bluuebunny/crossref_metadata_2025_split huggingface dataset:
Silicon Anodes Incorporating Few-Layer Graphene (FLG) for Improved Cyclability in Li-Ion Batteries
Authors: Huang Qianye , Loveridge Melanie , Wan Chaoying , Dashwood Richard , Bhagat Rohit 
Published: February 2020

Silicon remains a promising anode material for next generation lithium-ion batteries despite the well-documented issues associated with it, namely fast capacity fade and volume expansion. The element’s abundance and high capacity (3579mAh/g: almost 10 times higher than the capacity of graphite) has made it the focus of high profile global research for the last decade. However, the problems still facing Si-based battery commercialization are yet to be successfully overcome. To address this an optimized electrode composition and microstructure are considered as an effective approach. Several studies have been conducted towards hybrid silicon/graphene electrodes with promising results achieved[1], [2], [3]. However, most of these studies relied on synthetic routes to make silicon and graphene that relied on complicated chemical methods, such as electrophoretic deposition or chemical vapor deposition; neither of which are considered practical for large-scale manufacture.
In this study a matrix formulation of Si/FLG hybrid electrodes is used, manufactured with micron-sized silicon, using physical mixing methods that are employed in industrial electrode fabrication. A resulting formulation for a Si/FLG hybrid electrode will be described, which has achieved up to 1900mAh/g discharge capacity with 95% capacity retention after 200 cycles. Further characterisation has investigated the impact from graphene in terms of long-term electrochemical performance on an electrode formulated only with FLG as the active material. AC impedance and tensile property testing has also been performed, as the mechanical properties of graphene-containing electrodes has been minimally reported to date. This additional characterisation was included to indicate what exactly the graphene is contributing towards battery performance and to clarify the improvement of conductivity and flexibility with its incorporation.
[1] Ren, J.-G. et al. Silicon-Graphene Composite Anodes for High-Energy Lithium Batteries. Energy Technol. 1, 77–84 (2013).
[2] Chou, S.-L. et al. Enhanced reversible lithium storage in a nanosize silicon/graphene composite. Electrochem. commun. 12, 303–306 (2010).
[3] Zhang, Y. Q. et al. Silicon/graphene-sheet hybrid film as anode for lithium ion batteries. Electrochem. commun. 23, 17–20 (2012).

Figure 1
Characterization and Local Structure Analysis of Carbon Coated SiOx Using Confocal μ-Raman Microscope
Authors: Kim Jeonghan , Kang Byoungwoo 
Published: February 2020

High energy-density battery with reasonable cycle life is essential for large scale application. For this purpose, Si has attracted attention as a promising anode material. it has the highest theoretical capacity (Li22Si5, 4200mAh/g) and a low operating voltage compared to that of commercialized graphite anode material (LiC6, 372mAh/g).Unfortunately, in Si-based compounds a large volumetric change up to ~400% drastically decreases the specific capacity during charge/discharge.
To address the severe volumetric change, an alternative material, silicon monoxide (SiO
x
, x~1) has attracted a lot of attention because its unique microstructures can accommodate large volume change while maintaining a reasonable capacity. However, large 1st cycle irreversible capacity and still short cycle life are remained task. Though many researchers have studied reaction mechanism of SiOx to improve efficiency and cycle life, it is still challengeable. It is because SiOx has various structure models and is thermodynamically unstable at all temperatures. The structural complexity in metastable compounds draws various electrochemical properties even in the similar chemical formula.
We easily analyzed SiOx structures related with electrochemical properties, utilizing confocal μ-Raman spectroscopy. Two types of SiOx sample, SiOx and carbon(C)-coated SiOx were prepared to understand local microstructure of SiOx and its effects on electrochemical reactions. The bare SiOx showed inhomogeneous distribution of a-Si and c-Si in particles; some particles mainly had a-Si phase but other particles mainly consist of micro-sized Si phase. In contrast, C-coated SiOx is composed of a particle that had uniform microstructure such as nano-sized crystalline Si embedded in small amount of a-Si and a-SiO2 matrix. Even though the two samples had similar composition, quite different electrochemical properties were found out due to different local microstructure in SiOx. The C-coated SiOx achieved higher initial coulombic efficiency (ICE) and capacity retention compared to the bare SiOx. Therefore, the confocal μ-Raman spectroscopy helps to characterize local microstructure of the samples with amorphous and crystalline phases and relate the structures and its electrochemical behaviors.
Enhanced Rate Performance in Electrode Materials for Lithium-Ion Batteries
Authors: Billaud Juliette Marie , Bouville Florian , Magrini Tommaso , Villevieille Claire , Studart André 
Published: February 2020

