bluuebunny/crossref_metadata_2025 huggingface dataset:
Capacity Fading Machanism for Both Electrodes in Prismatic Lithium Ion Batteries with Long Calendar Life
Authors: Cai Sendan , Dai Yang , Xie Jingying , Yang Weijing , Wang Ting
Published: February 2020

lithium-ion batteries have been produced on a large scale and used extensively

in the commercial mobile devices, typically in the so-called 3C (cellular phones, camcorders, and computers) industry since they have high working voltage, large capacity, and no memory effect compared with other candidates such as metal-hydride batteries and nickel-cadmium batteries .[1]. Besides, lithium ion batteries are also good candidates in applications for electric vehicles (EV) and hybrid electric vehicles (HEV) if both electrodes are well matched in kinetic characteristics at high charge and discharge current rates.

The first commercial lithium ion battery developed by Sony in 1991 was composed of LiCoO2 as the cathode and carbon as the anode. One-dimensional lithium ion transport path means lower energy barriers and high ionic conductivity which makes layered-structure materials such as LiCoO2, LiNixCoyM1-x-yO2 ( M = Mn, Al, etc), and some carbon materials attractive to the researchers as well as the business developers although they suffer from structure changes during cycling.[2,3,4,5]

For a specific cell, the cathode and anode may contribute differently to the capacity fading since both electrodes possess different electrochemical properties. However, most literatural reports focused on one single electrode, i.e. either the cathode or the anode, when discussing the capacity fading machanism of a specific cell.

Here, we monitor the EOCV(end of charge voltage) and EODV (end of the discharge voltage ) of the both elecrodes in one cell in-situ to figure out the main fading factor of a LiNi0.8Co0.15Al0.05O2 / graphite prismatic cell at different calendar stages during cycling at the rate of 0.2C. And we find that, during the former 100 cylces, the cathode material is the controlling factor contributing to the capacity fading while the lateral 100 cycles see the controlling factor changing from cathode to the anode

[1] Abraham K M. Directions in secondary lithium battery research and development[J]. Electrochimica Acta, 1993, 38(9): 1233-1248.

[2] Muto S, Sasano Y, Tatsumi K, et al. Capacity-Fading Mechanisms of LiNiO2-Based Lithium-Ion Batteries II. Diagnostic Analysis by Electron Microscopy and Spectroscopy[J]. Journal of The Electrochemical Society, 2009, 156(5): A371-A377.

[3] Zheng S, Huang R, Makimura Y, et al. Microstructural Changes in LiNi0. 8Co0. 15Al0. 05O2 Positive Electrode Material during the First Cycle[J]. Journal of The Electrochemical Society, 2011, 158(4): A357-A362.

[4] Yoon W S, KYUNG Y C, McBreen J, et al. A comparative study on structural changes of LiCo1/3Ni1/3Mn1/3O2 and LiNi0. 8Co0. 15Al0. 05O2 during first charge using in situ XRD[J]. Electrochemistry communications, 2006, 8(8): 1257-1262.

[5] Bang H J, Joachin H, Yang H, et al. Contribution of the structural changes of LiNi0. 8Co0. 15Al0. 05O2 cathodes on the exothermic reactions in Li-ion cells[J]. Journal of The Electrochemical Society, 2006, 153(4): A731-A737.
Engineered Nanovoids in Si/C Composites for High Capacity and Stable Li-Ion Battery Anodes
Authors: Park Hongyeol , Yeom Dae Hoon , Kim Jaegyeong , Lee Jung Kyoo
Published: February 2020

Silicon is an ideal anode material for advanced Li-ion battery (LIB) because it offers a low voltage for charging and the highest specific and volumetric capacities (Li15Si4 » 3,579 mAh g-1 and 8,340 mAh ml-1) among known elements. In spite of these highly appealing features, it has long been a critical challenge to design silicon-based electrode materials in a scalable way which maintain their high capacity over prolonged cycling due to both disastrous electrode pulverization due to huge volume variations (~300%) and the instability of solid-electrolyte interface (SEI) layers. In this study, engineered carbon nanovoids were successfully introduced in the Si/C composites to efficeintly absorb the large volume expansions of silicon in the nanovoids and maintain electrical integrity of electrode as well as cycling stability for prolonged cycles. To explore the idea, chemical binding and electrostatic self-assembly between amine-functionalized Si nanoparticles and SiO2 nanoparticles were employed followed by carbon coating and SiO2 template removal. Thus prepared Si@Nanovoids delivered 1,350 mAh g-1 at the current of 100 mA g-1 and showed stable cycling up to 200 cycles at 500 mA g-1 while the standard Si/C reference electrode lost most of its capacity in 40 cycles. The Si@Nanovoids electrode exhibited minimal volume change thanks to the engineered nanovoids after long cycles. More details in materials synthesis, analysis and electrochemical properties of Si@Nanovoids are to be presented.
In Operando XRD/Electrochemistry Investigation of Lithium Insertion into Anatase-Derived Titanium Oxyfluoride TiOF2
Authors: Louvain Nicolas , Karkar Zouina , El-GHOZZI Malika , Cellier Joel , Fonquernie Claire , Bonnet Pierre , Guerin Katia , Willmann Patrick
Published: February 2020

