelithiated sample. These results indicate the great importance of crystallinity of the cathode materials.

Acknowledgement

The work at Brookhaven National Laboratory was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies under Contract No. DE-SC0012704. Use of the National Synchrotron Light Source II (NSLS-II) and Center for Functional Nanomaterials at Brookhaven National Laboratory were supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contracts No. DE-SC0012704.
Benefits of Water-Based Binder Electrodes for Li-Ion Batteries
Authors: Buqa Hilmi , Wussler Sabine , Studenik Erika , Melin Irina , Deghenghi Gianluca , Blanc Pierre
Published: February 2020

Leclanché implements the innovative water-based production process; applied to all cell electrodes, it results in cost effective large format 30Ah LTO- and 43 Ah graphite-based cells, while minimizing environmental impact of manufacturing and ensuring very high cell performances and lifetime stability.

Some of the benefits of water-based binder electrodes are:

No more usage of organic (toxic) solvents in the mixing and coating processes.

 

Reduced manufacturing cost of aqueous vs. solvent processing. Elimination of expensive solvent recovery steps, reduction of capital cost for coating equipment and elimination of expensive inactive components.

 

Simplification of machinery (no EX requirements). Machinery size reduction (water extraction is faster than NMP one, therefore the drying section for coating line is reduced).

 

Fast drying speed and low drying temperature require less electric power and yield to higher production rate.

 

No dry room required for cell assembly, only humidity control is required during electrolyte filling, etc.

 

The innovative high-quality manufactured electrodes lead to very high mechanical and electrochemical stability during cycling, e.g. Leclanché large-capacity LTO lithium-ion batteries allow for tenths of thousands full-DoD cycles to be reached, even in highly demanding conditions (see Fig.1). The lifetime estimation exceeds 20.000 cycles and is little affected by C-rate. 

Fig. 1: Lifetime characteristics at RT (21°C); influence of C-rate and lifetime estimation of 16 Ah cell

Figure 1
Addressing Reliability and Safety Issues on Battery Systems Via Quantitative Analyses and Validation
Authors: Liaw Bor Yann
Published: February 2020

As advanced batteries continue to grow in the sectors of electrifications of transportation and energy storage systems, risk management by the stakeholders has also become an emerging topic of concerns. To date, the practical approach in addressing such concerns has not been fully understood and implemented. One of the impediments is the lack of full appreciation of the complexity involved in handling the issues in the research community and need of technical competency in addressing them. The industry does not really have the luxury to learn from the hiccups and disasters of fire and explosion incidents to calm the anxiety from the consumers in the expectation of reliable and safe products in the marketplace, while we continue to learn from the mistakes and manage the risks in the “green energy transformation.”

Batteries have some unique aspects that traditionally mechanical and electrical devices need not to pay attention to: performance degradation by aging and its path dependency. This unique aspect makes the battery management of performance, including risks, much more difficult than usual. Not only the initial properties of the battery systems need to be compatible for manufacturing processes without trading off performance, but also the consequences of aging and degradation during operations need to be managed to endure reliability and safety challenges. Worse than that, those system properties are often affected by the environment they operate. Therefore, matured battery designers need to familiarize not only battery systems’ capability but also the nature of the environments and the operating conditions to cater in their designs. To understand such causality in battery design is inherently challenging. This is something needs to be overcome to address battery reliability and safety issues. This is why battery system diagnostics and prognostics are pivotal to addressing the battery reliability and safety issues.

Battery diagnostics and prognostics are a vital part of the solutions to deal with this situation. Through proper diagnostic and prognostic analyses, one can extract useful information from the failure analyses (FA), including failure mode and effect analyses (FMEA). However, for these analyses to be feasible in battery research, it requires additional efforts to ensure accurate and precise information being extracted from the analyses in a quantitative manner, which is not commonly practiced in the industrial and the research communities. Here, the issues with quantitative diagnostic and prognostic analyses are discussed and explained; using practical examples in some of the abuse studies to illustrate the critical aspects of such analyses with mechanistic understanding.
Fast Rechargeable All-Solid-State Lithium Ion Batteries with High Capacity Based on Nano-Sized Li2FeSiO4 Cathode By Tuning Temperature
Authors: Pan Fred
Published: February 2020

