bluuebunny/crossref_metadata_2025 huggingface dataset:
A Copper Plating Formula Development for through-Hole Filling without a Dimple on Top of the Hole Opening
Authors: Geng Hong-Jyun , Wen Shih-I , Dow Wei-Ping
Published: February 2020

In recent years, the butterfly technique (BFT1) was developed to achieve through-hole (TH) filling of a printed circuit board (PCB) by copper electroplating.1It not only can operate in direct current plating but also perform a void-free TH filling. However, a thick copper layer is plated on the surface of a PCB to cause a dimple issue on the TH opening. The dimple on the TH opening has to be leveled off, otherwise the following build-up process cannot be performed because there are a lot of dimples on the inner copper layer. In this work, we adjusted the plating formula to overcome the dimple issue of BFT for TH filling. The plating result shows that a thin copper layer plated on the PCB surface is obtained and the dimple is significantly improved. The enhancement in the TH copper filling performance is beneficial to the build-up process of advanced PCB. Keywords: Through-hole filling, Printed circuit board, Dimple, Copper Electroplating

 

 

Reference

W. P. Dow, H. H. Chen, M. Y. Yen, W. H. Chen, K. H. Hsu, P. Y. Chuang, H. Ishizuka, N. Sakagawa, R. Kimizuka, “Through-Hole Filling by Copper Electroplating”, Journal of The Electrochemical Society, 2008, 155, D750-D757.

Figure 1
Effect of Cu Diffusion on Electrical and Reliability Characteristics of Low Dielectric Constant Dielectrics
Authors: Cheng Yi-Lung , Zhuang Yao-Jia
Published: February 2020

The interaction between copper (Cu) interconnect and dense or porous low dielectric constant films (low-k) under thermal annealing was investigated in this study. A fabricated Metal-Oxide-Semiconductor (MOS; Cu/low-k/Si) capacitor was used to study the electrical and reliability characteristics of low-k films under Cu diffusion. The experimental results show that Cu diffusion depth increased with the annealing temperature and annealing time in both dense and porous low-k films. Moreover, the Cu diffusion rate in the porous low-k films is faster and is dominated by the annealing temperature, so that a large increase in the electrical properties was observed. Furthermore, the increase in the dielectric constant and the dielectric breakdown failure time were found to be proportional to the Cu diffusion depth for both dense and porous low-k films. Therefore, the Cu diffusion depth can be an indication for the fast reliability evaluation in the future Cu/low-k interconnects applications.
3D Printed Porous Dielectric Layers for Low Dielectric Applications
Authors: Oh Ji Young , Lee Kyu-Sung , Kim Kyung-Hyun , Yang Yong Suk , Lee Chang-Woo
Published: February 2020

3D printing is an additive manufacturing (AM) technique that constructs successive layers of materials to create three-dimensional architectures. Due to the possibility to build rapid prototypes in almost any geometry and internal structure, 3D printing has drawn much attention for development of advanced materials and equipment for a wide range of applications including biotechnology, microfluidics, aerospace, energy, and electronics.

Among the recently developed 3D printing applications, electronics fabricated by 3D printing are becoming increasingly attractive due to simple manufacturing process and more complicated 3D structures compared with electronics fabricated by traditional mechanical manufacturing process such as drilling and milling. In 3D printing electronics, material properties are directly related to performance of 3D designed electronics. Thus, it is important to develop good printable materials for 3D printing electronics such as high conductive material and low dielectric constant material. Especially, for the dielectrics, the low dielectric constant material can solve the electric drawbacks such as interconnection or signal delay for high performance devices. Introducing-porous structures into a polymer matrix is attractive approach to decreasing the dielectric constant by providing an architecture containing embedded air pockets (with a dielectric constant of 1).

In this work, we employed azodicarbonamide as a forming agent in 3D printable dielectric material to control the porosity of the dielectric film. The printed dielectric film was heated to 210 oC. As a result, a microporous structure was developed in the film and the morphologies was studied by SEM images. The details of the porous structures of our films, together with the dielectric properties of the 3D printed layer evaluated, will be presented at the session.

