bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation on the Anode Surface of High Specific Energy Li-Ion Batteries
Authors: Chao-xiang Xie , Xin-bin Zhou , De-Chao Jian , Hai-tao Gu , Ke Wang 
Published: February 2020

Lithium-ion batteries have become the most popular secondary battery of electric cars, electronic products and power grids with high specific energy and cycle life. Currently, the specific energy density of commercial lithium-ion battery is less than 250Wh / kg, with the continuous development of lithium-ion batteries, the indicator of the next generation of lithium-ion batteries energy density have reached 300Wh / kg. Lithium-ion batteries show good electrical performance advantages, are also facing a number of security issues and challenges, including the thermal decomposition of cathode electrodes , the decomposition reaction of the electrolyte, the surface of the anode electrode and aggregation effect, etc. which have become main factors affecting the security and stability of the cycle.
At present, the carbon materials dominate the anode materials of lithium ion batteries, and high specific energy Li-ion batteries mainly use graphite as the anode material, which enhances the specific energy density due to the high-capacity, long cycle life and high press density. However, this material tends to form lithium deposition in conditions of high C rate, charging at low temperature and higher polarization, and the deposited lithium becomes thicker to form the dendrite, which may penetrate through the separator, causing internal short circuit, even the safety issue.
In this paper, we investigate the mechanism of lithium deposited on the anode surface of high specific energy li-ion batteries(with NCA as the cathode，graphite as the anode) by the electrochemical method combined with the physical characteristics analysis. From the potential of the battery, measured by three-electrodes and electrochemical analysis tools, the results show that, the lithium deposited on the anode electrode surface is mainly owing to the polarization of cathode and anode. For the charging process, if the polarization is higher enough, the potential of the anode electrode constantly is reduced, even to 0V or less, i.e., the lithium will be deposited on the anode surface. The investigation also shows that, using the method of pre-charge can maintain the anode potential above 0V, and it can effectively suppress the deposition of metal lithium on the anode electrode surface.

Figure 1
In-Situ Fabrication of MS (M = Co and Ni) Nanomaterials Anchored on Graphene for Reversible Lithium Storage
Authors: Tan Yingbin 
Published: February 2020

We report a facile method to synthesize highly dispersive MS (M = Co and Ni) nanomaterials anchored on graphene sheets as an advanced anode material for reversible lithium storage. The obtained MS (M = Co and Ni) nanomaterials and graphene formed a sheet-on-sheet composite structure (Figure 1), which can not only facilitate ions/electrons transport along the interfaces, but also effectively prevent MS nanomaterials aggregation during the lithium storage processes. As a result, the graphene-supported CoS nanofibers and NiS nanosheets exhibit a high reversible capacity of 939 and 521 mA h g-1, respectively, with a Coulombic efficiency of over 98 % after 100 cycles at a current density of 100 mA g-1(Figure 2).
The excellent lithium storage properties of the MS-graphene composites can be attributed to the layered structure of the MS-graphene composites possessing the larger electrode-electrolyte contact area, the shorter ionic diffusion length and the easier transportation of lithium ions. This strategy of generating the composite structure can be extended to synthesize other metal sulfides-graphene nanomaterials for lithium-ion batteries.

Figure 1
Silyl and Silyl/Carbonate Blend Electrolytes for Lithium-Ion Battery Applications
Authors: Lyons Leslie J. , Peña Hueso Adrián , Johnson Tobias , West Robert 
Published: February 2020