Reactivity of pure molecular fluorine F2 allows the creation of new materials with unique electrochemical properties. We demonstrate that titanium oxyfluoride TiOF2 can be obtained under molecular fluorine from anatase titanium oxide TiO2, while the fluorination of rutile TiO2 leads only to pure fluoride form TiF4. Contrary to most fluorides, TiOF2 is an air-stable oxyfluoride that is a potential electrode material for Li-ion secondary batteries systems. It shows capacities as high as 220 mAh g-1 and good cyclability at high current rates in a potential window of 4-1.2V. In such window, only Li+ insertion occurs, as proven by in operando XRD/electrochemistry experiments.
Spherical Carbon Coated Li4Ti5O12 Materials with Stable Interface
Authors: Wen Lei , Wu Ze-Yi , Luo Hong-Ze , Li Feng
Published: February 2020

Spinel Li4Ti5O12
has become an alternative material to replace electrode in terms of solving these safety issues and improving the life time. Compared with carbon-based anode materials, Li4Ti5O12 exhibits a flatter operation potential plateau and higher operating voltage of about 1.55 V versus Li/Li+, which can make the issue of lithium dendrite deposition on the surface of anode materials entirely resolved. Unfortunately, as Li4Ti5O12 is an insulator, the low electrical conductivity becomes a major drawback which is unfavorable to higher rate capability. Besides the low electronic conductivity, severe gassing during charge/discharge cycles is a critical but often-overlooked problem of Li4Ti5O12 batteries. To date, this issue is at present unsettled but will clearly bear heavily on electrode materials, electrolyte and battery system. Gassing is not always occurs, the most serious swelling occurs only in Mn-contained cathode battery system, such as LiMn2O4 and LiNi1/3Mn1/3Co1/3O2 cathode based battery system. Stable cycle performance is more likely to occur when the cathode has high stability in electrolyte, such as LiCoO2. In this paper, our main goal is to synthesize Li4Ti5O12 materials with high rate electrochemical performance and stable interface, which can effectively suppress gassing in LiMn2O4/ Li4Ti5O12 battery system. For these purposes, the micro-spherical Li4Ti5O12 were prepared by clustering the nano-sized Li4Ti5O12 (100~200nm) without carbon and with carbon respectively. It was found that the spherical clusters of nano-Li4Ti5O12 assembled with carbon (SCN-LTO/C) exhibits significantly improved rate capability and cycling performance compared with that of non-carbon spherical clusters of nano-Li4Ti5O12 (SCN-LTO). More important, it also shows stable interface in LiMn2O4/Li4Ti5O12 system. This stable interface can significantly suppress the gas generation reaction during charging/discharging processes in LiMn2O4/Li4Ti5O12 system. In this paper, gas generation mechanisms in LiMn2O4/Li4Ti5O12 battery system are also discussed. For SCN-LTO, gassing phenomenon in the LMO/LTO batteries is ascribable to the manganese deposition in the anode materials, while for SCN-LTO/C materials, carbon coating can effectively cause the inhibition of manganese deposition and side-reactions, highlighting the importance of the stable interface for Li4Ti5O12 materials in high-performance LIBs.
3D Silicon Electrode Based on Stainless Steel Metal Fibril Current Collector for Flexible Lithium-Ion Batteries
Authors: Song Seonghyun , Kim chang-Hyeon , Choi Jaecheol , Ryou Mhyung-Hyun , Lee Yong Min
Published: February 2020

Although silicon (Si) has been extensively investigated for one of the next high capacity anode materials, large volume changes during cycling and low electric conductivity result in poor cycling and rate capability. As a result, Si/carbon composite materials having Si content less than 10% are being introduced for commercial lithium-ion batteries (LIBs). This cannot be a good way to utilize Si for electrochemical systems. Therefore, as a different point of view, we try to fully use Si capacity by modifying Si electrode structure with metal fibril current collector. Comparing to flat metal current collector, circular-type fibril current collector having the same Si loading value can mitigate volume-changing stress like Fig. 1. Inspired by this promising fact, we try to use stainless steel metal fibril (SF) of a diameter of 10 um as a current collector. And then Si is sputtered upon SF by using radio-frequency sputtering.

The Si coating thickness is controlled to be about 1um equivalent to the loading level of 0.2 mg/cm2 (0.6 mAh/cm2), which is considerably high comparing to conventional thin film Si electrode. The Si/SF electrode can not only deliver 3000 mAh/g at a 300mA/g during the initial cycling, but also maintain 1600 mAh/g at a 2000mA/g rate after 200 cycles without delamination of Si from SF current collector. The rate capability is also astonishing to give 1300 mAh/g at a 12000 mA/g. Finally, when the Si/SF electrode is applied for flexible lithium-ion batteries, the cycle performance is well maintained similarly to the original case.

References

[1] D.J. Lee et al, Journal of Materials Chemistry A, 10 (2014) 1039

[2] D.J. Lee et al, Electrochemistry Communications, 34 (2013) 98-101

[3] J.Y. Choi et al, Advanced Funtional Materials, 23 (2013) 2108-2114

Acknowledgements

This work was supported by the IT R&D program of MKE/KEIT. [10041142, Electrolyte Additive for 200Wh/kg High LIB of High Cycle Life]
Synthesis and Understanding of Layered Li-Rich Nickel Manganese Oxides for High Energy Density Lithium-Ion Batteries
Authors: Martinet Sebastien , Boulineau Adrien , Simonin Loic , Colin Jean François , Daniel Lise , Peralta David , Feydi Pierre , Fabre Frederic , Chapuis-Rey Marlene , Patoux Sebastien
Published: February 2020

In the search for high capacity cathode materials for Li-ion batteries, layered oxides with the general formula Li(LiXMnYMZ)O2 (M=Ni, Mn, Mg, ...) either described as xLi2MnO3 · yLiMO2 are receiving much attention. These oxides are characterised by the presence of lithium in the transition metal layers, and high Mn content, leading to high capacities up to 250mAh.g-1. However, upon cycling, they present complex structural changes that are still misunderstood.

