Lithium-ion Battery Chemistries Research Articles

Pseudoconcentrated Electrolyte with High Ionic Conductivity and Stability Enables High-Voltage Lithium-Ion Battery Chemistry

Electrolytes play a decisive role in determining the energy density, cycling life, safety, and temperature adaptability of lithium-ion batteries or any advanced battery chemistries. Here a “pseudoc...

30 Years of Lithium-Ion Batteries.

Over the past 30 years, significant commercial and academic progress has been made on Li-based battery technologies. From the early Li-metal anode iterations to the current commercial Li-ion batteries (LIBs), the story of the Li-based battery is full of breakthroughs and back tracing steps. This review will discuss the main roles of material science in the development of LIBs. As LIB research progresses and the materials of interest change, different emphases on the different subdisciplines of material science are placed. Early works on LIBs focus more on solid state physics whereas near the end of the 20th century, researchers began to focus more on the morphological aspects (surface coating, porosity, size, and shape) of electrode materials. While it is easy to point out which specific cathode and anode materials are currently good candidates for the next-generation of batteries, it is difficult to explain exactly why those are chosen. In this review, for the reader a complete developmental story of LIB should be clearly drawn, along with an explanation of the reasons responsible for the various technological shifts. The review will end with a statement of caution for the current modern battery research along with a brief discussion on beyond lithium-ion battery chemistries.

Cathode Coatings for Magnesium Ion Batteries

Over the past 25 years, significant effort has gone into perfecting lithium ion battery chemistries, including materials coatings, electrolytes, and electrolyte additives to improve safety, capacity, and cyclability. [1,2] By comparison, the area of non-lithium-based batteries is far less explored due to the relative novelty of the technology. Magnesium ion batteries in particular are promising as a next-generation energy storage technology due to the forecasted lower costs. The best cathode materials to date have been metal sulfides and have been demonstrated to achieve high cycleability; however, their capacity and voltage are relatively low compared to state of the art Li ion batteries. One of the challenges in demonstrating high voltage MV-based systems is identifying a cathode capable of desolvating Mg2+ at the cathode-electrolyte interface in order to allow Mg2+ insertion. [3] Additionally, magnesium electrolytes can become quite complicated, with highly solvated ions, large anions, and a variety of both solvents and ion pairs (i.e. MgxClx species). For most electrolyte/cathode pairs, the interaction between electrolyte and cathode surface is not well understood. In the case of the Chevrel Mo6S8 cathode and APC electrolyte, Wan and Prendergast calculated that Mg-Cl species actually interact quite favorably with Mo6S8, which facilitates breaking the Mg-Cl bond and Mg2+ insertion. [4] The cathode-electrolyte interface of magnesium cathode materials is what facilitates desolvation and Mg2+ insertion. By modifying the surface of these cathodes, improvements in performance and lifetime of magnesium ion batteries could be achieved. Materials such as metal sulfides and metal nanoparticles have been demonstrated to interact with the solvated Mg complex and improve the insertion rates of Mg2+into a host lattice. As the Chevrel Mo6S8 was calculated to favorably interact with magnesium electrolytes, it is possible that other transition metal sulfides will provide the same type of interactions and facilitate Mg2+ insertion into cathode materials. Here we focus on Prussian blue type cathode materials, as they have a relatively high voltage and have demonstrated issues with reaching their full theoretical capacity due to desolvation and ion pairing issues. [5] Coatings of Ag­2S and MnS were found to decrease the accessible capacity by about 40% (Figure 1), with similar behavior found in two different coating methods. As cathodes and electrolytes are highly particular in their interactions, coatings may also need to be tailored to the specific cathode/electrolyte system. Figure 1. Charge/discharge curves for Ni[Fe(CN)6] with Mg(TFSI)2 in propylene carbonate electrolyte, with Ag2S and MnS coatings. Cycled at 10 mA/g with a BP2000 carbon anode. References M. M. Thackeray, C. Wolverton and E. D. Isaacs, Energy & Environmental Science, 5 (2012).Z. Chen and J. R. Dahn, Electrochimica Acta, 49, 1079 (2004).P. Canepa, G. S. Gautam, D. C. Hannah, R. Malik, M. Lui, K. G. Gallagher, K. A. Persson, and G. Ceder, Chemical Reviews, 117, 4287 (2017).L. F. Wan, B. R. Perdue, C. A. Apblett and D. Prendergast, Chemistry of Materials, 27, 5932 (2015).A. L. Lipson, S.-D. Han, S. Kim, B. Pan, N. Sa, C. Liao, T. T. Fister, A. K. Burrell, J. T. Vaughey, and B. J. Ingram, Journal of Power Sources, 325, 646 (2016). Figure 1

