bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving High-Rate Performance of Nickel-Rich Cathode Active Materials for Fast Charging Rechargeable Lithium Batteries
Authors: Park Seong Jun , An Kihun , Song Seung-Wan
Published: July 2022

The needs of fast charging capability of high energy density Li-ion batteries are increasing to enable fast charge of battery-powered electric vehicles. However, not only lithium-plating event and sluggish diffusion kinetics of graphite anode but also limited diffusion kinetics of cathode hamper fast charging Li-ion batteries. Various approaches like surface coating of active materials, adopting new active materials, designing electrolytes and others are ongoing to improve high-rate performance of batteries. We have been developing a method to promote lithium diffusion kinetics of nickel-rich cathode active material through structural modification. In this presentation, we will report the effects of structural modification of NCM622 cathodes on the cycling performance under extremely fast charge conditions (4C~6C) and interfacial resistance change.

Acknowledgements

This research was supported by the National Research Foundation grant funded by the Ministry of Science, ICT and Future Planning (2019R1A2C1084024, 2020M3H4A3081874) of Korea.
(Invited) Nucleation and Growth of Small Atomic Aggregates into Superatom Nanoclusters
Authors: Nakajima Atsushi
Published: July 2022

One of the challenges in nucleation and growth of small atomic aggregates is to develop the novel research field of solid-state chemistry and material science using gas-phase-synthesized superatom nanoclusters. Among various superatoms, the greatest advantage of the central-atom-encapsulating binary superatoms, such as M@Si16, is that their electronic structures can be designed by optimizing the central metal atom M while retaining the geometrical symmetry of the Si16 cage [1], as shown in the figure below. We have systematically investigated the nucleation and growth of M@Si16 superatoms with gas-phase mass spectrometry, and then performed the surface immobilization of the M@Si16 cations and anions on a substrate monodispersively with the size-selective soft-landing. Initial products prepared via the surface immobilization of M@Si16 superatoms on solid surfaces decorated with monolayer films of C60 molecules were investigated using scanning tunneling microscopy (STM) [2] and X-ray photoelectron spectroscopy (XPS) [3]. Furthermore, we have developed a large-scale synthesis method for M@Si16 (M = Ti and Ta) by scaling up the clean dry-process with a high-power impulse magnetron sputtering (HiPIMS, nanojima®) [4] and by a direct liquid embedded trapping (DiLET) method [5]. The spectroscopic results reveal that the structures of soft-landed and isolated M@Si16 superatoms are the metal-encapsulating tetrahedral silicon-cage (METS) [5,6].

Furthermore, superatoms of group-5 metals (M = V, Nb, and Ta) encapsulating Si16 cage nanoclusters (M@Si16) can be efficiently generated to form assembled films [7]. Temperature-dependent current–voltage (I–V) characteristics of the M@Si16 assembled films revealed that the electrical conduction mechanism is not band transport, but hopping transport with Efros–Shklovskii variable range hopping for all central M atoms [8]. The results show that electrons involved in conduction are strongly correlated to localized electronic states.

[1] K. Koyasu, A. Nakajima, et al. J. Am. Chem. Soc. 127, 4998 (2005).

[2] M. Nakaya, A. Nakajima, et al. Nanoscale, 6, 14702 (2014).

[3] M. Shibuta, A. Nakajima, et al. J. Am. Chem. Soc. 137, 14015 (2015).

[4] C. H. Zhang, A. Nakajima, et al. J. Phys. Chem. A 117, 10211 (2013).

[5] H. Tsunoyama, A. Nakajima, et al. J. Phys. Chem. C 121, 20507 (2017).

[6] H. Tsunoyama, A. Nakajima, et al. Acc. Chem. Res. 51, 1735 (2018).

[7] M. Shibuta, A. Nakajima, et al. J. Phys. Chem. C, 124, 28108 (2020).

[8] T. Yokoyama, A. Nakajima, et al. J. Phys. Chem. C, 125, 18420 (2021).

Figure 1
(Keynote) An in Situ View of Nucleation and Coarsening at Solid-Electrolyte Interfaces
Authors: De Yoreo Jim , Chen Jiajun , De Yoreo Jim , Voictchovsky Kislon
Published: July 2022

