bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of New Synthesis Process of LiFePO4/C Composite
Authors: Aziam Hasna , Larzek Mohamed , Bilal Essaid , Solhy Abderrahim , Saadoune Ismael
Published: February 2020

Abstract:

At the present time, our way of life has become completely dependent on energy. In order to solve the depletion of fossil fuels, an energy transition towards renewable energies such as solar energy, wind power, hydropower, geothermal power, bio energy, heat pump became inevitable. The development of such renewable but intermittent energy requires the development of energy storage solutions.

Lithium ion (Li-ion) batteries had gained a lot of attention for powering portable electronic devices owing to its combination of high power and energy density, long cycle and stability.

Current Li-ion battery technology consists of LiCoO2 and graphite as the cathode and anode materials, respectively. Nevertheless, LiCoO2 has a limited abundance in nature, toxic and very expensive. Its main drawback indeed is thermal instability leading to many safety issues. For this reason, LiFePO4 was presented as a potential candidate to replace LiCoO2, especially in the stationary applications

LiFePO4 was first reported as positive electrode material for rechargeable Lithium batteries by Goodenough et al. in 1997. It shows a high theoretical capacity (170 mAh g-1), a high discharge potential (3.45 V Vs Li+/ Li), an excellent thermal stability, a low cost and it is environmentally friendly. Nevertheless, it has a poor ion diffusion coefficient (10-14 cm2 s-1) and low electrical conductivity (10-9 S cm-1). Carbon coating, reducing the particle sizes and doping with the conductive elements were the solutions suggested to overcome these drawbacks.

This study aims to develop a scalable synthesis process of LiFePO4/ C composite starting from H3PO4 produced by OCP group. The electrochemical performances of various samples prepared by varying many synthesis parameters will be presented in this conference.

Keywords: Li-ion batteries, LiFePO4, H3PO4, carbon coating.

 

Acknowledgement:

The financial assistance of the office Chérifien des Phosphates in the Moroccan Kingdom (OCP group): The authors are hereby acknowledged. Ms H. Aziam is grateful to Mohammed VI Polytechnic University for the scholarship.

References:

Tarascon, J.M., Armand, M., (2001) Issues and challenges facing rechargeable lithium batteries, Nature, 414 (6861), 359.

Goodenough, J. B, kim, Y., (2009) Challenges for Rechargeable Li Batteries, chem. Mate. 22 (3) 587.

Ohzuku, T., Brodd, R. J., (2007) An overview of positive-electrode materials for advanced lithium-ion batteries, Journal of power sources, 174, 449-456.

Padhi, A.K., Nanjundaswamy, K.S., and Goodenough, J.B., (1997) Phospho‐olivines as Positive Electrode Materials for Rechargeable Lithium Batteries, J. Electrochem. Soc. , Vol. 144, No. 4.

Fergus, J. W., (2010) Recent developments in cathode materials for lithium ion batteries, Journal of power sources, 195, 944-945.
Interphase Modification of Li(Ni0.5Co0.2Mn0.3)O2 Based Lithium Battery Electrode Materials By Depolarized and Pre-Lithiation for High Capacity and Cycling Performance
Authors: Wu Zhongzhen , Ji Shunping , Han Xiaogang , Hu Zongxiang , Zheng Jiaxin , Wei Yi , Qiao Ruimin , Hu Liangbing , Xu Kang , Lin Yuan , Yang Wanli , Pan Feng
Published: February 2020

Layered transition-metal oxides have served as the mainstream cathode materials for high-energy batteries due to their large theoretical capacity (≈280mAh/g),However, the actual usable capacity is much lower than the promised theoretical value. Additional, poor cycling performance and the first-cycle Coulombic efficiency, for which Mn(II)-dissolution, its immobilization in solid electrolyte interface (SEI), oxidation of electrolytes by Ni, and other parasitic process thereat have been held responsible, weight against their applications.. Here we report a significant enhancement of cathode capacity utilization through a novel concept of material design. By embedding Li(Ni0.5Co0.2Mn0.3)O2 in single wall carbon nanotube (CNT) network, a high charge/discharge reversible capacity up to about 250 mAh/g was obtained between 3.0-4.8V. Furthermore, to maintain this high capacity in long-term cycling, we proposes a unique “pre-lithiation process”, which brought the cathode to low potentials before regular cycling and led to an interphase that is normally formed only on anode surfaces. The complete coverage of cathode surface by this ~40 nm-thick interphase effectively prevented Mn(II) dissolution and minimized the side reactions of Ni, Co and Mn at the NMC interface during the subsequent cycling process. More importantly, such “pre-lithiation” process activated a structure containing two Li layers near the surface of NMC532 particles, as verified by XRD and first principle calculation. Hence, a new cathode material of both high capacity with depolarized structure; and excellent cycling performance was generated.
Application of Atomic Layer Deposition to Lithium-Oxygen Batteries
Authors: Park Da-Hee , Choi Yoo-Jin , Seo Ki-Won , Lee Jon-Won , Park Min-Sik , Kim Ki Jae , Hwang Jinha
Published: February 2020