Novel silyl solvents as components of electrolytes for lithium-ion batteries have improved lithium ion transport and safety in comparison to the conventional carbonate solvents most in use in lithium-ion electronic devices.1 This presentation will explore the ion transport of a variety of electrolytes composed of the silyl solvent families (generic structures shown in Figure 1): silyl glycol molecules where the number of ethylene oxide chain units on the silyl fragment has been varied as well as the number of carbons bonding the ethylene oxide chain to the silicon, and silyl nitrile molecules where the salt solvating moiety is a nitrile functionality instead of a glycol. Electrolytes of the silyl solvents with the salts LiPF6, LiTFSA, and LiBOB have been prepared and their variable temperature ionic conductivities measured by impedance spectroscopy. Ionic conductivities of electrolytes at 25°C range from 1.1 to 2.5 mScm-1 for salt concentrations at 0.8 M or 1 M. Based on these promising ionic conductivities, we have prepared a variety of solvent blend electrolytes in which the silyl solvent is mixed with conventional battery solvents such as the cyclic carbonates ethylene carbonate (EC) or propylene carbonate (PC), linear carbonates ethyl methyl carbonate or diethyl carbonate, and γ-valerolactone or methyl butyrate. In general, ionic conductivities of the silyl solvent/carbonate blend electrolytes increase in comparison to the comparable electrolyte of the pure silyl solvent achieving ionic conductivities at 25°C of 5-6 mScm-1. We have also measured variable temperature lithium and anion diffusion in PFG-STE NMR experiments which yield lithium and anion transference numbers. Lithium transference numbers in silyl electrolytes are higher than those in analogous cyclic carbonate electrolytes. From both the ionic conductivity and NMR diffusion measurements, we have calculated the extent of ion dissociation in these electrolytes. We will report on the trend for lithium transference numbers and ion dissociation over the temperature range of 300 to 330 K for a number of electrolyte blends. We also report the viscosities, glass transition temperatures, and dielectric constants of the silyl solvents which impact the variations in ion transport we find for the lithium salt electrolytes. Full carbon/lithium cells of some of these electrolytes have been prepared and cycle well.

1L. Zhang, L. Lyons, J. Newhouse, Z.

Zhang, M.

Straughan, Z. Chen, K. Amine,

R. Hamers,

and R. West J. Mater. Chem., 2010, 20, 8224-8226.

Figure 1
Organosilicon-Based Electrolytes with Superior Thermal and Electrochemical Stability to Enable High Energy Lithium Ion Batteries
Authors: Usrey Monica Lee , Peña Hueso Adrián , Du Peng , Zhou Liu , Johnson Tobias , Hamers Robert J , West Robert 
Published: February 2020

Organosilicon (OS) electrolytes have been developed as a viable alternative to conventional carbonate electrolytes for lithium ion batteries. A recent trend in the Li-ion industry toward adoption of new materials, including electrolytes, is driven by the desire to deploy larger capacity batteries under broader operating conditions. In addition, the development of new advanced Li-ion chemistries to meet these requirements often require electrolytes with enhanced thermal and electrochemical stability that provide performance across a wide temperature range. This novel organosilicon chemistry involves the merging of a silane with a lithium coordinating functionality. This combination results in solvents comprised of low molecular-weight molecules and having unique properties including high thermal stability, high flash point, low vapor pressure and relatively low viscosities.

Recently, Silatronix has developed an entirely new class of OS molecules to provide new (patent pending) “Gen-3” solvents whose thermal, chemical, and electrochemical properties greatly surpass those of the earlier suite of OS compounds. Multiple structural variations from the “Gen-3” OS family showcase greatly enhanced stability and performance attributes. Specific examples of performance improvement include higher conductivity and lower viscosity while concomitantly providing superior thermal stability with LiPF6 and reduced gassing.
In this work, we demonstrate the superior stability and performance attributes of the “Gen-3” family of molecules. For this we have evaluated the physical properties, thermal and electrochemical stability, and performance in coin and pouch cells across a wide temperature range with a variety of electrode materials. This work focuses on exploring the fundamental mechanisms underlying the enhanced stability, including a unique solvation sphere which provides salt stabilization and enhances the stability of all electrolyte components.
Understanding the Roles of Electrolyte Additives on the Surface Modification Mechanism of Silicon-Based Anodes in Lithium-Ion Batteries
Authors: Xu Chao , Lindgren Fredrik , Dupre Nicolas , Lestriez Bernard , Guyomard Dominique , Edström Kristina , Gustafsson Torbjörn 
Published: February 2020

