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This paper proposes low-melting-point eutectic salts containing RbCl as electrolytes for light weight thermal batteries. The handleability of the eutectic salts was remarkably improved for commercialisation. Their performance as thermal battery molten-salt electrolytes was verified using tests on a single cell and a 12-cell stacked battery.

This paper reports a novel synthesis of iron (Fe) powders in which high-purity and controlled primary and secondary assembled particles can be produced at low cost with safe process. Iron hydroxide powder precursors with fine-sized and acicular morphology were prepared and then reduced at an optimum temperature under reducing atmosphere by using single-step and two-step reduction. In the case of two-step reduction, the precursor powders were reduced by using a hydrogen/argon mixed gas for 1.5 h with a subsequent second reduction using higher hydrogen/argon mixed gas for 2 h. The morphology of the Fe powders strongly depends on the reduction conditions and precursor's morphology. The two-step reduced powders had pure iron powders with large elongated shape and porous sponge-like interlocking structure. The synthesized Fe powders were mixed with KClO4 and the pyrotechnic performance was examined. It is found that metal powder prepared by using two-step reduction is very suitable for producing porous sponge-like microstructure and for pyrotechnic applications.

Thin cathodes for thermal batteries with good homogeneity and a reproducible thickness were prepared using a tape-casting process. A single cell fabricated with a 100 µm thick cathode using tape-casting process exhibited a specific capacity of 1934.08 A s/g. In contrast, a single cell fabricated with a pellet type 500 µm thick cathode demonstrated a specific capacity of 1000.25 A s/g. The thin cathode, which exhibited excellent utilization of the electrode material due to the optimal thickness from an electrochemical point of view, showed good mechanical strength and excellent electrochemical properties making it suitable for use in thermal batteries.

The use of a thermally and chemically stable ceramic felt separator for thermal batteries is believed to enhance the reliability by minimizing the sudden failure of an electrolyte upon shock compared to the conventional pellet-pressed one. To achieve desirable electrochemical properties for applications in thermal batteries, the separator should hold a sufficient amount of molten electrolyte with a minimal leakage to prevent physical contact between the cathode and anode. In addition, the chemical stability of the separator materials should be maintained under a very reactive molten Li-salt electrolyte environment to confer high ionic conductivity and reliability. To assess the feasibility of 3 types of ceramic felt as a separator for thermal batteries, 2 types of Al2O3 felt with different porosity and one ZrO2 felt are examined using binary LiCl-KCl and ternary LiF-LiCl-LiBr as the electrolytes. This Part 1 explains the wetting, loading and leakage behaviors of the ceramic felts for molten electrolytes along with the chemical stability. The ionic conductivity of the electrolytes and electrochemical properties of the resulting thermal batteries will be presented in Part 2.

In this Part 2, the ionic conductivity of molten salt electrolytes, the electrochemical properties of single cells containing a ceramic separator infiltrated with an electrolyte, and the mechanical strength of the electrolyte layer are compared with those of the conventional pellet-pressed structure. The ionic conductivity for the molten electrolyte is higher than that of the previous report for both LiCl-KCl and LiF-LiCl-LiBr electrolytes, which is explained by the decrease in contact resistance using a graphite electrode instead of stainless steel. The electrochemical performance of the single cells containing a ceramic felt separator assembled with Li(Si)/FeS2 electrodes shows longer operating time to a cut off voltage of 1.3 V compared to the conventional MgO-contained single cell. In addition, the flexural strength of the electrolyte layer with the ceramic felt separators is in the range of 2.80–6.29 kgf cm−2, which is incomparable to that (=0.01 kgf cm−2) of the pellet-pressed conventional separator. These findings suggest that the ceramic felt separator can be an alternative to mitigate the current problems of pellet-pressed structure in thermal batteries, enhancing the mechanical strength and electrochemical properties.

In this study, we fabricated a cathode with lower amounts of additive materials and higher amounts of active materials than those of a conventional cathode. A thermal battery was fabricated using FeS2 treated foam as the cathode frame, and its feasibility was verified. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to analyze the effects of thermal sulfidation temperature (400 and 500°C) on the structure and surface morphology of the FeS2 foam. The optimal temperature for the fabrication of the FeSx treated foam was determined to be 500°C. The FeS2 treated foam reduced the interfacial resistance and improved the mechanical strength of the cathode. The discharge capacity of the thermal battery using the FeS2 treated foam was about 1.3 times higher than that of a thermal battery using pure Fe metal foam.