We report all-solid-state lithium ion batteries based on nano-sized Li2FeSiO4 coated by carbon cathode materials with fast rechargeable (67.5 mA h g1 at 30 C) and high capacity (258.2 mA hg1 with 1.55 Li-ion storage at 1 C within 1.5–4.5 V) performances for the ﬁrst time. By investigating and comparing with Li2FeSiO4, LiFePO4 and LiNi0.5Co0.2Mn0.3O2 cathode materials for all-solid-state lithium ion batteries, the mechanism of the higher rate performance of the Li2FeSiO4 based battery is found to be attributed to the high temperature depended diffusivity and electrical conductivity, which are increased by nearly four orders of magnitude from 300 K to 373 K, and also to permeation of the cathode/electrolyte solid-solid interface to generate the overlapping between Li2FeSiO4 particles and electrolyte.
Investigation of Fluorophosphate Cathode Materials for Na Ion Batteries By Ex Situ
23 Na Solid-State Nuclear Magnetic Resonance
Authors: Smiley Danielle L. , Goward Gillian R.
Published: February 2020

Sodium ion batteries have experienced a renaissance in recent years owing to the low cost and high abundance of sodium relative to lithium resources.1 Despite this renewed attention, there remains a need to realize sodium electrode materials that are suitable for commercial applications.  In light of this, there is significant motivation to identify and analyze various properties of novel electrode materials, including structural and ion diffusion changes that occur during the electrochemical cycling process.

Solid-state nuclear magnetic resonance (ssNMR) is implemented here in an attempt to characterize structure and site-specific ion mobility in the fluorophosphate family of cathode materials (Na2MPO4F), as they are known to exhibit high thermal and electrochemical stability.2,3
Ex situ
23Na NMR studies at fast magic angle spinning (65 kHz) allow for sufficient spectral resolution to observe local changes at unique Na environments in these paramagnetic electrode materials.  

Na atoms housed in the two crystallographically unique positions in the layered Na2FePO4F phase are distinguishable via this technique (Figure 1a), offering the opportunity to probe local properties in the pristine phase. Further, by incorporation of this material into a sodium ion cell, the changes to the 23Na NMR spectrum can be correlated ex situ to structural changes directly resulting from the electrochemical (de)intercalation process.  The appearance and relative increase of two new Na peaks in the NMR spectrum (Figure 1b) upon electrochemical desodiation of the material suggests that Na atoms in both crystallographic environments may in fact be mobile despite an apparent lack of chemical exchange between sites.  These new Na resonances can be assigned to the partially oxidized variant of the pristine material, where the dramatic shift in peaks in the NMR spectrum is attributed to the change in electron configuration of the transition metal from Fe2+ to Fe3+.  Ongoing efforts to quantify the diffusion of Na ions and characterize the mechanism of electrochemical desodiation will be presented.

References:

(1)      Palomares, V.; Serras, P.; Villaluenga, I.; Hueso, K. B.; Carretero-González, J.; Rojo, T. Energy Environ. Sci.
2012, 5(3), 5884.

(2)      Ellis, B. L.; Makahnouk, W. R. M.; Rowan-Weetaluktuk, W. N.; Ryan, D. H.; Nazar, L. F. Chem. Mater.
2010, 22(3), 1059.

(3)      Ellis, B. L.; Makahnouk, W. R. M.; Makimura, Y.; Toghill, K.; Nazar, L. F. Nat. Mater.
2007, 6 (10), 749.

Figure 1
Interface Storage and Diffusion in Titania-Based Na-Ion Battery Negative Electrodes
Authors: Hanzu Ilie , Prutsch Denise , Uitz Marlena , Wilkening Martin
Published: February 2020

