High-temperature Lithium Batteries Research Articles

Synergistically reinforced poly(ethylene oxide)-based composite electrolyte for high-temperature lithium metal batteries

Traditional liquid lithium-ion batteries are not applicable for extreme temperatures, due to the shrinkage of separators and volatility of electrolytes. It is necessary to develop advanced electrolytes with desirable characteristics in terms of thermal stability, electrochemical stability and mechanical properties. Solid-state electrolytes, such as polyethylene oxide (PEO), outperform other types and bring the opportunity to realize the high-temperature lithium-ion batteries. However, the softness of PEO at elevated temperatures leads to battery failure. In this work, a three-dimensional fiber-network-reinforced PEO-based composite polymer electrolyte is prepared. The introduced polyimide (PI) framework and trimethyl phosphate (TMP) plasticizer decrease the crystallinity of PEO and increase the ionic conductivity at 30 °C from 8.79 × 10−6 S cm−1 to 4.70 × 10−5 S cm−1. In addition, the PEO bonds tightly with PI fiber network, improving both the mechanical strength and thermal stability of the prepared electrolyte. With the above strategies, the working temperature range of the PEO-based electrolytes is greatly expanded. The LiFePO4/Li cell assembled with the PI-PEO-TMP electrolyte stably performs over 300 cycles at 120 °C. Even at 140 °C, the cell still survives 80 cycles. These excellent performances demonstrate the potential application of the PI-PEO-TMP electrolyte in developing safe and high-temperature lithium batteries.

Three-Dimensional Thermal Modeling of High-Temperature Primary Lithium Battery with Nickel Disulfide Cathode

Three-Dimensional Thermal Modeling of High-Temperature Primary Lithium Battery with Nickel Disulfide Cathode

Facile hydrothermal synthesis of double shelled Si@SnO2@C as advanced cathode for high-temperature lithium batteries

The elaborately prepared Si-based composites with core-shell structure have greatly optimized the issues of Si electrode volume expansion. However, the preparation processes of most of them are tedious and the solvents used to remove templates is harmful, which affects the development and application of Si-based electrode materials. Herein, a novel double-shelled Si@SnO2@C composite is successfully designed in one-step by hydrothermal method and verified by X-ray diffraction analysis combined with X ray photoelectron spectroscopy analysis. As the cathode of high-temperature battery, the discharge behavior of Si@SnO2@C composite in the Li–Mg–B alloy/LiNO3–KNO3/Si@SnO2@C battery system has been carried out. It is demonstrated that the as-prepared Si@SnO2@C composite has excellent discharge performance at current densities of 10 mA cm−2 and the specific capacity can be achieved 782.12 mAh g−1 at 200 °C. Even at a much higher temperature of 300 °C, the capacity can still reach 613.67 mAh g−1, and these favorable properties are mainly due to outstanding structure characteristics. The synthesis process is simple and economical, which provides a feasible alternative method for preparation of advanced silicon-based electrode materials to alleviate violent volume expansion.

Design of Downhole Automatic Power Supply Device based on TPS2121

Maintaining a consistent power supply for downhole drilling devices has proved to be very problematic. For that reason, a downhole automatic power supply device was designed. In the case of the MWD instrument powered by disposable high-temperature lithium battery, the problem of seamless switching of multiple power sources in power supply could only be addressed by selecting an appropriate power multiplexing method for a series-parallel battery pack, thus the downhole automatic power supply device was designed. After analyzing the shortcomings of the original power supply method, it was found that the battery utilization rate of the diode power multiplexing method was low. Further, the microcontroller-based power supply technology failed to cope with the instantaneous voltage loss of battery and occupied the microcontroller resources. Through comprehensive comparison, the priority power supply multiplexer chip TPS2121 was used to realize the seamless switching between multiple power sources, and the DC/DC converter was designed by using the LM5166 synchronous step-down converter to form an automatic downhole power supply device. The indoor test and field test demonstrated that this downhole automatic power supply device could achieve the automatic switching of multiple battery packs, improved the battery utilization rate by using each battery pack in sequence, and achieved the seamless power supply of MWD instrument by cooperating with the DC/DC converter. In addition, this device presented high reliability and economic benefits.

