bluuebunny/crossref_metadata_2025 huggingface dataset:
Sulfurized Polyacrylonitrile Cathode and Polyacrylic Acid Binder for High Performance Potassium–Sulfur Batteries
Authors: Kim Hee Min , Sun Yang-Kook
Published: February 2020

Room-temperature metal–sulfur batteries have attracted extensive interest because of their advantages of high theoretical capacity, high elemental abundance, and low cost. Towards improving the electrochemical performances of the sulfurized polyacrylonitrile (SPAN) composite cathode in potassium–sulfur batteries (KSBs), an advanced electrode design has been developed by applying a polyacrylic acid (PAA) binder to the SPAN electrode. By integrating the merit of the SPAN composite cathode and PAA binder, the proposed SPAN cell generates a high reversible capacity of 1,050 mA h g-1 and has excellent cycling stability after 100 cycles (95% retention of the initial cycle) at a high current density of 837.5 mA g-1 . Ex situ Raman spectra show that the PAA binder is evidently more effective at improving the structural stability of the SPAN electrode than the PVdF binder during cycling. Despite the large volume changes during reduction/oxidation steps in the wide voltage window of 0.1–3.0 V, the SPAN electrode with the PAA binder gave an excellent electrochemical performance in KSBs. To better understand the electrochemical reaction mechanism of SPAN in KSBs, XPS analysis was further performed in a wide discharge cut-off voltage range.
Development of a New UV-Crosslinking Polymer Electrolyte for Extra-Thin Li Metal Batteries
Authors: Piana Giulia , Armel Vanessa , Oukassi Sami , Martin Steve , Amiran Johnny , Franger Sylvain , Porthault Hélène
Published: February 2020

The increasing miniaturization of electronic devices and the needs for stand-alone systems require adapted power sources in terms of dimensions and energy. With these new demands, new constraints come out like flexibility, limited thickness or tighter security requirements. To achieve these requests, both battery core materials and packaging need to be redesigned.

In this work, we developed simultaneously a new gel polymer electrolyte (GPE) material and a new battery design to reach both security (no leakage concern, no flammability, thermal stability) and application requirements (flexibility, thin system (<400µm)). We worked on a quaternary GPE based on a bi-components UV-curable polymer network giving the mechanical strength combined with a binary liquid phase composed of ionic liquid and Li salt. The GPE was optimized in terms of mechanical and electrochemical properties by varying the nature and the proportion of each components (polymer network, ionic liquid and Li salt) and the UV-curing parameters. The optimized GPE exhibits a good conductivity at room temperature (0.375mS.cm-1) and a Li+ transference number of 0.299 (NMR measurements) which is relatively high for this GPE type (Fig.a).

Our new battery design is composed of LiCoO2 cathode realized by standard coating processes. The liquid solution of GPE precursors is then deposited on the LiCoO2 cathode and directly polymerized by UV-curing (Fig.b). This step allows a good soaking of the electrolyte in the electrode pores. This system was then integrated in our thin battery design with Li metal foil as anode material (Fig.c). By optimizing each component dimension and sealing parameters (sealing conditions and adhesive type), we succeeded in producing a flexible, less than 400µm thick working battery (Fig.d) with interesting electrochemical performances (more than 2mAh.cm-2).

This work was done as part of the project EnSO. EnSO has been accepted for funding within the Electronic Components and Systems For European Leadership Joint Undertaking in collaboration with the European Union's H2020 Framework Programme (H2020/2014-2020) and National Authorities, under grant agreement n° 692482

Figure 1
Hidden Structural Order Controls Li-Ion Transport in Cation-Disordered Oxides
Authors: Ji Huiwen , Urban Alexander , Kitchaev Daniil A , Kwon Deok-Hwang , Artrith Nongnuch , Ophus Colin , Shi Tan , Ceder Gerbrand
Published: February 2020

The development of cost-effective lithium-ion batteries depends on the discovery of high-energy-density cathode materials composed of nonprecious elements. Traditionally, lithium-ion cathodes are based on two categories, i.e., layered oxides and polyanionic compounds. However, most polyanionic compounds have low specific capacity due to their heavy polyanions. Layered oxides, though more favorable for energy density purposes, often contains the element cobalt, the supply of which is scarce and not sustainable.

The discovery of cation-disordered rocksalts and their percolation rules unlocked an unprecedented chemical space for the exploration of high-capacity lithium-ion cathodes which do not contain Co and have high capacity[1]. The facile Li diffusion in these materials is enabled through a network of Li-rich environments (so-called 0-TM channels) created by excess Li. Following this insight, many new high-energy-density cathode materials that involve mostly earth-abundant elements have been developed, such as Li1.2Mn0.4Ti0.4O2[2], Li1.2Ni1/3Ti1/3Mo2/15O2[3], as well as their fluorinated variants[4, 5].

A prevailing assumption when studying disordered rocksalt cathodes is that all the cation species are randomly distributed. However, we will demonstrate that even minor deviations from randomness, not detectable by typical X-ray diffraction (XRD), can have profound influence on performance. We employ a combination of thorough experimental characterization and multi-scale computer simulations to reveal that cation short-range order is ubiquitous in these long-range disordered materials. More importantly, the short-range order controls Li transport by altering the distribution of local environments and the connectivity between them. By considering a variety of different chemistries, we explain the microscopic origin of short-range order and identify general guidelines for local-structure manipulation for the benefit of Li transport. This breakthrough in the fundamental understanding of structure-property relationship in disordered Li-ion cathodes sets an exciting new direction for future optimization.

