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Discovery of new electrochemical redox motifs is essential to expand the design landscape for energy-dense batteries. We report a family of fluorinated reactants based on pentafluorosulfanyl arenes (R-Ph-SF5) that allow for high electron-transfer numbers (up to 8-e−/reactant) by exploiting multiple coupled redox processes, including extensive S–F bond breaking, yielding capacities of 861 mAh·greactant−1 and voltages up to ∼2.9 V when used as catholytes in primary Li cells. At a cell level, gravimetric energies of 1,085 Wh·kg−1 are attained at 5 W·kg−1 and moderate temperatures of 50 °C, with 853 Wh·kg−1 delivered at >100 W·kg −1, exceeding all leading primary batteries based on electrode + electrolyte (substack) mass. Voltage compatibility of R-Ph-SF5 reactants and carbon monofluoride (CFx) conversion cathodes further enabled investigation of a hybrid battery containing both fluorinated catholyte and cathode. The hybrid cells reach extraordinarily high cell active mass loading (∼80%) and energy (1,195 Wh·kg−1), allowing for significant boosting of substack gravimetric energy of Li−CFx cells by at least 20% while exhibiting good shelf life and safety characteristics. [ABSTRACT FROM AUTHOR]

The high energy density of fluorinated graphite (CF x) based lithium primary battery has aroused tremendous attention. However, the nonconductive CF x always induces high interface impedance and low power density. Herein, the carbon conductive network is generated by thermal treatment of resorcinol/formaldehyde (RF) resin on CF x and RF resin spheres (RF RSs), a conductive carbon layer coats on CF x surface, the electrical conductivity of CF x is improved. The oxygen functional groups in incomplete carbonized RF RSs also dedicate to the electrochemical performance of CF x. When different mass ratios of CF x /RF RSs are employed, the cathodes exhibit improved rate performance and voltage plateaus, and the initial voltage delays observed in CF x are significantly reduced. Notably, CF x /RF RSs−13 cathode delivers an impressive discharge capacity of 843.8 mAh g−1 with a voltage plateau of 2.68 V at 10 mA g−1. This leads to the maximum energy density of 2174.9 Wh kg−1 and a peak power density of 18600 W kg−1. Additionally, CF x /RF RSs−13 cathode demonstrates commendable electrochemical stability across a wide temperature spectrum (−20–70 °C). Given these superior electrochemical attributes, the CF x /RF RSs combination holds significant promise for deployment in high-power devices and for standard operations under extreme temperature conditions. • Carbon conductive network is induced by heat treatment of RF resin on CF x and RF RSs. • Oxygen functional groups in RF RSs also make for electrochemical performance of CF x. • CF x /RF RSs−13 gives peak energy and power densities of 2174.9 Wh kg−1, 18600 W kg−1. • CF x /RF RSs−13 demonstrates commendable electrochemical stability from −20 to 70 °C. [ABSTRACT FROM AUTHOR]

We present a Hybrid Multiphase Porous Electrode Theory (Hybrid-MPET) model that accurately predicts the performance of Medtronic's implantable medical device battery lithium/carbon monofluoride (C F x) - silver vanadium oxide (SVO) under both low-rate background monitoring and high-rate pulsing currents. The distinct properties of multiple active materials are reflected by parameterizing their thermodynamics, kinetics, and mass transport properties separately. Diffusion limitations of Li + in SVO are used to explain cell voltage transient behavior during pulse and post-pulse relaxation. We also introduce change in cathode electronic conductivity, Li metal anode surface morphology, and film resistance buildup to capture evolution of cell internal resistance throughout multi-year electrical tests. We share our insights on how the Li + redistribution process between active materials can restore pulse capability of the hybrid electrode, allow C F x to indirectly contribute to capacity release during pulsing, and affect the operation protocols and design principles of batteries with other hybrid electrodes. We also discuss additional complexities in porous electrode model parameterization and electrochemical characterization techniques due to parallel reactions and solid diffusion pathways across active materials. We hope our models can complement future experimental research and accelerate development of multi-active material electrodes with targeted performance. • Hybrid-MPET model of Medtronic's high-rate Li/CF x -SVO battery is presented. • Separate material properties, diffusion limitation, and aging are accounted for. • Model prediction accuracy is validated on large battery dataset. • Cell pulse capability restoration is explained by Li＋ redistribution across materials. • Li＋ redistribution impact on general cell operation and design principles are discussed. [ABSTRACT FROM AUTHOR]