Acknowledgements: This work was supported by the National Research Council of Science & Technology (NST) grant by the Korea government (MSIP) (No. CRC-15-03-KIMM).
(Keynote) Solid Electrolytes and Metallic Lithium Anodes
Authors: Goodenough John B.
Published: February 2020

The development of oxide cathodes enabled the Li-ion rechargeable battery of the wireless revolution, but the extension to large-battery applications has been hampered by safety concerns and the assumption that it is not possible to plate an alkali-metal anode on charge without dendrite formation. The development of a glass from which metallic lithium or sodium can be plated without dendrites and that has a Li+ or Na+ conductivity greater than 10-2 S/cm at room temperature with an activation energy less than 0.1 eV for cation mobility offers a safe, long-cycle-life promise for large rechargeable alkali-metal batteries.
Controlled Deposition of Li Metal
Authors: Li Yejing , Wang Xuefeng , Wang Zhaoxiang , Chen Liquan
Published: February 2020

The increasing demand for higher density of energy storage requires breakthroughs in secondary battery techniques and systems. Metallic lithium (Li0) is attractive because it can be a common anode material for the lithium-sulfur (Li-S), lithium-oxygen (Li-O2 or Li-air) and all-solid lithium batteries due to its low electrode potential (-3.04 V vs. SHE) and high specific capacity (3860 mA h g-1) among the known anode materials. However, it is not viable in commercial secondary batteries at present because of its high activity towards the liquid electrolytes, and safety issues associated with the growth and fracture of Li dendrites during cycling. These issues have been obsessing the scientists and hindering the commercialization of secondary lithium batteries for decades.

Herein, controlled deposition of Li metal was realized on specially designed micro-/nano-architectured Si wafer and ZnO nanowires array, on the basis of preferential deposition of Li in the grooves of micro-patterned Ti foil, all showing the confining or guiding effect of the porous structure on Li metal deposition. The preferential deposition (and sometimes the growth) of lithium in the defected grooves of inactive Ti foil, in the micro-wells of active Si, and in the nanopores formed by bunches of active ZnO nanowires, indicate that the Li-storage activity of the material becomes less important in some particular cases but their appropriately designed micro- or nano-architectures become the dominating factor, to determine where the lithium will be deposited. These findings enrich our understanding on the intercalation and deposition properties of lithium and provide important revelations on effectively controlling the intercalation, deposition and growth of lithium, and suppressing the growth of lithium dendrites. The hetero-epitaxial growth of lithium on ZnO nanowires further demonstrates that the crystallographic structure of the electrode material can even affect the growth direction of the lithium nanowires.

We expect that the concept of designing micro-/nano-architectured electrodes be a promising strategy to tackle some of the obsessing issues of the Li metal anode and promote the commercialization of the secondary lithium batteries.

Acknowledgements

This work was financially supported by the National 973 Program of China (No. 2015CB251100).

Figure 1
Core-Shell Structure in Li-Battery Application: Phase Control and Electrochemical Property
Authors: Hu Linhua , Freeland John W , Cabana Jordi
Published: February 2020

Architectures based on core-shell structures have been employed in different approaches for materials design in order to tune physical characteristics and chemical function. In the case of batteries, using active cathode materials as core and non-active metal oxide shells is a prevailing strategy to decrease chemical degradation at electrode/electrolyte interfaces. The main challenge becomes to balance the need for high Li ion diffusion while enable electronic insulation to avoid secondary redox processes that degrade the electrolyte or induce the loss of the active transition metals into solution. Traditional synthetic methods based on high temperature treatments induce compositional inhomogeneity in core-shell structures due to excessive diffusion, resulting in difficulties to form uniform, yet ultrathin shells. Further, any synthetic strategy must enable the tuning of the chemical species in the surface inactive oxide shell is important to influence the protective function of the inner active oxide core.

Herein, we report a new strategy to synthesize well-defined LiCoO2 nanocrystals with ultrathin shells based on Al. Through variations in Al loading and post-synthetic treatment, the specific phase and durability were tailored. The progression between amorphous Al2O3 and LiAlxCo1-xO2 with temperature was evaluated by XRD and EDX line-scan analysis. Soft X-ray was used to probe the changes in chemical bonding both at the surface and bulk of the material. The electrochemical properties were found to vary depending on these compositional parameters. Compared to bare LiCoO2 nanocrystals, amorphous Al2O3 led to higher capacity and average stability, with LiAlxCo1-xO2 providing much higher stability but lower capacity. A tailored compromise between these two end situations will be discussed.
Olivine-Based Blends As Positive Electrodes for Lithium Batteries
Authors: Julien Christian M , Mauger Alain , Trottier Julie , Zaghib Karim , Hovington Pierre , Groult Henri
Published: February 2020