Facile synthesis of Li2MoO4 coated LiNi1/3Co1/3Mn1/3O2 composite as a novel cathode for high-temperature lithium batteries

High-temperature lithium battery system operated between 150 and 300 °C is highly desirable to be applied in oil/gas and geothermal explorations. However, the development of cathode material for high-temperature lithium batteries is relatively sluggish. In this study, LiNi1/3Co1/3Mn1/3O2 (NCM) is coated with Li2MoO4 by a facile solid-state reaction between MoO3 and surface lithium residue and the resulting composite is applied in high-temperature lithium batteries as a novel cathode material. Such a strategy can not only remove lithium residue components, but also facilitate lithium-ion transport in NCM through the resulting Li2MoO4 coating layer. At 200 °C, the discharge capacity and rate capacity of Li2MoO4 coated NCM are dramatically improved compared to the pristine one. At 300 °C, the electrochemical performance of 4m-NCM is better than other samples, and each sample exhibits better electrochemical performances than it is at 200 °C due to the enhanced kinetics in high temperature.

The discharge performance of Li2MoO4/LiNO3-KNO3/Li-Mg-B alloy cell as a novel high-temperature lithium battery system

High-temperature battery system operated at or below 300 °C is highly desired for geothermal borehole applications. However, it remains a challenge to find suitable electrode materials meeting the need of wide borehole temperature. In this study, the discharge performance of Li2MoO4/LiNO3-KNO3/Li-Mg-B alloy battery system was studied over the temperature range of 150~300 °C with different current densities ranging from 10 to 30 mA cm−2. The electrochemical test result showed that the single cell delivered maximum discharge capacity at 250 °C, with value of 1178.6 mAh g−1 at a current density of 10 mA cm−2. Besides, it is found that the discharge capacities of the single cell increased as the current density rose at 300 °C attributed to the enhanced ionic conductivity at high temperature. As a result, the Li2MoO4/LiNO3-KNO3/Li-Mg-B alloy system is capable of being used in instrumentation for geothermal and oil/gas borehole explore between 200 and 250 °C.

Single-ion conducting polymer electrolytes with alternating ionic mesogen-like moieties interconnected by poly(ethylene oxide) segments

Solid single-Li+-ion conducting polymer electrolytes are currently explored for safe high-temperature lithium batteries. In the present work we have prepared and studied materials based on alternating mesogen-like naphthalene sulfonate units interconnected by flexible poly(ethylene oxide) (PEO) segments in order to induce microphase separation and physical crosslinking. These segmented polymers were readily prepared in polycondensations of a naphthalene diol sulfonate and chain-end chlorinated PEO. The ionic content of the final materials was conveniently controlled by using PEOs of different molecular weights. Analysis by X-ray scattering showed a morphology with nanoscopic domains of naphthalene sulfonate units dispersed in a matrix of amorphous PEO segments. The aggregation of the naphthalene sulfonate units increased with temperature up to at least 100 °C, while the crystallization of the PEO segments in some materials reversibly dissolved the naphthalene sulfonate domains upon cooling. The crystallinity decreased and the glass transition temperature increased with decreasing PEO molecular weight, i.e., increasing in ionic content, because of increasing ionic coordination and a decreasing PEO segment length in-between the naphthalene sulfonate domains. At 80 and 120 °C, the present single-Li+-ion conductors reached conductivities up to 1.4·10−6 and 5.5·10−6 S cm−1, respectively, which after addition of 29 wt % triglyme increased to 2.9·10−6 and 8.2·10−6 S cm−1, respectively. The combined results showed that the macromolecular design with ionic mesogen-like units that form stable physically cross-linked morphologies by interconnecting flexible polyether segments is advantageous for polymer electrolytes for safe high-temperature operation.