In this study, we fabricated a cathode with lower amounts of additive materials and higher amounts of active materials than those of a conventional cathode. A thermal battery was fabricated using FeS2 treated foam as the cathode frame, and its feasibility was verified. X-ray diffraction, transmission electron microscopy, and scanning electron microscopy were used to analyze the effects of thermal sulfidation temperature (400 and 500°C) on the structure and surface morphology of the FeS2 foam. The optimal temperature for the fabrication of the FeSx treated foam was determined to be 500°C. The FeS2 treated foam reduced the interfacial resistance and improved the mechanical strength of the cathode. The discharge capacity of the thermal battery using the FeS2 treated foam was about 1.3 times higher than that of a thermal battery using pure Fe metal foam.

The polymer binder, poly(imide-co-siloxane) (PIS), was synthesized and applied to form a thin cathode layer composites for a thermal battery that has an unusually high operating temperature of 450 °C. The PIS was prepared through cross-linking of the polyimide with polysiloxane. The morphology of FeS2/PIS composites showed that FeS2 particles was coated with the PIS cross-linked gel. The FeS2/PIS composites enabled to fabricate mechanically stable thin cathode layer that was 20–10% of the thickness of a conventional pellet-type cathode. The FeS2/PIS composites were stable up to 400 °C and maintained their morphology at this temperature. PIS coating layers decomposed at 450 °C and a new residue was generated, which was observed by transmission electron microscopy and the compositional change was analyzed. The FeS2/PIS composites showed enhanced thermal stability over that of FeS2 in thermogravimetric analysis. The thermal battery with the PIS polymer binder showed a 20% discharge capacity increase when compared to a conventional pellet-type cathode.

The three-dimensional (3D), nitrogen doped reduced graphene oxide (N-RGO) monoliths have been synthesized using graphene oxide and melamine through an ice-templated assembly. The self-assembled monoliths are accompanied with the considerable reduction of graphene oxide after annealing and specific surface area of 190 m 2 g −1 . The blue shift of approximately 22 cm −1 and 4 cm −1 in D and G bands for N-RGO is notified in Raman analysis, confirming the incorporation of nitrogen onto the graphene sheet. In addition, an extra peak at 1251 cm −1 appears possibly due to the stretching vibration of C–N bonds. The detailed doping configurations analyzed by x-ray photoemission spectroscopy indicate the nitrogen content of around 6.2 at% in the N-RGO with predominant pyridinic N-type configuration. The specific capacitance is enhanced up to 217 F g −1 at a scan rate of 5 mV s −1 , which is approximately three times higher than that of the pristine 3D RGO owing to the pseudocapacitive behavior of N-RGO. The high electronic conductivity of the N-RGO electrode with low charge transfer resistance as confirmed by electrochemical impedance spectroscopy is associated with good rate capability. Furthermore, the N-RGO sample exhibits an excellent cyclic stability with no decay in capacitance even after 5000 cycles at scan rate of 100 mV s −1 .

Micro/meso-porous reduced graphite oxide (MMRGO) nanosheets were produced using precursor carbide-derived carbon (CDC), which was produced at a high temperature of 1200 °C, through a massive wet chemistry synthetic route involving graphite oxidation and microwave reduction. X-ray diffraction (XRD) and transmission electron microscopy (TEM) show that the MMRGO nanosheets were fabricated with 2–3 layers and ripple-like corrugations. N2 sorption isotherms confirmed that micro/meso-pores coexisted in the RGO sample from CDC. In the anode application of Li-ion batteries, this RGO sample had an enhanced capacity performance at the 0.1 C rate and 1 C rate, with ∼1200 mAh g−1 at the 100th cycle and ∼1000 mAh g−1 at the 200th cycle, respectively.

