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There are a large number of accounts about rapidly declining costs of batteries with potentially transformative effects, but these accounts often are not based on detailed design and technical information. Using a method ideally suited for that purpose, we find that when experts are free to assume any battery pack design, a majority of the cost estimates are consistent with the ranges reported in the literature, although the range is notably large. However, we also find that 55% of relevant experts’ component-level cost projections are inconsistent with their total pack-level projections, and 55% of relevant experts’ elicited cost projections are inconsistent with the cost projections generated by putting their design- and process-level assumptions into our process-based cost model (PBCM). These results suggest a need for better understanding of the technical assumptions driving popular consensus regarding future costs. Approaches focusing on technological details first, followed by non-aggregated and systemic cost estimates while keeping the experts aware of any discrepancies, should they arise, may result in more accurate forecasts.

The lithium–sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium–sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte. The use of sparingly solvating electrolytes in lithium–sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach. Herein, we demonstrate that sparingly solvating electrolytes based on compact, polar molecules with a 2:1 ratio of a functional group to lithium salt can fundamentally redirect the lithium–sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge. Moreover, operation at intermediate temperatures ca. 50 °C allows for minimal overpotentials and high utilization of sulfur at practical rates. This discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation–dissolution chemistries, lithium–sulfur and beyond., Achieving sparing solubility of polysulfides in electrolytes for Li−S cells induces fundamental changes in the reaction pathway that give rise to low polarization.

This study investigates the representation of battery degradation in grid level energy storage applications. In particular, we focus on energy arbitrage, as this is a potential future large-scale application of energy storage and there is limited existing research combining the modelling of battery degradation and energy storage arbitrage. We implement two different representations of battery degradation within an energy arbitrage model, and show that degradation has a strong impact on battery energy storage system (BESS) profitability. In a case study using historical electricity market prices from the MISO electricity market in the United States, we find that the achievable net present value (at an interest rate of 10%) for a battery system with a C-rate of 1C dropped from 358 $/kWh in the case considering no degradation to 194–314 $/kWh depending on the battery degradation model and assumptions for end of life (EOL) criteria. This corresponds to a reduction in revenue due to degradation in the 12–46% range. Moreover, we find that reducing the cycling of the battery via introducing a penalty cost in the objective function of the energy arbitrage optimization model can improve the profitability over the life of the BESS.

The understanding of the reaction mechanism and temporal speciation of the lithium–sulfur batteries is challenged by complex polysulfide disproportionation chemistry coupled with the precipitation and dissolution of species. In this report, for the first time, we present a comprehensive method to investigate lithium sulfur electrochemistry using in situ 7Li NMR spectroscopy, a technique that is capable of quantitatively capturing the evolution of the soluble and precipitated lithium (poly)sulfides during electrochemical cycling. Through deconvolution and quantification, every lithium-bearing species was closely tracked and four-step soluble lithium polysulfide-mediated lithium sulfur electrochemistry was demonstrated in never before seen detail. Significant irreversible accumulation of Li2S is observed on the Li metal anode after four cycles because of sulfur shuttling. The application of the method presented here to study electrolyte/additive development and lithium protection research can be readily env...

The rapidly expanding field of nonaqueous multivalent intercalation batteries offers a promising way to overcome safety, cost, and energy density limitations of state-of-the-art Li-ion battery technology. We present a critical and rigorous analysis of the increasing volume of multivalent battery research, focusing on a wide range of intercalation cathode materials and the mechanisms of multivalent ion insertion and migration within those frameworks. The present analysis covers a wide variety of material chemistries, including chalcogenides, oxides, and polyanions, highlighting merits and challenges of each class of materials as multivalent cathodes. The review underscores the overlap of experiments and theory, ranging from charting the design metrics useful for developing the next generation of MV-cathodes to targeted in-depth studies rationalizing complex experimental results. On the basis of our critical review of the literature, we provide suggestions for future multivalent cathode studies, including a strong emphasis on the unambiguous characterization of the intercalation mechanisms.

We develop three novel enhanced mixed integer-linear representations of the power limit of the battery and its efficiency as a function of the charge and discharge power and the state of charge of the battery, which can be directly implemented in large-scale power systems models and solved with commercial optimization solvers. Using these battery representations, we conduct a techno-economic analysis of the performance of a 10 MWh lithium-ion battery system testing the effect of a 5-min vs. a 60-min price signal on profits using real time prices from a selected node in the MISO electricity market. Results show that models of lithium-ion batteries where the power limits and efficiency are held constant overestimate profits by 10% compared to those obtained from an enhanced representation that more closely matches the real behavior of the battery. When the battery system is exposed to a 5-min price signal, the energy arbitrage profitability improves by 60% compared to that from hourly price exposure. These results indicate that a more accurate representation of li-ion batteries as well as the market rules that govern the frequency of electricity prices can play a major role on the estimation of the value of battery technologies for power grid applications.

The price of the cathode active materials in lithium ion batteries is a key cost driver and thus significantly impacts consumer adoption of devices that utilize large energy storage contents (e.g. electric vehicles). A process model has been developed and used to study the production process of a common lithium-ion cathode material, lithiated nickel manganese cobalt oxide, using the co-precipitation method. The process was simulated for a plant producing 6500 kg day −1 . The results indicate that the process will consume approximately 4 kWh kg NMC −1 of energy, 15 L kg NMC −1 of process water, and cost $23 to produce a kg of Li-NMC333. The calculations were extended to compare the production cost using two co-precipitation reactions (with Na 2 CO 3 and NaOH), and similar cathode active materials such as lithium manganese oxide and lithium nickel cobalt aluminum oxide. A combination of cost saving opportunities show the possibility to reduce the cost of the cathode material by 19%.