Nonflammable and thermally stable gel polymer electrolytes based on crosslinked perfluoropolyether (PFPE) network for lithium battery applications

A gel polymer electrolyte (FGPE) based on a perfluoropolyether (PFPE) crosslinker and liquid state PFPE doped with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is prepared, and its characteristics including ionic conductivities, Li+ transference numbers, and thermal/electrochemical stabilities are investigated. A commercial PFPE-dimethacrylate, Fluorolink MD700®, is found to be a suitable crosslinker for the FGPE preparation due to its good miscibility with the PFPE/LiTFSI electrolytes. The ionic conductivity and Li+ transference number of the FGPE at 60°C are 1.72×10−5Scm−1, and 0.53, respectively. The FGPE is nonflammable, thermally stable up to 175°C without any weight loss, and has a wide electrochemical stability window (∼5.0V vs. Li/Li+). Therefore, the FGPE is expected to be a promising electrolyte candidate for safety-reinforced high-temperature lithium batteries.

Inorganic-Organic Ionic Liquid Electrolytes Enabling High Energy-Density Metal Electrodes for Energy Storage

It has recently been shown, in the case of the bis(fluorosulfonyl)amide (FSI) based ionic liquids, that as the concentration of the alkali metal salt (LiFSI or NaFSI) is increased, the alkali metal cation transference number increases, despite an increase in viscosity and decrease in conductivity. At the same time significant enhancements in electrochemical stability and rate performance of devices are also observed. Here we overview some of the recent findings already in the literature and in addition demonstrate the feasibility of stable, high rate room temperature lithium battery cycling in an electrolyte comprised of 60 mol% LiFSI in a trimethyl, isobutyl phosphonium FSI ionic liquid using a high voltage NMC cathode. We also demonstrate that the high rate cycling of lithium and sodium metal in these phosphonium FSI electrolytes leads to a nanostructured anode deposit and a lowering of the interfacial impedance, suggesting a stable SEI layer formation. Finally, we propose a hypothesis that may explain some of the observations thus made, by which the high alkali ion concentration in these mixed electrolyte systems leads to the effective elimination of the mass transport limitations that are chiefly responsible for the formation of dendrites in traditional electrolytes. This work suggests that a new type of ionic liquid consisting of a mixture of metal cations with organic cations can provide a solution to the instability of the reactive alkali metal anodes and hence enable higher energy density technologies.

Influence of sintering temperature on the structure and high-temperature discharge performance of LiNi1/3Mn1/3Co1/3O2 cathode materials

Layered cathode materials of high-temperature lithium batteries, LiNi1/3Mn1/3Co1/3O2 are synthesized by a sol-gel method with variation in final sintering temperature for borehole applications. The structure, morphology and high-temperature discharge performance of these resulting products are investigated by X-Ray Diffraction (XRD), scanning electron microscopy (SEM), laser particle size analysis, galvanostatic and pulse discharge. The results of structural analysis indicate that the sample sintered at 800 °C has the characteristics of good crystallinity, narrow size distribution and large specific surface area at the same time. The discharge experiments also indicate that this sample has the best electrochemical properties, with the maximum discharge capacities of 314.57 and 434.14 mAh·g-1 at 200 and 300 °C respectively and the minimum cell internal resistances at both temperatures.

Electrochemical characterization of AlPO4 coated LiNi1/3Co1/3Mn1/3O2 cathode materials for high temperature lithium battery application

Aluminum phosphate (AlPO4) was used to modify the surface of LiNi1/3Co1/3Mn1/3O2 (NCM) cathode material. The surface structure and electrochemical properties of the coated materials were investigated by X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). The results confirm the formation of aluminum-containing solid solution on the surface of NCM particles. An aluminum phosphate coating blocks the Li+ insertion-extraction process in cells charged at high rates at room temperature, increasing surface film resistance and decreasing discharge capacity. However, an aluminum phosphate aids the formation of a stable solid electrolyte interface film on NCM surface and stabilizes the R ct of cell as samples electrochemically cycled at 55 °C. The electrochemical studies suggest that the initial columbic efficiency is significantly enhanced. An NCM sample coated with 1.0 wt% AlPO4 delivers a higher discharge capacity and shows excellent capacity retention ability.