Electrochemical Performance of Dry Battery Electrode

Li ion battery has been a key research and development topic in energy storage industry in past decade because of considerable consumer demand and market growth including consumer electronics and transportation. A significant effort is focused on development of new chemistry of battery materials such as nickel-rich layered cathode and high capacity silicon anode. Unlike recently reported solvent-free electrode manufacturing variants such as electrostatic spray coating1, dry powder painting2 and isothermal hot-pressing3, Maxwell Technologies unique heritage solvent-free dry electrode process4 used to commercialized Ultracapacitor electrodes can be adapted to existing lithium ion battery chemistries and advanced materials. Maxwell dry electrode manufacturing demonstrative benefits over conventional slurry wet coating process includes, (i)environmentally benign due to elimination of toxic solvent, (ii) lower cost by reducing capital and operating expenditures, resulting from elimination of solvent recovery and recycling system, (iii) improved energy and power density afforded by unique dense high loading electrode microstructures. Maxwell Technologies has applied its proprietary dry electrode process to produced lithium ion battery cathode and anode electrode with unparalleled energy density and enhance cycle life over conventional wet coated electrodes. We have demonstrated dry robust process capability, incorporating current and advanced chemistries such as graphite, silicon, metal alloy, and nickel-rich layered transition metal oxides. In addition, we have demonstrated roll-to-roll dry process scalability using common and advanced battery material chemistries. This paper presents physical properties of self-supporting dry electrode film and electrochemical performance of dry battery electrode in half cell and full cell. We will share electrochemical performance of dry battery electrode produced at the lab-level and pilot-level in single layer pouch cell as well as multilayer stacked pouch cell platform with capacity raging from about 200mAh to about 15Ah.

Heat Generation Measurement of Li-Ion Battery Cells Under Fast Charging Conditions By Employing Isothermal Calorimeter

Introduction Lithium-ion batteries are employed in so many applications including electric vehicles (EVs), hybrid electric vehicles (HEVs) and many consumer products such as cell phones, tablets and computers. Notwithstanding the foregoing, there are still concerns about the safety of Lithium-ion batteries. Abuse conditions such as excessing external heat, over-charging, over-discharging, nail penetration, crush, high charging currents and external and internal short-circuit can cause battery temperature to go far beyond the manufacturer ratings. If the heating rate exceeds dissipation rate for the longer time, then thermal runaway will occur. Thermal runaway leads to many unwanted accidents such as a leak, smoke, gas venting , flames and rapid battery disassembly. Several previous studies have been conducted on the thermal safety of Lithium-ion batteries. Bernardi et al. [3] constructed a heat-generation model for battery systems containing the mixing enthalpies ,electrochemical reactions and phase changes. Guo et al. [4], by employing a finite element method, developed a three-dimensional thermal model. Kim et al. [5] developed a three-dimensional thermal abuse model concerning the chemical reactions. He et al. [6] investigated the thermal management of a Li-ion battery module by employing a two-dimensional computational fluid dynamics model. Wang et al. [7] studied the thermal management of the battery module and optimum structure through employing a lumped model and three-dimensional computational fluid dynamics method. Future electric vehicles will need to be charged in time comparable to refilling time of nowadays conventional combustion vehicles. In consequence, in this work, the thermal behaviour and heat generation of different Lithium-ion battery chemistries subjected to fast charging protocols will be investigated. Heat generation of different Lithium-ion battery cells will be measured by employing isothermal calorimeter. Methodology The experiment is performed by means IBC (Isothermal Battery Calorimeter) 284 from NETZSCH, which is illustrated in Figure 1. Calibration of the IBC 284 consists in applying a controlled electrical current to a precision resistance located inside the calorimeter chamber of the IBC 284[8]. Figure 1: External system components - IBC 284 [8]. First,the calibration of the calorimeter was performed at different temperatures (from -30°C to +60°C). Results Three different chemistries (LTO, NMC and LFP) will be tested during fast charging. Heat generation will be quantified and will be compared amongst these three li-ion battery cell chemistries. Processing of the data was accomplished by means of Proteus Analysis Software (PAS). An example of standard calibration graph and calibration polynomial are shown in figure 2. Exemplary graphs for determination of different parameters are shown in figure 3. Figure 2: Standard calibration graph and calibration polynomial [8]. Figure 3: Example of the graph [8]. References 1 J. Wen, Y. Yu and C. Chen, Mater. Express, 2, 197–212(2012). 2 C.-Y. Jhu, Y.-W. Wang, C.-M. Shu, J.-C. Chang and H.-C. Wu,J. Hazard. Mater.,192, 99–107(2011). Bernardi, D.; Pawlikowski, E.; Newman, J. A general energy balance for battery systems. J. Electrochem. Soc., 132, 5–12(1985).Guo, G.F.; Long, B.; Cheng, B.; Zhou, S.Q.; Xu, P.; Cao, B.G. J. Power Sources, 195, 2393–2398(2010).Kim, G.H.; Pesaran, A.; Spotnitz, R. J. Power Sources, 170, 476–489(2007).He, F.; Li, X.; Ma, L. Int. J. Heat Mass Transf., 72, 622–629(2014).Wang, T.; Tseng, K.; Zhao, J.; Wei, Z. Appl. Energy, 134, 229–238(2014).http://www.netzsch-thermal-analysis.com.

