bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Chemical, Mechanical and System-Level Approach to Lithium-Ion Cell and Battery Safety
Authors: Gitzendanner Rob , Puglia Frank , Moore Greg , Trebukhova Svetlana 
Published: February 2020

Lithium-ion cell and battery safety, or limitations thereof, have been hot-button topics for everyone in the energy storage industry for many years. Safety concerns have limited Lithium-ion adaptation in many large-format applications, most naval and undersea applications and several applications where the high energy density, long life characteristics, and many other advantages of the technology would have been mission-enabling. Safety is not a single-point problem, and addressing safety of electrical, chemical and mechanical systems such as batteries requires a semi-holistic approach to provide a meaningful advancement of system-level safety. In many applications, it is not a question of IF an abuse condition will occur, or IF a safety issue will arise, but WHEN; and thus, the need to know how to detect, manage and mitigate the effects of an uncontrolled release of energy in a highly energy dense system.
The Yardney Division of EaglePicher Technologies has looked at safety from multiple sides to address Lithium-ion safety. Recent work on improvements in the chemical safety, utilizing reduced flammability electrolytes, ionic liquid based electrolytes, and stable active materials will be presented; as well as test data in small and large format cells to demonstrate the effectivity of these enhancements in real-world applications. Mechanical and Thermal design aspects of both cells and batteries have been evaluated to develop designs that can manage the thermal load from a single cell thermal runaway event and prevent propagation to nearest neighbors in a battery pack. Similarly, system-level safety designs and approaches have been developed to mitigate the effects of an abuse event within the battery and control impact to exterior systems and personnel. All of these design enhancements have been tested in large-format cells and batteries, and results of these tests will be discussed.
Development of Novel Electrolyte Additives to Reduce Impedance of Lithium Ion Batteries
Authors: Milien Mickdy S , Lucht Brett L 
Published: February 2020

The reaction of non-aqueous electrolytes on the surface of the anode during the first few charging cycles results in the generation of a solid electrolyte interphase (SEI) which is critical to the performance of LIB’s, however lithium ion intercalation through the SEI and into the anode is one of the largest limitations for high rate performance. Electrolyte additives, which result in the generation of phosphate or sulfur rich SEI’s (as opposed to the carbonate rich SEI which results from the decomposition of electrolyte solvents such as EC), have been reported to reduce cell impedance and improve high rate performance. The novel organophosphorous additive, α, has been investigated as an anode-film forming additive, which decreases impedance. A comparative study of LiNi1/3Mn1/3Co1/3O2/Graphite cells with the standard electrolyte and the standard electrolyte with 0.1% (wt.) of added α was conducted in order to assay the effect of the additive on cycling behavior. Although incorporation of α does not significantly alter the cycling behavior at standard rates, cells containing α demonstrate improved capacity retention at elevated rates. Electrochemical impedance spectroscopy reveals that the improved rate performance of cells containing electrolyte with added α is the result of a significant decrease in charge transfer resistance on the anode. X-ray photoelectron spectroscopy reveals changes to the composition of the anode SEI upon incorporation of α, which is likely the source of improved first cycle efficiency and reduced impedance. Incorporation of α into a standard electrolyte formulation results in improved first cycle efficiency, improved rate performance, and decreased cell impedance on the graphitic anode.
Na1+XFexTi2-X(PO4)3/C (x = 0-1) Electrode Materials for Na-Ion Batteries
Authors: Lippens Pierre-Emmanuel , Sougrati Moulay Tahar , Difi Siham , Saadoune Ismael , Hakkou Rachid , Edstrom Kristina 
Published: February 2020