Nucleation of crystalline films at liquid-solid interfaces is widespread in both natural and synthetic systems. Observing this process is challenging, because it is a consequence of unstable density fluctuations, making the structures and events that must be probed both transient in nature and small in extent. Thus, the application of high-speed, molecularly resolved AFM to systems that assemble on surfaces provides a powerful method to quantify the dynamics and extract the underlying physics. Here we illustrate the fundamental insights into the pathways and energetics of nucleation and self-assembly made possible by this method using results from two contrasting systems: gibbsite (Al(OH)3) films grown on muscovite mica (001) and 2D arrays of peptides that self-assemble on both MoS2 (0001) and graphite. The results on gibbsite show that a dynamic population of clusters is created by continuous attachment and detachment of adsorbed ions, consistent with the basic concept of classical nucleation theory (CNT). However, severe discrepancies emerge when the values of key thermodynamic parameters are extracted from the data. Comparison to kinetic Monte Carlo simulations shows that electrostatic interactions between positively charged aluminum hydroxide clusters and the negative surface potential of mica is the source of these discrepancies, modifying both the chemical potential of the accumulating ions and the edge tension of the clusters. These interactions stabilize a nanostructured surface mesophase, which evolves gradually via a process of cluster growth and coalescence not limited by formation of a critically sized nucleus. The results for peptides on MoS2 show that the high anisotropy of inter-peptide interactions drives 2D assembly to occur row-by-row, starting with 1D nuclei. In agreement with expectations of CNT, these 1D nuclei form without a free energy barrier and there is no critical size. However, on graphite, two new phenomena emerge. First, peptide rows become highly mobile, enabling to a molecular level form of growth by oriented attachment. Second, appearance of the final phase is preceded by formation of a metastable phase, which dissolves as the stable phase nucleates. This manifestation of Ostwald’s Rule of Stages cannot be rationalized with the usual thermodynamic arguments due to the barrier-free nature of 1D nucleation. Instead, we propose a rationale rooted in chemical kinetics and applied here to peptide dimer formation at the surface.
(Invited) Charge Attachment–Induced Transport: Toward New Paradigms in Solid State Electrochemistry
Authors: Weitzel Karl-Michael
Published: July 2022

Modern applications in solid state electrochemistry, e.g. in the field of energy storage and conversion, involve the transport of charge carriers through surfaces or interfaces as a key aspect. Many of the electrochemical concepts in fact originate from the field of liquid state electrochemistry. The transfer of concepts from the liquid to the solid state causes some problems which have been addressed in a recent review [1]. This contribution coveres some of the topics from ref. [1] e.g. (i) electrode potentials and half-cell potentials, (ii) charge carrier blocking and dielectric breakdown, and (iii) activities versus particle densities. Additional topics to be discussed are transfer of charge carriers across interfaces, work functions and electrodeposition.

Many of these topics can be addressed by the charge attachment–induced transport technique developed in the authors group. The discussion involves modifying some of the paradigms we became acquainted to in the liquid state.

[1] K.-M. Weitzel, Current opinion in electrochemistry, 26:100672, (2021)
(Digital Presentation) Small Angle X-Ray Scattering Studies Investigating the Degradation of Electrocatalysts
Authors: Arenz Matthias
Published: July 2022

In the presentation, the application of small angle X-ray scattering (SAXS) in the investigation of degradation phenomena for electrocatalysts is discussed based on recent examples from my work group. In contrast to local methods such as identical location (IL) microscopy1, SAXS probes a microscopic volume of a catalyst film providing representative data for the catalyst. Furthermore, the method can be coupled to operando measurements or to ex situ measurements in gas diffusion electrode setups2. It is demonstrated that the analysis of SAXS data leads to reliable information of change in mean particle size of the catalysts as function of the applied degradation protocol, however, that a proper measurement and control of a background is essential due to the concomitant degradation of the support material. Keeping this in mind SAXS can play a crucial role for not only elucidating and rationalizing degradation phenomena, but also for the testing of concepts for new electrocatalysts with improved stability.

Arenz, M. & Zana, A. Fuel cell catalyst degradation: Identical location electron microscopy and related methods. Nano Energy
29, 299–313 (2016).

Schröder, J. et al. A New Approach to Probe the Degradation of Fuel Cell Catalysts under Realistic Conditions: Combining Tests in a Gas Diffusion Electrode Setup with Small Angle X-ray Scattering. J. Electrochem. Soc.
167, 134515 (2020).
(Invited) The Impact of Interface Layer on Li Plating and Stripping Morphology
Authors: Qi Yue
Published: July 2022

Li metal is the preferred anode material for high energy Li batteries. However, a stable plating and stripping of Li metal at the anode−solid electrolyte interface (SEI) remains a significant challenge, particularly at practically feasible current densities. The formation of the SEI layer can significantly change the Li-nucleation density and growth morphology. With multiscale modeling, these factors can be investigated in more detail. Upon, lithiation, while a classical nucleation and growth model can describe the nucleation density of Li clusters and the charging rates in ultrahigh vacuum, a trace amount of reactive gas (oxygen for example) can change Li growth morphology. Reactive molecular dynamics simulations revealed that the fine balance between Li growth rate and the reaction rate of the thin lithium-oxide shell on the surface of the metallic Li can lead to Li nanowire formation. During delithiation, the accumulation of Li vacancies can lead to void generation and interface delamination. A DFT-informed kinetic Monte Carlo (KMC) model was developed to investigate the impact of the SEI layer, stack pressure, and alloying effects. The contact area is then incorporated into a 1D Newman battery model to simulate the impact of the contact area on the battery performance.
(Invited) Electrochemical Nucleation and Growth of Lithium Fluoride at Lithium Battery Interfaces
Authors: Gallant Betar M.
Published: July 2022

Lithium fluoride (LiF) is a commonly observed phase in many battery interfaces including at the solid-electrolyte interphase (SEI) of graphite and Li metal, and the cathode electrolyte interphase (CEI) of many high-voltage cathode materials in Li-ion batteries, given the battery field’s reliance on fluorinated salt anions and increasingly, on fluorinated solvents. For Li electrodeposition, LiF formation has been proposed to correlate with high Coulombic efficiency (CE) of Li plating/stripping, which still remains below 99.9%. Analytical methodologies to study LiF within the SEI have historically been limited, relying on techniques such as X-ray photoelectron spectroscopy that can detect presence of LiF and quantify bulk-average amounts, but lack spatial or morphological information. Meanwhile, the processes by which LiF nucleates and grows at battery interfaces, the morphology and properties of LiF particles formed in relevant battery electrolytes, and the relation to their properties and functionality remain poorly understood.