Lithium-ion batteries are dominating the field of energy storage and have already started to enter the electric vehicle market. This market is striving for better electrochemical performance, such as higher specific energy and energy density, longer lifetime and improved safety. In order to fulfil these challenges, the exploration of new materials is usually preferred. Through this study we prove that electrode design using established anode chemistry is a powerful tool to enhance the performance of Li ion batteries.
One of the main limitations of current batteries lies in the transport of lithium ions, especially at high cycling rates and in high loading electrodes. This shortcoming does not arise from the insertion/extraction kinetics within the bulk active particles [1] but from the slow diffusion of lithium ions across the electrode. In particular, reduction of the tortuosity would accelerate such rate-limiting transfer process [2]. Minimising the ion and electron path tortuosity within thick electrodes would lead to batteries capable of sustaining higher cycling rates and power densities. We used a combination of electrochemical measurements, 3D imaging and diffusion modelling by Finite Element Analysis to study the charge carrier transport properties in architectured electrodes.
Through this presentation we will show that advanced electrode engineering can be used to greatly improve the electrochemical performance of anodes for lithium-ion batteries. Tortuosity of electrode materials is significantly decreased in favor of higher specific charges (up to three times) at high cycling rates.
References
[1] M. Heß and P. Novák, “Shrinking annuli mechanism and stage-dependent rate capability of thin-layer graphite electrodes for lithium-ion batteries,” Electrochim. Acta, vol. 106, pp. 149–158, 2013.
[2] M. Ebner, D. W. Chung, R. E. García, and V. Wood, “Tortuosity anisotropy in lithium-ion battery electrodes,” Adv. Energy Mater., vol. 4, no. 5, pp. 1–6, 2014.
The Effect of Upper Voltage Limits on Electrochemical Performance of Li-Rich Cathode for Lithium Ion Batteries
Authors: Cetintasoglu Mehmet Emre , Yuca Neslihan , Taskin Omer Suat , Dogdu Murat Ferhat , Avci Ipek 
Published: February 2020

The growing energy use of modern societies has created a major need for better approaches to not only the production and management of energy, but also its storage. As they have high energy density and cyclability lithium-ion batteries (LIBs) serve currently as the secondary rechargeable battery systems for portable devices and electric vehicles (EVs). However, there are weight and volume constraint for the LIB systems especially for vehicle applications due to the limited space and energy consumption. Energy density limitation of LIBs is the main drawback for successful commercialization of EVs because of its direct effect on the vehicle's driving range, so enhancing the negative and positive electrodes by increasing their capacities and operating voltage is the best approach to improve the electro chemical performance of LIBs.
Lithium rich layered oxides, which are solid solutions between layered Li[Li1/3Mn2/3]O2 (commonly designated as Li2MnO3) and layered Li[Mn1-y-zNiyCoz]O2, have been comprehensively studied as next generation cathode materials as they show much higher specific capacity (∼250 mAh/g) and operating voltage (>4.5) compared to the commercial cathodes.
One of the defining characteristics of lithium-rich layered oxides (LLOs) is that they exhibit a unique first charge profile. The first charge profile can be divided into two regions, the sloping (below 4.5 V) and plateau regions (above 4.5 V), depending on the mechanism of oxidation during lithium-ion extraction. However, increase in voltage results O2 release from Li2MnO3 structure in the form of LiO2. This mechanism is one of the crucial drawbacks for Li-rich cathodes that results in huge capacity fade during cycles because of the structural change that occurs in Li2MnO3 phase (at high voltages). Therefore, in this study, different upper voltage limits (4.2-4.8 V) are investigated for Li[Li0,2Mn0,54Ni0,13Co13]O2 in order to analyze and optimize the capacity retention.
Controlling the Shape of LiMPO4 and Li2MSiO4 By Supercritical Fluid for High Energy Density Li-Ion Battery
Authors: Truong Quang Duc , Devaraju Murukanahally Kempaiah , Honma Itaru 
Published: February 2020

