bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lithium Plating–a Life-Limiting and Safety Issue in a Li-Ion Cell
Authors: Ratnakumar Bugga V. , Smart Marshall C. , Jones John-Paul , Krause Frederick C. 
Published: February 2020

Despite their advances and widespread use in various applications for the last two decades, Li-ion batteries continue to exhibit occasional failures from Li plating on the anode. Li plating can have immediate effects on performance and more devastating effects upon the safety, if the Li plating occurs in a dendritic form that could pierce through the separator causing an internal short. Even in a benign form, plated Li—lacking the protective SEI that protects the carbon anode —tends to react with electrolyte which results in a rapid growth in interfacial impedance and capacity loss during cycling. Li plating will manifest whenever intercalation kinetics (into carbon) are slower compared to lithium plating over carbon, despite the lower reversible potential of the latter. Poor cell design factors, i.e., improper matching of anode and cathode in terms of electrochemical capacities and geometric aspects with localized hotspots in current distribution, and inappropriate electrolyte, can cause Li plating on the anode. The nature of the anode, electrolyte and SEI are among the most important factors that can influence Li plating.1

Apart from the design/chemical abnormalities, lithium plating is also triggered by the operational conditions, such as fast charge rates and low operating temperatures relevant to planetary space missions. In our earlier study, we have demonstrated that the choice of the electrolyte is critical in determining the propensity towards lithium plating.2 Specifically, these studies indicate that the Li intercalation kinetics are mainly dictated by the anode surface films (SEI), which in turn could be controlled by a judicious selection of electrolyte solution, i.e., both solvent and salt. We have established a correlation between the poor lithium intercalation kinetics and the propensity towards lithium plating using different electrolytes with different solvent blends and different electrolyte additives.
Recently, Li plating was observed in cells upon extended cycling at ambient temperature in a Low Earth Orbit (LEO) satellite simulation condition, involving 30 minutes of discharge and 60 minutes of charge continuously, possibly due to impeded intercalation kinetics at the anode. Likewise, exposure to high intensity radiation environments may have led to Li plating in prototype 18650 cells upon subsequent cycling. In this paper, we will discuss the Li plating phenomenon in these specific examples, and with reference to anode/cathode interfacial kinetics at low temperatures in different electrolytes.
ACKNOWLEDGEMENT
The work described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA).
REFERENCES

B. V. Ratnakumar and M. C. Smart, ECS Trans. 25 (36), 241 (2010).

M. C. Smart and B. V. Ratnakumar, J. Electrochem. Soc.
2011, 158 (4), A379.
Degradation Mechanism of Ni-Rich Layered Cathode Materials during High Voltage Cycling Revealed By Multi-Model Synchrotron X-Ray Imaging and Spectroscopy Techniques
Authors: Shadike Zulipiya , Bak Seong-Min , Hu Enyuan , Lin Ruoqian , Lee Hung-Sui , Yang Xiao-Qing 
Published: February 2020

Ni-rich layered cathode materials are important candidates for lithium-ion batteries used for high energy density applications, such as electric vehicles. However, these materials are suffering severe capacity fade caused by surface reconstruction, unstable cathode-electrolyte interface (CEI) formation and micro crack formation during cycling, especially when a high cut off charge voltage is applied (such as 4.6 and 4.8V). To understand the origin of this capacity fade, state-of-the-art diagnostic tools are applied to understand their structure, chemical and morphological properties of LiNi0.94Co0.06O2 (NC) and LiNi0.92Co0.06Al0.02O2 (NCA) cathode materials during cycling. Electrochemical measurement results show that the NCA cathode delivered higher capacity and stable cyclic performance even cycled at a high cut of voltage of 4.8V. In situ X-ray absorption spectroscopy (XAS) results of NC and NCA electrodes measured during the first and 51st charge/discharge cycling between the voltage range of 2.8-4.4V showed that both Ni and Co contribute to the capacity by going through the Ni3+/Ni4+ and Co3+/Co4+ redox couples. The Ni-K edge XAS spectra of NC cathode charged to 4.8V showed slightly reduction of Ni4+ during the high voltage charging. While, XAS spectra of NCA cathode did not showed reduction of Ni4+ when the cell charged to the higher voltage. More interestingly, C, F, O, Ni and Co soft XAS spectroscopy of NC and NCA electrodes at the different state of charge provided more comprehensive insight into surface and bulk chemical properties. The results showed that much thicker CEI layer formed on the NC surface compared with the NCA cathode, indicated that Al-doping effectively reduced the side reaction of cathode materials with the electrolyte. We have also compared the morphological and chemical evolution of NC and NCA secondary particles using full-filed in-situ transmission X-ray microscopy (TXM) during the initial cycle. Results will be presented at the meeting.
Acknowledgement
This project was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies through Advanced Battery Material Research (BMR) program (Battery500 consortium) under Contract No. DESC0012704.
Stability and Functionality for PEDOT-Coated LiFeSO4F
Authors: Gustafsson Torbjörn , Blidberg Andreas , Björefors Fredrik , Alfredsson Maria , Tengstedt Carl , Valvo Mario 
Published: February 2020