In this talk, I will present insights gained into the physicochemical properties and nucleation and growth behavior of electrochemically formed LiF under highly reducing conditions such as those found at Li anodes. We first studied a series of exemplar conversion reactions based on cathodic reduction of fluorine-rich carrier molecules (dissolved-gas or liquid solutions up to 5 M) that yield LiF upon reduction, with redox potentials ranging from 2–3 V vs. Li. The resulting particle size, morphology and crystallinity are highly sensitive to solvent donor number and discharge rate, evidencing a solution-mediated growth pathway involving supersaturation and precipitation of LiF crystallites onto a carbon or Cu substrate. The LiF growth modes are altered from cubic particles with large average particle sizes (> 1 µm) and sparse coverage in DMSO-based electrolytes to < 50 nm in carbonate- and ether-based electrolytes more relevant to battery applications. Next, we investigated how pre-nucleated LiF particles of varied morphologies and coverage influences Li plating on Cu current collectors. Nucleation overpotentials, Coulombic efficiencies as a function of plated/stripped capacity, and resulting Li deposition morphology are investigated to shed light on structural-electrochemical interplays relevant to those occurring at a Li metal interface.
Depolarization of Cu Electrodeposition in the Presence of Ag: A Cyclic-Voltammetry Study
Authors: Sun Yunkai , Shao Wenbo , Xu Yin , Zangari Giovanni
Published: July 2022

During our investigation of Cu-Ag alloy electrodeposition from acidic sulfate bath, peculiar behavior of Cu reduction was found in the CV profiles when the Cu deposition overpotential is very small. An early Cu(II) reduction peak, which is revealed to be a full reduction of Cu(II) to Cu(0) based on the EQCM-CV measurement, was observed in addition to the main Cu(II)/Cu(0) deposition peak. To our surprise, this early Cu deposition peak occurs when the deposition bath contains Ag(I) cations, or the substrate contains Ag metals.

EQCM-CV profile shows that the early Cu deposition peak is associated with a 65% deposition efficiency, slightly smaller than that of the main Cu(II)/Cu(0) reduction peak (~78%). The amount of Cu deposited associated with the early Cu reduction peak is estimated based on the total charge associated with this peak. The early Cu reduction peak is associated with Cu deposit thicker than 3 nm, with the thickness increases with decreasing scan rate or increasing Ag(I) concentration in the electrolyte. Meanwhile, from the CV profiles, the early Cu reduction peak is associated with a Tafel slope ~30mV/dec. We hypothesize that by the catalytic effect of Ag, either in the substrate or in the initial deposit, on the intermediate reduction step of Cu(II)/Cu(I) causes the early Cu reduction peak by shifting rate determining step of Cu(II)/Cu(0) deposition from Cu(II)/Cu(I) to Cu(I)/Cu(0).

Disclaimer:

This work has been submitted at Electrochimica Acta (manuscript id: EA21-4167RR1), with title "Depolarization of Cu electrodeposition in the presence of Ag: a cyclic-voltammetry study". Figure attached is chosen from this manuscript.

Figure. Cyclic voltammograms at electropolished Cu substrate from 0.3 M CuSO4 + 0.5 M H2SO4 (a) with or without 0.5 mM NaNO3, and (b) with 0-0.5 mM AgNO3.

Figure 1
The Distribution of Nucleation Activities: A New Local Perspective with Scanning Electrochemical Cell Microscopy
Authors: Torres Daniel , Bernal Lopez Miguel , Ustarroz Jon
Published: July 2022

Electrodeposition is a convenient strategy for the synthesis of functional nanostructures, for which electrochemical nucleation and growth (EN&G) processes need to be well understood [1]. As a heterogenous process, understanding the distribution of nucleation sites on a substrate is fundamental to relate the microscopic events to the macroscopic properties of the new deposit. In this work, we have explored the EN&G process on a glassy carbon substrate with a local electrochemical approach based on the Scanning Electrochemical Cell Microscopy (SECCM), using copper as a case of study [2]. Since the studies of EN&G are extremely sensitive to the state of the surface, the diversity of the nucleation process is revealed by performing hundreds of spatially resolved experiments on the heterogeneous surface of the glassy carbon [2,3]. The spatially-resolved characterization opens up the opportunity to correlate the electrochemical information to the local surface state, which can be modified with common surface pretreatments (i. e., polishing and preanodization). This unique perspective of the EN&G can help to deconvolute the individual contributions to the overall process, bringing forward information on nucleation sites that is unavailable with the conventional macroscopic approach.

[1] J. Ustarroz, Current atomic-level understanding of electrochemical nucleation and growth on low-energy surfaces, Curr. Opin. Electrochem. 19 (2020) 144–152.