In this context, our group worked jointly on synthesis development and understanding of the structure evolution occurring into the lithium rich layered cathode material Li1.2Mn0.61Ni0.18Mg0.01O2.

The first step was to study one material synthesized using a solid state route. 1st cycle characterization was investigated by XANES, in situ XRD and SQUID magnetic measurements. We showed that the main first-charge plateau is a twophase process where a new phase is created. This extra phase apparition was confirmed by Electron Energy Loss Spectroscopy (EELS) spectra interpretation. Therefore, Squid magnetic measurements allow a 1st cycle mechanism proposition.

Evolutions after cycling test (50 cycles) have also been investigated using advanced microscopy tools (High Resolution STEM EELS spectrum imaging). The stability of the spinel defect structure is pointed out to explain the material ageing and the electrochemical performances decrease on cycling.

Others synthesis routes were developed, especially solvothermal way enabling a better primary particles size, composition and morphology control. This synthesis route depends on many input parameters such as pH, temperature, duration… We used the methodology of the design of experiments that allows minimizing the number of experiences to optimize the synthesis and understand the effect of the main parameters of the synthesis. Higher performances and cycling behaviour have been obtained and further understanding studies are under progress to match with experimental observations.
High Performance Li[Li0.2Ni0.13Co0.13Mn0.54](BO4)0.75x(BO3)0.25xO2-3.75x Cathode with Polyanion for Li-Ion Batteries
Authors: Huang Weifeng , Li Biao , Yan Huijun , Ma Jin , Xia Dingguo , Chu Wangsheng , Wu Ziyu
Published: February 2020

Lithium rich manganese-based layered material is a promising high-capacity cathode candidate for lithium ion batteries, but it usually exhibits poor cycling stability and low safety because of the issues of oxygen ions unstability under high voltage. A strategy to promote the electrode performance of lithium rich manganese-based layered material through incorporation of boracic polyanion has been developed. As-synthesized Li[Li0.2Ni0.13Co0.13Mn0.54](BO4)0.015(BO3)0.005O1.925 showed superior reversible capacity of 300 mAh/g after 80 cycles, excellent cycling stability with a capacity retention of 89% within 300 cycles, higher thermal stability and enhanced redox couple potentials in comparison with pristine Li[Li0.2Ni0.13Co0.13Mn0.54]O2 when used as an cathode material for lithium ion batteries, which can be attributed to the tuned electronic structure after the incorporation. This facile enhanced strategy is expected to be extended to other high capacity electrode systems.
Searching for the Best Electrolyte Composition for the C/Li2MnSiO4 Based Battery Systems
Authors: Swietoslawski Michal , Molenda Marcin , Dziembaj Roman
Published: February 2020

Li2MnSiO4 is one of the most promising among all of polianionic cathode materials for Li-ion batteries [1-5]. Thanks to its unique composition the material is characterized by high theoretical capacity (333 mAh g-1) and potentially low production costs. On the other hand, the main disadvantage of Li2MnSiO4 is its extremely low electrical conductivity [2]. Preparation of nano-sized material and its modification by carbon coating is in this case essential to provide good electrochemical properties [1,2]. Another drawback of this material is its structural instability in charge/discharge process. There is a number of reports showing that Li2MnSiO4 cathode material undergoes amorphization in the first few charging/discharging cycles [3-5]. Degradation of crystalline structure can be explained by Jahn-Taller distortion associated with changes in lattice parameters during Mn3+ → Mn4+ transition. Another explanation may be occurrence of secondary reactions between electrolyte and delithated forms of lithium manganese silicate (LiMnSiO4 and MnSiO4). The aforementioned structural changes of the material entail variations in electrochemical properties of Li2MnSiO4.

The goal of these studies is to examine influence of different electrolyte composition on C/Li2MnSiO4stability and its electrochemical properties in the first charging/discharging cycles.

For the purpose of this studies we chose a set of electrolytes characterized by different chemical behavior toward electrode materials. The various electrolytes compositions based on LiPF6, LiClO4, LiBOB and LTFSi salts in different solvents mixtures (EC/DMC, EC/DEC, TMS/EMC) were tested with C/Li2MnSiO4 nanocomposite. Li2MnSiO4was obtained via sol-gel synthesis. Active material was carbon coated using poly-N-vinylformamide with pyromellitic acid additive as carbon precursor. Electrochemical properties of assembled cells (CR2032 housing) were studied by galvanostatic charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods.

This work was supported by the International PhD-studies programme at the Faculty of Chemistry Jagiellonian University within the Foundation for Polish Science MPD Programme co-financed by the EU European Regional Development Fund. The authors acknowledge a financial support from the European Institute of Innovation and Technology under the KIC InnoEnergy NewMat project.

References:

[1] M.E. Arroyo-de Dompablo, M. Armand, J.M. Tarascon, U. Amator, Electrochem Commun 81292-1298 (2006).

[2] A. Kokalj, R. Dominko, G. Mali, A. Meden, M. Gaberscek, J. Jamnik, Chem Mater 193633-3640 (2007).

[3] M. Molenda, M. Świętosławski, A. Rafalska-Łasocha, R. Dziembaj Functional Material Letters 4135-138 (2011).

[4] V. Aravindan, S. Ravi, W.S. Kim, S.Y. Lee, J Colloid Interf Sci 355472–477 (2011).