Rechargeable  lithium-oxygen  (or  lithium-air)  batteries  have been recognized as next-generation batteries which can replace the prevailing lithium-ion batteries. The non-aqueous Li-O2 batteries involve carbon materials as cathode materials due to their natural abundance and high surface areas per weight. However, the exposure of carbon to air and Li2O2 deteriorates the stability of cathodes, in association with the subsequent electrolyte decomposition, leading to the low round-trip efficiency and poor cycle performance. The atomic layer deposition (ALD) of oxide materials possesses several unique features: self-limiting surface reactions and atomic-scale deposition, and conformal deposition. Such features can be applied to control artificially the deposition morphology on the underlying carbon cathodes, which affects the performance of Li-O2 batteries. In order to improve the well-known issue present in the Li-O2 (Li-air) batteries, the ALD of oxide materials was combined with the carbon materials with the aim to controlling the cathode degradation issues. The current work reports zinc oxide and aluminum oxide as coating materials deposited onto carbon cathode materials, i.e. carbon nanotubes (CNTs): zinc oxide (ZnO) shows a semiconducting property, while aluminum oxide (Al2O3) exhibits an insulating property. The ALD-coated ZnO and Al2O3 onto the carbon electrodes are characterized using analytical electron microscopy. The implications of ALD-based ZnO and Al2O3 are discussed in terms of the performance of Li-O2 secondary batteries in connection with the underlying microstructure and chemistry.
Ni-Sn-Si/C Based Composite As Negative Electrode for Li-Ion Batteries
Authors: Bibent Nicolas , Lippens Pierre-Emmanuel , Olivier-Fourcade Josette , Jumas Jean-Claude , Azib Tahar , Cuevas Fermin , Latroche Michel
Published: February 2020

New electrode materials and battery design are required to improve the electrochemical performances of Li-ion batteries. Some metals like Al, Si or Sn can form alloys with Li by reversible electrochemical reactions and can be used as negative electrodes of high specific capacities (600 - 4000 Ah/kg) for high density Li-ion batteries. However, alloying reactions cause large volume variations resulting in the loss of electronic percolation and SEI instability at the origin of the usually observed poor cycle life of such materials. Different approaches were considered to overcome these problems based, for example, on the nanostructuration of the active material, the dispersion of the particles and the use of intermetallics or composites [1]. Recently, we have proposed a family of new composite materials formed by Si nanoparticles dispersed within a tin based intermetallic matrix Ni3Sn4 that exhibits high specific capacity and coulombic efficiency [2]. In order to improve the performances and reduce the cost of such composites, we propose now a new material with a lower tin content with the overall composition Ni0.15Sn0.14Si0.26Al0.04C0.41.

In this communication, the synthesis method, the material characterization and the electrochemical performances are presented. We show that the composite is formed by Si nanoparticles embedded in a matrix composed of Ni3Sn2 and Ni3Sn4 particles (Figure 1). The specific capacity after 200 cycles is of about 500 Ah/kg (Figure 2), which is surprisingly close to that obtained by the Ni3Sn4 based composite. To understand this results, X-ray diffraction and 119Sn Mössbauer spectroscopy were combined to explore in situthe reaction mechanisms that reveal the electrochemical activities of the different components of the composite.

Figure 1 SEM image of Si/Ni3Sn2-Ni3Sn4/Al/C composite as negative electrode for Li-ion batteries.

Figure 2 Specific capacity and coulombic efficiency vs. cycle number for the Si/Ni3Sn2-Ni3Sn4/Al/C composite at C/10 galvanostatic regime

References

(1) D. Larcher, S. Beattie, M. Morcrette, K. Edström, J.C. Jumas, J.M. Tarascon, J. Mater. Chem
. 17 (2007) 3759.

(2) Z. Edfouf, F. Cuevas, M. Latroche, C. Georges, C. Jordy, T. Hézèque, G. Caillon, J. C. Jumas, M.T.Sougrati,  J. Power Sources, 196 (2011) 4762.

Acknowledgments

The authors would like to thank the French National Research Agency for the funding of the project NEWMASTE under the grant N°ANR-13-PRGE-0010.

Figure 1
Structural Influence of Magnetron-Sputtered Silicon-Carbon Thin Films on the Anode Performance in Lithium-Ion Batteries
Authors: Reyes Jiménez Antonia , Winter Martin , Placke Tobias
Published: February 2020

The next generation of lithium-ion batteries (LIBs) for the application in miniaturized electronic devices and traction batteries need further development of new active materials with higher specific capacities to increase the resulting energy and power of the battery cells. In particular, new anode materials with high specific capacities and improved cycling performance are of great interest.[1]

Since silicon provides a very high gravimetric and volumetric capacity, a low operation potential and low costs, it is widely regarded as the most promising anode material in LIBs for the future.[1] However, major issues arise from its poor capacity retention due to mechanical degradation caused by the large volume expansion during lithium insertion/extraction. In recent years, several attempts have been undertaken to overcome this problem.[2] Compared to bulk silicon anodes, which contain at least 10 wt.% of inactive binders and conductive additives, silicon thin film anodes contain no inactive materials, giving an increased specific capacity.[3]

In this work, silicon-carbon thin films have been prepared by magnetron sputtering. The silicon-carbon thin films have been prepared by alternatively sputtering layers of silicon and carbon (layered structure of silicon and carbon) or by co-sputtering silicon and carbon (mixed silicon-carbon layers). The characterization of the electrodes was performed by focused ion beam-scanning electron microscopy (FIB-SEM), Raman spectroscopy and electrochemical impedance spectroscopy. Furthermore, the influence of the carbon content and layered/non-layered silicon-carbon structure was thoroughly investigated in cycling experiments compared to the bare thin film silicon electrodes.