[2] D.Torres, M. Bernal, J. Ustarroz, distribution of copper nucleation activities on glassy carbon: a new local perspective, to be submitted 2022

[3] M. Bernal, D. Torres, S. Semsari, M. Čeh, K. Žužek Rožman, S. Šturm, J. Ustarroz, Diversity matters: Influence of surface heterogeneities in the electrochemical nucleation and dissolution of Au nanoparticles, under revision.

Figure 1
(Digital Presentation) The Evolution of Composition and Morphology during the Initial Growth of Electrodeposited Ni-Fe Films
Authors: Lin Qiyuan , Zangari Giovanni
Published: July 2022

The anomalous codeposition of Ni-Fe tends to develop a composition gradient zone along the growth direction within the near-substrate region. Although it has been shown that such a composition gradient can be mitigated by the pulsed deposition method, a fundamental understanding of this behavior based on the anomalous codeposition mechanism has not been achieved yet. In this work, the evolution of the composition and the morphology during the (pulsed) electrodeposition of Ni-Fe films was reported. A theory based on the Fe deposition mechanism originally described by Bockris, Drazic, and Despic [1] was proposed and described in detail, which was used to rationalize not only the occurrence and the decline of the composition gradient, but also the opposite signs of the composition gradient observed under the potentiostatic mode and the pulse-reverse potential mode.

[1] O’M. Bockris, D. Drazic, A. R. Despic, The Electrode Kinetics of the Deposition and Dissolution of Iron, Electrochimica Acta 4, no. 2 (1961) 325–361.
A New TiO with in-Situ Transformed Rutile TiO2 Nanothorns As a Superb Anode Material for Lithium-Ion Battery
Authors: Kang Tong-Hyun , Lee Byong-June , Yu Jong-Sung
Published: July 2022

Developing high-performance anodes is highly desired to meet the recent ever-increasing demands for lithium-ion battery (LIB). Herein we report a uniquely integrated hybrid structure of rutile TiO2 (r-TiO2) nanothorns in situ grown over a new porous and conductive TiO core, which is generated from pyrolysis of anatase TiO2 with Mg metal at 650℃. The new hybrid exhibits superb LIB performance as an anode with high reversible capacity and almost no capacity decay during 1000 cycles at a high current density of 20 C (4000 mA g-1). Two independent reactions of intercalation and pseudocapacitive interaction are confirmed to occur in the composite of the r-TiO2 and TiO, respectively. In particular, the excellent rate capability along with long cycle life enables the new hybrid to have ultrafast charging of the system. Furthermore, the hybrid with the job-sharing property exhibits stable charge-discharge performance over a wider potential window range of 0.01 to 3.0 V, particularly even in the low potential range of 0.01~1.0 V, which usually causes irreversible Li-intercalation and rapid capacity decay for pristine TiO2. All the properties including the wider potential window allows the hybrid to realize the highest electrochemical performance that titanium oxides have ever achieved so far.
Elucidation of Discharge Mechanism in CFx As a High Energy Density Cathode Material for Lithium Primary Battery
Authors: Sayahpour Baharak , Bai Shuang , Cheng Diyi , Zhang Minghao , Li Weikang , Meng Ying Shirley
Published: July 2022

Fluorinated graphite (CF
x
) is a class of cathode materials with the high theoretical capacity (865 mAh g-1 in case of x=1) for primary (non-rechargeable) batteries. When using Li metal as the anode material, the system possesses a very low self-discharge rate (< 0.5% per year at 25 °C) compared to other current alternative chemistries. This system, with the proposed general governing reaction of CF
x
+Li→LiF+C, is one of the best candidates for a wide range of applications, such as implantable medical devices and equipment for extreme environment.

Although the lithium fluorinated graphite system has been under investigation for a few decades, there is still a lack of fundamental understanding of the reaction mechanism in this system. Here, a multiscale investigation on the CFx discharge mechanism was performed using a novel cathode structure to minimize the carbon and fluorine additives for precise cathode characterizations. Titration gas chromatography (TGC), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), cross-sectional focused ion beam (FIB), high-resolution transmission electron microscopy (HRTEM), and scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) were utilized to investigate this system.

The results demonstrated that: (i) There is no lithium deposition or intercalation through the entire discharge. (ii) The CFx structure transforms to a hard-carbon like structure with less sp2 content by increasing depth of discharge. (iii) The crystalline LiF particles uniformly covered the layers of CFx structure with a size range of < 10 nm. A three-step discharge reaction mechanism is proposed in agreement with our electrochemical performances. This work deepens the understanding of CFx as a high energy density cathode material and highlights the need for future investigations on primary battery materials to advance performance.

