bluuebunny/crossref_metadata_2025_split huggingface dataset:
Understanding the Evolution of the Li-Rich Antifluorite Li5FeO4 upon Electrochemical Delithiation
Authors: Zhan Chun , Lu Jun , Amine Khalil 
Published: February 2020

In order to boost the capacity of the lithium ion battery, cathode materials that can cycle with more than one lithium (Li) ion per transition metal (LM) ion are intensively investigated. The antifluorite family of Li8O4 (4Li2O unit cells) is an interesting structure to host high Li/TM ratio since the transition metal ions can substitute part of the tetrahedral Li ions the structure. A representative material is the Li5FeO4 (LFO), with one Fe3+ ion replacing one tetrahedral Li+ion and creating two vacancies. This material is capable of providing 5 Li/Fe or a capacity at about 867mAh/g in theory. Initial studies of LFO have yielded intriguing results that more than 4Li ions can be extracted at two plateaus at about 3.5 and 4.0V, with capacity higher than 700mAh/g. This super high delithiation capacity makes LFO a promising cathode material for the high energy Li-ion batteries. However, in the first discharge the plateaus decrease to 2.2V and 1.3V with a capacity of about 300mAh/g. In the following cycles, the capacity fades rapidly and the plateaus higher than 3V can’t be recovered. The cycle behavior of LFO shows that the deliathiation reaction of the LFO with the removal of over 4 Li ions is not reversible in conventional Li ion batteries.
In order to fulfill the reversible charge-discharge of the LFO,better understanding of the delithation reaction of LFO is required. In this work a series of comprehensive in-situ characterizations of the LFO electrode during the first charge were performed to understand the crystal structure, valance and bonding as well as the electronic structure evolution of LFO upon the Li removal. These studies indicate that the first charging of LFO can be divided into two stages. Stage I is a two-phase reaction in the first charging plateau, where the antiflorite LFO converts to pseudo-cubic Li3FeO4 (Li5FeO4→2Li++2e+Li3FeO4), and the oxidation state change of Fe and O in Stage I can be expressed as: Fe3+ →Fe(3+δ)++δ e- and 4O2- →4O(1.5+0.25δ)- +(2-δ)e-. Stage II is a one-phase reaction in the second plateau, with pseudo-cubic Li3FeO4 converting into pseudo-cubic LiFeO2 (Li3FeO4→2Li++2e+O2+LiFeO2) and the releasing of one O2 from the Fe-O framework. The valance evolution Fe and O in Stage II can be expressed as: Fe(3+δ)++ δ e- → Fe3+ and 4O(1.5+0.25δ)-→2O2-+O2+(2+δ)e-. Theoretical modeling confirms the formation of pseudo-cubic phase and O2 releasing in the second stage. High energy barrier was found for conversion from the pseudo-cubic phase back to antiflorite phase with lithiation and the O2 absorption, explaining the irreversibility of the LFO.

Figure 1
Phosphorus Electrodes for Li and Na-Ion Batteries: Structural Analysis and Reaction Intermediates
Authors: Griffith Kent J. , Mayo Martin , Morris Andrew J. , Grey Clare P. 
Published: February 2020

Phosphorus, in several allotropic variations, is emerging as a high capacity anode candidate for lithium and sodium batteries. The theoretical capacity for Li3P/Na3P is 2596 mA·h·g-1, far exceeding carbon and on par with the best known lithium and sodium battery anodes. To date, some composites of carbon with red phosphorus1,2, black phosphorus3–5, or phosphorene6–8have been investigated; however, the amorphous or poorly crystalline nature of these composites has hindered the understanding of phosphide intermediates and reaction mechanisms. Additionally, the nature of the phosphorus–carbon composites is not fully understood. A more complete chemical and structural picture is required to identify failure mechanisms and improve the lifetime of these promising electrodes.
Solid state nuclear magnetic resonance (NMR) offers unique insight into the complex chemistry of phosphorus composites and lithium phosphides. Nucleus-specific local atomic structure information is obtained for amorphous red phosphorus and its mechanochemical conversion to black phosphorus, which is relevant to all studies of phosphorus electrodes. Furthermore, the lithiation mechanism and lithium phosphide reaction intermediates are elucidated via 7Li and 31P NMR in combination with structure prediction from ab initio random structure searching and atomic species swapping methods. While Li3P is a known reaction product – observed via x-ray diffraction – other stable or metastable lithium phosphide intermediates have been hypothesized but not conclusively determined. We provide experimental and theoretical support for a range of amorphous and well-defined LixPy phases.
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Figure 1
Synthesis of Mono-Dispersed Olive-Shaped LiFePO4 Nanoparticles By Polyol Method
Authors: Shen Yue , Hai Chunxi , Zhou Yuan , Zeng Jinbo , Sun Yanxia 
Published: February 2020