Fabrication of a Novel Nanostructured SnO2/LiCoO2 Lithium-Ion Cell

ABSTRACTIncorporating nanotechnology processes and techniques to Li ion batteries has helped to improve the cycling capabilities and overall performance of several lithium ion battery chemistries. Nanostructuring a lithium ion battery’s anode and cathode, allows for extremely high surface area electrodes to be produced and utilized in many of these battery systems. Using a nanoporous Anodized Aluminum Oxide (AAO) membrane with nanopores of 200nm in diameter as a template, high surface area nanostructured electrode materials can be synthesized and utilized in a lithium ion cell. Through the use of RF magnetron sputter coating, these nanoporous AAO templates can be sputter coated with a thin film of active anode or cathode materials. The anode and cathode material in this research are SnO2 and LiCoO2, respectively. Nanostructured SnO2 has been investigated as an alternative high capacity anode to replace the more commonly used carbon based anodes of current lithium ion batteries. A novel nanostructured SnO2/LiCoO2 cell can be fabricated in a liquid electrolyte. The galvanostatic cell cycling performance will be discussed. Nanostructuring both electrode materials as well as the electrolyte can lead to a novel all-solid-state Li ion battery. Nanostructured SnO2 anode and LiCoO2 electrodes have been generated along with a polyethylene-oxide (PEO) based electrolyte nanoconfined in an AAO membrane, to generate a functioning nanostructured all-solid-state cell. The cell was investigated using AC impedance spectroscopy and galvanostatic cell cycling. The cycling results of both SnO2/LiCoO2 cell systems will be discussed.

Mechanistic Studies of Fluorinated Electrolyte for High Voltage Lithium-Ion Battery

Lithium ion batteries have dominated the portable electronics market and have the potential to dominate large-scale battery applications including hybrid and electric vehicles as well as grid storage because of their high energy and power densities.[1] It is well known that conventional electrolytes (such as 1.2 M LiPF6 in EC/EMC 3/7) show poor anodic stabilities above 4.5 V versus Li/Li+.[2] However, high voltage electrolytes play an intrinsic role in many applications such as hybrid and electrical vehicles, aerospace uses and power grids. As a result, high voltage electrolytes are essential for the development of next generation lithium ion batteries. One possible solution is to develop fluorinated electrolytes which not only form kinetically stable SEI interphase, but also are resistant to oxidative decomposition due to their high oxidation potential. [3] In this work, a novel fluorinated electrolyte was introduced in a graphite-LiNi0.5Mn0.3Co0.2O2 full cell operated between 3.0 - 4.6 V. The electrolyte contains 1.0 M LiPF6 dissolved in a mixture of FEC and HFDEC solvent with 1wt % LiDFOB used as the additive. Compared to a conventional EC and EMC based electrolyte, the fluorinated electrolyte shows an excellent cycle life under a 4.6V cut off voltage. NMR and GC-MS were used to analyze the harvested electrolyte post-cycling while SEM, XPS and FTIR were employed to study the interface between the electrolyte and the bulk electrodes. Most importantly, HR-XRD and XANS were conducted to investigate and compare the cycled bulk cathode electrode in different electrolytes. To the best of our knowledge, the structural change of the cycled cathode material in different electrolytes has never been reported. Therefore, we believe this research is a crucial breakthrough for studying the interaction between the electrolyte and electrode. The methodology developed could be fundamental in the design and investigation of better electrolytes for next generation lithium ion batteries. [1]Xu, Kang. "Nonaqueous liquid electrolytes for lithium-based rechargeable batteries." Chemical reviews 104.10 (2004): 4303-4418. [2] Xu, Kang. "Electrolytes and interphases in Li-ion batteries and beyond." Chemical reviews 114.23 (2014): 11503-11618. [3] Zhang, Zhengcheng, et al. "Fluorinated electrolytes for 5 V lithium-ion battery chemistry." Energy Environ. Sci. 6.6 (2013): 1806-1810.