Moving to lighter and less expensive battery chemistries compared to contemporary lithium-ion requires the control of energy storage mechanisms based on chemical transformations rather than intercalation. Lithium–sulfur (Li/S) has tremendous theoretical specific energy, but contemporary approaches to control this solution-mediated, precipitation–dissolution chemistry require large excesses of electrolyte to fully solubilize the polysulfide intermediates. Achieving reversible electrochemistry under lean electrolyte operation is the most promising path for Li/S to move beyond niche applications to potentially transformational performance. An emerging Li/S research area is the use of sparingly solvating electrolytes and the creation of design rules for discovering new electrolyte systems that fundamentally decouple electrolyte volume from sulfur and polysulfide reaction mechanism. This Perspective presents an outlook for sparingly solvating electrolytes as a key path forward for long-lived, high energy densi...

Successful deployment of electric vehicles requires maturity of the manufacturing process to reduce the cost of the lithium ion battery (LIB) pack. Drying the coated cathode layer and subsequent recovery of the solvent for recycle is a vital step in the lithium ion battery manufacturing plant and offers significant potential for cost reduction. A spreadsheet model of the drying and recovery of the solvent, is used to study the energy demand of this step and its contribution towards the cost of the battery pack. The base case scenario indicates that the drying and recovery process imposes an energy demand of ∼10 kWh per kg of the solvent n-methyl pyrrolidone (NMP), and is almost 45 times the heat needed to vaporize the NMP. For a plant producing 100 K battery packs per year for 10 kWh plug-in hybrid vehicles (PHEV), the energy demand is ∼5900 kW and the process contributes $107 or 3.4% to the cost of the battery pack. The cost of drying and recovery is equivalent to $1.12 per kg of NMP recovered, saving $2.08 per kg in replacement purchase.

Coin-cells are often the test format of choice for laboratories engaged in battery research and development as they provide a convenient platform for rapid testing of new materials on a small scale. However, reliable, reproducible data via the coin-cell format is inherently difficult, particularly in the full-cell configuration. In addition, statistical evaluation to prove the consistency and reliability of such data is often neglected. Herein we report on several studies aimed at formalizing physical process parameters and coin-cell construction related to full cells. Statistical analysis and performance benchmarking approaches are advocated as a means to more confidently track changes in cell performance. We show that trends in the electrochemical data obtained from coin-cells can be reliable and informative when standardized approaches are implemented in a consistent manner.

Increasing the areal capacity or electrode thickness in lithium ion batteries is one possible means to increase pack level energy density while simultaneously lowering cost. The physics that limit use of high areal capacity as a function of battery power to energy ratio are poorly understood and thus most currently produced automotive lithium ion cells utilize modest loadings to ensure long life over the vehicle battery operation. Here we show electrolyte transport limits the utilization of the positive electrode at critical C-rates during discharge; whereas, a combination of electrolyte transport and polarization lead to lithium plating in the graphite electrode during charge. Experimental measurements are compared with theoretical predictions based on concentrated solution and porous electrode theories. An analytical expression is derived to provide design criteria for long lived operation based on the physical properties of the electrode and electrolyte. Finally, a guideline is proposed that graphite cells should avoid charge current densities near or above 4 mA/cm2 unless additional precautions have been made to avoid deleterious side reaction.

Low-cost energy storage systems are required to support extensive deployment of intermittent renewable energy on the electricity grid. Redox flow batteries have potential advantages to meet the stringent cost target for grid applications as compared to more traditional batteries based on an enclosed architecture. However, the manufacturing process and therefore potential high-volume production price of redox flow batteries is largely unquantified. We present a comprehensive assessment of a prospective production process for aqueous all vanadium flow battery and nonaqueous lithium polysulfide flow battery. The estimated investment and variable costs are translated to fixed expenses, profit, and warranty as a function of production volume. When compared to lithium-ion batteries, redox flow batteries are estimated to exhibit lower costs of manufacture, here calculated as the unit price less materials costs, owing to their simpler reactor (cell) design, lower required area, and thus simpler manufacturing process. Redox flow batteries are also projected to achieve the majority of manufacturing scale benefits at lower production volumes as compared to lithium-ion. However, this advantage is offset due to the dramatically lower present production volume of flow batteries compared to competitive technologies such as lithium-ion.

The flexible plant postulated in this study would produce four types of batteries for electric-drive vehicles – a hybrid (HEV), 10-mile range and 40-mile range plug-in hybrids (PHEV), and a 150-mile range battery-electric (EV). The annual production rate of the plant is 235,000 battery packs (HEV: 100,000; PHEV10: 60,000; PHEV40: 45,000; EV: 30,000). The cost savings per battery pack calculated with the Argonne BatPaC model for this flex plant vs. dedicated plants range from 9% for the EV battery packs to 21% for the HEV packs including the battery management systems (BMS). The investment cost savings are even larger, ranging from 21% for EVs to 43% for HEVs. The costs of the 1.0-kWh HEV batteries are projected to approach $714 per unit and that of the EV batteries to approach $188 per kWh with the most favorable cell chemistries. The best single indicator of the cost of producing lithium-manganate spinel/graphite batteries in a flex plant is the total cell area of the battery. For the four batteries studied, the price range is $20–24 per m2 of cell area, averaging $21 per m2 for the entire flex plant.