[1] J. Lee, et al, Science 343 (2014) 519-522.

[2] N. Yabuuchi, et al, Nature communications 7 (2016) 13814.

[3] J. Lee, et al, Energy & Environmental Science 8 (2015) 3255-3265.

[4] R. Chen, et al, Advanced Energy Materials 5 (2015).

[5] J. Lee, et al, Nature communications 8 (2017) 981.
Synergistic Performance of Lithium Difluoro(oxalate)Borate and Fluoroethylene Carbonate in Carbonate Electrolytes for Lithium Metal Anodes
Authors: Lucht Brett L. , Brown Zachary Lee
Published: February 2020

There is significant interest in the development of rechargeable high-energy density batteries which utilize lithium metal anodes. Recently, fluoroethylene carbonate (FEC) and lithium difluoro(oxalate)borate (LiDFOB) have been reported to significantly improve the electrochemical performance of lithium metal anodes. This investigation focuses on exploring the synergy between LiDFOB and FEC in carbonate electrolytes for lithium metal anodes. In ethylene carbonate (EC) electrolytes, LiDFOB is optimal when used in high salt concentrations, such as 1.0 M, to improve the electrochemistry of the lithium metal anode in Cu||LiFePO4 cells. However, in FEC electrolytes, LiDFOB is optimal when used in lower concentrations, such as 0.05 – 0.10 M. From surface analysis, LiDFOB is observed to favorably react on the surface of lithium metal to improve the performance of the lithium metal anode, in both EC and FEC-based electrolytes. This research demonstrates progress towards developing feasible high-energy density lithium-based batteries.
Advanced Characterization of Solid-Solid Interfaces and Alkali Metal Anodes Via Cryogenic Focused Ion Beam and in Situ methodologies
Authors: Wynn Thomas Andrew , Lee Jungwoo Zema , Cheng Diyi , Meng Ying Shirley
Published: February 2020

All-solid-state batteries are a potentially safer and more energy dense alternative to the modern lithium ion battery, replacing flammable organic liquid electrolytes and enabling lithium metal anodes. While solid electrolytes have been developed with ionic conductivities far in excess of modern liquid organic electrolytes, electrolyte-electrode interfacial resistance remain an issue. In spite of their fundamental importance, the nature of these interfaces remains obscured, primarily due to the limited methods of characterization of both lithium metal and buried interfaces alike. Recently, cryogenic microscopy techniques—traditionally employed by biological field—have been employed to lithium ion batteries, elucidating the nature of solid-electrolyte interfaces and lithium metal morphologies alike. Of similar difficulty, observation of solid-solid interface dynamics is limited to very few techniques, and has only been demonstrated recently, primarily via in situ transmission electron microscopy (TEM) methodologies.

We present developments in the application of cryogenic focused ion beam (FIB) and in situ TEM to enable fundamental characterization of solid-solid interfaces for lithium ion battery applications. Use of cryogenic temperatures is shown to clearly reduce damage induced in the lithium metal, preserving the morphology and structure, as demonstrated by both three-dimensional FIB slice-and-view and the observation of crystallinity in cryogenic-TEM. This technique is further extended to polymer and sulfide electrolytes, overcoming instability during FIB milling and permitting further characterization via cryo-TEM. Such cryo-prepared samples enable lithium metal for in situ TEM cycling of metal-anode-based solid-state batteries. Further, progress in in situ characterization of solid-state interfaces by TEM will be presented, showing developments in the extraction of electrochemically active nanobatteries for in situ testing applications, providing a platform for dynamic solid-solid interface characterization.
Closed-Loop Optimization of Battery Fast Charging Procedures
Authors: Attia Peter , Grover Aditya , Jin Norman , Severson Kristen , Cheong Bryan , Liao Jerry , Chen Michael H. , Perkins Nicholas , Yang Zi , Herring Patrick H. , Aykol Muratahan , Harris Stephen J , Braatz Richard D. , Ermon Stefano , Chueh William C
Published: February 2020

Fast charging protocols for lithium-ion batteries are critical for widespread adaptation of electric vehicles. However, a limited understanding of degradation modes during fast charging and the large manufacturing variability of commercial lithium-ion batteries are major challenges to the development of high-performing fast charging protocols. In this work, we optimize a six-step charging protocol for commercial 18650 lithium-ion batteries that achieves 80% state of charge in ten minutes. We employ two key elements to reduce the optimization cost: early prediction of failure, which uses cycling data from the first 100 cycles to predict cycle lives that reach up to 1200 cycles, and adaptive Bayesian optimal experimental design, which reduces the number of experiments required. We identify promising fast charging protocols with identical charging times but high lifetimes out of a candidate pool of 224 protocols. This method can be extended to accelerate development of other tasks in battery manufacturing and deployment, such as formation cycling and state-of-health estimation.
Real-Time Identification and Understanding of Zinc Compounds in Rechargeable Zinc-Alkaline Electrodes
Authors: Hawkins Brendan E. , Turney Damon , Yadav Gautam Ganapati , Banerjee Sanjoy , Messinger Robert J.
Published: February 2020

Rechargeable zinc-alkaline electrodes are attractive forms of electrochemical energy storage for commercial applications because of the high theoretical energy density of zinc metal and the low cost, safety, and environmentally friendliness of aqueous zinc systems. The rechargeable zinc electrode has been historically limited in depth-of-discharge and cycle life, which has prevented it from being widely used on a commercial scale. This limitation is partly due to irreversible reactions occurring during discharge, which lead to passivation of the zinc electrode. Despite extensive study, the properties of these oxide species and the conditions leading to their formation are not fully understood. In this work, we identify different compounds that form on zinc electrodes using in operando optical microscopy, in operando X-ray diffraction, and scanning electron microscopy, as well as chemically identify these species and the conditions at which they form using in operando confocal Raman spectroscopy. Identification of zinc species that detrimentally affect zinc reachargeability and understanding their formation will promote the design of better electrodes and electrolytes, leading to improved cycle life and depth-of-discharge in rechargeable zinc-alkaline batteries.