[5] M. Świętosławski, M. Molenda, K. Furczoń, R. Dziembaj, J Power Sources 244 510-514 (2013).
A Study on the Production of NMC622 Cathode Materials Using a Novel Taylor-Couette Flow Reactor Process
Authors: Kim Junghoon , Song Jung-Hoon , Hong Jong-Pal
Published: February 2020

Li(Ni0.6Mn0.2Co0.2)O2 (NMC622) cathode materials have been recognized as the next generation cathode materials due to its higher capacity and lower raw material cost than commercialized cathode materials such as NMC532. Thus, many industrial companies have been made every effort to commercialize and apply the NMC622 to lithium ion battery system such as energy storage system (ESS). However, production cost of NMC622 still has been recognized as expensive material to be applied in the industrial field and it becomes main issues to be overcome. CSTR (Continuous Stirred Tank Reactor) has been widely applied in the industrial field to produce the NMC622 precursor but it has initial long stabilization time as well as low production efficiency. This is caused by the original limitation of CSTR such as the low mass transfer rate and required complete mixing zone to stabilize the system. Thus, in this study, we suggest the novel reactor system that shows the higher mass transfer rate as well as higher production rate than those of CSTR. Developed novel reactor system uses the taylor-couette flows to induce higher mass transfer rate and production efficiency with uniform particle size distribution.

In this study, we synthesized NMC622 using taylor-couette reactor to understand the function and mechanism of the operation. The effect of operating parameters, i.e. pH, operating rpm, and feed retention time, in the taylor-couette reactor, was investigated thoroughly to evaluate the feasibility to produce NMC622 precursor. Produced precursors are characterized using SEM, XRD, ICP, FIB, PSA. Then, cathode materials are prepared and tested using a galvanostatic intermittent titration method (GITT) to understand the electrochemical properties. This study verified that taylor couette reactor is feasible process to be applied to the commercial NMC622 production.
V2O5 Nanosheets/Reduced Graphene Oxide Nanocomposite As a High-Performance Cathode Material for Lithium-Ion Batteries
Authors: Cheng Jianli , Wang Bin
Published: February 2020

Among the existing cathode materials, V2O5 is a promising cathode candidate because of its high energy density, abundance, easy synthesis, as well as low cost. However, due to quite low diffusion coefficient of lithium ions (10-12-10-13 cm2 s-1), irreversible phase transitions during deep discharge, and vanadium dissolution into the electrolyte, the practical use of V2O5 as a cathode material shows poor rate capability and cycling stability1,2. Incorporating the nanostructured V2O5 with high conductive materials to build a hybrid material is one of the most promising strategies to improve the electrochemical property of the V2O5 based anod3. Among these conductive materials, graphene nanosheet (GNS), with the exceptional properties of excellent electronic conductivity of 103-104 S m-1, high theoretical surface area of 2630 m2 g-1, and high mechanical ﬂexibility is much more attractive. Extensive studies of GNS-V2O5 nanocomposites have been investigated. However, it is worth noting that most of the reported nanocomposites constitute by the GNS with the zero-dimensional (0-D) nanoparticles or one-dimensional (1-D) V2O5 nanofiber/nanorod. To the best of our knowledge, the 3-D nanocomposites combining the GNS layer with 2-D V2O5 nanosheets have not been reported so far.

Herein, we demonstrate a simple solvothermal method to directly self-assemble 2-D V2O5 nanosheets on the reduced graphene oxide, forming 3-D nanocomposite (V2O5 nanosheet/RGO hierarchical nanocomposite). Briefly, vanadium oxytriisopropoxide (VO(OiPr)3) and graphene oxide (GO) were dispersed into ethyl alcohol by ultrasonicaiton to produce a V-precursor/GO dispersion. Then, the dispersion was transferred to a Teflon-lined stainless steel autoclave and heat-treated in an electric oven. The obtained composite was further annealed at 300°C in air to make V2O5 crystallized and reduce GO to RGO. The detailed preparation procedures can be found in the experimental section.

When used as a cathode material, the V2O5 nanosheets/RGO nanocomposites exhibits highly reversible capacity and good rate capability over bulk material. The V2O5 nanosheets/RGO nanocomposite anode was able to charge/discharge at high current densities of 15A g-1 (50C), with the discharge capacities of approximately 176 mA h g-1. Meanwhile, a discharge capacity of 102 mA h g-1 can be delivered after 160 cycles at 2C, showing a good cycling stability. The improved performance could be attributed to the enhanced electron transport and Li+ diffusion that result from the hierarchical nanostructure of V2O5 nanosheets/RGO nanocomposite (showing in Figure 1).

Reference:

[1] S. Q. Wang, S. R. Li, Y. Sun, X. Y. Feng, C. H. Chen, Energy & Environmental Science 2011, 4, 2854.

[2] Y. X. Tang, X. H. Rui, Y. Y. Zhang, T. M. Lim, Z. L. Dong, H. H. Hng, X. D. Chen, Q. Y. Yan, Z. Chen, Journal of Materials Chemistry A 2013, 1, 82.

[3] X. H. Rui, J. X. Zhu, D. Sim, C. Xu, Y. Zeng, H. H. Hng, T. M. Lim, Q. Y. Yan, Nanoscale 2011, 3, 4752.
Water-Based PVDF Binder for Improved Performance and Stability of Batteries
Authors: Colombo Roberta , Pieri Riccardo , Stanga Milena
Published: February 2020

PVDF, a partially fluorinated semi-crystalline polymer, is one of the preferred choices as binder material for electrodes thanks to its stable and reliable performance in terms of longer cycle life, better power performance and higher energy density. Moreover PVDF brings advantages to the lithium battery industry in the design of the separators.

However, PVDF usually requires the use of solvent-based processing such as NMP, which is both costly and toxic.