LiMPO4 and Li2MSiO4 (M = Fe, Mn, Co, Ni) cathode materials holds promise for next-generation of lithium-ion batteries and future application in as hybrid electric vehicles or electric vehicles. In lithium intercalation compounds, the lithium diffusion along the channel is highly anisotropic which strongly depends on size and shape of the materials. Thus, controlling size and shape of cathode materials are crucial to improve the lithium intercalation rate and improve power density of the batteries. Here, we report a rapid, one-pot Supercritical Fluid process for the preparation of size, and morphology controlled LiMPO4 and Li2MSiO4 (M: Fe, Mn, Co, Ni) nanocrystals (Fig. 1) [1]. Various organic additives have been used to tailor the size, shape as well as surface functionality of the nanocrystals. Nanoparticles, nanoplates and their assembly into superlattices and microspheres has been obtained by SCFs. The effect of the nanocrystal morphology on the cathode performance was investigated in detail.

Fig. 1. TEM image of LiFePO4 nanosheets synthesized by supercritical fluid processing and schematic illustration of enhanced electrochemical performance.
[1] Q. D. Truong, M. K. Devaraju, T. Tomai and I. Honma, ACS Appl. Mater. Interfaces, 2013, 5 (20), 9926−9932; M. K. Devaraju, Q. D. Truong and I. Honma, RSC Adv., 2013, 3, 20633-20638; Q. D. Truong, M. K. Devaraju, Y. Ganbe, A. Tomai, I. Honma, Scientific Reports
, 2014, 4, 3975; Q. D. Truong, M. K. Devaraju, Y. Sasaki, H. Hyodo, T. Tomai, I. Honma, C
hemistry of Materials
, 2014, 26 (9), 2770−2773; M. K. Devaraju, Q. D. Truong, T. Tomai, I. Honma, RSC Advances
, 2014, 4 (52), 27452-27470; M. K. Devaraju, I. Honma, Jou
rnal of Materials Chemistry A, 2014, 2 (41), 17400-17407. Q. D. Truong, M. K. Devaraju, Y. Sasaki, H. Hyodo, I. Honma, Chemistry - A European Journal
, 2014, 20 (49), 16210-16215.

Figure 1
Black Li4Ti5O12 Anode Materials for High-Rate Li-Ion Batteries
Authors: Eom Ji-Yong , Han Dongwook , Yoo Seung-Eul 
Published: February 2020

Li4Ti5O12 (LTO) with a spinel structure has received much attention as the most promising alternative to the conventional graphite anode material of Li-ion batteries for hybrid electric vehicle, electric vehicle, and large-scale energy storage applications, due primarily to its advantageous material properties, such as enhanced safety, good capacity retention during cycling, and high power density. Also, LTO is a zero-strain insertion material, which has excellent Li+ insertion/extraction reversibility with no volume change. In spite of these advantages, LTO presents a relatively poor rate capability due to its low electrical conductivity and Li+ diffusion coefficient. Recently, the nanostructured LTO materials coated with carbon-based materials have been extensively studied in the hope of achieving further improvement in the rate capability due to both good electrical conductivity and short Li+ diffusion length. However, these nanomaterials present relatively low volumetric energy density and difficulty in the electrode coating process, and also high production cost. Therefore, it is very important to develop a novel method to achieve simultaneously the enhanced electrical conductivity and volumetric energy density of LTO material.
In this work, we suggest a facile method to achieve the improved electrochemical performance of LTO anode material composed of the micro-sized primary particles for high-power Li-ion batteries. The electrochemical performances of the micro-sized LTO particles, including the rate capability and cycling stability were significantly improved by hydrogenation. The hydrogenated LTO (denoted as H-LTO) particles were obtained by thermal annealing of the P-LTO (denoted as P-LTO) particles at 800 °C for 2~7 h in hydrogen atmosphere. Thermal annealing was performed in a quartz tube furnace filled with ultrahigh purity hydrogen gas. The H-LTO particles exhibited vastly superior the rate capability and capacity retention property during cycling to the P-LTO particles at high current density, since the insertion and extraction of Li+ through the H-LTO particles were preferable to those through the P-LTO particles, which were probably attributed to the short diffusion length for Li+, innumerable reaction sites, and relatively high electrical conductivity.
Formation of a Lithium-Plated Reference Electrode in Lithium-Ion Batteries: Characterization Using Dynamic Impedance and Simulation Using an Electrochemical Model
Authors: Wang Ziheng , Huang Jun , Li Zhe , Zhang Jianbo 
Published: February 2020