Since the use of olivine-structured lithium iron phosphate (LiFePO4, LFP) as a cathode material for rechargeable lithium batteries was first reported by Goodenough and co-workers in 1997, LFP has been extensively and intensively studied, owing to its significant advantages including high theoretical capacity (170 mAhg-1), long cycle life(≥2000), acceptable operating voltage (3.4V vs. Li+/Li), environmental benignity, high safety, and low cost. Unfortunately, LFP possesses a major drawback in its sluggish kinetics of electron and lithium-ion transport, which restricts its rate performance. To date, many studies have been made to reduce the particle size and incorporate carbon additives of LFP, so as to improve the electronic conductivity and thus enhance the diffusion of Li ions across the LFP/FePO4 interface. Many techniques have been developed to synthesize nanosized LFP with uniform size distributions, which include the hydrothermal method, polyol and solvothermal methods, sol-gel methods, reverse micelle process and spray pyrolysis. Among them, the polyol method is considered one of the most facile and efficient methods to synthesize nanosize LFP with high crystallinity. Therefore, in this study, we would like to control the size, crystallization degree, morphology of LFP particles via a facile, low temperature polyol method to improve its ionic and electric transport properties. In this method, the polyol solvent (ethylene glycol) could generate a reductive atmosphere even in the absence of any reductive agent. Highly-dispersed LFP cathode nanospheres with olive-shape was synthesized by a simple polyol refluxing process without any post heat treatments. As-obtained samples were characterized by XRD, FE-SEM, TEM, BET etc. As confirmed by these characterization results that olive-like LFP nanoparticles with high crystallization degree were successfully prepared in this study. And the sizes of these nano/micro-particles are ranged from 50 nm to 800 nm. The various processing parameters, namely, reaction temperature and material ratio, have been varied, and the effects on the growth of LFP particles have been analyzed systematically to optimize the preparation condition. Finally, the electrochemical properties especially the rate performance of as-resulted LFP nanoparticles, employing the reported as comparison, were discussed, which is the key point of their application in Li ion batteries.

Figure 1
Enhanced Electrochemical Properties of LiNi0.5Co0.2Mn0.3O2 Cathode Materials with RuO2 Coating Layer By Atomic Layer Deposition
Authors: Hong Tae Eun , Byeon Mi Rang , Jang Yujin , Jeong Euh Duck , Kim Soo-Hyun 
Published: February 2020

Ni-based cathode materials have been as an alternative to LiCoO2[1,2]. Therefore, many studies have been performed to solve the inherent problems of Ni-base cathode materials [3]. However, reasonable solution for rate performance and thermal stability of Ni-based cathode materials has not been reported. Coating method on the cathode material may become the solution technique for electrochemical properties.
In this study, LiNi0.5Co0.2Mn0.3O2 cathode materials were prepared by co-precipitation method. RuO2 coating layer was deposited on LiNi0.5Co0.2Mn0.3O2powder using a shower head type PEALD reactor (Lucida-M100, NCD Technology), with IMBCH Ru [IMBCH = (η6-1-isopropyl-4-methylbenzene)(η4-cyclohexa-1,3-diene)] as a precursor.
We propose a new coating method for cathode materials using atomic layer deposition. The physical and electrochemical properties of RuO2 coated LiNi0.5Co0.2Mn0.3O2 cathode materials have been thoroughly investigated. Compared to various metal oxides, we will show that the optimization of RuO2 coating layer can be significantly improved the electrochemical performance of LiNi0.5Co0.2Mn0.3O2cathode materials.
References
[1] Y. S. Lee, D. Ahn, Y. H. Cho, T. E. Hong, J. Cho, J. Electrochem. Soc., 158 A1354 (2011)
[2] E. Rossen, C. D. W. Jones, and J. R. Dahn, Solid State Ionics, 57 311 (1992)
[3] Y. Kim, H. S. kim, S. W. Martin, Electrochim. Acta, 52 1316 (2006)
All-Solid-State Flexible Lithium Batteries on Polyimide Substrate Using Excixmer Laser Annealing
Authors: Yim Haena , Sung Yung-Eun , Choi Ji-Won 
Published: February 2020