Lithium resources are unevenly distributed worldwide and might not meet the increasing global demand for energy. Rechargeable Na-ion batteries can be considered as a serious alternative due to the natural abundance and the low cost of sodium especially for electrical energy storage associated with the deployment of sustainable and renewable energy sources. In addition, aqueous electrolytes improves the safety of the batteries and are environmentally benign. Thus, there is an increasing interest in the research of new electrode materials that can be used in such systems. Transition metal phosphates with NASICON structure are good candidates due to their high ionic conductivity and the possibility of tuning the potential by selecting the transition metal. However, they present low electronic conductivity that require doping, nanostructuration or coating to improve electrochemical performances.
Na1+xFexTi2-x(PO4)3/C composites, with x=0-1, could be used as anode or cathode materials for Na-ion batteries since they exhibit three different potential plateaus at 4 V, 2.2 V and 0.4 V vs. Na+/Na0 depending on the amount of inserted Na+. These composite materials were obtained by solid state reaction with sucrose as carbon source for conductive coating and were characterized by different experimental and theoretical methods (Figure 1). The electrochemical mechanisms were identified from operando techniques, especially for the intermediate potential plateau at 2.2 V vs. Na+/Na0 that is related to changes in the oxidation states of both Ti and Fe. For example, the reduction of Fe3+ into Fe2+ was observed at the beginning of the discharge from 57Fe Mössbauer spectroscopy. High electrochemical performances were obtained at this potential including long cycle lifetime, high specific capacity and high power rate that are explained by the morphology of the particles, the carbon coating and the substitution of Fe for Ti (Figure 2).
Acknowledgments
Financial supports by Campus France (PHC Toubkal 008/SM/13), the Centre National de la Recherche Scientifique (CNRS, France), the Centre National de la Recherche Scientifique et Technique (CNRST, Maroc), the Institut de Recherche en Energie Solaire et en Energies Nouvelles (IRESEN, Maroc), the Swedish Research Council (contract 2012-3392) and StandUp for Energy (Sweden) are gratefully acknowledged.

Figure 1
Implementation of Monitoring Algorithms for the Battery Pack Optimal Design and Control in an Electric Vehicle
Authors: Makinejad Kamyar 
Published: February 2020

Battery monitoring algorithms and exclusively state of charge (SOC) estimation is the key function for successful operation of the battery management system (BMS). Enabling high storage utilization, safe operation environment for the battery pack and individual cells, cost reduction by avoiding over engineering, fault detection and lifetime enhancement are among all other benefits provided by monitoring algorithms. In this work, up-scaled dynamic voltage simulation and SOC estimator are described for the high power lithium ion cell (63Ah) used in parallel-series connection (2X108) to form the battery pack used in concept electric vehicle (EV) taxi ‘‘EVA‘‘ developed at TUM CREATE Singapore. Models are developed in offline platform with matlab/Simulink based on the aging experiments. Models are evaluated in realtime hardware in the loop (HIL) system and the interaction between HIL and experimental set up are described. Verified models are implemented on target microcontroller for small scale evaluation and BMS of the EV for large scale implementation in the final stage.
Each individual cell affects the overall performance of the pack, to deal with this, single cell SOC estimation within the battery pack is considered critical feature of the BMS. Battery pack is the most expensive component of the EV and conducting aging experiments on the pack is very expensive and requires specific laboratory equipment, hence extensive experimental tests are performed on the cells level at various controlled ambient temperature to simulate different conditions for the cells which they will go through in real application. These experimental tests are also used to create reliable reference data under controlled laboratory conditions, cell parameterization, diagnostics and aging studies on the cells among all.
Not all the cells in the battery pack are identical; external/internal influences lead to cell to cell discrepancies. These influences can be from slight manufacturing process differences, hot spots due to cell locations inside the pack, sudden failures among other influences causes different behavior between cells.
Weakest cell in the pack dictates the charging and discharging limits and safety level of the battery pack. This is due to the fact that the weak cell charges faster among other cells and reaches it critical voltage/temperature values before other cells being charged and discharges faster due to less capacity compared to other cell. This work demonstrates the simulation method to estimate the SOC for individual cell among the battery pack and the overall battery pack SOC considering the cell to cell variations, surface temperature differences and aging influences of the cell. This method leads to battery utilization of the high storage system and safe and reliable operation of the cells and is beneficial as well in cell balancing applications as it will be shown that these variations can be as high as 5-10% capacity difference between two cells in the battery pack.