Silicon is considered as a promising candidate of the anode material for the next generation lithium-ion batteries, due to its substantially higher gravimetric and volumetric capacity compared to conventionally used graphite. Electrolyte additives, fluoroethylene carbonate (FEC) and vinylene carbonate (VC) particularly, are usually applied for silicon-based lithium-ion batteries to tackle the problems such as poor capacity retention and low coulombic efficiency.1-3 In the present work, the decomposition mechanism of FEC as well as the surface modification of Si electrodes were investigated.4 It was observed that the FEC additive degrades at a higher reduction potential prior to the other carbonate solvents. A conformal solid electrolyte interphase (SEI), which consists of the decomposition products of FEC, is instantaneously formed on the silicon electrode as a result. This stable SEI layer sufficiently limits the emergence of cracks and suppresses the additional SEI formation from the decomposition of other electrolyte components. Both of these effects lead to a slower increase in polarization, thus a slower capacity fading, for the FEC containing cell. The differences in the SEI layer, formed with or without the presence of FEC, are schematically demonstrated in Fig 1. Besides, it was also observed that the LiPF6 decomposition can be influenced with the presence of FEC, and this was further studied with a combination of X-ray photoelectron spectroscopy (XPS) and solid-state nuclear magnetic resonance (NMR) techniques.
We also demonstrated that by forming an effective SEI layer with the FEC and VC electrolyte additives, the silicon electrodes can be equally well functioning with a novel lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI)-based electrolyte as with the state-of-art LiPF6-based electrolyte.5

Figure 1
Microwave Sintered Cubic Si-Doped Li7La3Zr2O12 with Improved Li-Ion Conductivity and High Density
Authors: Xu Dinghao , Wu Yongmin , Tian Wensheng , Tang Weiping 
Published: February 2020

Microwave Sintered Cubic Si-Doped Li7La3Zr2O12 with Improved Li-Ion Conductivity and High Density

XU Ding-hao, WU Yong-min, TIAN Wen-sheng, TANG Wei-ping
(Shanghai Institute of Space Power-Sources,
Shanghai 200245, China)
High energy density and high security batteries have been widely used in intelligent has been widely used in intelligent devices and power and energy areas. With significant advantages on the specific energy and safety by using a solid electrolyte, all solid state lithium batteries are the future direction of development. Among all solid electrolytes which are suitable for all solid state lithium battery, Li7La3Zr2O12(LLZO) with its high theoretical density, small grain boundary impedance and low interfacial reaction dendrite probability has become an extremely promising material. In order to obtain a high density of Li7La3Zr2O12, calcinations is the primarily preparation method. The sintering temperature is higher than 1200℃ and sintering time is more than 30 hours. The calcinations can be repeated to reduce porosity. At the same time, in order to improve the ion conductivity of the interface and reduce grain boundary surface of the lithium-ion overflow barrier, it generally doped zirconium-bit or lanthanum-bit types of metal elements such as Ta, Nb, Hf, Al, etc, so as to reduce the structural barriers and improve ion transmission capacity. Microwave reaction is particularly suitable for the manufacture of high density material because of its high efficiency high heating rate and high reaction uniformity. Therefore, we chose to use the microwave sintering method, the auxiliary powder tab letting process, at a temperature of 900℃ and no more than 12 hours, to obtain high purity cubic Li7La3Zr2O12. This method greatly improves the efficiency of the reaction. At the same time, an amount of Al, Si oxide is adding to the powder through ball mill. These oxides adjust the microwave absorption rate of each micro region, thereby improving reaction uniformity. On the basis of improve the density of the solid electrolyte film, doping at the A-bit and C-bit can increase lattice size, improve cell symmetry, increase vacancy concentration and improve lithium ion transport kinetics rate of the solid electrolyte. The results show that the doped Li7La3Zr2O12 prepared by microwave method oxygen, its room temperature ionic conductivity is about 0.7ms/cm. this method with advantages of low energy consumption, high reaction efficiency can not only promote the all solid-state lithium battery technology, but also be applied to the preparation of Li1.4Al0.4Ti1.6(PO4)3, Li10GeP2S12 and other types of solid electrolyte so as to broaden the research and development ideas of the solid electrolyte material.
Novel Ionic-Liquid Type of Polymer Electrolytes for Lithium Batteries
Authors: Zhang Chaofu 
Published: February 2020