Literature:

[1] R. Wagner, N. Preschitschek, S. Passerini, J. Leker, M. Winter, J Appl Electrochem. 43 (2013) 481-496.

[2] M.N. Obrovac, L.J. Krause, J Electrochem Soc. 154 (2007) A103-A108.

[3] U. Kasavajjula, C. Wang, A.J. Appleby, J Power Sources, 163 (2007) 1003-1039.
Hierarchical Porous Anatase TiO2 Derived from a Titanium Metal-Organic Framework As Superior Anode Materials for Lithium Ion Batteries
Authors: Xiu Zhiliang , Kim Dongyun , Alfaruqi Muhammad Hilmy , Song Jinju , Kim Sungjin , Kim Jaekook
Published: February 2020

Hierarchical meso-/macroporous anatase TiO2 (HPT) was synthesized from the hydrolysis of a titanium metal-organic framework precursor followed by calcination in air. The HPT possesses bimodal and hierarchical porosity: mesopores with pore diameters of 12, 16 and 28 nm along with macropores with pore diameters of up to 185 nm.This unique porous feature enables the superior rate capability and excellent cycling stability of anatase TiO2 as an anode for rechargeable lithium-ion batteries(LIBs). At a rate of 5 C, the specific discharge capacity of the HPT electrode is about 155 mA h g-1. After 200 cycles at 5 C charging/discharging rates, the capacity loss was only ~6.5 %. The superior rate capability and excellent cycling stability make HPT a promising anode material for fast rechargeable LIBs.

Figure 1
Synergetic Effects of Inorganic Components in Solid Electrolyte Interphase on High Cycle Efficiency of Lithium Ion Batteries
Authors: Zhang Qinglin , Pan Jie , Verbrugge Mark W , Lu Peng , Liu Zhongyi , Sheldon Brian W. , Cheng Yang-Tse , Qi Yue , Xiao Xingcheng
Published: February 2020

The solid electrolyte interphase (SEI) is a passivation layer formed on an electrode surface that can enhance long-term electrode stability. The inorganic components formed in SEI layer, including lithium carbonate and lithium fluoride, play a critical role in terms of providing both mechanical and chemical protection as well as accommodating lithium ion transport. Although lithium carbonate and lithium fluoride have relatively low ionic conductivities, surprisingly, we find that a synthetic composite coating made of both components creates a defect-intensive interface, which significantly improves lithium transport. The synergetic effect of both inorganic components leads yields higher current efficiencies and cycling stability. We envision that the defect-intensive composite coating is a promising artificial SEI layer for the suppression of undesirable side reactions and improvement in the life of lithium ion batteries employing silicon negative electrodes.
High-Throughput Method to Study the Electrochemical Performance of Ag-Doped Olivine Based Cathode for Libs
Authors: Lee HyunSeok , Yim Haena , Kim Kwang-Bum , Choi Ji-Won
Published: February 2020

LiMPO4 (M=transition metal) has advantages of excellent structural and thermal stabilities, non-toxicity, low cost and excellent electrochemical properties. Among these compounds of materials, LiFePO4 is nontoxic and remarkably stable even in rough operating conditions. However, the problem of the low energy density of LiFePO4 resulting from its relatively low potential (~3.4 V) remains unresolved. LiMnPO4 has attracted tremendous attention due to the higher redox potential of Mn3+/Mn2+ vs. Li+/Li than that of Fe3+/Fe2+. However, there are numerous limitations related to its intrinsic electrochemical properties, mainly coming from the slow kinetics. Hence, the electrical conductivity is improved through carbon coating, Ag-embedded or the decrease in particle sizes in recent works. In this study, we find that the formation of a solid solution between LiFePO4 and LiMnPO4 is energetically favored, and each transition metal actively participates in the electrochemical reaction within a reasonable voltage range. Its electrochemical properties and phase stability are explored with continuous composition spread (CCS) radio frequency (RF) magnetron sputtering. We describe for Ag-doped olivine based cathode materials deposition on Pt/Ti/SiO2/Si substrates. The olivine compound Ag-doped thin film cathode materials was deposited by CCS RF magnetron sputtering. The CCS RF sputtering is a feasible method to deposit various compositions on a substrate with two targets. Two independent RF magnetron sputtering guns installed with LiFePO4 and Ag-doped LiMnPO4 targets are located vertically to a Pt/Ti/SiO2/Si substrates. Consequently, we have investigated the full range of LiFePO4 and LiMnPO4 compositions to find optimized composition with continuous composition spread RF magnetron sputtering.
Porous Li-Rich Cathode Material with Carbonaceous Modified Surface for High Performance Lithium Ion Batterie
Authors: Li Jie , He Xin
Published: February 2020

Li-rich layered oxides (Li1+zMnx
NiyCo1-x-y
O2) are considered as a most promising family of intercalation cathode materials for rechargeable lithium batteries, due to the advantages of high discharge capacity and high specific energy. Coupled with other benefits like high safety, low toxicity and costs, Li-rich materials are currently significantly attractive for high-power applications. However, weaknesses like intrinsic poor rate capability, dramatically decrease in the discharge potential plateau, irreversible volume expansion and capacity fade during long-term cycling are bringing up concerns about their practical utilization, which need to be surmounted.