Thermal batteries are primary power sources for military applications requiring high reliability, robustness and long storage life. Conventional electrodes for thermal batteries are prepared by compacting powder mixtures into pellets. Separator is composed of halide mixture, such as LiCl-KCl eutectic salt, blended with MgO to immobilize the molten salt. In order to increase the power density and energy density, the resistance of electrolyte should be reduced because the resistance of electrolyte is predominant in thermal batteries. In this study, wetting behaviors and impregnation weight of molten salts as well as the micro structures of ceramic felt were investigated to be applicable to thin electrolyte. Discharge performances of single cell with the ceramic separator impregnated by molten salt were evaluated also. Zirconia felt with high porosity and large pore outperformed alumina felt in wetting characteristics and molten salt impregnation as well as discharge performances. Based on the results of this study, ceramic felt separator impregnated with molten salt have revealed as an alternative of conventional thick MgO based separator with no conspicuous sign of thermal runaway by short circuit.

The effects of particle size of Li-Si alloy and LiCl-KCl addition as a binder phase for raw material ofanode were investigated on the formability of the thermal battery anode. The formability was evaluated with respect tofilling density, tap density, compaction density, spring-back and compressive strength. With increasing particle size ofLi-Si alloy powder, densities increased while spring-back and compressive strength decreased. Since the small spring-back is beneficial to avoiding breakage of pressed compacts, larger particles might be more suitable for anode forming.The increasing amount of LiCl-KCl binder phase contributed to reducing spring-back, improving the formability ofanode powder too. The control of particle size also seems to be helpful to get double pressed pellets, which consistedof two layer of anode and electrolyte. Keywords: Thermal battery, Anode, Li-Si alloy, Powder compaction, Formability ······························································································································· ·································································································

has been widely used for cathode materials in thermal battery because of its high stability and current capability at high operation temperature. Salts such as a LiCl-KCl were added as a binder for improving electrical performance and formability of cathode powder. In this study, the effects of the addition of in LiCl-KCl binder on the formability of powder compact were investigated. With the increasing amount of addition to LiCl-KCl binder salts, the strength of the pressed compacts increased considerably when the powder mixture were pre-heat-treated above . The heat-treatment resulted in promoting the coating coverage of particles by the salts as was added. The observed coating as addition might be attributed to the enhanced wettability of the salt rather than its reduced melting temperature. The high strength of compacts by the addition and pre-heat-treatment could improve the formability of raw materials.

In this study, effects of pyrite () particle sizes on the electrochemical characteristics of thermal batteries are investigated using unit cells made of pulverized pyrite by ball-milling. At unit cell discharge test, the electrochemical capacity of pyrite-cell largely increases compared to pyrite-cell, and their internal resistances also decrease. These results are attributed to the increase in the active reaction area of pyrite by ball milling. However, at unit cell discharge test, a pyrite cell shows lower internal resistance than that of pyrite cell only at Z-phase region (). After that, a pyrite cell shows a decrease in the cell voltage and an rapid increase of the internal resistance in J-phase region () is observed compared to those of pyrite cell. It can be concluded that at the higher temperature, the thermally unstable pulverized pyrite is decomposed thermally as well as self discharged, simultaneously, which causes the higher resistance and lower capacity at in J-phase than that of pyrite cell.

Microstructure and thermal stability of mechanically ball milled were investigated. The average particle size and distribution of powder were changed in two steps with the increased ball milling time. The average particle size drastically decreased from to 1.01 and after ball milling of 10 h and 30 h, respectively. However, the distribution was broad and a shoulder appeared at because the pulverization was still in process at 10 h ball milling. After 60 h ball milling, the distribution became narrower. After ball milling of 120 h, the average particle size increased because of particle agglomeration. Therefore, the particle size distribution became broaden again. Finally, after ball milling of 170 h, with the narrowest size distribution can be obtained. Thermal stability of was unstable as the particle was pulverized. Therefore, the activation energy of the fine size particles is 27% lower than that of the as-received .

Lithium-impregnated metal foam anodes (LIMFAs) are fabricated and investigated. The LIMFAs are prepared by the impregnation of lithium into molten-salt-coated nickel metal foam. A single cell with the LIMFA exhibits a specific capacity of 3009 As g−1. For comparison, a single cell with a LiSi alloy anode is also discharged, demonstrating a specific capacity of 1050 As g−1. These significant improvements can be attributed to the large amount of lithium impregnated into the metal foam as well as the molten lithium holding capability of the foam. Due to their excellent electrochemical properties, LIMFAs are suitable for use in thermal batteries.