"Ionic liquids-in-salt"--a promising electrolyte concept for high-temperature lithium batteries?

A novel electrolyte concept for lithium-ion batteries, termed "ionic liquid-in-salt", is introduced. Our feasibility study on (1 - x)EMIMTFSI:(x)LiTFSI, 0.66 ≤ x ≤ 0.97, showed that at elevated temperatures the various dual liquid and solid phase regions are characterized by a wide thermal stability window, high ionic conductivities and appreciable mechanical integrity. The highest conductivity values are obtained for the compositions x = 0.70 and x = 0.75 (σ ≈ 6 × 10(-3) S cm(-1)) and are related to the final melting of the materials. Overall, high conductivities are observed for 0.70 < x < 0.90 while low ones are found for x > 0.90. Raman and NMR spectroscopies reveal the presence of highly mobile Li-containing species, partly identified as [Li(TFSI)2](-), albeit rather unexpected for these high x values, which might explain the high ionic conductivities observed. To prove the general value of our concept in more detail, some first results on BMIMTFSI and PY13TFSI based systems are also presented.

Sol–gel synthesis of Co-doped LiMn2O4 with improved high-rate properties for high-temperature lithium batteries

Co-doped samples are synthesized by a sol–gel method and investigated in detail to improve the high-rate discharge performance of the spinel LiMn2O4 cathode in high-temperature lithium batteries. The results of X-ray diffraction and scanning electron microscopy confirm that the cobalt additive incorporates into the LiMn2O4 lattice and that the lattice parameters decrease gradually with increasing Co substitute content. The galvanostatic discharge results indicate that the Co-doped LiMn2O4 satisfies both high-capacity and high-rate discharge requirements at 200–300°C when proper substitute contents are chosen. At a high current density of 30mAcm−2, enhanced high-rate capacities of 219.71mAhg−1 at 200°C and 307.38mAhg−1 at 300°C are obtained in LiMn1.7Co0.3O4 and LiMn1.5Co0.5O4, respectively, which have promising applications in high-temperature lithium batteries. These improvements are partly attributed to the enhanced electrical conductivity, as observed through electrochemical impedance spectroscopy.

LiMn2-xNixO4 Spinel Oxides as High-Temperature Lithium Battery Cathode Materials for Borehole Applications

LiMn2-xNixO4 Spinel Oxides as High-Temperature Lithium Battery Cathode Materials for Borehole Applications

Ionic Liquid-In-Salt: Characterization of Electrolytes for High Temperature Lithium Batteries

not Available.

Electrochemical characterizations of surface modified LiMn 2O 4 cathode materials for high temperature lithium battery applications

LiMn 2O 4 spinel cathode materials were coated with 2.0 wt.% of La 2O 3 by polymeric process followed by calcinations at 400 °C and 800 °C for 6 h in air. The surface coated LiMn 2O 4 cathode materials were physically characterized using X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy and X-ray photoelectron spectroscopy. La 2O 3-coated LiMn 2O 4 coating did not affect the crystal structure and space group Fd3m of the cathode materials compared to the uncoated LiMn 2O 4. The surface morphology and particle agglomeration were investigated and compact coating layer on the surface of the core materials. La 2O 3 was completely coated over the surface of the LiMn 2O 4 core cathode materials. The galvanostatic charge and discharge of the La 2O 3-coated LiMn 2O 4 cathode materials were carried out at 0.1 mA/g in the range of 3.0 and 4.5 V at 30 °C and 60 °C. Based on the results, La 2O 3-coated spinel LiMn 2O 4 cathode at 800 °C has improved the structural stability, high reversible capacity and excellent electrochemical performances of the rechargeable lithium batteries.