Figure 1
Atomistic Perspectives on Mechanical Properties of Nanoporous Li-Mn-O Cathode upon Li-Intercalation
Authors: Ledwaba Raesibe Sylvia , Shibiri Beauty , Ngoepe Phuti E
Published: February 2020

Atomistic modeling plays a vital role in advancement and understanding of microstructural evolution and mechanical properties of electrode materials. We present progress in the simulated synthesis of Li-Mn-O nanoporous electrode materials, from an atomic perspective during which the amorphization and recrystallization technique has been employed. The effect of lithiation on structural integrity and intercalation host capability of the LMO electrode are investigated under the NST ensemble. Evolution of a composite structured material is captured on the microstructures snapshots and XRD graphs, particularly co-existing formation of spinel and layered components. The nanoporous materials crystallize successfully although multiple grains are observed for Li1.75Mn2O4 (nanoporous structure corresponding to cubic lattice boxes of side lengths 67 Å and 75 Å) and subsequently yield a single crystals for Li2Mn2O4. However, this is not inherent on nanoporous 69 Å with the same concentration. Intercalation induced volume changes are observed during simulation of the discharge process, specifically when the lithium content in the system is increased above 75% (Li1.5Mn2O4). The nanoporous material contracts inwardly and such accommodative nature may be attributed to flexing/relaxation into its pore/channel, unlike in the bulk structure, which suffers from drastic volume expansion. It is imperative to exclusively note the single crystallinity of the nanoporous (69 Å), that potentially contributes to the retention of yield strength unlike in the case of nanoporous (67 and 75 Å), where the simulations reveal that Li intercalation weakens the systems as the yield stresses (particularly for Li1.75Mn2O4), are reduced with gradual lithium intercalation into the lattice.
Towards Computational Modeling and Design of Solid-State Lithium-Ion Battery Architectures
Authors: Cobb Corie Lynn , Allu Srikanth
Published: February 2020

Solid-state Lithium-ion (Li-ion) batteries can revolutionize battery performance due to their inherent safety, high voltage stability, and high conductivity. As the field grows, there is a need for computational tools that can allow engineers to explore the effects of material and geometry and their subsequent impact on battery performance as demonstrated in recent research.1 This will enable optimization of a given battery design without the need for expansive experimental tests. In this poster, we summarize the key components that are needed to enable a multi-physics modeling framework and highlight our initial progress. We use a three-dimensional (3D) computational framework called AMPERES,2 developed at Oak Ridge National Laboratory (ORNL), as a case study to examine the requirements of modeling the electrode-electrolyte interface of solid-state Li-ion batteries. Because AMPERES enables one to model arbitrary battery and electrode configurations, we also illustrate potential 3D architectures that can enhance battery performance. Longer term, our goal is to create a framework that enables rapid design, manufacture, and testing of new electrode architectures for solid-state Li-ion batteries with a focus on both current and emerging chemistries.

References

C. L. Cobb and S. E. Solberg, J. Electrochem. Soc., 164, A1339–A1341 (2017).

S. Allu et al., J. Power Sources, 325, 42–50 (2016).
Enable Model-Based Diagnostics and Prognostics for Lithium-Ion Batteries
Authors: Yang Chuanbo , Smith Kandler , Shi Ying , Santhanagopalan Shriram , Keyser Matthew
Published: February 2020

Physicochemical processes in lithium ion batteries occur in intricate geometries over a wide range of time and length scales. As the size of the battery increases, macroscopic design factors in combination with highly dynamic environmental conditions significantly influence the electrical, thermal, electrochemical, and mechanical responses of a battery system. Computer-aided engineering tools are helping to accelerate the design and validation of large format cells and battery pack systems, which heavily replies on costly and time-consuming experimental tests previously. Validated physics-based models are effective in predicting electrochemical performance, thermal and mechanical response of cells and packs under normal and abuse scenarios and provide valuable insights not possible through experimental testing alone for diagnostics and prognostic purpose.

NREL pioneered the Multi-Scale Multi-Domain (MSMD) battery model, overcoming challenges in modeling the highly nonlinear multi-scale response of battery systems. The MSMD model provides flexibility and multi-physics expandability through its modularized architecture. The presentation describes present efforts to develop approaches to make the models better suited for engineering diagnostics and prognostic for large lithium-ion battery units by

Enhancing computation speed and stability of the pack-level multi-scale model while still resolving nonlinearities of dynamic battery response across scales from particles to packs

Blending field simulation with system simulation in a selective fashion to balance speed and accuracy. Applicable techniques include domain decomposition, physics segregation and reduced-order models (ROM) that can integrate into the system model

Developing interactive system interface for enhancement of multi-physics integrity

Incorporating spatially distributed model to address 3D non-uniform usage and stress factors.
Tunable Syntheses of Advanced Silicon Anodes Using Cyclohexasilane
Authors: Elgammal Ramez Ahmed
Published: February 2020