Thermal batteries have excellent mechanical robustness, reliability, and long shelf life. Due to these characteristics as well as their unique activation mechanism, thermal batteries are widely adopted as military power sources. Li(Si)/ thermal batteries, which are used mostly in these days, use LiCl-KCl and LiBr-LiCl-LiF as molten salt electrolyte. However, it is known that Li(Si)/ thermal batteries have high internal resistance. Especially, cathode accounts for the greater part of internal resistance in unit cell. Many efforts have been put into to decrease the internal resistance of thermal batteries, which result in the development of new electrode material and new electrode manufacturing processes. But the applications of these new materials and processes are in some cases very expensive and need complicated additional processes. In this study, internal resistance study was conducted by adding carbon black and carbon nano-tube, which has high electron conductivity, into the cathode. As a results, it was found that the decrease of internal resistance of cathode by the addition of carbon black and carbon nano-tube.

Ceramic fiber separator is the promising material for thermal battery system because it reduces the production cost and offers the potential to a new application compared to a pellet type electrolyte. The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten lithium salt. Ceramic fibers were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. Leakage of molten salt (several lithium salts) leads to short-circuit during the thermal battery operation. In this study, a uniform and fine SiOC mat with fibers ranging from 1 to 3 ㎛ was obtained by electrospinning of polycarbosilane and pyrolysis. The optimum spinning conditions for obtaining fine diameters of SiOC fiber were controlled by the solution composition and concentration, applied voltage and spinning rate, release rate by porosity. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. The importance of the fiber size and porosity and their control was discussed and the mechanical properties were also discussed.

The electrolyte separator for thermal battery should be easily handled and loaded a large amount of the molten salt. Ceramic fibers, especially fibrous commercial glass filters were used as an electrolyte separator and the lithium based molten salts were infiltrated into the ceramic filters. The pore structures of the ceramic filter and the melting properties of the lithium salts affected to the electrolyte loading and leakage. During the infiltration, ions of Li? and F? in the molten salts were reacted with the glass fiber and caused to be weaken the fiber strength.

Ceramic Fiber separator is the promising material for thermal battery system because it reduces the production cost and offers the potential to a new application compared to a pellet type electrolyte. The molten salt electrolytes for thermal battery were prepared by the impregnation of the commercial glass filters such as GF-A, C and F (Whatman, USA) with two types of molten-lithium salts, LiCl-KCl and LiK-LiBr-LiF. The wetting properties were evaluated by wetting balance test and wetting angle measurement. The wetting behaviors were strongly affected by the composition of the molten salts and the pore structure of the glass separators. The optimum wetting conditions for maximum loading and effective retention of the molten electrolyte were also studied.

Objective.To develop new evaluation indices of infection control and to use them to evaluate Korean infection surveillance and control programs (ISCPs).Design.We performed a questionnaire-based survey to 164 acute care general hospitals throughout the Republic of Korea that had more than 300 beds. Study methods were based completely on those of the Study on the Efficacy of Nosocomial Infection Control (SENIC). Four SENIC indices (hospital epidemiologist index, infection control nurse index, surveillance index, and control index) and 4 newly developed indices (healthcare worker index, quality improvement index, resource index, and hand hygiene facilities index) were used to evaluate Korean ISCPs. Data were collected by questionnaire from June 17 to October 11, 2003.Setting.One hundred sixty-four general hospitals with more than 300 beds in the Republic of Korea.Results.Personnel from 85 general hospitals responded to the study questionnaire. The reliability and validity of the evaluation indices were statistically significant (PPConclusions.The reliability and validity of the SENIC evaluation indices and the newly developed evaluation indices were satisfactory in evaluating Korean ISCPs. However, surveillance should be improved to increase the efficacy of Korean ISCPs.

We have tried to develop a lithium/thionyl chloride reserve battery (560W). A cell consists of 5 double-sided cathodes and anodes (toroidal shape, electrode area: 100 cm2, cell surface area: 900 cm2, current density: 22mA/cm2). We have designed a unique internal serial connection, which is capable of obtaining a desired voltage by simply stacking the cells and then tightening the internal serial connection volts. A piston-type electrolyte reservoir is designed. Our dual-piston electrolyte reservoir requires smaller space for the piston movement than a single-piston reservoir. It also renders reliable opening of the diaphragm, and appropriate electrolyte transferring speed to avoid damage to the carbon electrodes. The batteries underwent performance tests, environmental tests, and accelerated aging test.