Medtronic Implantable Cardioverter Defibrillators (ICDs) and Cardiac Resynchronization Therapy Defibrillators (CRT-Ds) rely on high-energy density, lithium batteries, which are manufactured with a special lithium/carbon monofluoride (C F x)–silver vanadium oxide (SVO) hybrid cathode design. Consistently high battery performance is crucial for this application, since poor performance may result in ineffective patient treatment, whereas early replacement may involve surgery and increase in maintenance costs. To evaluate performance, batteries are tested, both at the time of production and post-production, through periodic sampling carried out over multiple years. This considerable amount of experimental data is exploited for the first time in this work to develop a data-driven, machine learning approach, relying on Generalized Additive Models (GAMs) to predict battery performance, based on production data. GAMs combine prediction accuracy, which enables evaluation of battery performance immediately after production, with model interpretability, which provides clues on how to further improve battery design and production. Model interpretation allows to identify key features from the battery production data that offer physical insights to support future battery development, and foster the development of physics-based model for hybrid cathode batteries. The proposed approach is validated on 21 different datasets, targeting several performance-related features, and delivers consistently high prediction accuracy on test data. • ICD battery reliability is ensured with life-test experiments spanning multiple years. • ML provides accurate prediction of life-test experiments based on production data. • Interpretable ML fosters the development of battery design and physics-based models. • Approach is validated on 21 datasets, analysed for the first time in the literature. [ABSTRACT FROM AUTHOR]

Although the primary lithium/fluorinated graphite battery has a high energy density of 3725 Wh kg−1, its complete irreversibility based on a conversion reaction between Li and fluorinated graphite hampers wide applications in rechargeable systems. Here, a new rechargeable three‐electrode battery configuration involving lithium, fluorinated graphite, and sulfur electrodes is developed, in which the initial middle‐fluorinated graphite cathode can be electrochemically transformed into a hybrid lithium anode, showing a low overpotential (12 mV), long cycle life (2000 h) and good deep stripping/plating features. This rechargeable battery delivers a high gravimetric energy density of 507.7 Wh kg−1 on the basis of the total mass of the three‐electrode materials. Moreover, the excessive consumption of lithium in the system can be in situ replenished, further lengthening the lifespan. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nitrogen doped sub-fluorinated graphite with larger layer spacing material. • Simple and effective modified method without high temperature or pressure. • Fluorinated graphite can obtain a power density of 40.23 kW kg−1. • The dependence of cathode material structure, LiF and cathode swelling is provided. Lithium/carbon fluorides batteries own a high theoretical energy density of 2180 Wh kg−1 and exceptional shelf life, but poor electrode kinetics, low electronic conductivity of cathode, and cathode swelling during discharge. In this work, fluorinated graphite is modified by a controllable solvent treatment using N-methyl-2-pyrrolidone at medium temperature (50 ∼ 90 °C). The modified fluorinated graphite is doped with nitrogen atoms and owns increased interlayer spacing and electrochemical active semi-ionic C F bonds, providing a higher conductivity and facilitating the diffusion of Li+ or solvent Li+. The maximum power density of the modified fluorinated graphite is 40.23 kW kg−1 at 25C. To elucidate the cathode swelling of the fluorinated graphite, in-situ confocal optical microscope and in-situ X-ray diffraction are conducted for the first time. It is found that the formation and accumulation of crystalline LiF during discharge, as well as the interlayer spacing of fluorinated graphite, are related to the cathode swelling in liquid electrolyte. [ABSTRACT FROM AUTHOR]

After a review on the wide variety of inorganic fluorinated components in modern technologies, in particular for energy conversion/storage systems, the use of fluorinated carbons as electrodes for primary lithium batteries will be highlighted; in particular conventional graphite fluorides will be compared to recently investigated fluorinated carbon nanoparticles (F-CNPs) prepared from electrochemical reduction of molten carbonates. [ABSTRACT FROM AUTHOR]