The ability to develop fast charging lithium-ion batteries with high-energy density is being pursued intensively due to increasing demands of portable electronics and electric vehicles. Replacing the conventional graphite anode with a silicon-based one offers several advantages, namely the roughly 10 times higher gravimetric capacity and the safer lithium alloying potential. However, full scale realization of replacing graphite with silicon has been hampered due to the large volumetric expansion silicon typically suffers which causes mechanical degradation, low electrical conductivity, and multiple-step syntheses from a traditional silicon precursor which leads to higher cost. Here we present a silicon precursor, cyclohexasilane, that can offer solutions to all three of those limitations. Cyclohexasilane (CHS) exists as a liquid at room temperature and is relatively low boiling (~ 200 °C) relatively facile synthesis of nanostructured silicon materials, significantly reducing the volumetric expansion typically observed. Cyclohexasilane can be readily used to manufacture silicon/carbon composite materials and is readily chemically functionalized allowing the development of tailored materials with improved electrical conductivity. CHS may also be tailored to deliver structures with engineered artificial SEIs during the device fabrication step, offering an efficient and direct route to electrode structures. Additional advantages of CHS include the ability to readily synthesize silicon nanoparticles of well-defined size and morphology, depending on the deposition conditions and the ability to produce materials with heteroatom doping, including silicon nitrides. Moreover, cyclohexasilane is relatively inexpensive and its physical properties allow for roll-to-roll manufacturing with significantly reduced capital costs. Relevant comparisons of this technology compared to incumbent technologies will be given.
Novel SEI-Forming Electrolyte Additives for Improved Performance of Silicon-Based Anodes
Authors: Vinograd Andrey , Röser Stephan , Edel Jan , Winter Martin , Placke Tobias
Published: February 2020

The broad commercial application of high capacity silicon (Si)-based anodes for lithium ion batteries (LIBs) is still hindered by their poor cycling stability caused by large volume changes upon lithiation/delithiation and by the associated continuous electrolyte decomposition and active lithium loss. One suitable strategy to improve the electrochemical performance is to develop improved electrolyte formulations resulting in an efficient solid electrolyte interphase (SEI) formation.

A recent study [1] has shown that the addition of 2 wt-% of 3-methyl-1,4,2-dioxazol-5-one (MDO) to a propylene carbonate (PC)-based electrolyte can significantly improve the cycling stability of lithium nickel manganese cobalt oxide (NMC532)/graphite full cells. Since electrolytes, based only on PC, do not lead to the formation of a stable SEI at the anode, the addition of MDO can be linked to an increased SEI stability, which is necessary for a high cycling stability.

In this study, we develop a systematic approach to investigate the electrochemical performance of MDO and its various side chain modified derivatives as additives for carbonate-based electrolytes in LIB cells with silicon-carbon (Si-C) composite anodes. Our results show that the addition of MDO improves the cycling stability of Si-C/NMC622 cells in comparison to the state-of-the-art additives, such as vinylene carbonate (VC) and fluoroethylene carbonate (FEC). The systematic evaluation of the electrochemical performance of MDO and its analogues, such as 3-phenyl-1,4,2-dioxazol-5-one (PDO), was done using a cycling protocol adapted from Tornheim et al [2]. This method enables the concurrent determination of the electrode capacity retention and area specific impedance (ASI). Post mortem analysis is performed in conjunction with computational studies to understand the decomposition mechanism.

[1] S. Röser, A. Lerchen, L. Ibing, X. Cao, J. Kasnatscheew, F. Glorius, M. Winter, R. Wagner, Chem. Mater. 2017, 29, 7733-7739.

[2] A. Tornheim, C. Peebles, J. A. Gilbert, R. Sahore, J. C. Garcia, J. Bareño, D. P. Abraham, J. Power Sources 2017, 365, 201-209.
LiTi(HPO3)2 A New Polyanion Based Anode for Lithium Ion Battery
Authors: Lallaoui Abdelfettah , Edfouf Zineb , Benabdallah Omar , Idrissi Siham , Abd-lefdil Mohammed , Cherkaoui El Moursli Fouzia
Published: February 2020

Lithium titanium (III) phosphite, LiTi(HPO3)2, a new material, has been synthesized under hydrothermal conditions. The solid-state structure of this material was determined from powder X-ray diffraction data in the tetragonal system, space group I 2d. The anionic inorganic skeleton is a 3D-framework structure, which is built up by TiO6 octahedral units linked together via bridging HPO3 pseudo pyramids, giving rise to tunnels along all the three crystallographic directions. IR and Raman spectroscopic studies show the vibrational modes of the (HPO3)2- oxoanions. This three dimensional structure shows interesting electrochemical behavior. The as-synthesized phase exhibits an insertion host for reversible accommodation of Li+ at ̴ 0.7 V and thus can be used as low voltage anode for lithium ion batteries. LiTi(HPO3)2 phosphite reversibly performs with excellent cycling stability and 100% columbic efficiency for 100 cycles at C/2 rate. After rapid cycling at different C-rates, the initial battery capacity has been recovered with a minimal loss of 3.7 %.

Reference:

F. Cherkaoui El Moursli, A. Lallaoui, Z. Edfouf, I. Saadoune, M. Abd-lefdil, Nouveau matériau d’insertion pour batteries rechargeables, le phosphite de titane (III) et de lithium LiTi(HPO3)2. Patent OMPIC N° 40700.