Solvay introduces a novel fluorinated binder in aqueous dispersion with proprietary chemical modification for improved performance (in terms of adhesion and chemical resistance) and a sustainable manufacturing process.

Differently from any other PVDF-based system, this novel PVDF latex ensures continuous film of binder between active material particles. The chemical modification in PVDF ensures also improved higher and more stable adhesion in combination with flexibility (cohesion) of the final electrode.

In negative electrode, taking advantage of PVDF binder high adhesion and lower volume at equal weight compared to SBR, reduced amount of binder can be used in the formulation increasing the amount of active material (to exploit the theoretical capacity and energy density of the battery). In other hands, increased electrode cohesion and adhesion onto current collector ensures required chemical resistance and dimensional stability of electrodes in electrolyte even in stressful conditions.

Moreover, chemical affinity of PVDF with commercial polyolefin separators allows to laminate (ensuring better interface) them together. SBR does not provide such advantage, due to lower polarity leading to lack of continuous contact at interface.
Impact of Cell Components on Rate and Power Capability of Li-Ion Cells
Authors: Rempel Jane , Ofer David , Dalton-Castor Sharon , Pullen Adrian , Barnett Brian , Sriramulu Suresh
Published: February 2020

Many applications require Li-ion cells that can support high rates and/or high-power pulses. In order to effectively design such cells, it is important to understand the factors that control the rate and/or power capability of Li-ion cells.

Work done at TIAX has shown a surprising impact of the separator employed in the cell on the rate/power capability of Li-ion cells. Figure 1 shows the rate capability of a high-nickel cathode material as a function of discharge rate for three different electrode loadings. The rate capability appears independent of loading for rates less than 1 C. However, at rates higher than 2C, the rate capability appears to depend strongly on the loading. From these data it is tempting to conclude that this result is a consequence of increased ion diffusion limitation in the thicker electrode – essentially the thickness of the electrode at the loading of 27.1mg/cm2 is almost twice the thickness of the electrode at a loading of 15.6mg/cm2. However, a different conclusion emerges if these same data are plotted as a function of areal current density instead of C-rate (Figure 2). The discharge capacities appear independent of the electrode loading, but depend strongly on the areal current density. Essentially, the ionic limitations are not in the electrode, but elsewhere in the cell.

Studies at TIAX have shown that the primary ionic limitation under these conditions occurs in the separator. Data presented in Figure 3 demonstrate this effect. Essentially, by changing only the separator the discharge capacity at a current density of 16 mA/cm2(corresponding to 5 C) can be increased by a factor of four.

These combined results discussed above show that the ionic transport limitations in the separator play a major role in determining the rate capability of Li-ion cells. In this paper, we will present rate data using separators with a wide range of physical properties, and demonstrate a correlation between the rate capability and separator properties. Using data comparing the rate capability of different cathode active materials, we will discuss the implications of our findings for research aimed at understanding the power and rate capability of active materials. Finally, we will provide coin cell design guidelines for measuring the rate capabilities of active materials.
Lithium Rich Layered Material with Excellnt Rate Performance and High Efficiency
Authors: Zhan Hui , Han Zenghui
Published: February 2020

Introduction

Lithium rich layered material has attracted much attention because of its high capacity, however, the low effciency in the 1st cycle and poor rate property is a big issue for its practical use. We adopted a (NH4)2S2O8 treatment on Li1.2Ni0.16Co0.08Mn0.56O2 material, the prodcut showed a greatly increased 1st cycle efficinecy of above 90% and a capacity as high as 200mAh. g -1at 4C rate.

Experiment

Li1.2Ni0.16Co0.08Mn0.56O2 was prepared by a rheological method. Stoichiometric amount of Li2CO3, Ni(CH3COO)2·4H2O, Co(CH3COO)2·4H2O, Mn(CH3COO)2·4H2O and oxalic acid were mixed. And then a proper amount of water was added. After stirring the mixture at 80-90 ºC for 4 h, it was dried at 120 ºC for 10 h, followed by annealing at 850 ºC for 20 h. (NH4)2S2O8 solution with different concerntration was used to treat the above Li1.2Ni0.16Co0.08Mn0.56O2 sample, the product was named as 20%-RL,30%-RL, 40%-RL, 50%-RL according the different concerntration of (NH4)2S2O8solution.

Cycling test was conducted to evaluate the cyclcing stability and rate property of the products. The samples were characterized in terms of XRD, SEM, XPS and Raman measurement.

Result and discussion

The 1st charge/discharge curves are compared in Fig.1. The pristine Li1.2Ni0.16Co0.08Mn0.56O2 shows an intial caapcity of 224.0 mAh g-1 but with a low efficiency of 79%. With the increasing of the (NH4)2S2O8 concerntration, the product shows an increased effciency and reachs 99% in the “40%-RL” sample. Additionally, the (NH4)2S2O8 treatment leads to an improvement in the cycling stability. In Fig.2, untreated Li1.2Ni0.16Co0.08Mn0.56O2 maintains 88% capacity in the 100thcycle, while the “40%-RL” sample shows capacity retention of 97% after 100 cyles.

The (NH4)2S2O8-treated samples also present greatly improved rate performance. In Fig.3, the increase of the current rate from 0.1C to 4C causes a capacity decrease from 255mAh.g-1 to 67mAh.g-1 for the pristine Li1.2Ni0.16Co0.08Mn0.56O2 sample. For the (NH4)2S2O8-treated samples, they all exhibit a much better rate property than the untreated phase. Especially for the “30%-RL” and “40%-RL” sample, they both present a capcity above 200mAh.g-1at the 4C rate.