Abstract: Fluorine compounds are quite useful as energy conversion materials, in particular as primary and secondary lithium battery materials. Primary lithium battery with graphite fluoride cathode was commercialized in 1973, based on the research on graphite fluoride. Since then, it has been shown that fluorine compounds are useful and attractive materials for lithium batteries. The present account paper reports the historical aspects and update topics on fluorine compounds such as graphite fluorides, fluorine–graphite intercalation compounds and organo-fluorine compounds as energy conversion materials. Surface modification by fluorine is also reported. [Copyright &y& Elsevier]

Abstract: Electrochemical studies of three types of CF x (F – fiber based, C – petroleum coke based, G – graphite based) have demonstrated different electrochemical performances in previous work, with fiber based CF x delivering superior performance over those based on petroleum coke and graphite. 13C and 19F MAS (magic angle spinning) NMR techniques are employed to identify the atomic/molecular structural factors that might account for differences in electrochemical performance among the different types of CF x . Small quantitative variations of covalent CF and LiF are noted as a function of discharge and sp3 bonded carbons are detected in discharged F type of CF x . [Copyright &y& Elsevier]

Abstract: The electrochemical performances of fluorinated graphite have been improved by coating a uniform carbon layer on commercial CF x (x =1) powder used as cathode material in lithium battery. In comparison with the cell using un-coated CF x as cathode, the cell using carbon coated CF x cathode has a higher energy density and higher power density, particularly at higher discharge current rates (1C above). This is because the conductive carbon coating provides the exterior connectivity between particles for facile electron conduction, resulting in high rate performance. [Copyright &y& Elsevier]

Abstract: Carbothermal treatment was used to improve the discharge rate performance of primary lithium/carbon monofluoride (Li/CF x with x =1) batteries. The treatment was carried out by heating a mixture of CF x and carbon black (CB) just below the decomposition temperature of CF x under nitrogen for 2h. In the treatment, poly(vinylidene fluoride-co-hexafluoropropylene) (Kynar) was used as a fluorinated polymer binder to press the CF x /CB mixture into pellets. It was shown that the content of Kynar significantly affected the discharge performance of the resulting treated-CF x (T-CF x ). This can be attributed to the catalytic effect of HF formed by the pyrolysis of Kynar on the decomposition of CF x and on the reaction of CB with the volatile fluorocarbons formed by the decomposition of CF x . The discharge performance of T-CF x cathode was also affected by the temperature of carbothermal treatment and by the ratio of CF x to CB. In this work the best result was obtained from a treatment conducted at 470°C on a 87CF x /10CB/3Kynar (by weight) mixture. In the discharge condition of C/5 and 20°C, the Li/CF x cell with such-obtained T-CF x cathode showed about 95mV higher voltage than the control cell while retaining nearly the same specific capacity. Impedance analyses indicate that the improved discharge performance is mainly attributed to a reduction in the cell reaction resistance (R cr) that includes an ohmic resistance related to the ionic conductivity of the discharge product shell and a Faradic resistance related to the processes of charge-transfer and Li+ ion diffusion in the CF x reaction zone. [Copyright &y& Elsevier]

Abstract: In this work, a 1:1 by weight blend of acetonitrile (AN) and γ-butyrolactone (BL) was studied as the solvent of low temperature electrolyte for high energy density Li/CF x batteries. Both visual observation and impedance analysis show that metallic Li is kinetically stable in a 0.5m LiBF4 1:1 AN/BL electrolyte. This property is attributed to the formation of a protective passivation film on the surface of metallic Li, and it has been successfully used to develop the low temperature electrolyte for Li/CF x cells. It is shown that the cell with such an electrolyte outperforms the control cell with 0.5m LiBF4 1:1 (wt.) propylene carbonate (PC)/1,2-dimethoxyethane (DME) electrolyte in both power capability and low temperature discharge performance. Impedance analyses reveal that the improved discharge performance is attributed to the reduction in both the bulk resistance and cell reaction resistance of the Li/CF x cell, which is related to the high ionic conductivity of the AN/BL electrolyte. Due to the chemical incompatibility between metallic Li and AN at high temperatures, the storage and operation temperature for the Li/CF x cells with 0.5m LiBF4 1:1 AN/BL electrolyte is limited to or below ambient temperature (30°C). [Copyright &y& Elsevier]