Three key questions have driven recent discussions of the energy and environmental impacts of automotive lithium-ion batteries. We address each of them, beginning with whether the energy intensity of producing all materials used in batteries or that of battery assembly is greater. Notably, battery assembly energy intensity depends on assembly facility throughput because energy consumption of equipment, especially the dry room, is mainly throughput-independent. Low-throughput facilities therefore will have higher energy intensities than near-capacity facilities. In our analysis, adopting an assembly energy intensity reflective of a low-throughput plant caused the assembly stage to dominate cradle-to-gate battery energy and environmental impact results. Results generated with an at-capacity assembly plant energy intensity, however, indicated cathode material production and aluminium use as a structural material were the drivers. Estimates of cradle-to-gate battery energy and environmental impacts must therefore be interpreted in light of assumptions made about assembly facility throughput. The second key question is whether battery recycling is worthwhile if battery assembly dominates battery cradle-to-gate impacts. In this case, even if recycled cathode materials are less energy and emissions intensive than virgin cathode materials, little energy and environmental benefit is obtained from their use because the energy consumed in assembly is so high. We reviewed the local impacts of metals recovery for cathode materials and concluded that avoiding or reducing these impacts, including SOx emissions and water contamination, is a key motivator of battery recycling regardless of the energy intensity of assembly. Finally, we address whether electric vehicles (EV) offer improved energy and environmental performance compared to internal combustion-engine vehicles (ICV). This analysis illustrated that, even if a battery assembly energy reflective of a low-throughput facility is adopted, EVs consume less petroleum and emit fewer greenhouse gases (GHG) than an ICV on a life-cycle basis. The only scenario in which an EV emitted more GHGs than an ICV was when it used solely coal-derived electricity as a fuel source. SOx emissions, however, were up to four times greater for EVs than ICVs. These emissions could be reduced through battery recycling.

The impedance of a lithium- and manganese-rich layered transition-metal oxide (LMR-NMC) positive electrode, specifically Li1.2Ni0.15Mn0.55Co0.1O2, is compared to two other transition-metal layered oxide materials, specifically LiNi0.8Co0.15Al0.05O2 (NCA) and Li1.05(Ni1/3Co1/3Mn1/3)0.95O2 (NMC). A more detailed electrochemical impedance spectroscopy (EIS) study is conducted on the LMR-NMC electrode, which includes a range of states-of-charge (SOCs) for both current directions (i.e. charge and discharge) and two relaxation times (i.e. hours and one hundred hours) before the EIS sweep. The LMR-NMC electrode EIS studies are supported by half-cell constant current and galvanostatic intermittent titration technique (GITT) studies. Two types of electrochemical models are utilized to examine the results. The first type is a lithium ion cell electrochemical model for intercalation active material electrodes that includes a complex active material/electrolyte interfacial structure. The other is a lithium ion half-cell electrochemical model that focuses on the unique composite structure of the bulk LMR-NMC materials. The LMR-NMC electrode impedance is much higher than the impedance of the NCA and NMC electrodes. The higher impedance of the LMR-NMC electrode suggests that it would be better utilized in a high energy battery rather than a high power battery. The intercalation active material electrochemical model and supporting studies indicate the source of the higher impedance can be associated with a much higher electronic contact resistance between the oxide active material and the conducting carbon additive, as well as the material’s interfacial and bulk transport and kinetic characteristics being significantly worse than the other oxides, as typified by the active material lithium diffusion coefficients for the surface layer and bulk material (DSi and DSb) and the kinetic exchange current density (io). As typical of layered oxide active materials the LMR-NMC electrode impedance increases at low and high SOCs, corresponding to DSi, DSb, and io all decreasing. Further, the rate of decrease in the parameters with SOC (i.e increase in impedance) is higher than observed for the other layered oxides. When the LMR-NMC electrode is allowed to relax for a very long time (i.e. approximately 100 hours) the impedance is observed to be significantly higher. Also, the resulting DSi, DSb, and io parameters determined by the intercalation electrochemical model from the EIS studies during charge and discharge where found to correlate with electrode voltage. This unique behavior for the LMR-NMC electrode is explained by the LMR-NMC bulk reaction and transport electrochemical model, which accounts for the individual domains in the active material. Specifically, the Li2MnO3 domains when allowed to relax are either nearly full or empty depending on the SOC. Because of the large characteristic time constant for the Li2MnO3 domains’ transition, when the LMR-NMC material is used in transportation applications the Li2MnO3 domains typically never relax and the electrode exhibits a lower impedance. The LMR-NMC bulk reaction and transport electrochemical model describes much of the observed behavior that cannot be accounted for using a standard intercalation active material electrochemical model. This includes the voltage hysteresis as shown in Figure 1, as well as the slow relaxation phenomena. However, the complexity of this model makes determining the parameters for the individual domains quite a challenge. ACKNOWLEDGMENT Support from the Vehicle Technologies Program, Hybrid and Electric Systems, David Howell (Team Lead) and Peter Faguy, 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. Figure 1. Electrochemical model simulation of LMR-NMC standard electrode half-cell charge and discharge curves at a C/300 rate. Figure 1