Blended cathode materials made by mixing LiFePO4 (LFP) with LiMnPO4 (LMP) or LiNi1/3Mn1/3Co1/3O2 (NMC) that exhibit either high specific energy and high rate capability were investigated. The layered blend LMP-LFP and the physically mixed blend NMC-LFP are evaluated in term of particle morphology and electrochemical performance. Results indicate that the LMP-LFP (66:33) blend has better discharge rate than the LiMn1-yFeyPO4 with the same composition (y=0.33) and NMC-LFP (70:30) delivers a remarkable stable capacity over 125 cycles. Finally, in situ voltage measurement methods were applied for the evaluation of the phase evolution of blended cathodes and gradual changes in cell behaviour upon cycling.
Enhancing Surface Diffusion in Battery Electrodes Using Solvent Adsorbates
Authors: Li Yiyang , Chen Hungru , Guan Zixuan , Attia Peter , Lim Jongwoo , Bazant Martin Z. , Islam M. Saiful , Chueh William C
Published: February 2020

LiFePO4 is one of the most well-studied positive electrode materials. A well-established doctrine is that Li only diffuses within one-dimensional channels, with negligible diffusivities in the other directions, and almost no movement of Li between channels. However, existing experimental measurements and density functional theory calculations have generally been conducted for bulk LiFePO4, and have largely neglected surface diffusion at the solid/liquid interface. In our work, we directly study the ambipolar Li diffusion along these nominally slow directions perpendicular to the fast conduction channels.

Because ambipolar transport of Li is controlled by the slow species, it is difficult to quantify using standard electrical measurements, which generally probe the fast species. To overcome this challenge, we measure the time for a solid solution Li0.5FePO4 electrode to separate into Li-rich and Li-poor phases. Because phase separation necessitates the movement of Li within a particle between the fast conduction channels, this technique directly provides the ambipolar transport of Li. Our results show that phase separation is extremely slow under dry, inert conditions. However, when placed in an organic solvent containing ethylene carbonate but no electrolyte salt, the rate of phase separation is enhanced by more than two order of magnitude. Because the ethylene carbonate only interacts with the surface of the LiFePO4 particles, the enhancement in Li transport demonstrate that surface diffusion is many orders of magnitude faster than bulk diffusion. Additionally, the rate of surface diffusion can be tuned by environmental adsorbates. We confirm our findings through density functional theory calculations, which show a significant reduction in migration enthalpy in the presence of a solvent adsorbate.

Our results show that surfaces diffusion enhances the conductivity of Li along the nominally slow directions by several orders of magnitude, and thus reduces the anisotropy of Li diffusion in LiFePO4. Additionally, by demonstrating that the conductivity can be tuned using environmental adsorbates, we offer a novel approach towards enhancing the conductivity of electrode materials. By choosing the correct adsorbates to activate surface diffusion, nominally insulating materials can be conductive at the solid/liquid interface. This introduces a new paradigm in interfacial engineering of electrodes, and could significantly expand the class of insulating materials which are suitable as electrodes in Li-ion batteries.
A Porous Silicon Anode Material Prepared By Chemical Etching for High-Performance Lithium-Ion Batteries
Authors: Sohn Myungbeom , Park Hyeong-Il , Lee Dong Geun , Kim Hansu
Published: February 2020

Lithium-ion batteries (LIBs) have played a critical role in the development of portable electronics and have gained a great deal of attention as power sources for emerging applications such as wearable devices, electric vehicles and robots. However, current LIBs reached technological limits for increasing their energy densities. In order to solve this, much research effort has been devoted to finding high capacity electrode materials to replace currently used materials such as graphite anode in LIBs. Although silicon-based materials are regarded as one of the most promising candidates for anodes because of their huge capacities, the huge volume expansion/contraction of Si during cycling lead to drastic capacity degradation. Recently, porous silicon materials have been revealed to accommodate the large volume change of Si, thus showing outstanding electrochemical performances. However, their use in LIBs suffers from the complicated and limited routes for their synthesis. In this presentation, we represent a porous Si material prepared by scalable and nontoxic chemical etching process as a high capacity lithium storage material for LIBs. This material synthesis concept presented herein represents a means of improving the electrochemical properties of porous Si anode materials for use in commercial LIBs.
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
Dual-Type Si Nanocrystals Embedded Si/SiO
x
Nanocomposites As a High Capacity Anode Material for Lithium-Ion Battery
Authors: Park Eunjun , Yoo Hyundong , Park Min-Sik , Kim Young-Jun , Kim Hansu
Published: February 2020