LiFeSO4F can be synthesised in two different polymorphs, tavorite- and triplite-type, depending on the synthesis conditions1. We have used a solvothermal route to synthesise the tavorite-type, which offers a decent energy storage capacity with an open crystal framework providing fast solid-state Li-ion transport2. It’s functionality is strongly affected by surface modification. It shows minimal polarization during electrochemical cycling when coated with p-doped PEDOT3. This coating alleviates a kinetic barrier for its lithium insertion/extraction reactions4. The redox activity of this material has been studied with S and Fe K-edge X-ray Absorption Near Edge Spectroscopy (XANES) together with Raman and 57Fe Mössbauer spectroscopies. The results indicated a stable p-doping of the PEDOT coating in the entire potential window for the electrochemical cycling. The iron-ligand electronic interaction increased during delithiation.
Fig. 1. Linear combination fit of S K-edge XANES spectrum for LiFeSO4F-PEDOT conditioned at 2.5 V vs. Li+/Li.
Ref: 1. N. Recham et al. Nat. Mater. 9 (2010) 68–74. 2. R. Tripathi et al. Chem.
Mater. 23 (2011) 2278–2284. 3. A. Sobkowiak, et al., Chem. Mater. 25 (2013) 3020–3029. A. Blidberg, et al. ChemElectroChem 4 (2017) 1896–1907.

Figure 1
New Insights in the Prolonged Cycle Life of Si Electrodes Prepared in Aqueous Buffered Media at Low pH
Authors: Jeschull Fabian , Trabesinger Sigita 
Published: February 2020

Silicon as an anode material in lithium-ion batteries (LIB) has the 10-fold storage capacity of lithium ions than graphite and is thus an interesting candidate for next generation LIB.[1] However, due to the sever volume expansion during the alloying reaction of Si with Li, the physical inter-particle connections mediated by the electrode binder are broken. As a result the electrode disintegrates and its capacity fades rapidly.
The mechanical and interfacial properties can be enhanced when the Si electrodes are prepared in an aqueous solution of a citric acid buffer at pH=3, instead of neutral pH, such as water.[2] This behavior was previously ascribed to the acid-catalyzed formation of a silyl ester between binder and the native silicon oxide surface.[3] However, many questions still remain unanswered, e.g. what is the impact of the pH or how does the type of acid affect the surface functionalization? Additionally, recent results suggest that citric acid itself interacts strongly with the Si surface, thus forming an artificial SEI layer.[3]

In our study we are providing a deeper insight in the role of the carboxylic acids by examining a series of different carboxylic acids, namely glycolic acid (GlyAc), malic acid (MalAc) and citric acid (CitAc) (Figure 1). The carboxylic acids carry a different number of functional groups, which helps to interpret the rather complex FTIR spectra (Fig. 1a) of these silicon:acid:binder composites. The impact of the carboxylic acid on other cell components (e.g. electrolyte salt or current collectors) was investigated by on-line mass spectroscopy, electron microscopy and electrochemical techniques (e.g. Fig. 1b). Our aim is to evaluate how the capacity retention of acid-treated Si electrodes could be further improved by rational choice of the buffer chemistry and to identify the key control parameters in the functionalization process and during slurry preparation (e.g. pH and acid strength) in order to advance the slurry fabrication process and the performance of Si-containing electrodes.