Morphology tailoring is considered to be an efficient way to address these issues. It has been proved that the particle size, crystallinity and structural morphology have obvious effects on electrochemical performance of electrode materials. In order to improve the electrochemical performance of Li-rich, the special morphology of the material, with extra space between particles to buffer the volume change and the modified surface to enhance the electronic conductivity, was synthesized in this work.

Specifically, high crystallinity Li1.2Mn0.56Ni0.16Co0.08O2 Li-rich porous materials integrating with an in-situ formed surface containing carbonaceous compounds are obtained through a novel facile approach. The rationally designed procedure involves the formation of a specific morphology of a hydroxide precursor assisted by a self-made template and subsequent high temperature treatment. The porous morphology is investigated using field-emission scanning electron microscopy and its surface area quantitatively examined by gas sorption analysis couple with the Brunauer-Emmett–Teller method. The porous morphology can be viewed from SEM image (Figure 1a), and it owns large surface area which is five time more than the sample in the normal shape. The crystallinity is characterized by X-ray diffraction and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy, CHN element analysis confirm the presence of the carbonaceous compounds in the surface composition. The prepared material exhibits superior discharge rate capability and excellent cycling stability. It shows minor capacity loss after 100 cycles at 0.5 C and maintains 94.9% of its initial capacity after 500 cycles at 2 C. Even more notably (Figure 1b), the “voltage decay” during cycling is also significantly decreased. It has been found that carbonaceous compounds play a critical role for reducing the layered to spinel structural transformation during cycling. Therefore, the present porous Li-rich material with surface modified a carbonaceous compounds represents an attractive material for advanced Lithium-ion batteries.

Figure 1
Pseudocapacitive Negative Electrodes Based on Mxene Ti2CT
x
for High-Power Li-Ion Batteries
Authors: Kajiyama Satoshi , Iinuma Hiroki , Lucie Szabova , Sodeyama Keitaro , Sugahara Akira , Gotoh Kazuma , Tateyama Yoshitaka , Okubo Masashi , Yamada Atsuo
Published: February 2020

Development of rapid charging systems in Li-ion batteries is one of the urgent tasks for the widespread use of environmental-friendly electric vehicles towards a sustainable and green society. However, in spite of numerous efforts devoted to realizing the high-power systems, their power density is not satisfactory, partly due to the poor rate capability of the negative electrodes.

A novel family of layered compounds, MXene (M
n

+1X
n
T
x
: M = Ti, V, Nb, etc.; X = C, N; n = 1-3; T = surface termination groups) has attracted increasing attention as negative electrode material with high-rate capability for Li-ion batteries.[1] MXene is the derivative phase of ternary layered compounds, MAX phase (M
n
AX
n
: A = Al, Si, S, etc.), first synthesized with concentrated hydrofluoric acid (HF) solution to extract selectively the A element.[2] Due to the tunable compositions and structures in MXene, there are huge choices for the development of the high-power electrode materials. Gogotsi and colleagues have recently discovered that lithium fluoride (LiF) and hydrochloric acid (HCl) solution also selectively extracts the A element from MAX phase, and Ti3C2T
x
synthesized with the LiF and HCl solution exhibits higher performance as pseudocapactior in aqueous systems than HF-synthesized Ti3C2T
x
.[3]Therefore, the synthetic method for MXene is a key process to determine its electrochemical property.

In this work, we have successfully synthesized Ti2CT
x
with the LiF and HCl solution. The charge-discharge measurement reveals that the Ti2CT
x
delivers large reversible capability of 260 mAh/g in 1M LiPF6/EC-DMC (1:1, v:v) electrolyte, which is larger than that of Ti2CT
x
prepared with concentrated HF solution (180 mAh/g).[4] Reaction mechanism was investigated with combined approach using XANES, XRD, and 7Li-MAS-NMR. We construct the prototype full cell with the Ti2CT
x
and LiNi1/3Co1/3Mn1/3O2 negative/positive electrodes, and demonstrate that the Ti2CT
x
is the promising electrode material for the high-power Li-ion batteries.

[1] M. R. Lukatskaya, et al. and Y. Gogotsi, Science
341, 1502 (2013).

[2] M. Naguib, et al. and M. W. Barsoum, Adv. Mater.
23, 4248 (2011).

[3] M. Ghidiu, et al. and Y. Gogotsi, Nature
516, 78 (2014).

[4] J. Come, et al. and P. Simon, J. Electrochem. Soc.
159, A1368 (2012).

Figure 1. Charge-discharge profile of Ti2CT
x
in 1M LiPF6/EC-DMC (1:1, v:v) electrolyte and comparison in the rate capability synthesized with different solutions.

Figure 1
High Performance Porous Silicon Anodes By Chemical Etching Metal Si Alloy Powders
Authors: Kim Jong Seok , Kim Yang Soo , Kim Sung Chan , Kim Tae Hyun
Published: February 2020

We describe a simple process for prepare three-dimensional porous silicon powders by acid etching process. Subsequently, the aluminum-silicon alloy particles were chemically etched to synthesize porous silicon particles, without changing the chemical and physical properties of Si. The silicon monoxide-coated porous silicon anodes exhibited excellent electrochemical properties, including a high specific capacity and a high rate capability. High electrochemical performance of porous silicon powder could be attributed to its porous structure, which provides enough tiny space to buffer the huge volume change of Si anode during charging and discharging processes. The firm connection between Si nanobars in spongy porous structure prevented the breakdown of porous Si particles. This easy acid etching process for preparing high performance porous Si material is simple and inexpensive, effective way for a rich variety of applications, including lithium-ion batteries.
Characterizing Aging Behavior in Li-Ion Batteries Using Micro-XRF
Authors: Boesenberg Ulrike , Michalak Barbara , Ravnsbaek Dorthe Bomholdt , Falk Mareike , Garrevoet Jan , Fittschen Ursula E. A. , Janek Jürgen , Falkenberg Gerald
Published: February 2020