As the demands of wearable electronics increase, the development of flexible power sources has become very important to satisfy them. All-solid-state lithium batteries have attracted huge attention over the recent years due to their safe characteristic and wide electrochemical stable window compared to those of liquid electrolyte-based lithium rechargeable batteries, which allows high operating voltage without any worries on safety problems at bending state.However, the cathode thin film, which is a critical component of thin film battery, certainly needs to be crystallized at high temperature because of the hindrance of solid-state lithium diffusion from any imperfections in the crystal. Eventually, the polymer substrate goes through sudden changes because of its poor resistance to high temperature, so a new direction of crystallization should be considered.
In this work, we present a new fabricating method for all-solid-state flexible lithium batteries using excimer laser annealed cathode thin films, which facilitates fast crystallization of active materials with no damage on substrate. The excimer laser annealed cathode thin films were crystallized without a damage of polyimide substrate. Structural properties of the thin films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The electrochemical properties were carried out using WBC3000 battery cycler. The initial capacity of developed flexible battery on polyimide substrate was 20 μAh μm-1 cm-2 at 0.2 C-rate. It was confirmed that red light-emmitting diode light was turned on continuously during the bending state. We expect that this approach for fabricating flexible batteries will be practically applied for micro-powered flexible electronic devices.
Towards an All Solid State Lithium Battery Beyond 5 V
Authors: Windmüller Anna , Tsai Chih Long , Gehrke Hans Gregor , Uhlenbruck Sven , Guillon Olivier 
Published: February 2020

Spinel cathodes for Lithium Ion Batteries (LIB), such as LiCoMnO4, offer higher operational voltages and higher energy densities than common LIB cathodes, like LiCoO2 [1]. Compared to LiCoO2 the energy density of a LiCoMnO4 cathode is increased by 25%. Therefore, high voltage LIBs based on spinel cathodes are considered as possible candidates for future lithium battery technologies. However, commonly used liquid electrolytes are unstable at potentials above 4.5 V , which is the minimum operational voltage for spinel cathodes [2,3]. To access the full energy density of LiCoMnO4 cathodes (~5.3 V) an all solid state approach is chosen by replacing the liquid electrolyte by a solid state electrolyte ceramic [4]. The processing of a cathode for an all solid state battery comes along with new requirements to the cathode material. Compared to common particulate based cathodes a different functional structure has to be developed to assure electronic and ionic diffusion paths. Additionally, it has to be compatible to the given solid electrolyte and – depending on the processing techniques – withstand higher temperatures during manufacturing. Lithium-manganese spinels in particular are known to be unstable at higher temperatures and tend to release lithium and oxygen from their lattice [5,6]. Therefore, sintering and stability studies for LiCoMnO4 were carried out to find a processing route that leads to a high relative density without decomposition of the material. Additionally, different conceptual cathodes were tested and characterized structurally, microstructurally and regarding their electrical properties. The completion of this study finally leads to a cathode supported all solid state battery with lithium phosphorous oxy-nitride as solid electrolyte processed by physical vapour deposition.
References
[1] Whittingham MS. Chem. Rev. 2004;104:4271–302.
[2] Goodenough JB, Kim Y. Chem. Mater. 2010;22:587–603.
[3] Xu W, Chen X, Ding F, Xiao J, Wang D, Pan A, Zheng J et al. Journal of Power Sources 2012;213:304–16.
[4] Li J, Ma C, Chi M, Liang C, Dudney NJ. Adv. Energy Mater. 2015;5:n/a-n/a.
[5] Pasero D, Souza S de, Reeves N, West AR. J. Mater. Chem. 2005;15:4435–40.
[6] Thackeray MM, Mansuetto MF, Dees DW, Vissers DR. Materials Research Bulletin 1996;31:133–40.
The Effect of Carbon Starting Material on Li/CFx Batteries with Graphene Paper As Flexible Current Collector
Authors: Yang Weijing , Dai Yang , Zhang Maohui , Dang Guoju , Min Fanqi , Xie Jingying 
Published: February 2020