On Battery Recovery Effect in Wireless Sensor Nodes

With the perennial demand for longer runtime of battery-powered Wireless Sensor Nodes (WSNs), several techniques have been proposed to increase the battery runtime. One such class of techniques exploiting the battery recovery effect phenomenon claims that performing an intermittent discharge instead of a continuous discharge will increase the usable battery capacity. Several works in the areas of embedded systems and wireless sensor networks have assumed the existence of this recovery effect and proposed different power management techniques in the form of power supply architectures (multiple battery setup) and communication protocols (burst mode transmission) in order to exploit it. However, until now, a systematic experimental evaluation of the recovery effect has not been performed with real battery cells, using high-accuracy battery testers to confirm the existence of this recovery phenomenon. In this article, a systematic evaluation procedure is developed to verify the existence of this battery recovery effect. Using our evaluation procedure, we investigated Alkaline, Nickel-Metal Hydride (NiMH), and Lithium-Ion (Li-Ion) battery chemistries, which are commonly used as power supplies for Wireless Sensor Node (WSN) applications. Our experimental results do not show any evidence of the aforementioned recovery effect in these battery chemistries. In particular, our results show a significant deviation from the stochastic battery models, which were used by many power management techniques. Therefore, the existing power management approaches that rely on this recovery effect do not hold in practice. Instead of a battery recovery effect, our experimental results show the existence of the rate capacity effect , which is the reduction of usable battery capacity with higher discharge power, to be the dominant electrochemical phenomenon that should be considered for maximizing the runtime of WSN applications. We outline power management techniques that minimize the rate capacity effect in order to obtain a higher energy output from the battery.

A Lithium-Ion Battery with Enhanced Safety Prepared using an Environmentally Friendly Process.

A new lithium-ion battery chemistry is presented based on a conversion-alloying anode material, a carbon-coated Fe-doped ZnO (TMO-C), and a LiNi1/3 Mn1/3 Co1/3 O2 (NMC) cathode. Both electrodes were fabricated using an environmentally friendly cellulose-based binding agent. The performance of the new lithium-ion battery was evaluated with a conventional, carbonate-based electrolyte (ethylene carbonate:diethyl carbonate-1 m lithium hexafluorophosphate, EC:DEC 1 m LiPF6 ) and an ionic liquid (IL)-based electrolyte (N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide-0.2 m lithium bis(trifluoromethanesulfonyl)imide, Pyr14 TFSI 0.2 m LiTFSI), respectively. Galvanostatic charge/discharge tests revealed a reduced rate capability of the TMO-C/Pyr14 TFSI 0.2 m LiTFSI/NMC full-cell compared to the organic electrolyte, but the coulombic efficiency was significantly enhanced. Moreover, the IL-based electrolyte substantially improves the safety of the system due to a higher thermal stability of the formed anodic solid electrolyte interphase and the IL electrolyte itself. While the carbonate-based electrolyte shows sudden degradation reactions, the IL exhibits a slowly increasing heat flow, which does not constitute a serious safety risk.

Fast charging technique for high power LiFePO4 batteries: A mechanistic analysis of aging

One of the major issues hampering the acceptance of electric vehicles (EVs) is the anxiety associated with long charging time. Hence, the ability to fast charging lithium-ion battery (LIB) systems is gaining notable interest. However, fast charging is not tolerated by all LIB chemistries because it affects battery functionality and accelerates its aging processes. Here, we investigate the long-term effects of multistage fast charging on a commercial high power LiFePO4-based cell and compare it to another cell tested under standard charging. Coupling incremental capacity (IC) and IC peak area analysis together with mechanistic model simulations (‘Alawa’ toolbox with harvested half-cell data), we quantify the degradation modes that cause aging of the tested cells. The results show that the proposed fast charging technique caused similar aging effects as standard charging. The degradation is caused by a linear loss of lithium inventory, coupled with a less degree of linear loss of active material on the negative electrode. This study validates fast charging as a feasible mean of operation for this particular LIB chemistry and cell architecture. It also illustrates the benefits of a mechanistic approach to understand cell degradation on commercial cells.