Abstract: dc-polarization and ac-impedance techniques were used to analyze the discharge characteristic of a primary Li/CF x cell. In most cases, impedance spectrum of a Li/CF x cell shows a suppressed semicircle followed by a sloping straight line. The semicircle is shown to present a cell reaction resistance (R cr), which reflects an ohmic resistance (mainly, ionic conductivity of the discharge product shell) and a charge-transfer process. It is shown that the overall resistance of a Li/CF x cell is dominated by the CF x cathode, whose resistance is further dominated by the R cr that is found to be extremely sensitive to the temperature. Therefore, the low temperature performance and rate capability of a Li/CF x cell are mainly determined by the CF x cathode. In addition, based on the discharge curve and open circuit voltage (OCV) recovery of a Li/CF x cell, we proposed a “core-shell” model consisting of a shrinking “CF x core” and a growing “product shell” for the discharge process of CF x cathode. The “product shell” plays an important role in the discharge performance of Li/CF x cells. [Copyright &y& Elsevier]

Herein, we suggest a new way to improve the cycling stability of the lithium-metal battery by using a separator coated by carbon monofluoride (CF x). CF x has been used as a cathode material for a lithium primary battery and is converted to LiF and carbon during the discharge process. The CF x -coated separator with 5 μm thickness is obtained by casting a CF x -containing slurry on a bare polyethylene separator and the CF x -coated separator is characterized in a LiCoO 2 (LCO) // Li cell. The CF x -coated separator enables a better cycling stability up to 200 cycles than the bare separator due to its dual functions: 1) capturing cobalt ions dissolved from the LCO cathode and 2) formation of a thin and stable SEI layer containing LiF on the lithium metal anode. Employment of the CF x -coated separator also leads to much suppressed dendritic growth of lithium and stable interfacial resistance during the cycle. Unlabelled Image • We prepare a separator coated with carbon monofluoride (CF x) for Li-metal battery. • The CF x on the separator is converted to LiF and carbon in the 1st discharge process. • The cobalt ions dissolved from the LCO cathode are captured by the CF x coating layer. • A thin and stable SEI layer containing LiF is formed on the lithium metal anode. • The bifunctions of the CF x -coating enables good cycling stability of a LCO//Li cell. [ABSTRACT FROM AUTHOR]

A new electrochemical method is demonstrated for the synthesis of carbon-metal fluoride nanocomposites at room temperature. • A new electrochemical method is demonstrated for the synthesis of C-MF x at RT. • Electrochemical intercalation of transition metal ions into graphite fluoride (CF x). • C-FeF 2 , C-NiF 2 was synthesized by electrochemical intercalation of Fe2+, Ni2+ in CF x. • Electrochemical method for the synthesis of carbon-metal fluoride nanocomposites. Herein we have demonstrated an electrochemical method for the synthesis of carbon-metal fluoride nanocomposites (CMFNCs). Electrochemical intercalation of transition metal ions into graphite fluoride (CF x) resulted in the formation of CMFNCs. As a proof-of-concept, we have synthesized C-FeF 2 and C-NiF 2 nanocomposites by the electrochemical intercalation of Fe2+ and Ni2+ into CF x from corresponding non-aqueous electrolytes. The C-FeF 2 and C-NiF 2 nanocomposites synthesized by this method showed high reversible capacity and cycling stability compared to chemically synthesized analogs as cathode materials for lithium batteries. The reversible capacity of chemically synthesized C-FeF 2 is 181 mAh g−1, whereas electrochemically synthesized material is 349 mAh g−1 after 20 cycles. The better cycling performance of electrochemically synthesized C-FeF 2 was attributed to the homogeneous distribution of FeF 2 nanoparticles within the carbon matrix enabled by the electrochemical intercalation of Fe2+. The electrochemical method described here is emission-free, cost-effective, occurs at room temperature, and extendable to the synthesis of several other CMFNCs. Moreover, it might provide new avenues for the synthesis of advanced functional materials. [ABSTRACT FROM AUTHOR]