Ordered, nanostructured transition metal oxides are currently in the spotlight of battery research. To exploit, however, the full potential of self-assembled titania nanotube layers in Na-ion battery technology we need to close the gap in knowledge about the underlying storage mechanisms as well as ion dynamics. For this purpose, amorphous TiO2 nanotubes (70-130 nm in diameter, 4.5 – 17 µm in length) were fabricated by anodization, i.e., electrochemical oxidation. The electrochemical behaviour with respect to sodium insertion was studied by cyclic voltammetry and galvanostatic cycling with potential limitation. It turned out that the nanotubes are very resilient to cycling, some being able to withstand more than 300 charge-discharge cycles without significant loss of capacity. Compared to classical insertion reactions, the mechanism of reversible electrochemical storage of Na+ in the nanotubes seems to differ significantly. There is strong evidence that a large amount of the Na+ ions is stored on the surface or in the surface-influenced regions while only a smaller fraction is inserted in the walls of the tubes. The interfacial Na+ storage is governed by a faradaic adsorption phenomena, which is essentially different from the (pseudo-)capacitive model hitherto used in the literature. The finding that, in the case of sodium, interfacial storage is more important than ion insertion into the crystal lattice is supported by the very low Na+ diffusion coefficients determined at various electrode potentials (in the order of 4 · 10-20  -  10-21 cm2/s). This dominant interfacial storage mechanism  may explain the high specific capacity and the very good cycling performance recently reported for some nanostructured titania phases as well as for other nanosized titanate materials.

Figure A. Chemical diffusion coefficient of Na+ into amorphous TiO2 at room temperature (23 ±1°C) after subtracting the interfacial storage contributions for different sample types. Figure B. Pseudo-capacitance values corresponding to the interfacial storage of Na+ ions on various nanotube layers plotted as a function of the electrode potential.

Figure 1
Better Than Li-Ion Batteries: An Ultrafast and High Capacity Na-Ion Battery Enhanced By Tunable Pseudocapacitance
Authors: Zhu Changrong , Fan Hong Jin , Chao Dongliang
Published: February 2020

Sodium ion battery (SIB) is a potentially low-cost and safe alternative to the prevailing lithium ion battery (LIB) technology. It has been a great challenge to achieve fast charging and high power density for most SIB electrodes because of the sluggish sodiation kinetics. Here we demonstrate a high-capacity and high-rate SIB anode based on ultrathin layered SnS nanostructures, in which a maximized extrinsic pseudocapacitance contribution is first identified and verified by kinetics analysis. The graphene foam supported SnS nanoarray SIB anode delivers a high reversible capacity of ~1100 mAh g-1 at 30 mA g-1 and ~420 mAh g-1 at 30 A g-1, which even outperforms its Li ion storage performance. The surface-dominated redox reaction rendered by our tailored ultrathin SnS nanostructures may also work in other layered materials for high-performance Na ion storage.
Prelithiated Silicon Alloy (Si-Fe-Mn): Dodging the Irreversible Capacity Loss for High Performance Lithium Ion Batteries
Authors: Alaboina Pankaj Kumar , Uddin Md-Jamal , Cho Jong-Soo , Cho Sung-Jin
Published: February 2020

In this work, silicon alloy (Si-Fe-Mn) was pretreated with a number of lithium compounds and investigated on improvements in electrochemical properties for high efficiency and better capacity retention. The motivation was to prefill the cracks and any voids of the silicon alloy with lithium-based compounds, to avoid unnecessary solid electrolyte interface (SEI) reformations, and thus to dodge the capacity drains to a certain extent. Prelithiation was performed by simply heat treating the grounded mixture of silicon alloy and lithium compounds. The temperature for heat treatment was maintained slightly above the melting point of the lithium compound to allow diffusion into the cracks and voids of silicon alloy. Lithium stearate (C18H35LiO2), lithium carbonate (Li2CO3), lithium tetrafluoroborate (LiBF4), and lithium nitride (Li3N) were chosen for prelithiation. Investigations were performed by changing the chemicals and amount of the materials, heat treatment temperature, and the order of the processes. Out of which, silicon alloy with 5 wt.% lithium stearate treated at 300°C for 4 hours demonstrated the best electrochemical performance.
Highly Compressible and Conductive N-Doped Graphene Foam for Lithium Batteries
Authors: Moon In Kyu , Chun Kyoung-Yong , Oh Jungwoo
Published: February 2020

Over almost five years, 3-dimensional graphene and graphene-based nanostructured foams have been widely progressed. These materials have potential for use in next-generation energy-related technology for energy storage and generation as well as use in sensors and actuators. Among graphene-based materials, graphene oxides (GOs) can be described as rising material candidates because they show multiple advantage of ultra-light, strong, flexible, elastic, and porous. In addition, they have excellent properties such as high surface area, robust mechanical strength, resistive chemical behavior, and scaffolds with high conducivity.