Figure 1
Optimization of Electrochemical Performance of Waste LCD Glass-Derived Silicon As Anodes for Lithium Ion Batteries
Authors: Kang Woohyeon , Kim Jae-Chan , Kim Dong-Wan
Published: February 2020

Silicon has been widely studied as a promising alternative that can replace graphitic anodes owing to its high theoretical specific capacity of 3580 mA h g-1 and appropriate working voltage (~0.1 V vs. Li/Li+) for lithium ion battery (LIB) anodes [1]. Recently, the industrial wastes such as windshields, glass bottles, and rice husks have been utilized as a low cost and eco-friendly Si source [2,3,4]. Waste LCD glass-derived silicon is one of the attractive candidate and this materialization technique also can be a future green technology for resolving an immense LCD waste and insufficient recycling process [5].

In this study, high purity Si were fabricated as LIB anode materials using waste LCD glasses via magnesiothermic reduction. Firstly, we eliminated containing inert impurities (Al2O3, CaO, B2O3, In2O3 etc.) by ball-milling and acid leaching. Then, pre-treated waste LCD glasses were reduced to Si particles at 650 °C for 6 hours in Ar through magnesiothermic reduction and subsequent acid treatment. As the crystallographic analyses, waste LCD glasses were successfully reduced to highly crystalline and pure Si. Waste LCD glass derived Si electrodes exhibited the high initial discharge capacity of 4290 mA h g-1. However, the capacity decreased rapidly, indicating that the electrode underwent rapid pulverization due to drastic volume expansion/fracture upon cycling [6].

To overcome this problem, diverse strategies have been proposed including nanostructuring, incorporating with carbon mediums, and post-processing of the electrode [2,7]. Herein, we elevate the electrochemical performance of waste LCD derived Si through carbon coating and electrode post-processing, that called maturation [7]. Firstly, obtained Si materials were coated by carbon using sucrose at 800 °C in Ar. Then, the electrode was matured by storing it in chamber at ~99% relative humidity for 2 days. The prepared Si electrodes exhibit much better cycling stability than untreated electrodes. This improvement originated from coated carbon and maturation process, which strengthens the cohesion of active materials and the adhesion of active material/current collector, thus less pulverization of the electrode.

References

[1] J. Entwistle, A. Rennie, S. Patwardhan, J. Mater. Chem. A, 6 (2018) 18344-18356.

[2] M. Choi, J.C. Kim, D.W. Kim, Sci. Rep., 8 (2018) 960.

[3] C. Li, C. Liu, W. Wang, Z. Mutlu, J. Bell, K. Ahmed, R. Ye, M. Ozkan, C.S. Ozkan, Sci. Rep., 7 (2017) 917.

[4] Y.-C. Zhang, Y. You, S. Xin, Y.-X. Yin, J. Zhang, P. Wang, X.-s. Zheng, F.-F. Cao, Y.-G. Guo, Nano Energy, 25 (2016) 120-127.

[5] C.-T. Lee, J. of Ind. Eng. Chem., 19 (2013) 1916-1925.

[6] X. Zuo, J. Zhu, P. Müller-Buschbaum, Y.-J. Cheng, Nano Energy, 31 (2017) 113-143.

[7] C.R. Hernandez, A. Etiemble, T. Douillard, D. Mazouzi, Z. Karkar, E. Maire, D. Guyomard, B. Lestriez, L. Roué, Adv. Energy Mater., 8 (2018) 1701787.
Improving Electrochemical Performance of 0.4Li2MnO3-0.6LiNi1/3Co1/3Mn1/3O2 Cathode Materials for Lithium Secondery Batteries with Coating LiNi0.5Mn1.5O4
Authors: Chen Yufang , Zheng Chunman , Xu Jing
Published: February 2020

Two components of the xLi2MnO3-yLiNi1/3Co1/3Mn1/3O2 have the same framework offer good structure compatibility, but exist large irreversible capacity loss[1] and structure transformation[
2
] when initially charged to 4.5V or higher. Hence there are many researchers focus their interest to investigate the possibility of integrating core-shell structure on reducing the irreversible capacity loss and improving cycle stability[3]. This paper is mainly on the improvement of electrochemical properties of 0.4Li2MnO3-0.6LiNi1/3Co1/3Mn1/3O2. The core cathode material was prepared from co-precipitation process. And the Shell material of LiNi0.5Mn1.5O2 has been integrated onto the surface of the core material using with assistance of PVP, since PVP has an effect of constraining particle size. After absolutely dried, both the coated and pristine samples were post-treated at the same thermal condition (Figure1).

Figure 2(a). presents a compare of first charge-discharge process of the coated and pristine sample, a remarkable change in the activate process, as coating bring up first cycle efficiency from 73.3% to 83.7% operated at a voltage of 2.0~4.8V vs Li0 at an current rate of c/20(1c=250mAh/g).Figure 2(b). shows an enhancement of cycling properties after coated.

Figure 1
Ageing Analysis of Miniature Cylindrical Cell for Fitbit Flex 2 Wristband
Authors: Tan Chaou Choak , Loveridge Melanie J , Remy Guillaume , Walker Marc , Dixon Shaun , Bhagat Rohit , Williams Mark A
Published: February 2020

Lithium ion battery (LIB) is gaining popularity in energy storage device due to its high energy density per unit mass and has found application in mobile phone, laptops, power tools and electric vehicle. More recently, LIB has also been utilised to power smart wearable devices such as fitness tracker, smart watches and smart glasses. Wearable device is gaining popularity and the market will continue to grow1. With devices shrinking so drastically, the need for smaller but higher energy density battery and good cycle life is more demanding than ever. Understanding battery performance and its degradation process are therefore crucial to give insights on how to extend battery life and reduce capacity-fading.