Li/CFx batteries are known to have the highest theoretical specific capacity in comparison to other primary lithium batteries, which are commonly used for many applications such as emergency power source, cameras, memory back-up, electronic counter, electrical lock, electronic measurement equipment, military and implantable medical devices. However, the low electrical conductivity of CFx limits the development of Li/CFx batteries where high power density is needed. Graphene paper has been developed as flexible current collector to improve the power density of Li/CFx batteries. As known the importance of carbon starting materials, recently, three different types of carbon(coke, mesoporous carbon and graphite) have been fluorinated and developed, in order to promote some particular electrochemical parameters, namely the power density, the discharge potential, or the energy density.
Overall, the carbon fluorides with graphite as precursors present no voltage delay at the beginning of discharge and excellent electrochemical properties at high current density. The carbon fluorides with mesoporous carbon as precursors own the highest discharge potential. While, carbon fluorides with coke as precursors deliver the highest energy density(810 mAh/g). As the result shown, carbon starting materials strongly influence the electrochemical performances of Li/CFx batteries. It is necessary and significant to choose precursors and design the battery system according to varied applications.
The main part of this work was supported by National Nature Science Foundation of China (No.21373137) and Shanghai Municipal Science and Technology Commission (No.15DZ2282000 and No.14JC1491800).

Figure 1
Mapping of Spatial Inhomogeneities with Laboratory X-Ray Diffraction
Authors: Wolf Mark , Khawaja Sara , Cabana Jordi 
Published: February 2020

We have developed a new laboratory X-ray diffraction technique to probe
meso-scale inhomogeneities in battery cathode materials. Conventional
diffraction uses an X-ray beam that covers most of the cathode
surface, giving average properties over all locations. In contrast,
our technique uses a laboratory diffractometer with a sub-millimeter
beam to extract location-specific structure information. Up until now,
this has only been reported with synchrotron radiation. We have used
this technique to uncover inhomgeneities related to a variety of
factors, such as preparation technique, the size and position of the
anode, and the charge rate of the cell. For example, in one
experiment, sections of an LiMn₂O₄ cathode were found to lag behind
the global state in areas of poor contact with the current
collector. This effect was not seen at slow rates (C/10), however,
suggesting that alternate electrical pathways are still available,
though kinetically less viable. This technique can also be used to map
an electrode's cross-section to find effects occuring along the
direction of charge flow.
In-Situ X-Ray Studies of Unmodified Commercial Pouch Cells
Authors: Bond Toby M , Zhou Jigang , Reid Joel 
Published: February 2020