Li- and Mn-rich layered oxides with composition xLi2MnO3·(1 − x)LiMO2 enable high capacity and energy density Li-ion batteries, but suffer from degradation with cycling. Evidence of atomic instabilities during the first charge are addressed in this work with X-ray absorption spectroscopy, first principles simulation at the GGA+U level, and existing literature. The pristine material of composition xLi2MnO3·(1 − x)LiMn0.5Ni0.5O2 is assumed in the simulations to have the form of LiMn2 stripes, alternating with NiMn stripes, in the metal layers. The charged state is simulated by removing Li from the Li layer, relaxing the resultant system by steepest descents, then allowing the structure to evolve by molecular dynamics at 1000 K, and finally relaxing the evolved system by steepest descents. The simulations show that about ¼ of the oxygen ions in the Li2MnO3 domains are displaced from their original lattice sites, and form oxygen–oxygen bonds, which significantly lowers the energy, relative to that of the starting structure in which the oxygen sublattice is intact. An important consequence of the displacement of the oxygen is that it enables about ⅓ of the (Li2MnO3 domain) Mn ions to migrate to the delithiated Li layers. The decrease in the coordination of the Mn ions is about twice that of the Ni ions. The approximate agreement of simulated coordination number deficits for Mn and Ni following the first charge with analysis of EXAFS measurements on 0.3Li2MnO3·0.7LiMn0.5Ni0.5O2 suggests that the simulation captures significant features of the real material.

Lithium- and manganese-rich (LMR) transition metal oxide cathodes are of interest for lithium-ion battery applications due to their increased energy density and decreased cost. However, the advantages in energy density and cost are offset, in part, due to the phenomena of voltage fade. Specifically, the voltage profiles (voltage as a function of capacity) of LMR cathodes transform from a high energy configuration to a lower energy configuration as they are repeatedly charged (Li removed) and discharged (Li inserted). We propose a physical model of voltage fade that accounts for the emergence of a low voltage Li phase due to the introduction of transition metal ion defects within a parent Li phase. The phenomenological model was re-cast in a general form and experimental LMR charge profiles were de-convoluted to extract the evolutionary behavior of various components of LMR capacitance profiles. Evolution of the voltage fade component was found to follow a universal growth curve with a maximal voltage fade capacity of ≈20% of the initial total capacity. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any

In valuing new active materials chemistries for advanced batteries, the theoretical specific energy is commonly used to motivate research and development. A packaging factor is then used to relate the theoretical specific energy to the pack-level specific energy. As this factor is typically assumed constant, higher theoretical specific energies are judged to result in higher pack-level specific energies. To test this implicit assumption, we calculated the fraction of the theoretical specific energy achieved on the pack level for hypothetical cell chemistries with various open-circuit voltages and theoretical specific energies using a peer-review bottom-up battery design model. The pack-level specific energy shows significant dependence on the open-circuit voltage and electrochemical impedance due to changes in the quantity of inactive materials required. At low-valued average open-circuit voltages, systems with dramatically different theoretical specific energies may result in battery packs similar in mass and volume. The fraction of the theoretical specific energy achieved on the pack level is higher for the lower theoretical specific energy systems mainly because the active materials mass dominates the pack mass. Finally, low-valued area-specific impedance is shown to be critical for chemistries of high theoretical specific energy and low open-circuit voltage to achieve higher pack-level specific energies.

Li–S batteries are a promising next-generation battery technology. Due to the formation of soluble polysulfides during cell operation, the electrolyte composition of the cell plays an active role in directing the formation and speciation of the soluble lithium polysulfides. Recently, new classes of electrolytes termed “solvates” that contain stoichiometric quantities of salt and solvent and form a liquid at room temperature have been explored due to their sparingly solvating properties with respect to polysulfides. The viscosity of the solvate electrolytes is understandably high limiting their viability; however, hydrofluoroether cosolvents, thought to be inert to the solvate structure itself, can be introduced to reduce viscosity and enhance diffusion. Nazar and co-workers previously reported that addition of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (TTE) to the LiTFSI in acetonitrile solvate, (MeCN)_2–LiTFSI, results in enhanced capacity retention compared to the neat solvate. Here, we evaluate the effect of TTE addition on both the electrochemical behavior of the Li–S cell and the solvation structure of the (MeCN)_2–LiTFSI electrolyte. Contrary to previous suggestions, Raman and NMR spectroscopy coupled with ab initio molecular dynamics simulations show that TTE coordinates to Li^+ at the expense of MeCN coordination, thereby producing a higher content of free MeCN, a good polysulfide solvent, in the electrolyte. The electrolytes containing a higher free MeCN content facilitate faster polysulfide formation kinetics during the electrochemical reduction of S in a Li–S cell likely as a result of the solvation power of the free MeCN.