Figure 1
Synthesizing Microporous Carbon from Soybean and Use It to Develop Cathode Material for High Performance Lithium-Selenium Batteries
Authors: Ahmadian Hoseini Amir Hosein , Aboonasr Shiraz Mohammad Hossein , Tao Li , Arjmand Mohammad , Liu Jian
Published: July 2022

Selenium is considered as a promising cathode material for lithium-ion batteries due to its high electrical conductivity (10−3 S m−1) and volumetric capacity (3253 mA h cm−3). Though, feasibility of high-performance lithium-selenium (Li-Se) batteries depends on designing a cost-effective substrate for Se with desired porous structure. In this study, porous carbon was synthesized from soybean in a two-step carbonization/activation process and used as Se host to develop cathode for lithium-selenium (Li-Se) batteries. The activated carbon/selenium (C/Se) composites were prepared using a melt diffusion process at 260 ℃ inside an argon-filled autoclave. The cathode material consisted of C/Se composite, carbon black, and sodium alginate with a mass ratio of 8:1:1. The effect of activation temperature (500, 600, and 700 ℃) on the porous structure of activated carbon was investigated. It was revealed that both specific surface area and pore volume increased with activation temperature. Moreover, the carbon activated at 500 ℃ (C500) possessed mainly mesopores while the pore structure in the other carbon samples was microporous. The quality of Se impregnation in C/Se composites and their distinct electrochemical performance were correlated to the porous structure of the activated carbon. Using the carbon obtained at 600 ℃ (C600), the Li-Se coin cell exhibited a superior discharge capacity (664 mAh g-1 at 0.1C current density), rate capability, and long cycling stability at higher current densities. It was believed that the microporous feature of C600 along with high surface area and pore volume could favor effective confinement of Se, electrolyte wetting of the cathode, lithium-ion diffusion, and charge transfer, which resulted in better electrochemical performance. This work suggests the sustainable development of microporous carbon with a unique structure suitable for cathode material in Li-Se batteries.
(Invited) John B. Goodenough's Centenarian : Success Story of LiFePO4 (LFP) As Cathode Material for Rechargeable Lithium Batteries
Authors: Zaghib Karim , Trudeau Michel L. , Reddy M.V. , Mauger Alain , Julien Christian , Armand Michel
Published: July 2022

Lithium-ion and solid-state battery (SSB) are now playing a central role in consumer electronic, energy storage and electric vehicles thanks to their excellent cycle life and high energy density. One of the key components that have paved the way for this success story in the past 27 years is LiFePO4 (LFP) which has served as a lithium-ion host structure for the cathode electrode. Today only LFP is used in both commercial Li-ion and SSB batteries, due their safety, low cost (cobalt free), fast charge and discharge, and over 20 years of calendar life.

In this presentation, we will show the progress of the physical chemistry of the olivine compounds since the pioneering work of Prof. John B. Goodenough. This major improvement has positioned LiFePO4 as the active cathode element of a new generation of Li-ion batteries from cell to pack, hence making a breakthrough in the technology of energy storage and electric transportation. This achievement is the fruit of about 27 years of intensive research in the electrochemical community during which chemists, electrochemists, physicists, and engineers added their efforts to understand the properties of the material, to overcome the obstacles that were met on the way, and finally to reach the state of the art enabling its ubiquitous use in technology today and in the future.
Improving High-Nickel Cathode Active Material Performance in Lithium-Ion Batteries with Functionalized Binder Chemistry
Authors: Matts Ian L , Klementov Andrei , Sisco Scott , Kumar Kuldeep , Lee Se Ryeon
Published: July 2022

As the lithium-ion battery (LIB) market expands, driven mostly by the mass adoption of electric vehicles, LIB development is continually being pushed in the direction of higher energy density and lower cost. Both of these trends are leading to widespread development of LIB formulations using high-nickel cathode active materials, such as NMC811. In these materials, the high nickel content increases the amount of electrochemically accessible lithium in the cathode, increasing the cell energy density, while decreasing the amount of cobalt used, which decreases the cost of the cathode material. However, these materials also have drawbacks. First, NMC811 suffers from lower cycle life than higher-Co NMC materials such as NMC111 or NMC622. Second, NMC811 has poorer safety characteristics than lower energy density materials. Finally, NMC811 cathodes are known to experience gassing issues during cycling, which creates challenges in commercialization, especially for pouch cell battery designs.

Many approaches have been explored in the industry to address these shortcomings, including active material modification, electrolyte design, etc. In this presentation, binder functionalization will be presented as an alternative pathway to improve high-Ni cathode performance. LIB cathode binder is commonly high molecular weight PVDF, which provides good mechanical properties at low weight fractions as well as high electrochemical stability, but it is predominantly inert. Here, approaches of introducing novel binders tailored for high-Ni cathode systems will be discussed. Effectiveness of modifications, specifically their impact on LIB cycle life and safety, will be discussed.
(Digital Presentation) Synthesis and Properties of Llithium Iron Phosphate Cathode Materials without Carbon Coating with High-Rate Property
Authors: Nakamura Hitoshi
Published: July 2022

Lithium iron (ferrium) phosphate (LFP) use iron as a transition metal, so there is lower resource risk. And because of tolerant to overcharging, they have excellent safety and durability. Lithium-ion secondary batteries using LFP have become widely used as main power sources for EVs and ESSs in recent years. Originally, LFP has higher bulk resistance than other layered rock salt-based positive materials, so that carbon-coating was applied to surface of LFP particles. This idea was extremely effective in putting LFP into practical use. However, the use of the carbon coat has led disadvantage of high cost despite the use of cheaper iron because the manufacturing process increases. We report that we have developed LFP that has extremely high-rate charge and discharge performance even though it does not have carbon coating.