The rapid growing market of electric transportation i.e. electric vehicles, laptop and cellular phones, has raised a large interest in safety of lithium batteries in the recent years. So, much attention has currently been paid to the solvent-free batteries, especially the case of solid-state batteries, which are made of inorganic solid components, and of batteries using solvent-free polymer electrolytes. In lithium battery field, solvate lithium ionic liquids are a new class of room-temperature ionic liquids (ILs), who exhibit desirable properties, including high lithium transport, high Li+ capacity and improved oxidative stability. Lithium ILs type solid polymer electrolyte which improve the performance is attributed to the weak static interaction between Li+ and the counter ion, and the immobilized anions therefore might lead to a favored cationic charge transport.
Is Succinic Anhydride a Successful Additive for Graphite/Lmno Cells?
Authors: Charton Christopher , Santos Pena Jesus , Biller Agnès , LE Digabel Matthieu , Lemordant Daniel , Galiano Hervé 
Published: February 2020

Nowadays lithium-ion batteries (LIBs) are widely used in nomad applications and electric vehicles. There are a lot of developments focused on electrode materials to improve the energy density. Lithium nickel manganese oxide (LMNO) is currently considered as one of the most promising cathode material for future 5 V lithium ion batteries. Nevertheless common electrolytes which are based on mixtures of alkylcarbonates containing LiPF6 as salt are strongly oxidized at the LMNO cathode [1]. As a result, battery performances are very limited. To improve the high voltage tolerance of the electrolyte, various formulations have been developed. Electrolyte additives can affect the reactions of decomposition of the electrolyte leading to the formation of a protective passive layer on the surface of the active material. Succinic anhydride (SA) seems to have a beneficial effect in LMNO based cells, lowering significantly capacity losses (or enhance capacity retention) and improving battery cycling life and the coulombic efficiency [2]. However, the role of SA on electrode/electrolyte interfacial mechanisms isn’t fully understood in graphite/LMNO cells. In this communication, the influence of SA as electrolyte additive is studied in various type of cells (half, full or symmetrical cells) based on LMNO and graphite electrodes. Preliminary results showed that SA does not operate efficiently at 20°C in EC:EMC – LiPF61 M mixture (see figure 1) in Li/Gr and Gr/Gr symmetrical cells. This study is completed by identifying the nature of electrolyte degradation products formed upon cycling (GC-MS analysis) and characterizing the protective layer on the surface of electrodes (X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS)).
[1] J. Demeaux, E. De Vito, M. Le Digabel, H. Galiano, D. Lemordant and B. Claude-Montigny, ECS Transactions
2013, 53, 5-21.
[2] V. Tarnopolskiy, J. Kalhoff, M. Nádherná, D. Bresser, L. Picard, F. Fabre, M. Rey and S. Passerini, Journal of Power Sources
2013, 236, 39-46.

Figure 1
One-Pot Synthesis of Chemically Bonded NaTi2(PO4)3/rGO 2D Nanocomposite for Sodium-Ion Batteries
Authors: Roh Ha-Kyung , Kim Myeong-Seong , Lee Geon-Woo , Kim Kwang-Bum 
Published: February 2020

Abstract

NASICON-structured NaTi2(PO4)3 has been considered as an outstanding potential cathode material for Na-ion batteries (NIBs) because of its good Na-ion intercalation reversibility and extremely small structural changes during charge/discharge cycling.1 Despite these advantages, NaTi2(PO4)3 suffers from intrinsically poor electronic conductivity, which leads to poor charging/discharging rate performance of NIBs. Up to now, several effective ways have been proposed to improve the electrochemical properties such as specific capacity and cycling stability, including reduction of the particle size to nanoscale, the addition of a surface coating and the synthesis of composite materials with conductive carbons.2