References

[1] Obrovac, M. N.; Chevrier, V. L. Alloy Negative Electrodes for Li-Ion Batteries. Chem. Rev. 2014, 114 (23), 11444–11502.
[2] Mazouzi, D.; Lestriez, B.; Roué, L.; Guyomard, D.; Electrochem. Solid-State Lett. 2009, 12 (11), A215–A218.
[3] Chandrasiri, K.W., C. C. Nguyen, B. S. Parimalam, S. Jurng, B. L. Lucht, J. Electrochem. Soc.
2018, 165, A1991–A1996

Figure 1
Modeling Transport Properties in Concentrated Systems Considering Species Association
Authors: Li Guanchen , Monroe Charles W 
Published: February 2020

Species association – including effects such as ion pairing and solvent complexation – can complicate electrochemical transport dynamics. As a liquid electrolyte becomes more concentrated, driving forces for association become stronger and may profoundly impact system performance. Ion pairing has been proposed to explain the extended diffuse double layers observed at ionic-liquid/electrode interfaces [1]. Researchers also have justified the low or negative cation transference numbers observed for many lithium electrolytes by suggesting that ions associate [2]. These discussions motivated our systematic study of species association effects in concentrated electrolytes.
The Nernst–Planck theory has been used to study reactive multi-species liquid electrolytes [3], but it ignores solute/solute interactions, limiting applicability to dilute solutions [4]. In concentrated solutions, such interactions can alter transport dynamics substantially, even when species concentrations are relatively low. Monroe has illustrated that interactions between lithium salts and dissolved oxygen can manifest diffusion potentials that change open-circuit voltages of metal-air batteries considerably [5]. Accordingly, even the minor species produced by weak association should not be ignored in concentrated electrolytes. A multi-species concentrated-solution model considering species association will provide a more general and comprehensive interpretation of experimental transport-property data.
Monroe and Delacourt derived flux-explicit transport laws from Onsager–Stefan–Maxwell equations, and emphasized the need for thermodynamic rigor in multi-species transport characterization [6]. The present research advances their framework further, by accounting for species association. In systems were species associate, the Onsager–Stefan–Maxwell transport equations are further constrained by local association equilibria and kinetics. Thus some transport properties may be intrinsically correlated. We will present reformed flux-explicit transport equations and clarify how locally equilibrated association affects apparent transport dynamics.
Three systems, namely, doped ion-conductive ceramics, ionic liquids, and binary solutions, will be analyzed: we will investigate carrier/carrier interaction in doped solid electrolytes, and illustrate how defects or doped elements induce diffusion polarization; we will model the ionic-liquid double layer in cases where ions can combine to form a neutral pair; and we will discuss how the association of solutes affects transference-number measurements in liquid binary solutions.
[1] M.A. Gebbie, et al., PNAS. 110, 9674-9679 (2013)
[2] G. Richardson, et al., J. Electrochem. Soc., 165(9), H561-H567 (2018)
[3] S. Clark, et al., ChemSusChem,10, 4735 – 4747 (2017)
[4] A.M. Bizeray, et al., J. Electrochem. Soc., 163(8), E223-E229
[5] C. W. Monroe, J. Electrochem. Soc., 164(11), E3547-E3551 (2017)
[6] C. W. Monroe and C. Delacourt, Electrochimica Acta, 114, 649–657 (2013)
Tuning the Electrochemistry of Magnesium Electrode
Authors: Yuwono Jodie A 
Published: February 2020