This paper reports the results of an initial investigation into the phenomenon of hysteresis in the charge–discharge profile of high-capacity, lithium- and manganese-rich “layered–layered” xLi2MnO3·(1–x)LiMO2 composite cathode structures (M = Mn, Ni, Co) and “layered–layered-spinel” derivatives that are of interest for Li-ion battery applications. In this study, electrochemical measurements, combined with in situ and ex situ X-ray characterization, are used to examine and compare electrochemical and structural processes that occur during charge (lithium extraction) and discharge (lithium insertion) of preconditioned cathodes. Electrochemical measurements of the open-circuit voltage versus lithium content demonstrate a ∼1 V hysteresis in site energy for approximately 12% of the total lithium content during the early cycles, which is markedly different from the hysteresis commonly observed in other intercalation materials. X-ray absorption data indicate structural differences in the cathode at the same stat...

Athree-dimensionalelectrochemicalmodelwasdevelopedtoexaminetheperformance(i.e.impedancedeterminedbyapulsechangeinpotential)ofalithium-ionintercalationpositiveelectrodesingleparticle.Acomprehensiveparameterstudywasconducted,basedona layered nickel oxide parameter set previously developed. The dominance of the interfacial impedance on the particle performanceaccentuates the impact of the secondary particle porosity and electrolyte wetting of the porosity. Electronic distribution effects,includingconductivityandparticlecontacts,alsobecomesignificantwhenthesecondaryparticle’seffectiveconductivityislessthanabout 10

Vehicles with electrified powertrains such as hybrid electric vehicles, plug-in hybrid electric vehicles (PHEVs), and all-electric vehicles (AEVs, which use grid-supplied battery energy exclusively) are potentially marketable because of their low operating costs. However, each vehicle type incurs a significant initial cost penalty compared with a conventional vehicle powered by an internal combustion engine. Three PHEV cars and an AEV car are selected to assess cost-effectiveness from the consumers' perspective. Daily travel to and from work is isolated from other vehicle travel data from the U.S. National Household Travel Survey, and five daily distance categories are investigated. Three driving cycle runs are used: one developed by following cars in Los Angeles, California, in 1992, the Worldwide Harmonized Light-Duty Test Cycle, and a real driving record selected from the Kansas City metropolitan area in Kansas and Missouri. Probable charging patterns for each PHEV and the AEV are investigated for three of five daily distance categories. Overnight charging and workplace charging also are examined. The possibility for multiple charges at work is considered, as is the possibility of a charge after work, before the day's end. The degree of importance of spending a given pool of money to upgrade a residential (versus workplace) charging station is discussed. Two indicators of effectiveness of battery pack utilization are developed [a charge-depleting effectiveness factor and grid kilowatt-hours used per day per dollar of incremental vehicle expense (cost-effectiveness)], and target markets for cars used for work for each powertrain type are suggested.

The concept of embedding a spinel component in high capacity, composite xLi2MnO3•(1−x)LiMO2 (M = Mn, Ni) ‘layeredlayered’ structures to improve their electrochemical properties and cycling stability has been exploited. In this paper, we report the preparation and electrochemical characterization of three-component ‘layered-layered-spinel’ electrodes, synthesized by lowering the lithium content of a parent ‘layered-layered’ 0.3Li2MnO3•0.7LiMn0.5Ni0.5O2 material while maintaining a Mn:Ni ratio of 0.65:0.35; such compounds can be designated generically by the system, LixMn0.65Ni0.35Oy, for which the end members are 0.3Li2MnO3•0.7LiMn0.5Ni0.5O2 (x = 1.3; y = 2.3), in which the average manganese and nickel oxidation states are 4+ and 2+, respectively, and LiMn1.3Ni0.7O4 (x = 0.5; y = 2) in which the corresponding average oxidation states are expected to lie between 4+ and 3.77+ for Mn, and 2.57+ and 3+ for Ni, respectively. For this study, compounds with a lithium content of x = 1.3, i.e., the parent ‘layered-layered’ composition, and 1.25 were selected for detailed and comparative investigation, the latter value corresponding to a targeted spinel content of 6%. The beneficial effects of 1) using Mg 2+ as a dopant ion and 2) treating the electrode particle surface with an acidic solution of AlF3 to enhance cycling stability, reduce first-cycle capacity loss, and to slow voltage decay on cycling are discussed. © 2012 The Electrochemical Society. [DOI: 10.1149/2.049301jes] All rights reserved. Manuscript submitted August 31, 2012; revised manuscript received October 12, 2012. Published November 6, 2012. Since the first rechargeable lithium-ion battery products, based on a C/LiCoO2 electrochemical couple, were commercialized by Sony Corporation in 1991, an explosive growth of the portable electronics industry and the urgent requirement for electrically-powered vehicles to offset the burgeoning cost of gasoline has resulted in intense worldwide efforts to design and develop higher capacity, higher power, safer and environmentally-benign anode and cathode materials. 1–3 Layered LiCoO2 cathodes and their nickel-based analogs have limitations with respect to capacity, thermal stability, and chemical stability at high states of charge, typically when x is >0.5 in Li1−xMO2 (M = Co, Ni). Therefore, there is a need to find alternative cathode materials to replace conventional Co- and Ni-based electrodes. Although considerable progress has been made in increasing the capacity of these electrodes by small amounts of Al or Mg substitution, 4,5 the intrinsic instability and strong oxidizing power of tetravalent nickel and cobalt in highly charged cells in the presence of flammable electrolyte

There are a large number of accounts about rapidly declining costs of batteries with potentially transformative effects, but these accounts often are not based on detailed design and technical information. Using a method ideally suited for that purpose, we find that when experts are free to assume any battery pack design, a majority of the cost estimates are consistent with the ranges reported in the literature, although the range is notably large. However, we also find that 55% of relevant experts’ component-level cost projections are inconsistent with their total pack-level projections, and 55% of relevant experts’ elicited cost projections are inconsistent with the cost projections generated by putting their design- and process-level assumptions into our PBCM. These results suggest a need for better understanding of the technical assumptions driving popular consensus regarding future costs.