Lithium Sulfide/Metal Nanocomposite as a High‐Capacity Cathode Prelithiation Material

DOI: 10.1002/aenm.201600154 due to their limited specific capacity.[18,19] Very recently, we have proposed that conversion reaction materials can be attractive high capacity prelithiation materials for cathodes and demonstrated using Li2O/metal and LiF/metal nanocomposites.[20,21] For example, a high “donor” lithium-ion specific capacity of 609 mAh g−1 has been achieved for a stable nanoscaled mixture of Li2O and Co in the cutoff potential range of current cathodes.[20] Herein, we would like to explore the potential of Li2S and metal nanocomposites for cathode prelithiation. We believe that having a new set of lithium compounds beyond Li2O for cathode prelithiation is important. Li2S possesses a high theoretical specific capacity of 1166 mAh g−1 and can be paired with lithium free anodes (e.g., graphite, Sn, and Si). It has been widely investigated as one of the best cathode candidates for the next-generation rechargeable lithium batteries and significant achievements have been demonstrated.[22–26] Here we propose that Li2S can be used as a high-capacity cathode prelithiation material for the existing LIBs. To this end, four significant challenges need to be overcome: (1) The compatibility of electrolytes. Previous investigations on pristine Li2S and S particles for cathodes were usually carried out in ether-based electrolytes instead of the widely used carbonate-based electrolytes in commercial LIBs.[4,22,27,28] Because carbonate-based solvents chemically react with the intermediate polysulfides, such solvents are inappropriate for S and Li2S cathodes.[29] (2) The compatibility of working potential. The widely used cathode materials usually have a cutoff charge potential higher than 4.2 V versus Li+/Li (e.g., 4.3 V for LiCoO2, LiNixCoyMnzO2, and LiMnO4, and 4.2 V for LiFePO4) and a cutoff discharge potential higher than 2.5 V (e.g., 2.5–3 V) in the carbonate-based electrolytes. To maximize the “donor” lithium-ion capacity, relative low delithiation (e.g., <4.2 V) and lithiation potentials (e.g., <2.5 V) are desirable for a cathode prelithiation material, so that all the stored lithium can be irreversible extracted during the first charge/discharge cycle. (3) The diffusion of the intermediate polysulfides and low conductivity of Li2S. Due to the loss of polysulfide active material into the electrolyte, it is challenging to maximize the lithium-ion capacity. Additionally, it is hard to extract lithium from Li2S due to its insulating nature. (4) The instability under ambient and battery fabrication conditions. Li2S is highly reactive with moisture in air. Such property makes it incompatible with ambient and industrial battery fabrication conditions. Despite the great knowledge obtained from the previous work on Li2S-based cathode material, the solutions to this issue remain to be developed. Therefore, it is highly desirable to solve these inherent problems of Li2S via a rational structure and component design to pave the path for its application as Two approaches to increase specific energy and energy density of batteries include the exploration of new battery chemistries and the continuous improvement of the existing lithium-ion battery (LIB) chemistries.[1,2] The exploration of new highcapacity electrode materials, such as Si for anodes and S/Li2S for cathodes, has recently become an important focus of materials research and will potentially revolutionize energy storage technologies.[3,4] At the same time, the improvement of the existing LIB systems could also offer more practical avenues and faster performance increment in the near future. Accompanied by the formation of a solid electrolyte interphase (SEI) layer on the anode surface during the initial battery charge process, some lithium from the cathode is consumed, which reduces appreciably the specific energy and energy density of current LIBs (5%–20% of a total battery capacity).[5–8] In the past few years, increased efforts have been devoted to exploring prelithiation strategies to compensate for the initial lithium loss of LIBs. Although electrochemical prelithiation approaches have been successfully demonstrated, an electrochemical cell needs to be built and disassembled, resulting in complex operations.[9,10] Sacrificial lithium salts can be used as prelithiation additives to electrolytes or electrodes. However, as Armand and co-workers mentioned, undesired gas, such as N2, CO, or CO2, was produced upon the release of lithium.[11] Specifically designed prelithiation additives to electrodes can deliver high “donor” lithium-ion specific capacities to offset the initial lithium loss and hence improve the electrochemical performance of current LIBs. To date, anode prelithiation materials, including stabilized lithium metal powders[12–15] and lithium silicide particles,[16,17] have been investigated due to their high specific capacities. However, their high chemical reactivity and instability under ambient and battery fabrication conditions remain as challenges. Cathode prelithiation materials have relatively high open circuit voltage (OCV) and chemical stability, offering another attractive route. However, little success has been shown on the cathode prelithiation materials, probably

(Invited) Can Basic Research in Academia Predict Battery Field Failures?

Cell and battery field failures can occur in a number of ways. Cause of failures can vary from inadequate cell and battery safety controls to poor manufacturing quality. Oftentimes, basic research in academia is focused on improving materials to obtain higher specific capacity or power density. The practical issues of failure scenarios created due to scaling up from a lab scale to a large Mega or giga Watt energy storage application are seldom mimicked or studied. This paper will discuss the areas that have gaps in safety research with a focus on lithium-ion battery chemistry.