SiO
x
-based materials have gained much attention as high capacity materials for lithium-ion battery because of their good cycle performance. However, the commercial use is still limited by their low initial coulombic efficiency as well as complex synthetic method. In this work, we propose a dual-type Si nanocrystal-embedded SiO
x
nanocomposites using a cost-effective sol-gel reaction of SiO
x
precursor with commercial crystalline Si particles. This core shell structured high-capacity Li+ storage materials showed a reversible capacity of 1914 mAh g-1 with excellent cycle performance. The SiO
x
matrix would be helpful in accommodating the volume changes of Si nanoparticles core during cycling. To further improve electrochemical performance, we employed additional carbon coating on the surface of the dual-type silicon nanocrystal-embedded SiO
x
nanocomposites for sufficient electrical conductivity of active materials. The resulting carbon coated anode materials showed improved cycle performance with capacity retention of 80.3% after 100 cycles. The microstructure and electrochemical properties of the dual-type silicon nanocrystal-embedded SiO
x
nanocomposites will be discussed in more detail.
Nanostructured MoS2/Graphene Composite As Superior Anode Material for Li-Ion Batteries
Authors: Teng Yongqiang , Zhao Hailei , Zhang Zijia , Li Zhaolin , Xia Qing , Zhang Yang
Published: February 2020

To meet rising demands for energy density of lithium ion batteries (LIBs), a novel nanostructured MoS2/graphene (MoS2/G) composite with MoS2 nanoplates (NPs) perpendicularly grown on graphene sheets was prepared by a facile hydrothermal method. The direct coupling of edge Mo of MoS2 lattice with oxygen of functional groups from graphene oxide (forming C-O-Mo bond) is achieved by adjusting the synthesis parameters, which is beneficial to the electron transport and structural stability of MoS2/G electrode, and thus to the improvement of rate performance and long-cycle life of the electrode. The graphene sheets can enhance the electrical conductivity of the composite and meanwhile act not only as a substrate to disperse active MoS2 NPs homogeneously but also a cushion to accommodate the volume change during cycling. As an anode material for LIBs, MoS2/G manifests a high specific capacity (1077 mAh g-1 at 100 mA g-1 after 150 cycles), excellent rate capability and a stable cycling performance (907 mAh g-1 at 1000 mA g-1 after 400 cycles). The prepared MoS2/G composite is a promising anode material for next generation high performance LIBs.
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.
Capacity Fade Modeling of a Lithium Ion Cell with a Spinel-Based Cathode and an Artificial Graphite Anode
Authors: Appiah Williams Agyei , Park Joonam , Byun Seoungwoo , Kim Hee Joong , Kim Tae Shin , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

To enhance the understanding of capacity fade mechanism in lithium ion batteries consisting of a spinel-based cathode and an artificial graphite, an all-inclusive mathematical model describing the cycling performance of LiMn2O4/graphite lithium ion cell is developed in this work. The proposed model assumes the formation and dissolution of the solid electrolyte interphase (SEI) at the anode, Mn(II) dissolution of LiMn2O4 cathode active material due to Mn(III) disproportionation reaction and its effects on the SEI at the anode as well as the formation of SEI on the cathode. The decrease of Li ion diffusion coefficient in the cathode due to the formation of passive film and active material dissolution is added as a factor that results in capacity fade. Temperature effects on the capacity fade parameters and its kinetic reaction are incorporated in this model via an Arrhenius-type dependence of the rate constants and apparent diffusion coefficient. The developed model is incorporated into the Newman’s Porous Composite Electrode framework (PCE) and implemented in the battery module of COMSOL Multiphysics. The proposed model is used to study the effects of variations in temperature and voltage range of cycling on the capacity fade and changes in volume fraction of cathode active material, resistance in the cell and SEI thickness.