Synchrotron techniques, including synchrotron X-ray diffraction (SR-XRD) and X-ray absorption spectroscopy (XAS), have been widely used over the past twenty years to investigate the chemical and physical behavior of batteries. The uniquely high brilliance and coherence of synchrotron light has made it especially well-suited for in-situ analysis of batteries, as data can be acquired very quickly with excellent spectral and spatial resolution
[1]
.
Generally in-situ studies of batteries employ a custom-made research cell that is designed with “windows” in the casing that are x-ray transparent. Such cells typically employ a simple coin-cell-type design where two discs of electrode material are pressed together in an air-tight assembly
[2, 3]
. While these types of cells are very useful and convenient for most materials research, they cannot exactly replicate the conditions present in many common commercial cells, and they are not generally suitable for long-term studies on ageing and degradation.
The work presented here demonstrates several examples of how synchrotron techniques can be used to analyze unmodified commercial pouch cells. With high brilliance and tunability of incident wavelength, synchrotron light can be used to penetrate commercial cell casings and analyze active electrode material in-operando. At the Canadian Light Source, SR-XRD was used to analyze the crystal structure and phase changes in an operating commercial nickel-manganese-cobalt-oxide/graphite pouch cell. Transmission SR-XRD was also used to map structural inhomogeneities in cell components with high spatial resolution. In-operando XAS was also successfully carried out on an unmodified commercial pouch cell, which will provide a simple means of monitoring changes in structure and redox chemistry as commercial batteries undergo long-term ageing, cycling, and stress testing.

[1] Yoon W-S, Grey CP, Balasubramanian M, Yang X-Q, Fischer DA, McBreen J. Electrochem Solid-State Lett., 2014, 13, 1051-1061.

[2] De Marco R, Veder JP. Trends in Analytical Chem., 2010, 29, 6.

[3] Herklotz M, Scheiba F, Hinterstein M, Nikolowski K, Knapp M, Dippel AC, Giebeler L, Eckert J, Ehrenberg H. J. Appl. Cryst., 2013, 46, 1117-1127.
One-Pot Synthesis of Iron Oxide Nanoblock Deposited on 3D Porous Graphene Architecture for Lithium Ion Storage
Authors: Yun Sol , Park Ho Seok 
Published: February 2020

The hierarchical architecturing and hybridization of iron oxide is very important for achieving multifunctional capability that makes it possible for practical applications. In particular, hierarchical architecturing of graphene/iron oxide hybrids in a three-dimensionally (3D) manner is expected to become an innovative chemical approach for full potential of respective functionality. In addition to intrinsic material properties, such a hierarchical structure constructed by graphene nanosheets and iron nanoparticles takes advantages of 3D interconnected macroscopic structure in terms of a large accessible area, fast mass and ion transport, percolated charge transfer, and structural integrity.
In this study, hierarchically structured reduced graphene oxide (hrGO)/α-Fe2O3 nanoblock hybrids (hrGO/α-Fe) are synthesized via a one-pot, hydrothermal self-assembly process. All in one synthetic approach is very simple yet useful for simultaneously constructing 3D macroscopic rGO structures and growing α-Fe2O3 NBs. The 3D macroporous structure of hrGO/α-Fe NBhs is constructed, while α-Fe2O3 nanoblocks (NBs) in a proximate contact with the hrGO surface are simultaneously nucleated and grown during a hydrothermal treatment. The discrete α- Fe2O3 NBs are uniformly distributed on the surface of the hrGO/α-Fe and confined in the 3D architecture, thereby inhibiting the restacking of rGO layers and maximizing their functionalities.
In order to demonstrate the superiority of the hrGO/α-Fe NBhs, we applied them into lithium ion battery anodes. The specific capacity of the commercial rGO/α-Fe dramatically decreased from 662.6 mAh/g at 50 mA/g to 83.6 mAh/g at 1000 mA/g with the capacity retention of 12.6%. In a sharp contrast to the commercial rGO/α-Fe, the hrGO/α-Fe NBhs exhibited better rate performance from 497.7 mAh/g to 210.3 mAh/g with the capacity retention of 42.3%. After 60 cycles at 100 mA/g, the commercial rGO/α-Fe showed highest initial discharge capacity of 566.5 mAh/g, but it was further decreased to 380.8 mAh/g (67.2%) of initial capacity. By contrast, the hrGO/α-Fe NBhs showed no capacity fading, maintaining initial capacity of 472.8 mAh/g. Despite lower coulombic efficienty and initial capacity, the hrGO/α-Fe NBhs show better rate and cyclic performances than those of commercial rGO/α-Fe due to the uniform distribution of discrete α-Fe2O3 NBs and electronic conductivity, macroporosity, and buffering effect of the hrGO for an application into lithium ion battery anode.