XRD measurements prove that the (NH4)2S2O8-treatment weakens the super lattice in the Lithium rich layered material. ICP and Raman analysis furtheres reveal that the Li content in Li2MnO3 decreased after the (NH4)2S2O8-treatment, which can be the main reason of the efficiency increase in the 1st cycle.
Optimization of Full Concentration Gradient Li[NixCo0.16Mn0.84-X]O2 (x=0.64, 0.59, 0.51) Cathode Material for Lithium-Ion Batteries
Authors: Noh Hyung-Joo , Ju Jin-Wook , Lee Eung-Ju , Yoon Chong seung , Myung Seung-Taek , Sun Yang-Kook
Published: February 2020

Lithium batteries are being developed as power sources for plug-in hybrid electric and electric vehicles, and for these applications, high energy cathodes are necessary to reduce battery size because the mounting space is significantly limited (1-2). However, these cathodes exhibit some serious problems such as capacity fade and poor thermal stability, which hinders their use in vehicle applications. In particular, oxygen evolution from the delithiated cathode can cause serious safety concerns. These limitations necessitate the development of new materials to resolve the above-mentioned difficulties. Recently, we introduced unique materials, which have a core-shell (core with gradient shell) or full concentration gradient (FCG) structure in a particle level (3). The structure is basically composed of a Ni-rich core that delivers high capacity and a Mn-rich shell that provides outstanding thermal stability. However, the Mn concentration could not be varied because of the difficulty of the rod-shaped particle synthesis.

We report the design of FCG Li[NixCo0.16Mn0.84-x]O2 (x = 0.64, 0.59, and 0.51) cathode materials with fixed Mn contents of 20, 25, and 33% in the transition metal layer. These cathode materials with concentration gradients followed the general performance trend of conventional layered materials; an increase in Ni content improved the capacity, whereas a higher amount of Mn delivered better capacity retention and thermal properties at the expense of capacity. We also report the effects of Mn concentration in terms of structural, electrochemical, and thermal characteristics of the FCG materials. As a result, we determined an optimal level of Mn concentration among the tested FCG cathodes, which maximized the discharge capacity of 188 mAh g-1 and had an excellent capacity retention of 96 % over 100 cycles operated up to 4.3 V at 25 oC, with a composition of FCG Li[Ni0.59Co0.16Mn0.25]O2.

Reference

1. J. B. Goodenough, Y. Kim, Chem. Mater.22 (2010) 587

2. V. Etacheri, R. Marom, R. Elazari, G. Salitra, D. Aurbach, Energy Environ. Sci.4 (2011) 3243

3. Y.-K. Sun, S.-T. Myung, M.-H. Kim, J. Prakash, K. Amine, J. Amer.

Chem. Soc. 127 (2005) 13411
The Influence of Solvents and Salts on the Properties of High-Voltage Cathode Materials at High Loads and High Temperatures
Authors: Kazda Tomá , Vondrák Jiri , Sedlaříková Marie , Čudek Pavel , Visintin Arnaldo
Published: February 2020

Lithium - ion batteries play an increasingly important role in the battery industry and they have become the dominant source of energy in the recnt years, especially for portable electronic devices due to their high gravimetric energy density. The new generations of lithium – ion battery cells are based on high-voltage cathode materials. These materials are characterized by a voltage near 5 V and higher energy density than the one currently used in lithium -ion cells. This advantage could help to increase battery expansion especially in transport. Representatives of this type of cathode materials are for example LiNi0,5Mn1,5O4, LiCoPO4 and Li2CoPO4F. The advantage of these materials is also their disadvantage - high working voltage means a big ballast for the electrolytes leading to deterioration of their stability. The stability of conventional carbonate electrolytes is strongly related to the stability and properties of cathode materials in the de-lithiated state. This article examines the influence of mixtures of solvents with different combinations of lithium salts on the stability of two types of high-voltage cathode materials: LiNi0,5Mn1,5O4 and LiCr0,1Ni0,5Mn1,5O4 produced by a solid phase reaction. These materials were combined with several different electrolytes, cycled at various loads and elevated temperature. For these measurements various combinations of solvents ethylene carbonate (EC), dimethyl carbonate (DMC) and sulfolane were used. Salts LiPF6 , LiNO3 and LiTFSI were used.

Authors gratefully acknowledge financial support from the Centre for Research and Utilization of Renewable Energy under project No. CZ.1.05/2.1.00/01.0014, FEKT-S-11-7 and Company FEI.
New PVDF-Based Separator for Consumer Electronic Battery
Authors: Hamon Christine , Abusleme Julio A. , Pieri Riccardo , Rouault Helene , Mourzagh Djamel , Salomon Jérémie
Published: February 2020

Li-ion batteries are used in most of our portable electronics by virtue of their high energy and power density. The consumer electronics market is rapidly expanding the range of applications into unconventional fields as flexible and wearable, conformable and curved devices, which require advanced lithium ion battery technologies capable of being accommodated into different shapes without constraining their form factor. Therefore the battery core has to keep its physical integrity to be capable to deliver its best performances, whatever its position.

And the battery components must be redesigned to be able to be deformed for a better integration in electronic devices. In particular the standard porous polyolefin separator does not fully match these requirements and there is always the risk that mechanical distortion can cause the leakage of liquid electrolytes.

Consequently Solvay is developing a new polymeric separator, based on thin and dense PVDF film obtained by extrusion process. The advantages of high chemical and electrochemical stability of PVDF associated with its good mechanical integrity and excellent affinity with liquid electrolyte have been coupled with the presence of a plasticizer which guarantees sufficient ionic conductivity for use in consumer electronics.