References

W. A. Appiah, J. Park, L. Van Khue, Y. Lee, J. Choi, M.-H. Ryou and Y. M. Lee, Electrochimica Acta, 187, 422 (2016)

S. Ramesh and B. Krishnamurthy, Journal of The Electrochemical Society, 162, A545 (2015)

L. Cai, Y. Dai, M. Nicholson, R. E. White, K. Jagannathan and G. Bhatia, Journal of Power Sources, 221, 191 (2013)

Acknowledgement

This work was supported by the Sebang Global Battery and the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977).
Structural Changes in Copper-Tin Alloy Anodes Observed with X-Ray Microtomography
Authors: Ausderau Logan , Buckley Joseph , Jibhakate Piyush , Xiao Xianghui , Nelson George J.
Published: February 2020

Tin intermetallic alloy anodes for Li-ion batteries present a route for incorporating the high capacity of tin while potentially mitigating the attendant volumetric expansion issues. While initial cycling performance of these alloy anodes is encouraging, significant capacity fade is observed as cycle number increases. In an effort to better understand the coupling of microstructural changes and electrochemical stimuli for intermetallic alloy anodes a combined electrochemical and 3D microstructural investigation was performed for Cu-Sn alloy anodes. The tin intermetallic alloy Cu6Sn5 was produced by pressing and sintering copper and tin powders mixed in stoichiometric proportions. The resulting pellet electrodes measured 13 mm in diameter by 1 mm thick. Using these pellets as the working electrode, half cells were assembled using Li foil as the counter electrode and LiPF6 in diethyl carbonate as the electrolyte. The half cells were tested in a galvanostatic configuration. Lithiation and cycling of the pellet electrodes were performed within two voltage windows: 0.2-1.5 V vs. Li/Li+ and 0-1.5 V vs. Li/Li+. It has been proposed that distinct reaction products are formed in these two voltage windows. In the higher voltage window a lithiated Cu-Sn phase is formed, while in the lower voltage window Sn is fully lithiated and Cu is expelled from the alloy phase. Distinct structural changes are expected to occur in these voltage windows, particularly due to the volume change that occurs on full lithiation of Sn. To test for these structural changes synchrotron-based x-ray microtomography was performed on samples extracted from the pellet electrodes. Applying microtomography at a resolution of 1.3 μm, imaging of the full sample cross-section was achieved. This permitted observation of affected and unaffected sample regions. Samples from lithiated, cycled, and pristine electrodes were imaged and compared. Significant structural changes were observed in the tested electrodes, particularly those lithiated and cycled in the window of 0-1.5 V vs. Li/Li+. In this window pulverization of the active electrode is clearly observed at the working electrode interface that was closest to counter electrode in the half cells. These observations appear to support structural evolution mechanisms proposed in the literature.
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).
Interconnected Ni Nanowire Scaffolds for Fast-Charging 3D Thin-Film Lithium-Ion Batteries
Authors: Zankowski Stanislaw Piotr , Vanpaemel Johannes , Vereecken Philippe M
Published: February 2020

The growing market of small consumer electronics, such as cell phones, smartwatches or electronic eyewear requires development of small power sources that allow for both satisfactory usage time and fast charging. Lithium-ion batteries (LIBs) are currently the systems of choice thanks to their high energy and power density. However, downscalling these batteries for small device applications still possess a big challenge. Due to electronically and ionically resistive nature of the active materials, mini-LIBs are currently made only in thin film technology, thus the total output energy and power density are still far too low for consumer device applications. Also, the manufacturing of thin film batteries requires sophisticated PVD/CVD deposition techniques. To overcome these issues, 3D architecturing of the current collector can be employed [1, 2]. This can provide a system where very thin active materials are stacked over enormously large surface area of a 3D current collector to yield a cell with both high power density (due to reduced materials thickness) and high energy density (thanks to large total volume of the active materials). Herein, we report reproducible fabrication of 3D-interconnected nickel nanowires (Fig. 1) prepared by electrodeposition of nickel into anodized aluminum oxide (AAO) template. The inter-branching of the wires provides rigidity of the structure, together with increase of the surface area of the current collector. The total surface area enhancement of the electrode was characterized by electrochemical passivation of the nickel nanowires and reached values up to 60x for 3 μm-long 3D nanoscaffolds. Additionally, we present results of electrodeposition of thin films of electrolytic manganese dioxide (EMD) on our 3D current collector and their activity as battery electrodes. This shows the potential of the 3D Ni-meshes for cheap fabrication of high power density electrodes for thin-film lithium-ion batteries.

J. F. M. Oudenhoven, L. Bagetto, P. H. L. Notten, Adv. Energy Mater., 2011, 1, p. 10-33.

J.Vanpaemel, A. M. Abd-Elnaiem, S. De Gendt, P. Vereecken, J. Phys. Chem. C, 2015, 119 (4), pp 2105-2112

Figure 1