Figure 1
(Invited) Elucidating the Structure and Function of the Electrode-Electrolyte Interface By New Solid State NMR Approaches
Authors: Leskes Michal
Published: July 2022

The development of high-energy, long-lasting energy storage systems based on rechargeable batteries relies on our ability to control charge storage and degradation processes in the bulk of the electrode materials and at the electrode-electrolyte interface. NMR spectroscopy is exceptionally suited to follow the electrochemical and chemical processes in the bulk of the electrodes and electrolyte, providing atomic scale structural insight into the charge storage mechanisms and ion transport properties. However, interfacial properties, such as the processes governing charge transport between the electrode and the electrolyte, are much harder to study. These processes typically involve thin, heterogeneous and disordered layers that are formed chemically/electrochemically in the battery cell or artificially through coating the electrode material. While NMR is in principle an excellent approach for probing disordered phases, its low sensitivity presents an enormous challenge in the detection of interfacial processes.

In this talk I will describe recent approaches to overcome the sensitivity limitation by the use of Dynamic Nuclear Polarization (DNP). In DNP, the large electron spin polarization is used to boost the sensitivity of NMR spectroscopy by orders of magnitude. I will show how we can use this approach to detect the solid-electrolyte interphase (SEI), electrode coatings as well as the electrode’s bulk, with unprecedented sensitivity. Furthermore, I will present new approaches to probe ion transport properties of various interfaces. These allow us to get insight into the functional role of interfaces, which along with the chemical and structural insight, can provide design rules for beneficial interfaces, an essential aspect for developing long-lasting energy storage systems.
On the Study of Lithium Diffusivity in Lithium Nickel Manganese Cobalt Oxide Cathodes
Authors: Jaberi Ali , Trudeau Michel L. , Song Jun , Gauvin Raynald
Published: July 2022

Climate change, population growth, and rising fossil fuel prices have encouraged governments and scientists for alternate energy resources. This energy transition requires a high-performance energy storage device to satisfy the high energy and power demand and lithium-ion battery (LIB) is one of the promising one. The performance of these batteries ultimately relies on the properties of their components. In this regard, to meet the high-power demand in high-power applications (such as electric vehicles (EVs) and hybrid EVs), materials with rapid lithium transport are required. Lithium Nickel Manganese Cobalt Oxide (NMC) has attracted scientists’ attentions due to its outstanding performance as a cathode material. Therefore, understanding the effect of various factors on lithium diffusivity in NMC is critical to develop high-performance LIBs for high-power applications.

Electrochemical methods such as potentiostatic and galvanostatic intermittent titration techniques (PITT and GITT) have been frequently utilized to experimentally quantify lithium diffusivity in NMC. These techniques need the knowledge of electrode particle shape and dimension, and uncertainty about these parameters leads to substantial errors in predicting the diffusion coefficient. In addition, because these techniques consider the response of the whole electrochemical cell, it is hard to distinguish the effect of different structural factors on Li diffusivity in a single NMC active material. Therefore, an appropriate method still needs to be developed to capture the structural effects on lithium diffusivity in NMC. For this purpose, a multi-level modelling from Density Functional Theory (DFT) to kinetic Monte Carlo (KMC) should be implemented.

In this study, we will use DFT to find the ground state energy of NMC at different lithium concentrations and configurations. Also, the minimum energy path of lithium migration and the related activation barrier will be found by Climbing Image-Nudge Elastic Band (CI-NEB) method. Then by implementing the configurational dependent activation barrier into the KMC simulation, the lithium diffusivity will be studied. This atomistic simulation gives insight about the structural effects on lithium diffusivity in NMC to further develop this cathode material for high performance LIBs.
Impact of Laser Structuring and Calendering on Electrode Characteristics and Cell Performance of Li-Ion Battery Graphite Anodes
Authors: Hille Lucas , Schriever Charlotte , Zaeh Michael F.
Published: July 2022

The strong compression of electrode coatings is a common approach to enhance the volumetric energy density of Li-ion batteries (LIBs). However, it results in a deterioration of the charge and discharge performance due to an increase in the ionic resistance of the electrodes. This conflict can be addressed by microscopic ion diffusion channels in the electrode coatings, which reduce the ionic resistance and thus enhance the performance of a LIB.

In this study, the impact of laser micro structuring on different electrode properties was experimentally investigated for graphite anodes with varying initial porosities. All electrodes showed higher porosities after laser structuring, which can be attributed to an increase in the electrodes’ thicknesses and the removal of material. An equivalent circuit was fitted to the electrochemical impedance spectra of symmetric coin cells consisting of structured and pristine graphite anodes, respectively, to determine the ionic resistances, MacMullin numbers and tortuosities. The values were found to increase for decreasing initial porosities. Laser structuring significantly reduced the ionic resistances, MacMullin numbers and tortuosities of the electrodes in comparison to their pristine counterparts. Furthermore, the different graphite anode configurations were paired with NMC cathodes in coin cells and examined in a discharge rate test. At rates over 1 C, a significant increase in the discharge capacity through laser structuring was observed especially for cells with highly compressed anodes. Conclusively, this study empirically quantifies how laser structuring and calendaring influence different electrode characteristics of graphite anodes and the respective performance in LIBs.
Investigation of Manufacturing Strategies for Advanced Silicon/Graphite Composite Anodes for Lithium-Ion Cells
Authors: Meyer Alexandra , Lin Jin , Pfleging Wilhelm
Published: July 2022