Synthesis, structure and ionic conductivity in scheelite type Li0·5Ce0·5−x Ln x MoO4 (x = 0 and 0·25, Ln = Pr, Sm)

Scheelite type solid electrolytes, Li0·5Ce0·5−x Ln x MoO4 (x = 0 and 0·25, Ln = Pr, Sm) have been synthesized using a solid state method. Their structure and ionic conductivity (σ) were obtained by single crystal X-ray diffraction and ac-impedance spectroscopy, respectively. X-ray diffraction studies reveal a space group of I41/a for Li0·5Ce0·5−xLn x MoO4 (x = 0 and 0·25, Ln = Pr, Sm) scheelite compounds. The unsubstituted Li0·5Ce0·5MoO4 showed lithium ion conductivity ~10−5–10−3 Ω−1cm−1 in the temperature range of 300–700°C (σ = 2.5 × 10−3 Ω−1cm−1 at 700°C). The substituted compounds show lower conductivity compared to the unsubstituted compound, with the magnitude of ionic conductivity being two (in the high temperature regime) to one order (in the low temperature regime) lower than the unsubstituted compound. Since these scheelite type structures show significant conductivity, the series of compounds could serve in high temperature lithium battery operations. Scheelite type solid electrolytes, Li0.5Ce0.5−xLnxMoO4 (x = 0 and 0.25, Ln = Pr, Sm) have been synthesized by a ceramic method and their structures solved by single crystal X-ray diffraction. These scheelite type compounds could serve in high temperature lithium battery operations due to significant conductivity in the desired temperature range.

New ternary molten salt electrolyte based on alkali metal triflates

A novel molten salt electrolyte composed of lithium triflate (CF3SO3Li, LiTf), sodium triflate (CF3SO3Na, NaTf), and potassium triflate (CF3SO3K, KTf) has been prepared and characterized by thermogravimetry/differential thermal analysis (TG/DTA), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry. TG/DTA shows that the electrolyte was thermally stable when the temperature was under 400 °C. Its thermal stability gradually decreased with increase of LiTf concentration. The ionic conductivity of molten salt electrolyte has been evaluated by EIS and its value exceeds 10−2 Scm−1 in the temperature range from 230 to 270 °C. The electrochemical window of the electrolyte at the molar ratio of 0.5/1/1 is about 4.7 V at 250 °C. This electrolyte with low melting point exhibits promising characteristics for high-temperature lithium batteries.

Synthesis and characterization of lithium holmium silicate solid electrolyte for high temperature lithium batteries

A new Li-ion conducting holmium based solid electrolyte by the sol–gel method was synthesized. The synthesis was carried out at low temperature compared to conventional methods by which lanthanoid silicates are synthesized. The formation temperature of the compound was found through differential thermal analysis and thermogravimetric analysis (DTA-TG). The sintered samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and ac impedance spectroscopy. The temperature dependence of conductivity was analysed. The experimental results show that the formation temperature of the lithium holmium silicate was found to be above 500 °C. Highest conductivity obtained was in the order of 10−4 S cm−1 at 750 °C.

Li1−x Sm1+x SiO4 as solid electrolyte for high temperature solid-state lithium batteries

Lithium lanthanoid silicates are projected as promising solid electrolytes for solid-state high-temperature lithium batteries. Synthesis of Li1−xSm1+xSiO4 (x = 0.2 to 0.6) was carried using sol–gel method, and these compounds were characterized by thermogravimetry differential thermal analysis, X-ray diffraction, Fourier transform infrared, and SEM. Impedance measurements were carried out at different temperatures, and conductivity at different temperatures was calculated. The effect of an increase of samarium content on the conductivity of the solid electrolyte was studied in this paper. It was found that less samarium content exhibits good conductivity at higher temperatures.