Using gas chromatographic analyses, the effects of additives (PdCl2, Al2O3, or La2O3) on the alcohol sensing properties of SnO2-based sensors were investigated with respect to the distribution and the reaction steps of the products formed from the reactions of alcohols over the SnO2-based powder. Ethanol was catalytically oxidized with the SnO2-based powders. With the PdCl2-doped SnO2, the C–C bond cleavage product, methane, was produced. This seems to be related with the significant promotional role of PdCl2-doping in ethanol sensing especially at temperatures below 300 oC. For the La2O3-doped SnO2, relatively large amounts of CO and CO2 were produced, resulting in an enhanced sensitivity. On the other hand, for the Al2O3-doped SnO2, selective dehydration, which consumes smaller amounts of the adsorbed oxygen species (O- ads), seems to degrade the sensitivity. When exposed to methanol, the SnO2-based sensors showed oxidation products consisting of CO, CO2 and H2O and sensing characteristics similar to those observed with ethanol.

The direct formation of CN and CO bonds from inert gases is essential for chemical/biological processes and energy storage systems. However, its application to carbon nanomaterials for improved energy storage remains technologically challenging. A simple and very fast method to form CN and CO bonds in reduced graphene oxide (RGO) and carbon nanotubes (CNTs) by an ultrasonic chemical reaction is described. Electrodes of nitrogen- or oxygen-doped RGO (N-RGO or O-RGO, respectively) are fabricated via the fixation between N2 or O2 carrier gas molecules and ultrasonically activated RGO. The materials exhibit much higher capacitance after doping (133, 284, and 74 F g-1 for O-RGO, N-RGO, and RGO, respectively). Furthermore, the doped 2D RGO and 1D CNT materials are prepared by layer-by-layer deposition using ultrasonic spray to form 3D porous electrodes. These electrodes demonstrate very high specific capacitances (62.8 mF cm-2 and 621 F g-1 at 10 mV s-1 for N-RGO/N-CNT at 1:1, v/v), high cycling stability, and structural flexibility.

The decomposition rate of toxic acetonitrile (CH3CN) in the presence of SnO2 sensor elements was greatly affected by the addition of a Pd dopant. When the PdCl2 was doped into the SnO2 sensor elements, the oxidation reaction was predominant owing to both the enhanced oxygen adsorption and the effective oxygen supply in the presence of Pd catalysts. To clarify such effects, we analyzed the mechanisms of the reaction between CH3CN gas and the PdCl2-doped SnO2 elements using gas chromatography. From the results of the analysis of the decomposition products of CH3CN gas in the presence of the doped SnO2 sensor elements, we suggested a possible surface reaction mechanism of acetonitrile gas decomposition.

Supercapacitor have been widely researched in order to apply many fields such as a hybrid electric vehicles, high pulse power sources, and emergency power sources requiring high power instantly. However, supercapacitor has low energy density compared to batteries. In order to increase the energy density of supercapacitor, electrode is the very important. Until now, porous carbons, which have low energy density (5~10 Wh kg-1) are the widely used for electrode materials. Recently, many reports have been released using a surface treated carbon or graphene, RGO and CDC, etc. However, these ways have much time and costs in order to compensate the energy. In this study, the CO2 laser treated carbon electrode is investigated for high-performance supercapacitors. First of all, in order to investigate the effect of CO2 laser radiation on energy density and microstructure, carbon electrode was fabricated as a mixture of active material, conductive material, and PVDF binder. The mixed slurry with NMP was coated onto an aluminum plate and dried at 100 oC for 12h. And then CO2 laser was radiated onto the surface of the carbon electrode. A 2032coin cell was assembled with the TEABF4 as electrolyte and separator. The microstructure difference was investigated with SEM and cyclic voltammetry tests also were carried out in the potential range of 0 to 2.7 V for comparison to CO2 laser radiated and un-radiated carbon electrode.