Thus in collaboration with CEA-Liten, new PVDF polymers have been studied for a better affinity with the plasticizer in order to optimize mechanical properties, ionic conductivity and performances in lithium-ion battery. Furthermore in addition to excellent flexibility, the separator shows excellent colamination properties with the electrodes, good adhesion and low interface issues.

The first tests in conformable small pouch batteries show the possibility to integrate this new separator in flexible and curved batteries.
All Solid State Lithium–Sulfur Battery Using a Glass-Type P2S5–Li2s Electrolyte
Authors: Agostini Marco , Hassoun Jusef , Yamada Takanobu , Aihara Yuichi , Scrosati Bruno
Published: February 2020

Introduction

Lithium-sulfur battery has attracted great attention since its electrochemical process, i.e. 16Li + S8 = 8Li2S, theoretically provides a specific energy of 2500 Wh Kg-1 much larger than the 650 Wh Kg-1 of the conventional lithium battery presently offered by the market and largely used in the electronic devices. However, to realize the practical battery based on the sulfur cathode, its red-ox shuttle of polysulfide originated in the dissolution into the organic electrolyte is strongly required to prevent for improving the charge/discharge cycle ability. On the contrary, solid state sulfide electrolytes are of considerable practical concern in these days. Application of a solid-state ion conductor is one of promising candidates for avoiding the red-ox shuttle due to the dissolution of polysulfide in Li-S battery. Its applicability of Li2S-P2S5 based solid electrolyte to the sulfur cathode has been reported using Li-In alloy for the anode1). To obtain higher energy density, we adopted pure Li and verified its applicability to the all solid-state Li-S battery.

Experimental

A solid state lithium ion conductor was prepared by using high energy ball milling method. Li2S:P2S5=80:20 mol% (SE) was adopted. A coin cell, 2032 was prepared by stacking and compressing Li foil, SE, and sulfur/MCMB(50:50wt%) mixture. The loading level of net sulfur was approximately 0.9mgcm-2. Another cell configuration, a compression metal cell was also used for verifying the electrochemical performances. The electrochemical measurements were mostly performed at 80 oC. The details are given in our previous paper2).

Results and Discussion

The Li/Li2S–P2S5/S-MCMB cell was prepared and its electrochemical characteristics were evaluated by Galvanostatic charge discharge cycle at 80 °C. The average discharge potential was approximately 2.1 V and a cycling capacity of 400 mAh g−1 at a C/20 rate was observed. The cycling tests show ca.100% Coulombic efficiency and stable capacity. However, only 25% of the theoretical capacity of the sulfur electrode was obtained in this system, because of the high resistance of the solid–solid interface at the cathode side and the associated ohmic polarization during cycling. Nevertheless, the very stable capacity of 400 mAh g−1 at a working voltage of 2.1 V results in a theoretical energy density of 840 Wh kg−1, In addition, the solid cell here reported is characterized by very high safety level, since the cell is completely based on solid-state. The details of the electrochemical characteristics on anode and cathode including recent progress are given in the poster.

1) M. Nagao, A. Hayashi, M. Tatsumisago, J. Mater. Chem. 22 (2012) 10015–10020

2) M. Agostini, Y. Aihara, T. Yamada, B. Scrosati, J. Hassoun, Solid State Ionics 244 (2013) 48–51
Li Ion-Sulfur Batteries with Glyme-Lithium Salt Solvate Ionic Liquid Electrolytes
Authors: Mandai Toshihiko , Yamazaki Azusa , Ueno Kazuhide , Zhang Ce , Yoshida Kazuki , Moon HeeJoon , Dokko Kaoru , Watanabe Masayoshi
Published: February 2020

We have reported that equimolar mixtures of certain Li salts and glymes (triglyme (G3) and tetraglyme (G4)) form molten complexes at ambient temperature, and behave like typical ionic liquids (ILs).1,2 In the mixtures, ligand glyme molecules strongly coordinate (or solvate) to Li+ ions to form complex cations, hence, this family is classified as “solvate” ILs. Because complexation of appropriate Li salts with appropriate glymes allows realizing ILs involving Li+ ions as single cationic species, lithium solvate ILs possess high Li+ ion conductivity and transference number. In addition, the dissolution of lithium polysulfides (Li2S
m
), the discharge products of elemental sulfur, was suppressed in certain solvate ILs due to their extremely low coordinating nature. Owing to these remarkable properties, they are fascinating electrolytes for Li-sulfur batteries.3,4

Recently, we found that solvate IL electrolyte allows successful charge-discharge of graphite electrode. These results inspire us to develop low-cost and safe batteries without Li metal anode. In this study, the battery performance of the graphite-sulfur full cells with the solvate IL electrolytes was evaluated employing a lithiated graphite (LiC6) anode or a lithiated sulfur (lithium sulfide, Li2S) cathode as a lithium source. A LiC6 anode and a Li2S cathode were prepared by chemical and electrochemical methods. Using these electrodes, two kinds of full cells in both charge and discharge states were fabricated.