In this presentation, we describe the simple synthesis of ultralow-density 3-dimensional reduced graphene oxide (rGO) foams that show high electrical conductivity and excellent compressibility for the applicaion of lithium batteries. The rGO foams are synthesized using the combination of hydrothermal and thermal annealing method in which hexamethylenetetramine is employed. We confirm that the N-binding configurations of rGO foams increase as evidenced by the change in pyridinic-N/quaternary-N ratio. The conductivity of this graphene foam is almost 12 S/m at 0 strain, whereas the conductivity is ≈704 S/m at the compressive strain (≈80%), which is comparable to previous reported any 3D sponge-like low-density carbon materials. The foam also has excellent hydrophobicity (contact angle on water surface: ≈137°) and shows selective absorption for organic solvents and oils. The compressive modulus of the rGO foam is higher than that of other carbon-based foams. This graphene foam is the simplified, light-weight architecture allowing for large mass loading of guest materials. Our graphen foam has unique electrical and mechanical properties due to the presence of N-doped monolithic graphene, and can be suitable for the use in electrodes for lithium batteries, fuel cells, energy absorption, energy storage, and sensing applications.

* K.-Y. Chun & J. Oh are equally contributed as corresponding authors in this study .
Correlation of Structural Changes in Li Rich Cathode Materials to Their Electrochemical Performance
Authors: Aryal Shankar , Timofeeva Elena V. , Segre Carlo U
Published: February 2020

Li rich oxides xLi2MnO3.(1-x)LiMO2, (M=Ni, Co, Fe, Al, Cr etc.) have attracted significant attention in recent years as the promising cathodes for Li-ion batteries because of their higher energy storage capacity, thermal stability, and lower costs. These materials are structurally integrated composites of two phases: monoclinic C2/m Li2MnO3 phase and trigonal R-3m LiMO2 phase [1]. The Li2MnO3 phase provides structural integrity to the LiMO2 during Li intercalation and also can be activated to LixMnOy at potentials higher than 4.5 V to further boost the energy storing capacity [2]. The reported performance of Li[Li1/6Fe1/6Ni1/3Mn1/2]O2  cathode is 282 mAh/g at first discharge [3], which is double the capacity of LiCoO2 cathode currently utilized in  commercial Li ion batteries. However, before those cathodes could replace traditional materials two issues with Li-rich cathodes need to be resolved: gradual capacity loss (71% of capacity after 50 cycles [3]), and drop off in discharge voltage upon cycling (3.57 V of midpoint voltage at the 4th discharge decreases to 3.38 V at the 100thdischarge [4]). Both degradation phenomena are closely related to structural changes within the cathode materials during cycling.

To improve the performance of Li-rich cathode detailed understanding of the degradation mechanisms in those materials is required. In this talk we will report on the experimental study of evolution of structure as the function of cycle number, charge modes and composition in low cost, Li rich, Co free Li(Li0.2Nix/2Mn0.8-xFex/2)O2, 0.2<x<0.4 layered-layered oxide cathode. Our study employs x-ray diffraction for crystallographic phase analysis, scanning electron microscopy for particle size and morphology characterization, infrared spectroscopy for molecular bonding and in-situ x-ray absorption spectroscopy for probing the oxidation state and local structure within the materials, during charge and discharge cycles.

References:

1. Thackeray, Michael M., et al. "Li 2 MnO 3-stabilized LiMO 2 (M= Mn, Ni, Co) electrodes for lithium-ion batteries." Journal of Materials Chemistry17.30 (2007): 3112-3125.

2. Armstrong, A. Robert, et al. "Demonstrating oxygen loss and associated structural reorganization in the lithium battery cathode Li [Ni0. 2Li0. 2Mn0. 6] O2." Journal of the American Chemical Society128.26 (2006): 8694-8698.

3. Zhao, Taolin, et al. "Organic-acid-assisted fabrication of low-cost Li-rich cathode material (Li [Li1/6Fe1/6Ni1/6Mn1/2] O2) for lithium–ion battery." ACS applied materials & interfaces6.24 (2014): 22305-22315.

4. Zheng, Jianming, et al. "Corrosion/fragmentation of layered composite cathode and related capacity/voltage fading during cycling process." Nano letters 13.8 (2013): 3824-3830.