Figure 1
A Fast, Efficient Discrete-Time Realization Algorithm for Reduced-Order Battery Models
Authors: Gopalakrishnan Krishnakumar , Zhang Teng , Offer Gregory James 
Published: February 2020

Research into reduced-order models (ROM) for lithium-ion batteries is motivated by need for a real-time embedded model with the accuracy of physics-based models but having computational simplicity comparable to that of equivalent-circuit models. An attractive approach to this problem was recently proposed by Lee et al [1] with a model order reduction method known as Discrete-time-Realization Algorithm (DRA). The ROM obtained in standard state-space representation could then be used to obtain the time-evolution of all the internal electrochemical quantities of the standard porous-electrode model. An unresolved issue of this reduced-order modelling approach is the high computation requirement associated with the DRA, which has to be performed multiple times to identify cell parameters at various SOC and temperatures.
In this presentation, we analyse the computational bottleneck in the existing DRA and propose a significant improvement to the overall modelling procedure. Our analysis indicates the Singular Value Decomposition of a large Block-Hankel matrix of the system’s Markov parameters is a key inefficient step for the overall high computational requirement of DRA. A fast computational approach is presented that significantly reduces both the memory and the floating-point operation count by bypassing the redundant step of forming the large Block-Hankel matrix. Comparisons with the existing DRA method highlight the significant reduction in computation time and memory usage (Figure 1), as well as the accuracy improvement in key electrochemical quantities, afforded by our new method. With the aid of the improved modelling procedure, the transfer functions forming the porous electrode model is reformulated and suitably combined to arrive at a physics-informed equivalent circuit model of the Panasonic NCA 18650 BD cells used in automotive applications.

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Copper Doped Cobalt Oxide As Efficient Catalyst for Li-O2 Battery
Authors: He Lewei , Zhang Wenqing , Wen Zhaoyin 
Published: February 2020

Rechargeable aprotic lithium-oxygen (Li-O2) batteries, owning a high theoretical energy density of , have received extraordinary attention for their potential applications in electric vehicles and energy storage.1 However, several challenges of the lithium-oxygen batteries are still perplexing the researchers and hindering the practical applications of Li-O2 batteries, which involve high overpotential, poor cyclic stability, weak power capability, low round-trip efficiency and so on. Hence, it is important and imperative to develop efficient cathode catalysts if a better Li-O2battery is required
Here, we show that copper doped cobalt oxide(CuxCo3-xO4) nanoneedles as efficient catalysts in Li-O2 batteries. This catalyst showed good catalytic activities in both ORR and OER that could reduce the recharge plateau to 3.9V versus Li/Li+. The synergistic effect of high electrocatalytical activity and large specific surface area ensures the improved cycle stability and enhanced capacity of Li-O2 batteries. Furthermore, we found that the catalytical activity of this catalyst was strengthened with more proportion of doped copper, which indicated that the mingle of copper promoted the performance of cobalt oxide as cathode catalyst. This study suggests that CuxCo3-xO4 nanoneedles could be used as a competent cathode catalyst in Li-O2 batteries, while we can control its catalytical activity by changing the amount of dopant. We expect that CuxCo3-xO4 nanoneedles are the promising candidate as the cathode catalyst to be used in practical Li-O2batteries.
Fig. 1. (a)Discharge and charge profiles of a Li-O2 battery containing 30% CuxCo3-xO4 in carbon matrix using TEGDME electrolyte with limited capacity of 1000 mAh/g at a constant current density of 100 mA/g; (b) Cyclability of the same cell shown in (a).

References

[1] Luntz, A. C., Bryan D. M. Chemical reviews. 2014, 114, 11721-11750.

[2] Shao Y, Park S, Xiao J, Zhang JG, Wang Y, Liu J. Acs Catalysis. 2012,2, 844-857

Figure 1
Voltage Variation of Lithium Transition Metal Oxides Caused by the Migration of Cations
Authors: Chen Zonghai , Li Yan , Qin Yan , Ren Yang , Amine Khalil 
Published: February 2020