Magnesium (Mg) metal is a promising electrode material for batteries application considering its high volumetric capacity, low cost, safety and environmentally benignity. This translates into the fact that Mg-based batteries can be manufactured in small dimensions (without decreasing the capacity) with a lower cost over the current state-of-art lithium (Li-) based batteries. In the recent years, this is evidenced from a growing number of prototype, showing the capability of Mg-based battery in producing a large current density with a high reversible capacity. However, the reliability of Mg electrode is critical as Mg metal undergoes a rapid Mg dissolution reaction, causing a short lifetime of the electrode and battery. The details of Mg electrochemistry is very complex and unique compared to other alkali and alkali earth metals. For instance, during anodic polarisation Mg has a capability to support hydrogen evolution reaction at a high rate. An understanding of reaction mechanisms at the interface can provide significant information on obtaining a desirable electrochemical performance for Mg electrode, which is beneficial for the development of stable and consistent performance of Mg-based batteries.
In this study, we recently investigated the electrode/ electrolyte interactions of Mg-based electrodes in aqueous electrolytes using a first-principles approach combined with the electrochemical characterisations. The classical description of the Mg electrochemical reaction is complicated by the formation of passive layer, dissolution of Mg and evolution of hydrogen gas. These reactions occur simultaneously and are often associated with the decreasing Coulombic efficiency and parasitic discharge that could lead to the premature battery failure. By recognising the importance of each individual reaction at the interface, we can selectively control the reactions; thus, providing a practical approach to engineer the electrochemical performance of Mg electrode and battery. With this knowledge, it is expected that a viable approach to optimise the use of Mg electrode can be achieved in both primary and secondary batteries, regardless of the electrolyte.

Figure 1
Design and Development of 21700 Type Cells for Electric Vehicle Applications
Authors: Yang Gang , Huang Chien-po , Huang Bryant , Mao Chengyu , Liu Ying 
Published: February 2020

The world’s transition to sustainable energy has been largely accelerated from the transportation field. Thanks to the increasingly wide deployment of charging station and government incentives, electric vehicles are seeing a fast growth in sales over years. Most of them are completely or partially powered by Li-ion batteries, which store and distribute the energy whenever is the needed for the operation of the vehicle. The battery pack consists of tens, hundreds, or thousands of individual cells, depending on the size (kWh) of the pack and cell as well as the form factor of the cell.
As an EV start up, SF Motors is trying to produce the intelligent EV for everyone. One prominent feature of EV is their fast acceleration. A high power is delivered during fast acceleration, which requires the cell to be discharged at extreme high rates. Simultaneously, extensive heat is generated during fast acceleration, causing cell temperature increase and stimulating safety concerns. Here, we’re developing 21700-type cylindrical cells which can deliver extreme high power safely in a short time without compromising its high energy density. Each factor affecting cell rate capabilities like electrode materials, areal loadings, electrode architecture and electrolytes are individually investigated by various electrochemical techniques such as symmetric cells and three-electrode cells. By integrating state-of-art electrode materials, advanced cell design and processing, we’re able to build cells with high energy density, high power, and long cycling life while keeping a high standard for safety. The successful implementation of this extreme high power cell will enable advanced electric vehicles with long drive range (> 300 miles) and top performance driving experiences.
Engineering Transport Pathways and Interfaces in Hybrid Solid Electrolytes at Roll-to-Roll Manufacturing Scales
Authors: Hatzell Kelsey , Dixit Marm 
Published: February 2020