Due to the advancing electrification in mobility, the production capacity of cells with high power and energy density needs to be increased, while a reduction in production costs is to be aspired. For the gravimetric energy density, 350 to 400 Wh/kg are defined as a goal from the European Union for the so-called cell generation 3b, which is to be achieved by approximately 2025. For this type of next generation lithium-ion batteries volumetric energy densities of about 750 Wh/L are targeted. For this purpose, novel anode materials with increased specific capacities have to be applied. Silicon is a promising candidate for this application, since it has a theoretical specific capacity of 3579 mAh/g at room temperature, which is one order of magnitude higher compared to the state-of-the-art graphite anode material (372 mAh/g). While silicon is lithiated, a volume change of about 280 % can be observed, which reduces the mechanical integrity of the electrodes and leads to a strong decrease in capacity and therefore a short cell lifetime. To overcome this issue, several approaches are pursued, whereof the most promising candidate to fulfil the requirements of scalability for industrial applications is the utilization of silicon nanoparticles. The establishment of a water-based slurry preparation process for silicon/graphite composite anodes with a fine dispersion of the silicon nanoparticles is crucial. Several manufacturing routes are investigated with special focus on the scalability, processability, spatial distribution of the binder, silicon and graphite active material as well as on the performance during galvanostatic cycling.

Fur this purpose, different binder configurations are applied, where the amount as well as the degree of polymerization and substitution of sodium carboxymethylcellulose (Na-CMC) and the content of styrene butadiene rubber (SBR) are of interest. Additionally, the destruction of the silicon nanoparticle agglomerates, which can only be achieved with high intensity impact realized by a ball mill, is separated from the whole mixing process. Therefore, the destruction of the graphite active material by the ball milling process is reduced. A dry mixing process of the graphite and the conductive carbon black is investigated as well.

The implementation of additional porosity with a laser patterning process was also proven to be effective to increase the cell lifetime of silicon/graphite composite electrodes. Therefore, an ultra-short pulsed laser source is applied to generate line patterns in the composite material. This significantly improves the wetting of the electrode with liquid electrolyte, but also reduces the mechanical stress inside the electrode due to the increased artificial porosity available for volume expansion which finally leads to an immense impact on cell lifetime.
Dry Particle Fusion Assisted Ceramic Coatings for High Nickel Cathode for Scalable 18650 Lithium-Ion Batteries
Authors: Sawangphruk Montree , Srimanon Krisara
Published: July 2022

Over the last several decades, energy storage has become one of the central tools for facilitating energy transformation from (electro)chemical reactions to electricity. Rechargeable lithium-ion batteries (LIBs) are among the most popular and promising mature technologies for portable electronics, grids, and transportation. The cathode, a working horse, mainly determines the overall capacity among the various components. Off-late layered Li-rich or Ni-rich material plays a vital role, especially Ni-rich LiNixMnyCo1-x-yO2; x ≥ 0.8 (NMC) get significant attention. However, it is unfortunate that such Ni-rich cathode materials encountered severe capacity degradation and poor thermal instability concerning the Ni-concentration. Several strategies have already been proposed to mitigate those issues, including electrolyte additive, cation doping, and coating or surface modification. Among them, the modification of the cathode surface, like core-shell construction, is a practical approach. Herein, a core-shell architecture was achieved by employing the cost-effective dry particle fusion method over Ni-rich (LiNi0.8Mn0.1Co0.1O2 (NMC811), where the nano aluminum oxide was used as a shell material with an average thickness of 150-200 nm. Such NMC@alumina core-shell exhibits excellent cycling stability compared with pristine NMC811. The chemical lithium diffusion coefficient was calculated using galvanostatic (GITT) and the potentio-dynamics process. Additionally, the control of parasitic reaction between the delithiated cathode and electrolyte was analyzed using the in-situ Differential Electrochemical Mass Spectrometry (DEMs) technique, where the onset potential and the amount of gas generated are compared with pristine material.
Graphene Wrapped Siox/C Hollow Spheres Composites Via Molecular Polymerization As High Performance Libs Anodes
Authors: Guan Xiang , Kinloch Ian , Bissett Mark
Published: July 2022

High-capacity silicon anodes have attracted researchers’ tremendous interest for next generation lithium-ion batteries (LIBs). However, its further application is limited by the large volume expansion during cycling, causing safety issues. Designing nanostructured silicon is an effective strategy to acquire high-performance anodes, but it will face problems of high cost and poor coulombic efficiency. Silicon dioxide and SiOx show relatively higher specific capacity and lower volume expansion than silicon anodes. So, they are now becoming popular among researchers. Structure design of silicon oxide composite is one of the main experimental schemes, like hollow structures. Within the composite materials, graphene becomes one of the main conductive composite matrixes which is ascribed to its superior conductivity and mechanical property since its application in energy storage areas. Hence, SiOx/C composites have been synthesized with carbon and SiOx dispersed uniformly via a simple template-free aldimine condensation between APTMS and dialdehyde. After freeze drying and pyrolysis, the hollow structure can be obtained, in which silicon oxide is derived from APTMS and carbon is derived from carbon chains from dialdehyde. The hollow structure can effectively buffer the volume expansion of silicon oxide during charging and discharging process. Then the hollow particles are wrapped by electrochemical exfoliated graphene. Optimal graphene contents and graphene layers in the composite will be determined to explore its application in LIBs. The introducing of graphene may suppress the volume expansion and improve the conductivity of composites at the same time. Various characterization methods will be conducted to confirm its electrochemical performance and find its potential as anode materials.