Probing Lithium-Ion Battery Safety in Mining Environments

Lithium-ion batteries are increasingly ubiquitous in portable consumer electronic devices, including laptop computers, cellular phones, and tablet computers. Lithium-ion batteries are also finding widespread deployment in many additional applications and settings, including underground mining environments, where lithium-ion batteries are used as electrochemical power sources for cap lamps, and in tracking and communications equipment.1,2 Battery safety is of paramount importance in any portable electronic device regardless of setting, and is particularly significant in enclosed and isolated areas such as passenger aircraft, or in underground mining environments, where potentially explosive methane/air mixtures can be ignited by a simple spark, which can be caused by shorting and thermal runaway of lithium-ion batteries. This presentation will summarize systematic abuse testing of different lithium-ion batteries used in underground mining safety and communication equipment, including lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt oxide (NMC), and lithium iron phosphate (LiFePO4) based cathode chemistries. Prismatic and cylindrical 18650 lithium-ion batteries were obtained from commercial vendors and subjected to both wedge and flat plate crush tests, in order to determine the relative safety of each cathode chemistry under two crush speeds and various states-of-charge (SOC). Battery voltage, case temperature and applied load were recorded for each crush test. Video recording of each crush test was also collected. In some cases, hard or soft electrical short circuits were caused by crushing the battery, resulting in thermal runaway, rapid temperature increases, and explosions or fires. Correlations will be drawn between choice of cathode chemistry, state-of-charge, type of crush test, and choice of atmosphere (air or methane/air mixtures), in order to determine the most suitable lithium-ion battery chemistry for underground mining applications. References 1) Dubaniewicz, T. H. Jr.; DuCarme, J. P. Journal of Loss Prevention in the Process Industries. 2014, 32, 165. 2) Dubaniewicz, T. H. Jr.; DuCarme, J. P. IEEE Transactions on Industry Applications. 2013, 6, 2451-2460.

Enabling the Next Generation of High Energy Lithium-Ion Battery Cathodes

Lithium-ion (Li-ion) battery chemistries have driven the portable electronics market for almost 25 years and are now poised to significantly impact the light-duty transportation and grid storage sectors as well. The versatility and proven record of Li-ion systems makes them an irresistible choice from a practical standpoint. However, each application continuously demands more from every new generation of battery products; the highly correlated parameters, energy, power, safety, cycle life, and cost, are constantly being pushed to their limits. Although much of the current effort in energy storage research is aimed at transformational gains, novel Li-ion systems, yet to be explored, have the potential of making continual and significant incremental impacts on next-generation technologies.This presentation will discuss insights into the atomic-level structure and transformation mechanisms of lithium-transition-metal-oxide cathode materials. These mechanisms explain, in part, the failure modes of layered cathodes at high states of delithiation. Furthermore, a discussion on a variety of elemental and structural compositions will be given. For example, unique layered, layered-layered, spinel, and layered-layered-spinel structures and chemistries will be presented that are pushing the boundaries of current Li-ion technology.Future directions and research in further enabling these new systems will also be discussed. Acknowledgment Support from the Vehicle Technologies Program, Hybrid and Electric Systems, in particular, David Howell, Peter Faguy, and Tien Duong at the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, is gratefully acknowledged. The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up, nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government.

The Development of Electrolytes with Flame Retardant Additives for Multiple Lithium-Ion Chemistries