In particular, the composites of NASICON-structured materials with carbonaceous materials such as mesoporous carbon and graphene of reduced graphene oxide (rGO) has been recently proposed to enhance electronic conductivity of the electrode for improving the cycling performance.3 Graphene acts as a template due to its high specific surface area not only to deposite nano-sized metal oxide but also to connect the nano particles along a 2-dimensional conduction path. Furthermore, graphene can provide a void space against the volume changes of the metal oxide particles during lithium ion insertion/extraction process, which can improve the cycling performance. However, previously reported methods to fabricate of these composites require multistep, time-consuming processes, and complicated.4 Moreover, in this multistep method, the sodiation and heat treatment steps unfavorably affect the size, morphology and homogeneity of the resulting NaTi2(PO4)3 particles. Accordingly, their electrochemical properties showed only a marginal improvement compared with the bare NaTi2(PO4)3.
In this study, we have developed a phase-pure NaTi2(PO4)3/rGO nanocomposite through a facile one-pot synthesis based on microwave-assisted solvothermal synthesis, in which rGO was used to selectively heat the substrate to facilitate the preferential precipitation of NaTi2(PO4)3 nanoparticles (30-40 nm). Ti-O-C bonds formed during the synthesis process, which could efficiently transfer the electrons from the NaTi2(PO4)3 nanoparticles to rGO substrates. The strongly bonded NaTi2(PO4)3/rGO nanocomposite prepared in this study exhibited an excellent rate capability and good cyclability as an anode material for SIBs.

References

1. Il Park et al, J Electrochem Soc
2011,
158, A1067.
2. Pang, G. et al, J Mater Chem A
2014,
2, 20659.
3. Li et al,J Electrochem Soc
2014,
161, A1181.
4. Pang, G. et al, Nanoscale
2014,
6, 6328.

Figure 1
Dynamic Study of (De)Sodiation in Tunnel-Based Manganese Oxides and the Capacity Retention Via Voltage Control
Authors: Yuan Yifei , Ma Lu , He Kun , Yao Wentao , Nie Anmin , Bi Xuanxuan , Wu Tianpin , Lu Jun , Amine Khalil , Shahbazian-Yassar Reza 
Published: February 2020

Developing advanced cathode materials for sodium ion batteries (NaIBs) with stable host structure and reliable capacity performance during cycling is crucial for the commercialization of NaIBs.[1] Nanostructured MnO2 is one competitive cathode candidate due to its low cost, environmental friendliness, and various open-framed polymorphs to facilitate cation insertion and extraction.[2] α-MnO2, which features 2×2 tunnels with 4.6×4.6 Å2 cavity, has recently become one research focus as such a tunneled structure in nanoscale was reported to be suitable for Na+ transport.[3] However, α-MnO2 suffers from structure instability, low coulombic efficiency and quick capacity decay during cycling, which prevent its further application to a large extent. The causes of these problems should be directly related to the repetitive tunnel-Na+interactions during (de)sodiation, which is currently poorly understood.
In this work, the (de)sodiation of α-MnO2 nanowires is dynamically studied and well understood using in situ TEM with an open cell design. The morphology, phase and structure of the electrode are characterized and recorded in real time. It is found that the sodiation starts with Na+ intercalation into the 2×2 tunnels without tunnel degradation up to Na/Mn equaling 0.5 (Mn3.5+). Then α-MnO2 phase gradually evolves into an intermediate Na0.5MnO2 phase. Upon deep sodiation to Na/Mn equaling 1 (Mn3+), the structure totally collapses and degrades to polycrystalline Mn2O3 and Na2O. The following (de)sodiation cycles confirm that the tunneled structure, once destroyed, can not be recovered, and the following cycles are dominated by the conversion reaction between Na0.5MnO2 and Mn2O3, whose reversibility is poor.
The galvanostatic voltage profile at bulk level coin cells shows that the intercalation reaction featuring a slope profile happens between 4-1.4 V, while the conversion reaction featuring a plateau region is below 1.4 V. Based on this, the cycling voltage windows of the Na/MnO2 coin cells are set to above 1.5 V to maintain the original tunneled structures of α-MnO2 for reversible Na+(de)intercalation. This voltage control results in the prominent capacity retention of the batteries compared to those cycled below 1.5 V, whose capacity decays very fast. The coulombic efficiency is also obviously improved when the cells are cycled above 1.5 V.

References:

[1] Chem. Rev., 2014, 114, 11636–11682
[2] Nano Lett., 2015, 15, 2998–3007
[3] Nano Energy, 2016, 19, 382-390.

Figure 1