Reference electrodes (REs), enabling one to differentiate the contributions of each electrode, have been widely used in the research of electrochemical systems, such as lithium-ion batteries (LIBs). Metallic lithium or lithium alloy (Li-Sn, Li-Al) is the usual material of choice for REs in LIBs. A typical approach is to form a layer of metallic lithium onto a stable substrate by in-situ plating, termed as lithium-plating method [1][2]. In the present study, a copper-wire based RE is embedded into a 2 Ah laminated LIB, and its formation process, crucial to stability of the RE, is scrutinized. During the formation process, the RE is set as the working electrode, and the positive and negative electrodes are used as the counter electrode successively to obtain a both-side-plated RE. Dynamic electrochemical impedance spectroscopy (DEIS) is used as a characterization tool. Being dynamic means that the impedance measurements are performed while there is a DC current between the RE and the counter electrode [3][4].
Figure 1. (a) shows the evolution of DEIS during the whole formation process. It is revealed that a new semi-circle attributed to the emergence of the solid/electrolyte interphase (SEI) film manifests immediately at the moment the formation starts. Ohmic resistance, SEI film resistance and charge transfer resistance all gradually decrease during the formation process, and arrive at their constant values after 2×104s. In comparison with the potential monitoring, DEIS allows better characterization of the formation process with higher sensitivity and resolution.
To understand the above phenomena, a two-dimensional (2D) model, accounting for growth of the RE size and concomitant decrease of the electrolyte porosity [5], is developed. Figure. 1 (b) shows non-uniform current distribution during the plating process with the positive electrode as the counter electrode. As expected, the plating current concentrates on the positive-electrode-facing side. Consequently, a thicker lithium layer is deposited onto this side. Impedance simulation results are compared with the experimental DEIS results. Based on this model, a multistep plating strategy is optimized to improve the stability and durability of RE.

Key words

Reference electrode; Lithium plating; Electrochemical impedance spectroscopy; Electroplating model; Solid/electrolyte interphase

Reference:

[1]. D. P. Abraham, S. D. Poppen, A. N. Jansen, J. Liu and D. W. Dees, ELECTROCHIM ACTA, 49, 4763 (2004).
[2]. A. N. Jansen, D. W. Dees, D. P. Abraham, K. Amine and G. L. Henriksen, J POWER SOURCES, 174, 373 (2007).
[3]. J. Huang, J. Zhang, Z. Li, S. Song and N. Wu, ELECTROCHIM ACTA, 131, 228 (2014).
[4]. J. Huang, H. Ge, Z. Li and J. Zhang, ELECTROCHIM ACTA, 176, 311 (2015).
[5]. J. Newman and W. Tiedemann, J ELECTROCHEM SOC, 140, 1961 (1993).

Figure 1
Surface Morphology Treatment of Lithium Metal Anode for Dendrite Suppression
Authors: Park Joonam , Byun Seoungwoo , Appiah Williams Agyei , Jeong Jiseon , Lee Yunju , Cho Kuk Young , Lee Young-Gi , Ryou Myung-Hyun , Lee Yong Min 
Published: February 2020

To accomplish higher mileage targets of electric vehicles (EVs), lithium/air or lithium/sulfur batteries using lithium metal as an anode have attracted much attention owing to their high energy density. However, lithium metal has a major drawback, the so-called lithium dendrite which results in inhibited battery performance and instability. Hence, it is essential to generate effective technologies for suppressing lithium dendrite formation on the lithium metal surface. We have proposed dendrite-free lithium metals by using surface morphology treatment technology. This has advantages of not only simple process but also improved battery performance such as rate capability and cycle performance. This work is focused on developing a more well-designed and improved dendrite-free lithium metal anode for lithium metal secondary batteries. We adopted a mathematical model to optimise the metal surface morphology of different shapes by considering process technique of the treatment tool. To reflect the simulation results, the electrochemical performance of cells assembled with and without controlled lithium metal surface was experimentally conducted. Field-emission scanning electron microscope (FE-SEM, S-4800, Hitachi) was also used to confirm dendrite formation on lithium metal surface during charge and discharge.