Here, we performed cell assessment on miniature cylindrical cell extracted from Fitbit Flex 2 fitness tracker and with an attempt to understand capacity-fading process of Fitbit cell utilising electrochemical, teardown and materials analysis. This miniature cylindrical cell is 3.65 x 20 mm in size with energy density of 503Wh/L and nominal capacity of 15mAh.

Teardown analysis on several numbers of non-cycled Fitbit cells have shown severe anode coating delamination from the copper current collector when the jelly roll were unravelled and with anode materials transferred to the separator. Nevertheless, Fitbit cell shows 82 % cell capacity retention after 500 continuous charging and discharging cycles at 3.0-4.35 V, 0.75C rate at 20 °C. Electrochemical Impedance Spectroscopy (EIS) shows increase in internal cell resistance, in which Li+ ion charge-transfer resistance (Rct) is the main contributor. Scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS) shows no visible morphological and compositional changes between fresh and aged cathode, anode and separator. X-ray photoelectron spectroscopy (XPS) reveals surface film contains organic compounds as well as lithium fluoride (LiF) and phosphates other than LiPF6 forming on both cathode and anode surface. XPS also shows increasing LiF and phosphates in cathode and anode surface film. The cause of increasing Rct and the possible source of LiF will be discussed.

1. https://www.statista.com/statistics/610447/wearable-device-revenue-worldwide/ [assessed on 17 January 2019]

Figure 1
Influence of Different Acids on Si/C Anode Pastes pH Values and the Corresponding Electrochemical Performance in Li Ion Cells
Authors: Keßler Elizaveta , Börner Markus , Niehoff Philip , Schappacher Falko , Winter Martin
Published: February 2020

Silicon particles are applied as anode active material in Li ion batteries to achieve higher energy densities. However, the usage of silicon particles today, comes along with increased aging and safety issues. The lithium uptake by the silicon particles during the charging process is accompanied by huge volume expansion (over 280%).1 Hence, the electrochemical performance suffers from ongoing capacity fading with each cycle due to contact loss between active material particles and the current collector. 2,3

To counter these issues different approaches have been done in literature including the reduction of the silicon particle size, the application of different binders, the use of silicon nanotubes, nanowires or core-shell particles.4,5,6 Acidic pretreatment is also well-known in the framework of surface functionalization of silicon particles. 7,8

In this work phosphoric, sulfuric, salt and oxalic acid were used to achieve better adhesion between active material particles and current collector. It also improves the electrochemical performance by lowering the discharge capacity fading. The pH value of the anode paste was varied to 3.6, 2.8 and 1.4, respectively, to investigate the effect on the adhesion between the silicon particles. To accelerate the reaction between the silicon particles and the appropriate acid the reaction conditions were optimized. The improvement in the electrochemical performance was coherent to the reaction progress, the period individually depended on the used acid.

For all four acid types the application resulted in a decrease of discharge capacity fading. An increase of the anode paste viscosity could be observed during the reaction time. Phosphoric acid turned out to be an appropriate acid for the application in the anode paste as it reached the highest capacity retention after 100 cycles at 1.0C and the best reproducibility. Oxalic acid showed the worst performance as a high ratio of parasitic reactions could be observed in the first charge cycle at 0.1C. With lower pH value bigger agglomerations between silicon particles were shown in SEM images simultaneously deteriorating the performance. The best performance was achieved with a pH value of 3.6 for every acid type.

References

[1] M. N. Obrovac, Chem. Rev. , 114, 23, 11444-11502 (2014).

[2] K. M. Abraham, J. Phys. Chem. Lett., 6, 830 (2015).

[3] W. J. Zhang, J. Power Sources, 196, 13 (2011).

[4] N.-L. Wu, J. Power Sources, 140, 1,139-144 (2005).

[5] R. A. Huggins, Materials for Sustainable Energy, 187-191 (2010)

[6] Y. Cui, Nano Lett., 9, 9, 3370-3374 (2009).

[7] B. L. Lucht, J. Electrochem. Soc., 165 (10), A1991-A1996, 2018.

[8] B. L. Lucht, Langmuir
33 (37), 9254-9261, 2016.

Figure 1
Pt Nanorods-Decorated Macroporous Carbon Nanofiber Free-Standing Cathodes for High-Performance Li-O2 Battery
Authors: Kim Do Youb , Bui Hieu , Kim Young Yun , Le Ngan Hong , KIM Dong Wook , Suk Jungdon , Kang Yongku
Published: February 2020

Controlling the pore structure of cathodes has a strong influence on the performance of Li-O2 battery. In the present study, macroporous carbon nanofiber (MCNF) mats are successfully fabricated through an electrospinning and templating methods using cross-linked polystyrene particles. Additionally, Pt nanorods are grown on the surface of the MCNF (PtNR-MCNF) as catalysts for Li/O2 reactions. As-prepared PtNR-MCNF has interconnected macropores along the MCNF interior and abundant surface openings. Those macropores are also connected to larger pores between individual MCNF through the orifices on the MCNF surface, rendering a hierarchical porous structure. Owing to the highly porous structure, Li-O2 cells using the PtNR-MCNF cathodes achieved a specific capacity of approximately 7,000 mAh/gc and even more at a current density of 200 mA/gc. In particular, the Li-O2 cell using the PtNR-MCNF cathode exhibited higher electrochemical performance in terms of rate capability, energy efficiency, and cycle stability. This study demonstrates that the growth of PtNRs resulted in the formation of poorly crystalized Li2O2, which significantly reduced the overpotentials, both during the discharge and the charge. Additionally, it contributed to the considerably prolonged cycle life of the Li-O2 cell using the PtNR-MCNF (468 cycles) compared to the cell using the MCNF cathode (272 cycles) with a limiting capacity of 1,000 mAh/gc at a current density of 500 mA/gc.
Graphene Oxide Membranes for Highly Efficient Rechargeable Li-O2 Batteries: Suppressing the Crossover of Redox Mediator
Authors: Park Se Hwan
Published: February 2020