In the past decade, major effort has been devoted to understanding the structure and the electrochemical benefit of lithium-rich transition metal oxides for high-energy density lithium-ion batteries because of their potentially high specific capacity of up to 250 mAh g-1 when the materials are electrochemically activated. However, a consensus has not been established yet on the local structure of this class of materials. It has been reported that the excess portion of lithium was homogeneously dissolved in the matrix of the transition metal layer (3b sites of space group 166 or R-3m), forming a solid solution. On the other hand, Thackeray and others believed that the excess lithium on 3b sites has a strong tendency to pair with manganese and segregate to form Li2MnO3 domains. Despite the discrepancy in these researchers’ findings on the local structure, both sides agreed that the excess lithium can be electrochemically activated at a potential above 4.5 V vs. Li+/Li to deliver more reversible specific capacity, offering great opportunity for use of these lithium-rich transition metal oxides as high-capacity cathode materials. However, the structural instability of the material after electrochemical activation causes a continuous decrease in its working potential, a phenomenon which we will call voltage fade, that hinders the commercial deployment of this class of high-capacity cathode materials. The migration mechanism of transition metal in the oxygen framework was investigated here to illustrate the voltage decay of lithium-rich transition metal oxides. For the first time, a voltage increase was observed during the cycling of a lithium manganese oxide spinel within a wide potential window. It was demonstrated that the voltage variation of these lithium transition metal oxides was caused by the continuous migration of transition metal ions, mostly Mn2+ and Co4+, between the octahedral and tetrahedral sites of oxygen framework, resulting in the ration change between the spinel component and layered component.

Figure 1
Fabrication of Li-Rich Cathodes with Enhanced Stability and Electrochemical Performances for Lithium Ion Battery
Authors: Li Liping , Li Guangshe 
Published: February 2020

Li-ion batteries, an ultimate rechargeable energy storage, play more and more important roles in modern people's life and activity. Developing energy storage equipments with high specific energy and stability that can work at very high charge-discharge rate is crucial for efficient use of energy at power-hungry laptops, cameras, mobile phones and electric cars. From the perspective of chemistry, these can be achieved by raising voltage window, controlling the structure transition during charge/discharge proces, and significantly improving the kinetics of lithium ions and electrons in electrode. Here, we will address the our recental finding for enhancing stability and electrochemical performances of Li-rich cathode materials, especially on (1) an simple methode to resolve kinetics problems of ultrafast charging-discharging Li-ion batteries by fabrication of layered LiMO2 (M=Mn, Co, Ni) hexagonal sheet exposing with facets {101}, (2) in situ potassium doping to stabilize the host layered structure by prohibiting the formation of spinel structure during cycling, and (3) optimizing the interactions between the components Li2MnO3 and LiMO2 in the Li-rich oxide (i.e. stabilizing the layered structure through Li2MnO3 and controlling Li2MnO3 activation through LiMO2).
References:
[1] Luo Dong, Li Guangshe, Fu Chaochao, Zheng Jing, Fan Jianming, Li Qi, Li Liping,
Adv. Energy Mater.
, 2014, 1400062
[2] Qi Li, Guangshe Li, Chaochao Fu, Dong Luo, Jianming Fan, Liping Li,
ACS Appl. Mater. Interfaces
, 2014, 6, 10330−10341
[3] Qi Li, Guangshe Li, Chaochao Fu, Dong Luo, Jianming Fan, Dongjiu Xie, Liping Li,
J. Mater. Chem. A
, 2015, DOI: 10.1039/c5ta00929d
[4] Qi Li, Guangshe Li, Chaochao Fu, Dong Luo, Jianming Fan, Jing Zheng, Dongjiu Xie, Liping Li,
Electrochim. Acta
154, 2015, 249–258
[5] Fu Chaochao, Li Guangshe, Luo Dong, Zheng Jing, Li Liping,
J. Mater. Chem. A
, 2014, 2, 1471-1483
[6] Luo Dong, Li Guangshe, Guan Xiangfeng, Yu Chuang, Zheng Jing, Zhang Xinhui, Li Liping,
J. Mater. Chem. A
, 2013, 1, 1220-1227
[7] Zhang Xinhui, Luo Dong, Li Guangshe, Zheng Jing, Yu Chuang, Guan Xiangfeng, Fu Chaochao, Li Liping,
J. Mater. Chem. A
, 2013, 1, 9721-9729J.F. Gieras, Permanent Magnet Motor Technology, 3rd ed., CRC: BocaRaton, 2010, pp. 68-73.
Nanoconfinement of Metal Hydride-Based Li-Ion Battery Anodes
Authors: Huen Priscilla , Jensen Torben René , Ravnsbaek Dorthe Bomholdt 
Published: February 2020