Some have raised concerns regarding the contribution of lithium-ion battery pack production to the total electric vehicle energy and emissions profile versus internal combustion vehicles, and about potential battery end-of-life issues. This detailed life cycle analysis (LCA) examines these issues and identifies potential hot-spots within the battery pack life cycle for five cathode materials and a proposed lithium metal anode. The battery assembly stage, identified by some as an energy concern, is determined to be problematic only for “pioneer” plants (i.e. low-throughput facilities), but not for at-capacity plants, and battery electric vehicles with batteries from either facility type outperform conventional vehicles in terms of lowering GHG emissions. For at-capacity plants, the battery materials dominate energy impacts, with cathode materials representing 10–50% of that energy, depending on cathode type. Recycling can further mitigate battery life-cycle impacts, while also being economically attractive for all cathode materials, even those with low elemental values.

There are a large number of accounts about rapidly declining costs of batteries with potentially transformative effects, but these accounts often are not based on detailed design and technical information. Using a method ideally suited for that purpose, we find that when experts are free to assume any battery pack design, a majority of the cost estimates are consistent with the ranges reported in the literature, although the range is notably large. However, we also find that 55% of relevant experts’ component-level cost projections are inconsistent with their total pack-level projections, and 55% of relevant experts’ elicited cost projections are inconsistent with the cost projections generated by putting their design- and process-level assumptions into our process-based cost model (PBCM). These results suggest a need for better understanding of the technical assumptions driving popular consensus regarding future costs. Approaches focusing on technological details first, followed by non-aggregated and systemic cost estimates while keeping the experts aware of any discrepancies, should they arise, may result in more accurate forecasts.

Nonaqueous redox flow batteries are a fast-growing area of research and development motivated by the need to develop low-cost energy storage systems. The identification of a highly conductive, yet selective membrane, is of paramount importance to enabling such a technology. Herein, we report the swelling behavior, ionic conductivity, and species crossover of lithiated Nafion 117 membranes immersed in three nonaqueous electrolytes (PC, PC : EC, and DMSO). Our results show that solvent volume fraction within the membrane has the greatest effect on both conductivity and crossover. An approximate linear relationship between diffusive crossover of neutral redox species (ferrocene) and the ionic conductivity of membrane was observed. As a secondary effect, the charge on redox species modifies crossover rates in accordance with Donnan exclusion. The selectivity of membrane is derived mathematically and compared to experimental results reported here. The relatively low selectivity for lithiated Nafion 117 in nonaqueous conditions suggests that new membranes are required for competitive nonaqueous redox flow batteries to be realized. Potential design rules are suggested for the future membrane engineering work., United States. Dept. of Energy. Office of Basic Energy Sciences. Joint Center for Energy Storage Research

An approach for the volume averaged numerical modeling of phase-transition intercalation electrodes is presented for lithiated graphite, LixC6, in lithium-ion batteries. The proposed method directly treats phase formation and growth through a modified form of the Avrami equation enabling the physics-based mathematical model to capture the additional time constant observed in the two phase regions of lithiated graphite as well as a portion of the hysteresis commonly observed between charge and discharge voltage. The graphite phase diagram was taken to be composed of three stages, or phases, each with a Nernstian or ideal solution based equilibrium potential function. The behavior of the potential rise from a current pulse in the two-phase region is matched well with this methodology resulting in higher valued diffusion coefficients than found when only a single-phase approach is used. Simulated results for mesocarbon microbeads show the co-existence of all three phases within the electrode during higher rate discharges. Concentration dependent diffusion coefficients are found to be necessary to match experimental results at rates significantly higher than 1C. The model is shown to be capable of exhibiting core-shell behavior when fitted phase-transformation rate constants are sufficiently high in value, although not observed for MCMB.