Lithium-oxygen (Li-O2) battery is a promising energy storage system with high energy density, but several challenges such as its high overpotential and poor cyclability have limited the commercialization of Li-O2 batteries. One of strategies to address such issues is introduction of redox mediators (RMs) as soluble catalysts, which have mobility for decomposition of tethered discharge products on air cathode. Although RMs are expected to efficiently perform the catalytic effects at the initial cycles, undesired crossover of RMs from cathode to Li metal anode could deteriorate the cell performance by accompanying parasitic side reactions. For instance, 5,10-dihydro-5,10-dimethylphenazine (DMPZ) was reported as an oxygen evolution reaction (OER) RM, which showed an exceptionally low charge overpotential at the first cycle, but rapidly lost its high performance due mainly to the transport of DMPZ to the Li metal during repeated operations. Here, we report an excellent suppression of RM crossover for highly efficient Li-O2 batteries using a graphene oxide (GO) membrane prepared by a facile vacuum filtration on a porous support. The size of GO nanochannels is narrow enough to selectively allow the transport of small Li+ ions while rejecting the larger DMPZ molecules. The negative surface charges of GO further repel negative ions via Donnan exclusion, greatly improving the lithium ion transference number. Ultimately, the Li-O2 cells with GO membranes maximize the redox-mediation activity of DMPZ with improved performance, achieving energy efficiency of above 80% for more than 25 cycles, and 90% for 78 cycles when the capacity limits were 0.75 and 0.5 mAh cm-2, respectively. Considering the facile method for GO membrane fabrication, combination of GO membrane and RMs can be cost-effective solution for pragmatic Li-O2 batteries.
Influence of Conductive Agent in C/Si-Composite Electrodes for High-Energy Lithium Ion Batteries
Authors: Ambrock Karina , Niehoff Philip , Winter Martin , Schappacher Falko
Published: February 2020

Lithium ion batteries outperform other energy storage technologies in the combination of specific power and specific energy [1]. However, continuous improvement is necessary regarding the ever-increasing demands in terms of high energy densities, long cycle life and improved safety properties. One strategy to increase the specific energy density and decrease the overall cost of lithium ion batteries is the partial substitution of graphite with silicon in the negative electrode. Silicon forms alloys with lithium and offers an extremely high theoretical capacity (3579 mAh g-1) [2, 3]. However, the lithiation and delithiation process of silicon generates mechanical stress due to particle swelling and contraction (∆V ≥ 300%). This stress eventually causes mechanical fracture and pulverization, which in turn leads to active material loss.

Inactive materials and the use of a composite of active materials, silicon and graphite (C/Si), can help to mitigate these degradation effects. The binder ensures adhesion and cohesion of and within the electrode and its different components. Conductive agents improve the electrical conductivity and provide inter-particle as well as particle-current collector contacts. Therefore, the electrode and cell design can largely influence the electrochemical performance and cycle life. Different applications require different ratios of active material, conductive agent and binder.

Especially considering the low electrical conductivity of silicon [4], the use of conductive carbon is inevitable to increase electrical conductivity within the composite electrode. However, with C/Si electrodes, the necessity of conductive agent is questionable, since the graphite present in the composite might be able to provide sufficient electrical conductivity. Furthermore, an excessive amount of inactive material reduces the energy density of the electrode and has to be optimized.

This study focuses on the impact of conductive agent in high energy C/Si composite electrodes. To ensure a high loading and high energy density, the amount of inactive materials were optimized. For that, electrodes were prepared with different amounts of conductive agent and electrochemically tested in coin cells (charge/discharge cycle).

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Intercalation/De-Intercalation Behavior of Li-Ion Encapsulated By 12-Crown-4-Ether into Graphite Electrode
Authors: Koya Taro , Shimizu Masahiro , Umeki Makoto , Arai Susumu
Published: February 2020