Aging in Li-ion batteries is accompanied by structural and compositional changes of the active and passive material of the electrodes. Visualization of spatial correlation between morphological properties and chemical phase can help to find origins of aging and failure mechanisms and to understand the ongoing processes. Micro X-ray fluorescence (XRF) analysis allows for chemical imaging of elemental distributions of multiple 3d elements simultaneously, or distribution of the state of charge even at low concentrations or under operando conditions. Utilizing focused synchrotron radiation, representative volumes of the electrodes can be studied with sub-micrometer resolution on acceptable time scales.

Cutting edge instrumentation in this field is the Maia fluorescence detector. It allows for ultra-fast mapping of areas of multiple mm² with high spatial resolution within minutes. This allows e.g. examination of large electrode areas. The backscattering geometry of the detector enables easy mounting of flat samples such as electrodes or pouch-cells. By variation of the energy in the vicinity of an absorption edge, conclusions on local variations of the state of charge can be drawn, probing the oxidation state of the redox-active element.  Furthermore, confocal XRF enables spatially resolved measurements of the deposition of transition metals on the graphitic anode without destruction. This will help to understand the impact on capacity fade and degradation.

For the present study, samples of LiNi0.5Mn1.5O4 electrodes cycled vs. Li or graphite were investigated at beamline P06 at DESY, Hamburg Germany.1 The experiment revealed significant inhomogeneities in the local Ni/Mn ratio upon cycling which is correlated to thinning of the electrode. Higher cycling rates showed an increased impact and higher material losses. Inhomogeneities in the phase transformation were also found during the charge and discharge process. The graphitic anodes showed significant amounts of deposited transition metals, few wt%, both Ni and Mn, deeply penetrating into the pores of the electrode. On the other hand, a study on commercial LiFePO4 cathodes with outstanding rate capabilities showed an extremely high degree of homogeneity throughout the investigated areas. These methods are by no means limited to the investigated materials, but are easily transferred to other transition metal containing electrode materials.

1. U. Boesenberg et al., Chem.Mater., 27, 2525–2531 (2015)
Process R&D and Scale-up of Advanced Battery Materials at Argonne's Materials Engineering Research Facility
Authors: Krumdick Gregory , Shin Youngho , Kahvecioglu Feridun Ozgenur , Pupek Krzysztof Z. , Dzwiniel Trevor L
Published: February 2020

Argonne's Materials Engineering Research Facility (MERF) supports the laboratory's Advanced Battery Materials Synthesis and Manufacturing R&D Program.  The MERF is enabling the development of manufacturing processes for producing advanced battery materials in sufficient quantity for industrial testing.  The engineering research conducted in this program is known as process scale-up.  Scale-up R&D involves taking a laboratory-developed material and developing a safe, reliable and economical commercial-scale process.  This represents one of the most significant hurdles in transitioning new battery materials and technologies to the market.  By bridging the gap between small-scale laboratory research and high-volume battery manufacturing, research at the MERF will lead to substantial progress in the development, validation and ultimate commercialization of advanced battery materials chemistries.  In addition, advanced manufacturing processes are investigated to determine performance and cost benefits to material production.  Advanced materials produced are then made available to the battery research community to further their work using high quality, standardized baseline materials.  An overview of the program will be given as well as a summary of current scale-up projects.
High Performance Separator Coated with Amino-Functionalized SiO2 Nanoparticles for Safety Enhanced Lithium-Ion Battery
Authors: Cho Jinhyun , Shin Won-Kyung , G Kannan Aravindaraj , Kim Dong-Won
Published: February 2020

The use of lithium-ion batteries has been rapidly expanding in portable electronic devices, electric vehicles and energy storage systems due to their high energy density and long cycle life.  In lithium-ion batteries, a separator is a critical component which prevents physical contact of the positive and negative electrodes while permitting free ionic transport within the cell.  Most of the separators currently used in lithium-ion batteries are based on microporous polyolefin membranes such as polyethylene (PE) and polypropylene (PP) as well as various combinations of the two [1,2]. Although these separators offer excellent mechanical strength and chemical stability, they shrink and even melt at high temperatures, which causes short circuit between electrodes in the case of unusual heat generation.  Furthermore, the large difference in polarity between the non-polar polyolefin separator and the polar organic electrolyte leads to poor wettability.  In order to solve these problems, ceramic-coated separators have been developed by combining the characteristics of a polymeric separator and ceramic materials.

In this study, we tried to improve the thermal safety and cycling performance of lithium-ion cells by using separators coated by amino-functionalized SiO2 (A-SiO2) nanoparticles.  These separators exhibited enhanced thermal stability and melt integrity.  Due to the high affinity of A-SiO2
with liquid electrolyte, the A-SiO2
coated separators exhibited good wettability and high ionic conductivity.  Furthermore, A-SiO2 nanoparticles played a role as HF scavenger, which suppressed HF generation and electrolyte decomposition at elevated temperature.  As a result, the lithium-ion cells assembled with A-SiO2
coated separator exhibited the improved cycling performance at both ambient temperature and elevated temperature.