The commercial introduction of the lithium-ion (Li-ion) battery nearly 25 years ago marked a technological turning point. Portable electronics, dependent on energy storage devices, have permeated our world and profoundly affected our daily lives in a way that cannot be understated. Now, at a time when societies and governments alike are acutely aware of the need for advanced energy solutions, the Li-ion battery may again change the way we do business. With roughly two-thirds of daily oil consumption in the United States allotted for transportation, the possibility of efficient and affordable electric vehicles suggests a way to substantially alleviate the Country's dependence on oil and mitigate the rise of greenhouse gases. Although commercialized Li-ion batteries do not currently meet the stringent demands of a would-be, economically competitive, electrified vehicle fleet, significant efforts are being focused on promising new materials for the next generation of Li-ion batteries. The leading class of materials most suitable for the challenge is the Li- and manganese-rich class of oxides. Denoted as LMR-NMC (Li-manganese-rich, nickel, manganese, cobalt), these materials could significantly improve energy densities, cost, and safety, relative to state-of-the-art Ni- and Co-rich Li-ion cells, if successfully developed.1 The success or failure of such a development relies heavily on understanding two defining characteristics of LMR-NMC cathodes. The first is a mechanism whereby the average voltage of cells continuously decreases with each successive charge and discharge cycle. This phenomenon, known as voltage fade, decreases the energy output of cells to unacceptable levels too early in cycling. The second characteristic is a pronounced hysteresis, or voltage difference, between charge and discharge cycles. The hysteresis represents not only an energy inefficiency (i.e., energy in vs energy out) but may also complicate the state of charge/depth of discharge management of larger systems, especially when accompanied by voltage fade. In 2012, the United States Department of Energy's Office of Vehicle Technologies, well aware of the inherent potential of LMR-NMC materials for improving the energy density of automotive energy storage systems, tasked a team of scientists across the National Laboratory Complex to investigate the phenomenon of voltage fade. Unique studies using synchrotron X-ray absorption (XAS) and high-resolution diffraction (HR-XRD) were coupled with nuclear magnetic resonance spectroscopy (NMR), neutron diffraction, high-resolution transmission electron microscopy (HR-TEM), first-principles calculations, molecular dynamics simulations, and detailed electrochemical analyses. These studies demonstrated for the first time the atomic-scale, structure-property relationships that exist between nanoscale inhomogeneities and defects, and the macroscale, electrochemical performance of these layered oxides. These inhomogeneities and defects have been directly correlated with voltage fade and hysteresis, and a model describing these mechanisms has been proposed. This Account gives a brief summary of the findings of this recently concluded, approximately three-year investigation. The interested reader is directed to the extensive body of work cited in the given references for a more comprehensive review of the subject.

Battery design is a critical aspect of material and system development that leads to the commercialization of effective electrochemical energy storage systems. Successful modeling of battery designs relies upon accurate calculation of the area specific impedance (ASI). A simplified calculation of the ASI is presented that accounts for physical limitations without performing computationally expensive calculations. The limiting currents for transport within the electrolyte and within the intercalation materials are implemented into a linear form of the Butler–Volmer equation to calculate the interfacial impedance. Lithium-ion batteries are then designed to examine the effect of power to energy ratio on battery dimensions. A large ASI is shown to be detrimental to battery design regardless if the increase in impedance results from mass transport limitations or a reduction in electrochemical active area due to small electrode loadings. The smaller electrochemical active area does not increase the voltage losses of a battery when a constant C-rate is maintained. However, the higher ASI values from low electrode loadings require a larger separator and current collector area resulting in a greater battery volume and weight to achieve similar energy and power requirements when compared to a system with a lower ASI.

Concentrated solution theory as it relates to the design of electrochemical systems is reviewed. Specific examples for lithium ion batteries and PEM fuel cells are presented.

The electrochemical oxidation of carbon black catalyst supports is recognized as a durability challenge to the commercialization of low-temperature fuel cells in the transportation sector. An investigation of the effect of the transient potentials experienced in this environment is presented. The exposure of carbon black to square wave potential cycling results in an oxidation process different than the constant potential hold historically used to characterize this corrosion process. The differences are characterized using the liquid half-cell and single fuel cell testing, coupled with electrochemical techniques and online gas analysis. Although cyclic voltammetry and X-ray photoelectron spectroscopy are unable to quantify significant differences in the surface oxide chemistry, online gas analysis measurements demonstrate different corrosion activities.

The Greenhouse gases, Regulated Emissions and Energy use in Transportation (GREET) model has been expanded to include four new cathode materials that can be used in the analysis of battery-powered vehicles: lithium nickel cobalt manganese oxide (LiNi0.4Co0.2Mn0.4O2 [NMC]), lithium iron phosphate (LiFePO4 [LFP]), lithium cobalt oxide (LiCoO2 [LCO]), and an advanced lithium cathode (0.5Li2MnO3∙0.5LiNi0.44Co0.25Mn0.31O2 [LMR-NMC]). In GREET, these cathode materials are incorporated into batteries with graphite anodes. In the case of the LMR-NMC cathode, the anode is either graphite or a graphite-silicon blend. Lithium metal is also an emerging anode material. This report documents the material and energy flows of producing each of these cathode and anode materials from raw material extraction through the preparation stage. For some cathode materials, we considered solid state and hydrothermal preparation methods. Further, we used Argonne National Laboratory’s Battery Performance and Cost (BatPaC) model to determine battery composition (e.g., masses of cathode, anode, electrolyte, housing materials) when different cathode materials were used in the battery. Our analysis concluded that cobalt- and nickel-containing compounds are the most energy intensive to produce.

Flow batteries are a promising technology for storing and discharging megawatt hours of electrical energy on the time scale of hours. The separator between the positive and negative electrodes strongly affects technical and economic performance. However, requirements for separators have not been reported in a general manner that enables quantitative evaluation of new systems such as nonaqueous flow batteries. This gap is addressed by deriving specifications for transport properties that are chemistry agnostic and align with aggressive capital cost targets. Three key transport characteristics are identified: area-specific resistance RΩ, crossover current density ix, and the coupling between crossover and capacity loss Ψ. Suggested maximum area-specific resistances are 0.29 and 2.3 Ω·cm[superscript 2] for aqueous and nonaqueous batteries, respectively. Allowable crossover rates are derived by considering the possible fates of active molecules that cross the separator and the coupling between Coulombic efficiency (CE) and capacity decline. The CE must exceed 99.992% when active species are unstable at the opposing electrode, while a CE of 97% can be tolerated when active molecules can be recovered from the opposing electrode. The contributions of diffusion, migration, and convection are discussed, quantified, and related to the physical properties of the separator and the active materials., United States. Department of Energy. Office of Basic Energy Sciences (Joint Center for Energy Storage Research)