From the viewpoint of abundance of Mg and advantage originated from divalent ion, Mg-ion batteries have much attention as a next-generation energy device. The development of electrolytes which can achieve reversible Mg-deposition/dissolution is still a challenge. Since Mg ion is a stronger Lewis acid than monovalent ion such as Li ion and Na ion when using carbonate-based solvent employed in commercially available Li-ion batteries (LIBs), Mg ion is more stabilized by solvation molecules. Consequently, in regard to graphite as a host material, carbonate-based electrolyte with high dielectric constant blocks intercalation (charge transfer) reaction involved in desolvation. Meanwhile, one of cyclic ether, crown ether with repeating unit being ethyleneoxy (−CH2CH2O−) has high affinity and selectivity to alkali metal ion and alkaline-earth metal ion and encapsulates in itself to form complex. As a strategy for storage of Mg ion in graphite interlayer, we considered a reversible battery reaction based on the intercalation of the solvated ions without desolvation. The electrochemical co-intercalation of solvated Li ion is mainly limited to the use of oligoether (glyme) regardless of carrier ion to the best of authors knowledge. As a preliminary stage to a study of an electrochemical behavior of graphite electrode in the presence of encapsulated Mg ion by crown ether, we investigated intercalation/de-intercalation properties of Li ion coordinated by 12-crown-4-ether having a suitable cyclic size for encapsulation. In the present study, solvation structure of Li ion and the influence of encapsulation on formation for electrochemical graphite intercalation is discussed. Electrochemical intercalation/de-intercalation behavior of Li ion encapsulated by 12-crown-4-ether into/from graphite electrode was studied and compared with a commercially available Li-ion battery electrolyte (1 mol kg-1 LiOTf/EC:DEC). In electrolyte solution in which Li ion is coordinated by 12-crown-4-ether, the interlayer of graphite expanded from 0.335 nm to 1.137 nm at charged state of 0.1 V, which is three times larger than that (0.371 nm) in the commercial electrolyte. Charge transfer reaction without desolvation process using Li ion encapsulated by 12-crown-4-ether was successfully progressed even at the high rate of 2C. The insight obtained in this study extend the diversity of carrier ion.

Figure 1
Electrochemical Design of Pt-Pd Nanostructures By Surface Limited Redox Replacement Method
Authors: Altowerqi Amal , Vasiljevic Natasa
Published: February 2020

The fuel cell technology is a green alternative to fossil fuels [1-2]. Fuel cells are electrochemical systems that use hydrogen and oxygen to create electrical energy with water and heat as biproducts. Besides the main interest of fuel cells applications in the automotive industry, most recent developments of miniature fuel cells that use biomass derived hydrogen have been attracting attention. Such systems require the design of new electrocatalysts with the high CO tolerance better than that of pure Pt. It has been shown that nanoscale Pt such as ultrathin layers and Pt-M nano-alloys, often have improved chemical and physical properties than those of Pt-bulk material due to the combination of electronic and geometric effects. Previous studies have reported that Pt-Pd system is a well-performing catalytic system for future use with the high CO tolerance [3,4].

Surface Limited Redox Replacement (SLRR) is one of the most successful approaches used to produce Pt bimetallic catalysts with high control of atomic structure [5, 6]. This method is based on the replacement of an underpotentially deposited (UPD) layer of a less noble metal by a more noble (such as Pt and Pd) through irreversible surface-controlled redox reaction. Here we will present SLRR based design of Pt-Pd nanoalloys of different composition on Au substrate. The advantages of using the SLRR method to design high quality 2D model Pt alloys will be demonstrated by studies of their electrochemical and catalytic behaviour as a function of structure such as film thickness and alloy composition. In our work, the epitaxial alloy thin films up to 10 ML thickness were grown in one-cell configuration using Cu UPD in sulphate solution as sacrificial layer. The alloys composition and structure were controlled by the concentration ratio of Pt and Pd complex in the solution. The structure of developed alloys was examined by a combination of electrochemical and surface science methods and correlated with their electrocatalytic behaviour during formic acid oxidation reaction.

References:

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[2] M.K. Debe, Nature, 486, 43-51, 2012.

[3] S. Dutta, C. Ray, S. Sarkar, A. Roy, R. Sahoo, and T. Pal, Electrochim. Acta, 180, 1075–1084, 2015.

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Si-Doped Carbon Xerogel for High Capacity Lithium and Sodium Ion Battery Anodes
Authors: Carabetta Joseph
Published: February 2020

The use of dopants such as silicon, tin, and, more recently, antimony in carbonaceous anodes is a promising area of research to increase the performance of lithium and sodium ion batteries [1-3]. The biggest obstacle to the progress of this technology is the stability of these inclusions in the carbon material during charging and discharging, most notably the volume change of the active material [4-8]. An electrode design was synthesized that consists of a carbon xerogel via a sol-gel process (CX), which acts as a support structure for a dopant, silicon nanoparticles (SiNPs), and provides electronic conductivity. Syntheses have been made using poly(sodium 4-styrenesulfonate) (PSS) as a coating or binder. These syntheses showed positive results on the cyclability of the CX/SiNPs composite. A 5-fold increase was observed in the number of charge/discharge cycles before the reversible capacity was less than 80% the initial capacity when compared with a composite with no coating and conventional binder. The gradual loss in capacity in the coated composite is still unknown, but may be due to the interplay between SEI formation and the volume expansion of the SiNPs. These problems are now being addressed by various techniques to improve the chemical and mechanical stability, and tailoring the microporosity and mesoporosity to reduce the irreversibly capacity loss and increase the accessibility to the dopant material.

References:

[1] W. Luo et al. Journal of Power Sources 304 (2016) 340–345 [2] B. Guo et al. Journal of Power Sources 177 (2008) 205–210 [3] RSC Advances, 2012, 2, 4311–431 [4] W.J. Zhang, J. Power Sources 196 (2011) 13–24 [5] H. Wu, Y. Cui, Nano Today 7 (2012) 414–429. [6] L.Y. Beaulieu, K.W. Eberman, R.L., et al. Electrochem. Solid-State Lett. 4 (2001) A137–A140. [7] J.H. Ryu, J.W. Kim, et al. Electrochem. Solid-State Lett. 7 (2004) A306–A309. [8] M.A. Rahman, G. Song, A.I. Bhatt, et al. Adv. Funct. Mater. 26 (2016) 647–678