References

[1] P. Arora, Z. Zhang, Chem. Rev. 104 (2004) 4419-4462.

[2] S.S.Zhang, J. Power Sources 164 (2007) 351-364.
Influence of Aging on Heat-Release of Lithium Ion Battery Under Adiabatic Conditions
Authors: Luo Ying , Lu Taolin , Yan Liqin , Xie Jingying , Feng Yi
Published: February 2020

Safety has been the primary issue in the use of the lithium ion technology in high energy and high power applications ranging from power tools to electric vehicles. The safety of lithium ion batteries is mainly derived from the thermal effects of the battery during normal and abnormal operation. Overheating may start exothermal reactions that release even more heat which in turn can lead to an accelerated process called a thermal runaway. In addition to the lithium ion batteries of the body factors (electrode materials [1], membrane [2] and electrolyte [3] and other internal materials) as well as the manufacturing process [4], the battery aging [5] process is also critical to the safety of the lithium ion batteries.

An accelerating rate calorimeter is employed to study the heat release of 5 Ah lithium iron phosphate battery with different aging status under adiabatic condition. We design four aging methods, consisting of cycled at 1 C and 0.5 C, stored at 55 ℃ with SOC 100% and SOC 50%. Thermal behavior of lithium iron phosphate battery charged and discharged at 1C is investigated, and the influence of cycle number, cycle rate, storage time and storage temperature on the overcharge test of lithium iron phosphate battery was studied. The results show that the lithium iron phosphate batteries have no accidents such as leakage, explosion, burning etc, after 600 cycles at 1C or storage for 4 months at high temperature 55 ℃. With the increase of the cycle numbers, the average heat power of the battery charge-discharge and overcharge increases. At the same cycle numbers, the raising range of the temperature and average heat power of the battery cycled at 1 C is decreased, compared with that of battery cycled at 0.5 C. With the increase of the storage time at the high temperature, the average power of the battery charge-discharge and overcharge increase as well. Furthermore, The raising range of the temperature and average heat power of the lithium iron phosphate battery with 100% SOC full power of the battery is smaller than that of battery with 50% SOC. This work was supported by National 863 Program (No. 2013AA050902) and Shanghai Science and Technology Engineering Research Center Program (No. 13DZ2280200).

Reference

[1] Jiang J, Dahn J R. Electrochemistry Communications, 2004, 6: 39~43.

[2] Chen J J, Wang S Q, Dandan Cai, Wang H H. Journal of Membrane Science, 2014, 449, 169-175.

[3] Tyunina, Yu E, Chekunova, Marina D. Journal of Molecular Liquids, 2013.11, 187: 332~336.

[4] Kise M, Yoshioka S,Hamand I.Electrochemistry, 2004,72(9)：641-646.

[5] Sarre G, Blanchard P, Broussely M. Journal of Power Sources, 2004, 127(1): 65-71.
Sulfide Electrolytes: Study of Local Li-Ion Dynamics in Li3PS4 Using Li(7) NMR Relaxometry
Authors: Prutsch Denise , Brandstätter Harald , Pregartner Veronika , Wohlmuth Dominik , Epp Viktor , Wilkening Martin
Published: February 2020

The attractive long-term stability and safety of so-called all-solid-state batteries has given new impetus to developing powerful solid Li+ electrolytes. Post Li-ion batteries equipped with solid electrolytes may also be very attractive for hybrid electric vehicles as these systems are expected to withstand high operation temperatures. Moreover, they may serve as attractive components in Li-oxygen and Li-sulfur batteries. In addition to the various oxides and phosphates studied so far, see, e.g., refs. [1,2], sulfide-based materials have attracted particular attention due to their very high ionic conductivities [3,4].

Li3PS4 represents such a promising candidate, since its achievable Li-ion conductivity is comparable to that of liquid electrolytes. Phase-pure Li3PS4 was prepared by joint high-energy ball-milling of Li2S and P2S5 for 35 hours and subsequent heat treatment at 260 °C for 17 hours. X-ray diffraction analysis corroborated the phase purity of the sample prepared. To study the elementary steps of ion hopping in Li3PS4
7Li solid-state nuclear magnetic resonance (NMR) spectroscopy was employed. In particular, we used temperature-variable relaxometry measurements carried out in both the laboratory and rotating frame of reference to shed light on local as well as long-range ion dynamics. Line shape measurements revealed fast Li-ion exchange able to completely average homonuclear dipole-dipole interactions at temperatures much below ambient. This perfectly agrees with a recent NMR study focusing on field gradient experiments [5]. Moreover, it is in line with our spin-lattice relaxation (SLR) measurements performed at low temperatures: From the low temperature flank of the diffusion-induced SLR rates an activation energy as low as 0.1 eV was determined. Such a low value indicates fast, localized Li jumps present in Li3PS4. The high Li+ diffusivity also manifests itself in the appearance of an SLR spin-lock NMR rate peak that shows up well below room temperature.