Reversible charge-discharge of both full cells can be performed at 60 ºC, however, the capacities decrease as repeating cycles and the coulombic efficiency for these cells is substantially low compared to our previous results. This is because relatively high operation temperature facilitate dissolution of elemental sulfur and/or Li2S
m
, leading to loss of active materials and undesired side-reactions. To overcome these problems, solvate IL electrolytes were diluted by an appropriate solvent with low donor ability. As a result, a stable cycle operation with a discharge capacity of 700–800 mA h g−1 and a coulombic efficiency of 90–95 % at 30 ºC was achieved over 100 cycles (Figure 1), irrespective of starting charge-discharge states.
Multi-Methodology Modeling and Design of Lithium-Air Cells with Aqueous Electrolyte
Authors: Grübl Daniel , Danner Timo , Kupper Christian , Schulz Volker P , Latz Arnulf , Bessler Wolfgang G.
Published: February 2020

Metal-air batteries are being investigated as alternative to state-of-the-art lithium-ion batteries for mobile and stationary applications due to their higher specific energy and potentially lower cost. Modeling and simulation techniques allow a better understanding and improvement of the complex mechanisms and properties of metal-air batteries. Here we present combined modeling and experimental results on a lithium-air (Li/O2) battery with aqueous alkaline (LiOH) electrolyte using three different modeling methodologies, (i) Lattice-Boltzmann simulations on the porous electrode scale, (ii) multi-physics continuum modeling on the single-cell scale and (iii) system simulation of a Li/O2-operated electric vehicle.

Lattice-Boltzmann simulations on experimentally reconstructed Ag-based gas diffusion electrodes (GDE) are performed in order to derive multi-phase transport parameters, in particular, saturation/pressure relationships and effective diffusion coefficients. The computational domain of the 1D continuum model consists of the gas-diffusion electrode as cathode, a porous separator, and a lithium metal anode. The model includes a detailed description of the multi-step electrochemistry including dissolution of O2into the liquid electrolyte, oxygen reduction to hydroxyl ions, and nucleation and growth of the solid reaction product LiOH [1]. The model is validated with experimental half-cell measurements over a wide range of conditions. The multi-physics model is integrated into a system simulation of a battery electric vehicle, including electric engine and regenerative braking. The model is used to simulate driving cycles (Fig. 1), which allow to quantify practical energy and power densities and to investigate the potential of lithium-air technology as next-generation battery for electromobility.

As key result, the alkaline lithium-air battery offers the interesting capability of high-power cycling using only liquid-phase dissolved intermediates (O2 + 4e– + 2 H2O ⇄ 4 OH–) coupled to high-energy content due to solid product formation (Li+ + OH– + H2O ⇄ LiOH·H2O). This dual functionality can be exploited for the driving cycle using model-based cell design.

[1] B. Horstmann, T. Danner, and W. G. Bessler, “Precipitation in aqueous lithium-oxygen batteries: a model-based analysis,” Energy & Environmental Science 6, 1299–1314 (2013).
Defect Anti-Fluorite Structures As Electrode/Electrocatalytic Materials for Li-O2 Cells
Authors: Chan Maria K. Y. , Trahey Lynn , Kirklin Scott J. , Wolverton Chris , Kinaci Alper , Thackeray Michael M.
Published: February 2020

A concept to design hybrid Li-ion/Li-O2 cells that use dual-functioning LixMO4 metal oxide electrodes/electrocatalysts (M=Fe, Co, Mn; x=5 or 6) with a defect antifluorite-type structure will be presented. Experimental data have suggested that Li5FeO4 (5Li2O·Fe2O3) releases lithium and oxygen (net loss = Li2O) between 3.5 and 4.0 V during charge, and re-accommodates lithium and oxygen (net gain = Li2O) during discharge between 3.2 and 3.0 V, i.e., above the theoretical potential for Li2O2 and Li2O formation, to regenerate the Li5FeO4 composition [1]. The discharge reaction coincides with the potential at which a small amount of lithium can be electrochemically inserted into Fe2O3, suggesting that the redox processes on the iron ions catalyze the reaction between lithium and oxygen. Density functional theory (DFT) calculations support these hypotheses and the experimental data. Remarkably, all the lithium, iron and oxygen required for the electrochemical reaction are contained in the parent Li5FeO4 structure. The concept has implications for designing electrode/electocatalyst materials for hybrid Li-ion/Li-O2cells that could offer an energy density higher than that of today’s Li-ion systems.

Reference

L. Trahey, C. S. Johnson, J. T. Vaughey, S.-H. Kang, L. J. Hardwick, S. A. Freunberger, P. G. Bruce, and M. M. Thackeray, Electrochem. Solid-State Lett., 14(5), A64-A66 (2011).
Redox Shuttles for Sustained Oxygen Reduction in Non-Aqueous Lithium Electrolyte
Authors: Owen John Robert , Garcia-Araez Nuria , Lodge Andy , Frith James T , Yang Roy
Published: February 2020

Direct electrochemical oxygen reduction in non-aqueous electrolytes results in the deposition of an insoluble product on the electrode surface, thereby blocking access of oxygen to the surface for continued reaction (Fig. 1). Once the surface is completely covered, the reaction stops and the discharge is ended. Alternatively, in the presence of a soluble redox shuttle, oxygen reduction can occur homogeneously in solution near the air interface (Fig. 2). This has the effect of displacing oxygen reduction away from the electrode surface, which remains active to regenerate the shuttle to the reduced form. A further possibility is mediation of the oxygen reduction reaction in order to favour the formation of lithium peroxide rather than radical products that may degrade the electrolyte (Fig. 3). Given a suitable shuttle reagent, this scheme may have several potential advantages, for example,

Avoidance of electrode passivation by insoluble lithium oxides

An increased, chemical driving force for oxygen adsorption into the electrolyte

Increased mass transfer to the electrode surface

Enhanced kinetics of lithium peroxide formation

Minimisation of side reactions that may degrade the electrolyte

We will present results on Ethyl Viologen acting as a shuttle, including its reduction at the electrode, its reactions with oxygen, and its stability to the products of oxygen reduction under various conditions.

Acknowledgement

This work was supported by the European Union’s Seventh Framework Programme under EC-GA No. 265971 ‘LABOHR’ and the University of Southampton.