A number of applications under NASA’s Exploration Technology Development Program would benefit from high specific energy rechargeable batteries that have improved safety characteristics. To meet these objectives, lithium-ion battery chemistries have emerged as the most promising energy storage devices, due to their high specific energy, long life, and ability to operate over a wide temperature range. In recent years, advances in anode and cathode materials have created a number of lithium-ion chemistries that that have the potential of exceeded 150 Wh/kg at the cell level. However, owing to the fact that these chemistries employ the use of organic electrolytes, possessing flammable solvents, there is a desire to improve the safety characteristics of these devises. The flammability of these electrolytes is mainly due to the use of cyclic and linear organic carbonates, which are necessary to provide (i) sufficient conductivity of the media with the use of lithium electrolyte salts, (ii) adequate stability over a wide voltage range, and (iii) the formation of protective surface films at the electrolyte/electrode interfaces.A number of approaches can be employed to reduce the inherent flammability of the lithium-based electrolyte systems, including (i) the use of phosphorus-based flame retardant additives (FRAs), (ii) the use of ionic liquids, which possess extremely low vapor pressures, and (iii) the use of non-flammable co-solvents, such as fluorinated ethers, esters, and carbonates. Although the use of ionic liquids and highly fluorinated co-solvents has led to electrolyte formulations that can display dramatically lower flammability, these approaches typically suffer from poor compatibility with the electrode chemistries of interest and lead to a sacrifice in performance. In contrast, the use of flame retardant additives has proven to be a viable way of reducing the flammability of the electrolytes without compromising the performance of the system. Toward this end, a number of flame retardant additives have been identified in traditional lithium-ion chemistry with success, including triphenyl phosphate (TPP)1, tris(2,2,2-trifluoroethyl) phosphate2, and dimethyl methyl phosphonate (DMMP).3 After comprehensively investigating the compatibility of a number flame retardant additives in various chemistries, we have identified triphenyl phosphate (TPP) as being the most versatile, being compatible with traditional LiNi0.8Co0.2O2 and LiNi0.8Co0.15Al0.05O2 –based systems as well as with high voltage, lithium excess, mixed metal oxide-based cathode systems.4,5 We would like to describe our recent results with TPP-containing electrolytes in both traditional lithium-ion chemistries (i.e., MCMB carbon-LiNi0.8Co0.2O2 and graphite-LiNi0.8Co0.15 Al0.05O2) as well as in advanced lithium-ion chemistries that possess high capacity anodes and cathodes (i.e., Si/C-LiNi0.8Co0.15Al0.05O2 and graphite-Li1.2Ni0.13Co 0.13Mn0.54O2). Electrolyte formulations have been specifically tailored for each chemistry to achieve the desired benefit to safety without compromising performance. This was achieved by optimizing the FRA content, the use of fluorinated co-solvents in conjunction with traditional carbonate-based solvents, and the use of film forming electrolyte additives. The compatibility of the electrolytes with the various chemistries were investigated in experimental coin and three-electrode cells (equipped with lithium reference electrodes), which enable us to perform a number of electrochemical characterization techniques including EIS, DC micropolarization, and Tafel polarization. We will also describe the electrical performance of the most promising electrolyte formulations in prototype lithium-ion cells of varying capacity (0.25Ah to 8.0 Ah) manufactured by various battery vendors (Quallion, LLC, Yardney Technical Products, Inc. and Saft America, Inc.).ACKNOWLEDGEMENTThe 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) and under sponsorship of the NASA-Exploration Technology Development Program (ETDP). 1. Y. E. Hyung, D. R. Vissers, K. Amine, J. Power Sources, 119- 121, 383, (2003). 2. (a) K. Xu, M. S. Ding, S. Zhang, J. L. Allen, T. R. Jow, J. Electrochem. Soc., 149, A622, (2002). (b) K. Xu, S. Zhang, J. L. Allen, T. R. Jow, J. Electrochem. Soc., 149, A1079, (2002), (c) Kang Xu, Michael S. Ding, Shengshui Zhang, Jan L. Allen, and T. Richard Jow, J. Electrochem. Soc., 150, A161 (2003). 3. (a) J. K. Feng, X. P. Ai, Y. L. Cao, and H. X. Yang, J. Power Sources, 177, 194-198 (2008), (b) S. Dalavi, M. Xu, B. Ravdel, L. Zhou, and B. L. Lucht, J. Electrochem. Soc., 157, A1113 (2010). 4 K. A. Smith, M. C. Smart, G. K. S. Prakash, and B. V. Ratnakumar, ECS Transactions, 16 (35), 33-41 (2009). 5 R. P. Dunn, J. Kafle, F. C. Krause, C. Hwang, B. V. Ratnakumar, M. C. Smart, and B. L. Lucht, J. Electrochem. Soc., 159 (12), A2100-A2108 (2012).

Nanoporous Li2S and MWCNT-Linked Li2S Powder Cathodes for Lithium-Ion Battery Chemistries