Metal hydrides as anode materials for Li-ion batteries are receiving increased attention due to the high theoretical capacities and low cost of many of these materials. Among conversion-type electrodes, metal hydrides have relatively high energy density and low polarization (ΔV ≈ 0.2 V) [1]. Similar to other conversion-type materials, the main challenges of metal hydrides are the large volume change and particle growth during operation, which leads to poor capacity retention.
Nanoconfinement, a bottom-up approach for preparing nano-sized materials, effectively limits the size of particles to the pore size of the nano-scaffold. In addition, nano-scale diffusion distances facilitate transport of Li-ions and enhance the kinetics of the conversion reactions.
In this study, we present the improved electrochemical performance of sodium aluminum hydride, NaAlH4 through nanoconfinement in mesoporous carbon scaffolds with different pore sizes. NaAlH4 has a theoretical capacity of 1985 mAh g-1. Although NaAlH4 is shown to be electrochemically active, large capacity fade is observed already during the first charge with a typical reversible capacity of only 30 % [2]. In contrast, nanoconfined NaAlH4 shows a 70 % recovery of capacity during the initial discharge-charge cycle.
We have investigated the reaction mechanism of the conversion reaction by operando synchrotron radiation powder X-ray diffraction (SR-PXD), and found important differences between nano-confined and non-confined samples. The mechanism and electrochemical performance are further investigated by detailed electroanalysis and conductivities of NaAlH4 electrodes are examined by electrochemical impedance spectroscopy (EIS). The electrochemical reactivity of empty carbon scaffold and its contribution to the battery performance will also be discussed.
This work is supported by European Marie Curie Actions under ECOSTORE grant agreement n° 607040.
References
[1] Y. Oumellal, A. Rougier, G. A. Nazri, J-M. Tarascon, L. Aymard, Nat. Mater., 2008, 7, 916.
[2] J. A. Teprovich, J. Zhang, H. Colón-Mercado, F. Cuevas, B. Peters, S. Greenway, R. Zidan, M. Latroche, J. Phys. Chem. C, 2015, 119, 4666.
(Invited) Tuning Molecular Singlet Fission – Strong Versus Weak Electronic Coupling
Authors: Guldi Dirk M. 
Published: February 2020

Innovative strategies are necessary to overcome the Shockley-Queisser limit, which places the maximum solar conversion efficiency for a single p-n junction to slightly more than 30%. One such strategy, singlet fission (SF), allows high energy, singlet excited state photons (S1) to be down-converted into up to twice as many low-energy, triplet excited state photons (T1). As such, SF is a fascinating many-electron problem from a physical chemistry perspective. In an optimal SF scenario, a chromophore in a singlet excited state (S1) interacts with a nearby ground state (S0) chromophore to yield up to two, non-interacting T1s. Doubling the number of excited states, thus, goes hand in hand with sacrificing half or more of the overall energy per excited state. The energetic requirement for SF is E(S1) ≥ 2(E(T1)), and the free reaction enthalpy for the S1 ® 2(T1) conversion governs the energy loss in SF. The SF rate depends on the free reaction energy and the electronic coupling matrix element between one chromophore in its S1 and another in its S0 ground state. A strict definition of the SF rate implies the formation rate of the two individual triplets (T1 + T1), not that of the correlated triplet pair, 1(T1T1). In (T1 + T1), the two triplets should have lost electronic coherence owing to interactions with the environment, but can retain spin coherence on much longer timescales. In a nutshell, electronic coupling between the chromophores should be sufficient to drive SF, while at the same time keeping the coupling sufficiently weak to allow spin decoherence leading to two independent triplet states.
The systematic variation / comprehensive understanding of electronic coupling between the individual pentacenes constitutes one of the grand challenges in the field of molecular SF, especially when experiments are conducted in solution. By means of tailoring the synthesis of pentacene dimers, trimers, and tetramers we will span our investigations from a weakly coupled, charge transfer to a strongly coupled, charge separated regime. In turn, we are confident to gain control over the rates and yields of intramolecular SF and, subsequent, inter- and intramolecular charge extraction. In particular, we plan to investigate pentacene materials, in which the energy of the charge transfer state and that of the charge separated state is tuned in the range around twice of the triplet excited state, and to explore the impact on the formation of pairs of independent triplets (T1 + T1).