[1] H. Buschmann, J. Dölle, S. Berendts, A. Kuhn, P. Bottke, M. Wilkening, P. Heitjans, A. Senyshyn, H. Ehrenberg, A. Lottnyk, V. Duppel, L. Kienle, J. Janek, Phys. Chem. Chem. Phys. 13 (2011) 19378

[2] V. Epp, Q. Ma, E.-M. Hammer, F. Tietz, M. Wilkening, Phys. Chem. Chem. Phys., 17 (2015) 32115

[3] M. Tatsumisago, M. Nagao, A. Hayashi, J. Asian Ceram. Soc., 1 (2013) 17

[4] V. Epp, O. Gün, H.-J. Deiseroth, M. Wilkening, J. Phys. Chem. Lett., 4 (2013) 2118

[5] K. Hayamizu, Y. Aihara, T. Watanabe, T. Yamada, S. Ito, N. Machida, Solid State Ion., DOI: 10.1016/j.ssi.2015.06.016
Mechanistic Illustration of Mononitriles Decomposition in Lithium Ambience Encompassing Development of a Dinitrile-Mononitrile Based Electrolyte System for Lithium Batteries
Authors: Rohan Rupesh , Li Chia-Chen , Lee Jyh-Tsung
Published: February 2020

In the quest of high voltage electrolytes for lithium batteries, we developed a dinitrile based   electrolyte, using mononitrile as a co-solvent with 1 M LiTFSI salt, which possesses electrochemical stability above 5.5 V under ambient conditions. It offers ionic conductivity in the order of 10−
3 Scm−
1 at 30 oC, analogous to the carbonate based electrolytes. However, the mononitriles, propionitrile and butyronitrile, decompose readily with lithium metal and form some dimers, trimer crystals and oligomers/polymers. These by-products are well characterized using NMR and single crystal XRD techniques, and a possible mechanism of the decomposition is demonstrated. To overcome the mononitrile decomposition, 5 wt % of vinylene carbonate is added to the glutronitrile/butyronitrile (6/4 ratio) electrolyte system, and several coin cells are fabricated with this electrolyte system using LiFePO4 cathode and Li metal anode. With capacity retention of more than 95%, the cells performs more than 100 cycles at 0.5 C charge/discharge rate and also found capable to perform upto 3C rate. The developed electrolyte system may pave way to use nitriles as the lithium battery electrolytes.

Figure 1
Electrochemical Investigation of Thermodynamic and Transport Phenomena in LP30 Electrolyte with Various Concentrations of Conducting Salt
Authors: Fröhlich Katja , Bimashofer Gesara , Fafilek Günter , Pichler Franz , Cifrain Martin , Trifonova Atanaska
Published: February 2020

The electrification of mobility has a strong potential to reduce fuel consumption and CO2emissions. This alternative to combustion engines, however, is hampered by battery systems still insufficient in terms of energy, power and lifetime. Therefore it is important to investigate and understand the electrochemical processes and mechanisms that can maximize the power-to-energy ratio. The electrolyte plays an important role for the efficient operation of the battery. For example, electrolytes with low lithium-ion transport numbers and salt diffusion coefficients cause large concentration polarizations during operation of Li-ion batteries. This leads to poor high-rate performance, unwanted side reactions and ageing. It is therefore important to characterize and model the transport phenomena in electrolytes under battery operation conditions.

There are numerous experimental methods that can be used to characterize the thermodynamic and transport phenomena in electro-diffusion processes (e.g. NMR, Raman spectroscopy, etc.), but the electrochemical methods are more powerful, as they can mirror the relevant working processes occurring in a battery.

In the presented work, the electrolyte characteristics such as viscosity, conductivity, diffusion coefficients of lithium ions and transfer numbers are determined for various LiFP6concentrations. Conductivity was measured by alternating current technique (PEIS and test cell with Pt-electrodes); the transfer numbers were obtained from the diffusion technique (concentration cell) and the diffusion coefficient was determined by the rotary disk electrode method and also calculated from conductivity measurements. Additionally, the temperature dependence of the studied properties was taken into account. The results were further used for the modelling of the mass transport processes in the real cell. The analysis of mass transport phenomena over a range of salt concentrations will be shown and discussed.

Acknowledgement

The authors would like to thank the Austrian Federal Ministry for Transport, Innovation and Technology (bmvit) and the Austrian Research Promotion Agency (FFG) for their financial support.
Interfacial Chemistry and Mechanics of Fluoroethylene Carbonate (FEC)-Derived Electrode/Electrolyte Interfaces
Authors: Shin Hosop , Park Jonghyun , Lu Wei
Published: February 2020

Fluoroethylene carbonate (FEC) has been commonly used as an electrolyte additive to improve the stability of the solid electrolyte interphase (SEI) at silicon and graphite-based anodes. Although the impact of FEC is well known, there is still lack of understanding how FEC has influence on interfacial chemistry and mechanics at the anode/electrolyte interface. In addition, relatively little attention has been paid to understanding of the effects of FEC on the cathode side.

In this work, we symmetrically investigated the effects of FEC on the graphite/electrolyte and LiMn2O4/electrolyte interfaces at room and elevated temperatures and revealed associated interfacial chemistry and mechanics at the interfaces, using various electrochemical and material characterizations.