6Li NMR spectroscopy is used to quantitatively characterize local lithium environments that dominate the free energy for site occupation and to monitor the evolution of local order and low concentration defect formation with the goal of correlating local structural changes with hysteresis and voltage fade phenomena observed in layered lithium and manganese rich TM oxide cathode structures. We have undertaken an isotopic enrichment strategy coupled with very long acquisition times to obtain unprecedented, and quantitative, high-resolution data for cycled electrodes using fully enriched cell components. This strategy has allowed the determination of structure-activity relationships and monitoring the evolution of local order and low concentration defect formation with the goal of correlating local structural changes with hysteresis and voltage fade phenomena. We report new 6Li resonances centered at ~1600ppm that are assigned to LiMn6-TMtet sites, specifically, a hyperfine shift related to a small fraction of reentrant tetrahedral transition metals (Mntet), located above or below lithium layers, coordinated to LiMn6 units. The intensity of the TM layer lithium sites correlated with tetrahedral TMs loses intensity after cycling, indicating limited reversibility of TM migrations upon cycling. These findings reveal that defect sites, even in dilute concentrations, can have a profound effect on the overall electrochemical behavior.

Electrochemical studies demonstrate a strong correlation between the phenomena of hysteresis and voltage fade in lithium- and manganese-rich layered transition-metal oxide electrodes. A mechanism is proposed that entails both the reversible and irreversible migration of transition metal ions. Their reversible migration to a metastable configuration, suggested to involve the occupation of tetrahedral sites in the lithium layer, is manifested as a 1 V hysteresis in site energy for 10–15% of the lithium content. The irreversible migration of the transition metal ions through the metastable ‘hysteresis’ sites to localized and lower energy cubic environments results in the observed voltage fade phenomenon. Keywords: Lithium-ion, Cathode, Decay mechanism, Destabilization, Tetrahedral site, Intercalation

Lithium sulfur (Li-S) battery is a promising alternative technology of lithium ion batteries. However, due to the complicity of the chemistry in Li-S batteries, the mechanism is not well understood. In addition, the co-existence of soluble species and insoluble species limits the application of other characterization techniques. The sensitivity and element selectivity make NMR spectroscopy a powerful tool to study the changes in local chemical environment and speciation process in Li-S batteries. In this study, in situ 7Li NMR spectroscopy was employed where plastic pouch cells were assembled and cycled in the magnet while NMR spectra were acquired simultaneously. Method to quantitatively study entire lithium inventory in a Li-S battery is developed and implemented, and the cell design is optimized for electrochemical performance and spectroscopic resolution. This methodology can be readily extended to Li-S batteries with other electrolytes where the speciation process can be tracked and analyzed. The development of electrolyte will also benefit greatly from the detailed understanding of the Li-S battery speciation process as well as the additive development. [1] See, et. al., J. Am. Chem. Soc., 2014, 136 (46), pp 16368–16377 [2] Xiao, et. al., Nano Lett., 2015, 15, 3309-3316

Achieving reversible electrochemistry under lean electrolyte operation is key to moving LiS chemistry to potentially transformational performance.1 The use of electrolytes that are sparingly solvating to Li polysulfide intermediates is a promising approach to decouple electrolyte volume from reaction mechanism, thus creating a pathway towards high energy density LiS batteries that deviates from the current catholyte approach.2In this work, we discuss the design rules for sparingly solvating electrolytes and the unique electrochemistry that arises through the use of this class of electrolytes. 1D. Eroglu, K. R. Zavadil and K. G. Gallagher, J. Electrochem. Soc., 2015, 162, A982. 2L. Cheng, L. A. Curtiss, K. R. Zavadil, A. A. Gewirth, Y. Shao and K. G. Gallagher, ACS Energy Lett., 2016, 1, 503.

It is well known that Li-ion cells containing manganese oxide-based positive electrodes and graphite-based negative electrodes suffer accelerated capacity fade, which has been attributed to the deposition of dissolved manganese on the graphite electrodes during electrochemical cell cycling. However, the reasons for the accelerated capacity fade are still unclear. This stems, in part, from conflicting reports of the oxidation state of the manganese species in the negative electrode. In this communication, the oxidation state of manganese deposited on graphite electrodes has been probed by X-ray absorption near edge spectroscopy (XANES). The XANES features confirm, unequivocally, the presence of fully reduced manganese (Mn(0)) on the surface of graphite particles. The deposition of Mn(0) on the graphite negative electrode acts as a starting point to understand the consequent electrochemical behavior of these electrodes; possible reasons for the degradation of cell performance are proposed and discussed.

Predicting the interrelation of lithium-ion battery performance and cost (BatPaC) is critical to understanding the origin of the manufacturing cost, pathways to lower these costs, and how low these costs may fall in the future. A freely available BatPaC model is presented that enables a direct evaluation of manufacturing cost. After the basis for the model is detailed, an in-depth discussion of the cost drivers highlights the most significant contributions to the total battery cost. Approaches to reducing battery cost are presented within the context of materials, engineering, and manufacturing.