Recently, there has been a push toward all solid-state batteries to eliminate flammability issues in portable electronics. Several solid conductors exist and broadly fall into two material categories: (1) polymers and (2) ceramics. Polymer ionic conductors are advantageous because they can be manufactured easily into thin films, are mechanically robust, and flexible. However, polymer conductors have lower ionic conductivities when compared with their ceramic counterpart. Ceramic conductors boast outstanding ionic conductivities (>10 mS/cm) but processing the electrolyte into thin films (50-100 micrometer) for efficient device integration still remains a challenge because of the brittle nature of the ceramic. There have been a few studies which have investigated a hybrid approach which combines the polymer and ceramic into a composite electrolyte to achieve both processing and performance requirements. A grand challenge with solid state batteries, independent of ion conductor composition, is transport at interfaces. There are both intrinsic interfaces formed within a material by grain, vacancies, and material junctions (composite). Furthermore, there are extrinsic interfaces formed when integrated with an electrode. There is a significant need to understand how we can tailor these interfaces during processing using state of the art manufacturing techniques.
Slot die coaters are extensively used in roll-to-roll processing industrially[2]. However, some challenges remain that deter realization of the full potential of this technique for scalable manufacturing of functional materials. Some of these challenges are multi-material coating ability, active control and feedback, coating intermittently and enhancing resolution among others[3]. Herein, we study a system of colloidal inks with a custom-made benchtop slot-die system. Initial results have shown that the nano-scale interactions in the ink phase impact the macroscopic ink properties and the coating structure [4,5]. This work focuses on demonstrating functional gradation capabilities in slot-die coating system through a novel multi-layer design and understanding how pathways can be engineered for efficient transport.
[1] Hatzell, Kelsey B., et al. "Understanding inks for porous-electrode formation." Journal of Materials Chemistry A 5.39 (2017): 20527-20533. [2] Department of Energy. Roll to Roll Processing Technology Assessment. Technical report, 2015. [3] Corie L Cobb and Christine C Ho. Additive Manufacturing: Rethinking Battery Design. Interface, 3–6, 2016 [4] Dixit, Marm B., et al. "Catalyst Layer Ink Interactions That Affect Coatability." Journal of The Electrochemical Society165.5 (2018): F264-F271. [5] Dixit, Marm, and Kelsey B. Hatzell. "Understanding Binary Interactions and Aging Effects in Catalyst Layer Inks for Controlled Manufacturing." ECS Transactions 80.8 (2017): 301-307.
Influence of Defect Reaction on Electrical/Electrochemical Behaviors of Oxide Electrodes for Li Batteries
Authors: Fung Kuan-Zong , Chang Li-Fu , Tsai Shu-Yi , Huang Bo-Yuan 
Published: February 2020

Functional oxides are known to show interesting electrical properties by introduction of desired defect structures. Electrode performance in Li batteries is also highly dependent on its defect reaction through synthesis and/or charging-discharging cycles. For examples, the reversible capacity of layered cathode such as LiCoO2 is limited by its highly defective layered structure when state of charge greater than 50%. On the other hand, capacity of spinel or olivine cathodes shows higher delithiation rate due to better structural stability. In this study, the behavior of Li-rich layered oxide cathode and Li4Ti5O12 (LTO) are investigated and illustrated based on their defect reactions.
For examples, the as-received zero-stain anode oxide Li4Ti5O12 shows conductivity as low as 10-9 S/cm and then causes high interface polarization and low rate capability. With proper processing under low pO2, the electron conduction and electrochemical properties of LTO was significantly improved. Such property enhancement may be well illustrated by defect reaction under low pO2 environment. In other words, lattice oxygen near surface of LTO tends to be removed under very low pO2. Consequently, positively charged oxygen vacancy is formed and then charge-compensated by the creation of two negatively charged electrons. These electrons are eventually associated with tetravalent Ti ions. The fast electron pathway is established by the coexistence of Ti+3 and Ti+4 in Ti cation sublattice.
Furthermore, Li-rich layer-structured cathode formulated as xLi2MnO3-(1-x)LiMO2(M = Mn, Ni, Co, etc.) during 1st charging process was found to exhibit oxygen oxidation, vacancy formation. In the following discharging, the manganese reduction (or activation) occurred. As a result, a reversible capacity as high as 250 mAh/g was observed (Fig. 1(a)). Such redox reactions may be illustrated by defect chemistry. In other words, during 1st charging, electrons and oxygen was extracted from lattice oxygen with the formation of oxygen vacancies. In the next discharging process, electrons was accepted by cathode oxides accompanied by valence changing of Mn+4 to Mn+3.
It is known that typical electrochemical reactions are highly dependent up movement of electrons and ions. With understanding of defect reaction during materials processing and charging/discharging, advanced electrode materials with much improved electrochemical and/or stability may be developed.