References

1. J. Park, J. Jeong, Y. Lee , M. Oh, M. –H. Ryou, Y. M. Lee, Adv. Mater. Interfaces, 1600140 (2016)
2. M. -H. Ryou, Y. M. Lee, Y. Lee, M. Winter and P. Bieker, Adv. Funct. Mater, 25, 825-825 (2015)
3. A. Ferrese, P. Albertus, J. Christensen and J. Newman, Journal of The Electrochemicla Society, 159, A1615-A1623 (2012)
4. W. A. Appiah, J. Park, L. Van Khue, Y. Lee, J. Choi, M.-H. Ryou and Y. M. Lee, Electrochimica Acta, 187, 422 (2016)

Acknowledgements

This work was supported by the international Collaborative Energy Technology R&D Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No. 20158510050020).

Figure 1
Development of Cathode Materials of Lithium-Ion Secondary Batteries for High Energy and Safety
Authors: Lim Byung-Beom , Yoon Chong seung , Kim Sung-Jin , Lee Juhyon J. , Sun Yang-Kook 
Published: February 2020

As a consequence of shortage of fossil fuels, development of electrified vehicles (EVs) has further raised the performance requirements of rechargeable battery system. The research and development efforts in meeting these challenges have focused on identifying and designing new cathode materials with capacity higher than 200 mAh g −1 and improved safety characteristics. In order to improve the thermal and structural stability of the Ni-rich layered cathode materials, cathodes enriched in Mn at the outer layer were proposed to suppress the undesired Ni 4+ reduction because Mn 4+ is naturally stable (MnO2 is a stable compound) and does not participate in the redox reaction during the charge and discharge cycle.
Recently, we developed a high-energy cathode material with not only full concentration gradient materials but also two-sloped full concentration gradient materials, in which the Ni concentration decreases and the Mn concentration increases toward the particle surface. These cathode materials are synthesized via a specially designed batch-type reactor. The cathode delivers high discharge capacity with excellent capacity retention. The cathode materials exhibits the best cycling stability, rate capability, and thermal stability compared to conventional cathode (CC) and Li[Ni0.8Co0.15Al0.05]O2 (NCA). While the chemical partitioning of the composition generated the observed high capacity and thermal stability, the unique microstructure of the FCG secondary particle provided excellent cycle stability and rate capability.
Comparative Study on Evaluation Methods of Entropy Change of Electrochemical Reaction in Lithium-Ion Batteries
Authors: Saito Yoshiyasu , Kobayashi Hironori 
Published: February 2020

In electrochemical system such as lithium-ion battery (LIB), the entropy change of the electrochemical reaction, Δ
s, is one of important factors of heat generation or absorption during working. Without information of Δ
s, we cannot estimate thermal behavior of LIB accurately, and consequently it contributes to design the LIB itself and the total energy system using LIBs as safety devices.
The entropy change of the electrochemical reaction can be evaluated theoretically from the temperature dependence of the electromotive force (EMF) without calorimetric technique, and precision of voltage measurement is higher than that of calorimetry in general. However, in LIB, the compositions of both the positive and the negative electrodes gradually change during charge and discharge run because those electrode reactions are caused by insertion/extraction of lithium ions into/from the active electrode materials, and the open circuit voltage (OCV) of LIB also depends on the compositions of the electrode materials as well as the state of charge (SOC). In addition, some active materials show structural phase transition depending on the composition. Hence, SOC dependency should be considered for Δ
s of LIB.
In this study, we have evaluated Δ
s of some LIBs in the full range of SOC by OCV measurement, using a high-precision digital voltmeter combined with temperature control system of the sample batteries. Furthermore, calorimetric approach has been also performed to obtain Δ
s where it is important to remove the influence of the other heat generation factors such as the inner resistance of the batteries including the electrochemical polarization at the electrode interfaces. In the presentation, we will discuss the advantage and disadvantage of both OCV and calorimetric methods for measurement of Δ
s for LIBs.
Acknowledgement
This work was partly supported by the New Energy and Industrial Technology Development Organization (NEDO).