The fully-lithiated Li2S (having theoretical gravimetric and volumetric capacities of 1166 mAhg-1 and 1935 mAh·cc-1) has been viewed as a promising cathode material because of its low cost, high capacity and compatibility with Li-free anodes (e.g., graphite or Si/Sn-based composites). In addition, the use of anodes that undergo small volume changes during cycling (such as graphite) makes it easier to form a stable electrically insulative SEI, which is permeable to Li ions but impermeable to polysulfides, thus eliminating the irreversible side reactions between polysulfide anion and Li metal and allowing one to minimize or avoid the gradual cathode dissolution and stabilize the chemistry of such cells [1, 2]. Unfortunately, the high melting point of commercial Li2S (~940 °C) makes it difficult to infiltrate it into conductive carbon hosts for the enhanced conductivity and capacity utilization, as commonly done with S [3-6]. Li2S cathodes also suffer from the dissolution and shuttling of lithium polysulfides during cycling as S cathodes do [3-6]. Several research groups utilized ball milling to reduce the size of commercial Li2S powders and distribute smaller particles together with carbon additives to improve their rate performance and capacity utilization [7, 8]. However, the ball milling procedure does not allow formation of uniform particles with controlled morphology or strong bonding between Li2S and carbon. In order to better disperse Li2S in carbon host and improve the strength of their interactions, lithium polysulfides were recently used to synthesize the Li2S by releasing H2S, and the electrodes maintained 20 cycles [9]. However, H2S is a rather toxic gas, harmful to environment. Overall, in contrast to the pleura of papers reporting advancement of S-cathodes, the research on Li2S cathodes has been quite limited.In order to achieve high capacity utilization and high rate performance of lithium sulfide (Li2S) cathode materials, it is critical to identify scalable methods for low-cost preparation of nanostructured Li2S or Li2S-carbon composites. We report the application of a versatile solution-based method to prepare nanoporous Li2S and MWCNT-linked Li2S particles (Figure 1) [10]. XRD studies revealed the lack of crystalline impurities in the produced samples, while electron microscopy (SEM and TEM) combined with N2 sorption measurements showed the impact of the preparation conditions on the morphology and porosity of the samples. Our studies have demonstrated that lower polarization, higher capacity utilization and better rate performance can be achieved in porous Li2S and MWCNT-linked nano Li2S samples when compared to that of commercially available Li2S powders. The nanostructured Li2S-based cathodes containing MWCNT showed promising discharge capacities of up to ~1050 mAhg-1 S at a slow rate of C/20 and ~800 mAhg-1 S at a C/2 rate. Quite remarkably, without any electrolyte additives (such as polysulfides or lithium nitrate) MWCNT-linked Li2S cathodes demonstrated up to ~90 % capacity retention after 100 cycles in half cells (vs. Li foil) at a C/5 and C/10 rates (Figure 2).

Sizing the Battery Power for PHEVs Based on Battery Efficiency, Cost and Operational Cost Savings

The incremental cost for increasing the power of Li-ion batteries for plug-in hybrid-electric vehicles (PHEVs) is moderate. Hence, the reduction of fuel consumption by using battery power at high vehicle speeds rather than engine power results in high net present value for the total cost of the battery and future fuel savings. The variation of designed efficiency at rated power is also evaluated to examine the cost for the thermal management system and improved life and cold temperature performance. Two types of PHEVs and two lithium-ion battery chemistries of batteries are considered in this study.

Higher-capacity lithium ion battery chemistries for improved residential energy storage with micro-cogeneration

Combined heat and power on a residential scale, also known as micro-cogeneration, is currently gaining traction as an energy savings practice. The configuration of micro-cogeneration systems is highly variable, as local climate, energy supply, energy market and the feasibility of including renewable type components such as wind turbines or photovoltaic panels are all factors. Large-scale lithium ion batteries for electrical storage in this context can provide cost savings, operational flexibility, and reduced stress on the distribution grid as well as a degree of contingency for installations relying upon unsteady renewables. Concurrently, significant advances in component materials used to make lithium ion cells offer performance improvements in terms of power output, energy capacity, robustness and longevity, thereby enhancing their prospective utility in residential micro-cogeneration installations. The present study evaluates annual residential energy use for a typical Canadian home connected to the electrical grid, equipped with a micro-cogeneration system consisting of a Stirling engine for supplying heat and power, coupled with a nominal 2kW/6kWh lithium ion battery. Two novel battery cathode chemistries, one a new Li–NCA material, the other a high voltage Ni-doped lithium manganate, are compared in the residential micro-cogeneration context with a system equipped with the presently conventional LiMn2O4 spinel-type battery.

Fluorinated electrolytes for 5 V lithium-ion battery chemistry

An electrolyte based on fluorinated carbonate solvents was evaluated with high voltage cathode materials at elevated temperature. The theoretically high anodic stability of these new electrolytes was supported by electrochemical evaluation results using LiNi0.5Mn1.5O4/Li and LiNi0.5Mn1.5O4/Li4Ti5O12 electrochemical couples. Fluorinated carbonate appears to be a suitable electrolyte candidate for transition metal oxide cathodes at high voltage (5 V vs. Li+/Li).

Performance of Three Different Lithium-Ion Battery Chemistries

not Available.