We demonstrated that FEC has different effects on the interfacial behavior of the anode and the cathode. In the anode side, the SEI layer derived from FEC exhibited lower interfacial resistance and excellent thermal stability, showing excellent rate capability and improved cycle retention of cells. While the chemical and mechanical instability of the SEI layer were overcome by using FEC additive in the electrolyte, adverse effects of FEC on the cathode side were observed, especially at elevated temperatures. Poor cycling retention and a rapid increase in the interfacial resistance of the cathode were observed at elevated temperature. The poorer performance of the cathode in the FEC-containing cell at elevated temperature was attributed to the formation of a thicker surface layer and to increased Mn dissolution catalyzed by hydrofluoric acid (HF), which resulted from FEC dehydrofluorination initiated or accelerated by elevated temperature. Accordingly, it is suggested that the amount of FEC in a full cell must be optimized to minimize the adverse effects of FEC on cathode.

Based on this work, the necessity of evaluating the effects of the electrolyte additive used on the cathode side should be emphasized in order to further improve the thermal stability of Li-ion batteries.
In Situ Engineering of the Electrode-Electrolyte Interface for Stabilized over-Lithiated Cathodes
Authors: Lee Sehee
Published: February 2020

In the race to develop a >400 Wh/kg, <$200/kWh lithium-ion battery, the lithium-manganese-rich (LMR) oxide cathode has drawn much attention. Boasting a high voltage cycling operating window with capacities exceeding 250 mAh g-1, the LMR cathode was once considered the key to enabling a market-viable electric vehicle. Despite its major advantages and the potential for massive technological impact, worldwide research has struggled to enable the high-energy LMR material due to its signature drawbacks: oxygen evolution during initial cycling and the lowering of cell operating voltage over cycling life. In an attempt to alleviate oxygen evolution and mitigate phase transformation-induced voltage fade in the LMR material, myriad efforts have focused on surface modification, ion substitution or doping, and morphological control of particles and grains, all with limited success in enhancing long term cell energy retention. In this study we discuss a less common approach to enabling stable LMR cycling, developing a modified ionic liquid (IL) electrolyte capable of forming a favorable cathode-electrolyte interface (CEI). We present the long-term cycling of LMR half-cells in this unique electrolyte, demonstrating the highest degrees of voltage fade mitigation to-date with >70% energy retention in 950 cycles at C/2 rate (100% depth-of-discharge). We investigate the CEI formed on the LMR surface and demonstrate its unprecedented ability to stabilize the LMR crystal structure using a comprehensive suite of characterization methodology spanning XRD, Raman, XAS, XPS, simulation, TEM, and electrochemical testing. Coincidentally, the same modified IL electrolyte enables high performance of our previously published nano-wire silicon anode. The dual functionality of this electrolyte composition provides the opportunity to fabricate high-energy full-cell Li-ion batteries. Our study culminates in the demonstration of Si/LMR full-cells capable of retaining >90% energy over early cycling and 90.84% capacity over more than 750 cycles at the 1C rate (100% depth-of-discharge). While much work remains to enable a commercially viable Si/LMR battery, this study presents the effectiveness of an electrolyte-centric approach while at the same time shedding light on the critical electrolyte-electrode interplay that affects LMR cycling.
Electrolyte-Electrode Interactions and Interphases
Authors: Russell Selena M. , Cresce Arthur v. , Xu Kang
Published: February 2020

As batteries evolve toward higher cell voltage and capacity, developing detailed knowledge of the electrolyte-electrode interface is critically important. The chemical composition and morphology of interphases dictate not only the reversibility (cycle or calendar life), but also the kinetics of the cell chemistry (power density), and it has been well-recognized that the complicated interplay among electrolyte components (solvent, salt anion, additive) and electrode surfaces affect interphasial properties. Our efforts focus on designing new electrolytes to increase the electrochemical stability window. One way to reach that goal is to modify the SEI through electrolyte composition. To advance these efforts and understand the underlying chemistry at electrolyte-electrode interfaces, we perform in operando EC-AFM and in situ confocal Raman experiments, often supported by XPS and DFT studies.  With these techniques we investigate the dependence on electrolyte composition on SEI formation, composition, and morphology on graphitic anodes and the elusive interphase on graphitic and thin film LNMO cathodes. The results of such investigations aid in the design of electrolytes that advance lithium ion battery technology and expand beyond traditional lithium ion chemistry to emerging energy storage types such as sodium ion and aqueous systems, which interfaces we have begun to study. This presentation will provide an overview of electrolyte-electrode interactions we have studied and their influence on interphases.
Synergistic Sodiation of Cobalt Oxide Nanoparticles and Conductive Carbon Nanotubes (CNTs) for Sodium-Ion Battery
Authors: Li Qianqian , Wu Jinsong , Dravid Vinayak
Published: February 2020

Replacing lithium with sodium in batteries for energy storage is of enormous interest, especially from practical and economic considerations. However, it has proved difficult to achieve competitive figures of merit for sodium-ion batteries due to lack of detailed understanding of the reaction mechanism(s). Herein we report sodium electrochemical conversion reaction with Co3O4 nanoparticles decorated on carbon nanotubes (Co3O4/CNT) utilizing in-situ TEM, down to the atomic-scale. We observe synergetic effects of the two nanoscale components, which provide insights into a new sodiation mechanism, facilitated by Na-diffusion along CNT backbone and CNT-Co3O4 interfaces. A thin layer of amorphous low conductivity Na2O forms on the CNT surfaces at the beginning of sodiation. Conversion reaction results in the formation of ultrafine metallic Co nanoparticles and polycrystalline Na2O, and surprisingly fast diffusion of the reaction products. In the desodiation, the dissociation of Na2O and formation of Co3O4 due to the de-conversion reaction are observed.