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(Digital Presentation) Synthesis and Characterization of Au-Doped TiO2
Authors: Rasouli Milad
Published: July 2022

We used a three-step anodization procedure to produce titanium oxide (TiO2) nanotubes in order to investigate the effects of varied electrolyte concentrations and anodization voltages on optical characteristics. Different electrolyte solution concentrations and anodization voltages altered wall thicknesses and tube diameters, according to our observations from the XRD pattern, TEM pictures, and optical examinations. While the band gap and band edge values of TiO2 nanotubes altered with different anodization voltages, the band gap, and band edge values remained constant. Furthermore, we discovered that at various electrolyte solution concentrations, the optimum solution concentration for growing compact TiO2 nanotubes is 70 percent porosity. Various morphologies of TiO2 nanostructures, such as sheet, rod, and tube, were obtained in the next section of the study by modifying the experimental settings (e.g., growth methods, differently used gases, and process temperatures). Titanium dioxide (TiO2) nanosheets, nanorods, and nanotubes were created utilizing anodizing methods and chemical vapor deposition (CVD). TiO2 nanorods were synthesized on treated Ti foil with HCl by CVD after TiO2 nanosheets coated with Au catalyst were grown in CVD. TiO2 nanotubes are then manufactured using a three-step anodization method. We found that produced nanostructures can be used for a variety of applications due to compatibility changes in morphological, structural, and optical properties.
(Digital Presentation) An Electrochemical-Thermal Coupled Thermal Runaway Multiphysics Model for Lithium Polymer Battery
Authors: Domalanta Marcel Roy , del Rosario Julie Anne
Published: July 2022

With the rising energy demand, safe and efficient energy storage technologies have been increasing in importance. Lithium-ion batteries (LIBs) have been dynamically prevalent as energy storage and power sources for various electrical systems, from communication purposes to transportation applications. Lithium Polymer (LiPo) batteries are a subcategory of LIBs that use a solid or semisolid (gel) polymer to act as both a separator and electrolyte for the system. Compared to a conventional liquid electrolyte, gel polymer electrolyte is more thermally and electrochemically stable and relatively safer. Various companies produce a vast number of different LiPo batteries; however, a limited number of studies have been conducted concerning modeling and simulation. Besides exploring new materials for performance enhancement, engineering a reliable model is equally vital to exploit and optimize existing LiPo batteries' potential.

In this study, a multiphysics model for a mobile Lithium Cobalt Oxide (LCO)-graphite- Poly(vinylidene fluoride - hexafluoropropylene) (PVdF-HFP) pouch LiPo battery was established to characterize the battery's behavior. The pseudo-2-dimensional electrochemical model and 3D thermal-thermal runaway model were coupled with temperature and heat generation variables. Working voltage and temperature during galvanostatic discharge were examined for the electrochemical-thermal model. In contrast, temperature as a function of time during an oven test was analyzed for thermal runaway models. The electrochemical-thermal and thermal runaway behavior was investigated using the simulation model, and validations were compared with experimental data. Overall, the models can be employed as a design tool to evaluate the component design and estimate the system performance of LiPo batteries for commercial applications.

KEYWORDS: Multiphysics model, Lithium-polymer battery, Thermal runaway
The Asymmetric Charge-Discharge Kinetics in Li1-XNi1+XO2 from First Principles
Authors: Xiao Penghao
Published: July 2022

The ever-increasing demand on Li-ion batteries requires the cathode materials to be inexpensive and environmentally friendly. LiNiO2 is such a promising Co-free cathode. However, the presence of Ni in the Li layer (NiLi) becomes more common in LiNiO2 than its cousin layered compounds, which limits its electrochemical performance. These excess Ni might randomly distribute in the bulk due to Li deficiency in synthesis, or/and form a surface densified phase due to oxygen loss in cycling. This study combines density functional theory (DFT), cluster expansion and kinetic Monte Carlo (KMC) simulations to identify the effects of these defects on Li transport. Both types of NiLi were found to impede Li transport at the end of charge and discharge, but not at the beginning. This asymmetry kinetics cannot be solely explained by the Li diffusivity as a function of Li contents but stems from the phase boundary between Li orderings. NiLi from synthesis smooths the voltage plateaus and contributes to the 1st cycle capacity loss. NiLi from degradation hinders Li transport more severely when the densified phase fully covers the particle surface. Interestingly, during charge the surface phase traps the last 25% Li for an extremely long time but shows little impedance when Li%>25%.

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