Thermal batteries have been used for many military applications such as missiles and ordnance devices. As the thermal battery is composed of anode, cathode, MgO based-molten salt electrolyte and additional heat source, its specific energy density is lower than those of commercial batteries. By means of substituting MgO based-electrolyte to increase energy density of thermal batteries, we have indentified various ionic solid electrolytes such as LLT(La0.5Li0.5TiO3), LSTZ(Li3/8Sr7/16Ta3/4Zr1/4O3) and LLZ(Li7La3Zr2O12). As a ruslt, we found out that the LLZ with additivies, Ca and Nb, presents not only excellent ionic conductivity but also stable discharge characteristics at high temperature(≈ 300oC). Additionally, we have verified that the LLZ solid electrolyte is suitable for the full scale of thermal batteries with high energy density.

The role of additives (PdCl2, Al2O3 and Nb2O5) in SnO2 gas sensors has been examined by X-ray photoelectron spectroscopy (XPS) and analyses of the gas-sensing behavior. Al2O3-doped SnO2 shows a slight increase in sensitivity to CO and CH3CN as compared with pure SnO2. On the contrary, Nb2O5-doped SnO2 shows the opposite trend. The sensitivity of PdCl2-doped SnO2 to both CO and CH3CN in the low-temperature region below 300 °C is greatly increased. The major oxidation states of Pd in 0.5 wt.% PdCl2-doped SnO2 sintered at 800 °C and 650 °C are 4+ and 2+, respectively. The binding energies (BEs) of Sn 3d 5 2 and O 1s 1 2 remain almost constant up to 1.0 wt.% PdCl2 loading. When exposed to H2 at room temperature, the major oxidation state of Pd in 0.5 wt.% PdCl2-doped SnO2 sintered at 800 °C changes from 4+ to 2+. This change in the oxidation state of Pd, along with the enhanced sensitivity to CO below 200 °C, may suggest the electronic interaction of Pd with SnO2 at low temperature. The combustion products of CH3CN with 1.0 wt.% PdCl2-doped SnO2 powder are confirmed to be CO2, H2O and CO by gas chromatography (GC).

A wide variety of supercapacitors has been developed for many high-power energy storage application. Especially, flexible supercapacitors with thin electrodes are being needed for powering flexible electronics for military applications. In this study, the inkjet-printed graphene electrode is investigated for high-performance thin film supercapacitors. In order to make the ink for printing, graphene flakes ware dispersed in a solvent and then printed onto a metal foil. The electrodes were inkjet-printed with the various graphene flake size and the film thickness. After the printing, the electrodes were dried to remove solvent. These electrodes were sealed together with the electrolyte and separator, and then assembled into a coin cell. The microstructures of the printed graphene electrodes were analyzed by SEM, TEM and XRD. The electrochemical performances were also investigated.

A Li-Si/FeS2 electrochemical system, which is widely used for thermal batteries, has limited energy density and power capability due to the partial utilization of the active materials. A single cell with a molten lithium anode or a molten sulfur cathode has a high energy density with a high open circuit voltage compared to that with a Li-Si/FeS2 couple. The main challenges in the molten electrodes arise from the instability of liquid active materials which can directly react with the other electrode and results in catastrophic thermal runaways, such as vent, fire or even explosion. For the practical application to thermal batteries which operates at above the melting point of the active electrode materials, the immobilization of the molten electrode is inevitably required. The combination of the porous metal foams with liquid active materials is found to be quite effective solution to attain unconventionally high energy density as well as high power capability. In this study, highly conductive nickel foam electrodes are incorporated with pure lithium or sulfur. The electrochemical characteristics are investigated along with the single cell tests and the microstructural analysis.

Using gas chromatography (GC), the effect of additives on the decomposition reactions of both reducing gases (CH/sub 3/OH, C/sub 2/H/sub 5/OH, etc) and an oxidizing gas (CH/sub 3/CN) was analyzed for the selection of proper additives. The effect of additives was further investigated in terms of the sensing characteristics. Based on these studies, two sensors, PdCl/sub 2/-added SnO/sub 2/ and La/sub 2/O/sub 3/-added SnO/sub 2/, showing discriminative sensing behaviors to CH/sub 3/CN were selected. By combining the signal patterns obtained from the two sensors, selectivity of the SnO/sub 2/ sensors for CH/sub 3/CN was highly enhanced.