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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Electroactive ZnO: Mechanisms, Conductivity, and Advances in Zn Alkaline Battery Cycling

Zinc oxide is of great interest for advanced energy devices because of its low cost, wide direct bandgap, non-toxicity, and facile electrochemistry. In zinc alkaline batteries, ZnO plays a critical role in electrode passivation, a process that hinders commercialization and remains poorly understood. Here, novel observations of an electroactive type of ZnO formed in Zn-metal alkaline electrodes are disclosed. The electrical conductivity of battery-formed ZnO is measured and found to vary by factors of up to 10 4 , which provides a first-principles-based understanding of Zn passivation in industrial alkaline batteries. Simultaneous with this conductivity change, protons are inserted into the crystal structure and electrons are inserted into the conduction band in quantities up to ≈10 20 cm –3 and ≈1 mAh gZnO –1 . Electron insertion causes blue electrochromic coloration with efficiencies and rates competitive with leading electrochromic materials. The electroactivity of ZnO is evidently enabled by rapid crystal growth, which forms defects that complex with inserted cations, charge-balanced by the increase of conduction band electrons. Furthermore, this property distinguishes electroactive ZnO from inactive classical ZnO. Knowledge of this phenomenon is applied to improve cycling performance of industrial-design electrodes at 50% zinc utilization and the authors propose other uses for ZnO such as electrochromic devices.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A Perovskite Electrolyte That Is Stable in Moist Air for Lithium‐Ion Batteries

Abstract Solid‐oxide Li + electrolytes of a rechargeable cell are generally sensitive to moisture in the air as H + exchanges for the mobile Li + of the electrolyte and forms insulating surface phases at the electrolyte interfaces and in the grain boundaries of a polycrystalline membrane. These surface phases dominate the total interfacial resistance of a conventional rechargeable cell with a solid–electrolyte separator. We report a new perovskite Li + solid electrolyte, Li 0.38 Sr 0.44 Ta 0.7 Hf 0.3 O 2.95 F 0.05 , with a lithium‐ion conductivity of σ Li =4.8×10 −4 S cm −1 at 25 °C that does not react with water having 3≤pH≤14. The solid electrolyte with a thin Li + ‐conducting polymer on its surface to prevent reduction of Ta 5+ is wet by metallic lithium and provides low‐impedance dendrite‐free plating/stripping of a lithium anode. It is also stable upon contact with a composite polymer cathode. With this solid electrolyte, we demonstrate excellent cycling performance of an all‐solid‐state Li/LiFePO 4 cell, a Li‐S cell with a polymer‐gel cathode, and a supercapacitor.

Li, Yutao↗
DOE OSTI2020

Enhanced Surface Interactions Enable Fast Li + Conduction in Oxide/Polymer Composite Electrolyte

Abstract Li + ‐conducting oxides are considered better ceramic fillers than Li + ‐insulating oxides for improving Li + conductivity in composite polymer electrolytes owing to their ability to conduct Li + through the ceramic oxide as well as across the oxide/polymer interface. Here we use two Li + ‐insulating oxides (fluorite Gd 0.1 Ce 0.9 O 1.95 and perovskite La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O 2.55 ) with a high concentration of oxygen vacancies to demonstrate two oxide/poly(ethylene oxide) (PEO)‐based polymer composite electrolytes, each with a Li + conductivity above 10 −4 S cm −1 at 30 °C. Li solid‐state NMR results show an increase in Li + ions (>10 %) occupying the more mobile A2 environment in the composite electrolytes. This increase in A2‐site occupancy originates from the strong interaction between the O 2− of Li‐salt anion and the surface oxygen vacancies of each oxide and contributes to the more facile Li + transport. All‐solid‐state Li‐metal cells with these composite electrolytes demonstrate a small interfacial resistance with good cycling performance at 35 °C.

Wu, Nan↗
DOE OSTI2016

An Aqueous Symmetric Sodium-Ion Battery with NASICON-Structured Na 3 MnTi(PO 4 ) 3

A symmetric sodium-ion battery with an aqueous electrolyte is demonstrated; it utilizes the NASICON-structured Na 3 MnTi(PO 4 ) 3 as both the anode and the cathode. The NASICON-structured Na 3 MnTi(PO 4 ) 3 possesses two electrochemically active transition metals with the redox couples of Ti 4+ /Ti 3+ and Mn 3+ /Mn 2+ working on the anode and cathode sides, respectively. The symmetric cell based on this bipolar electrode material exhibits a well-defined voltage plateau centered at about 1.4 V in an aqueous electrolyte with a stable cycle performance and superior rate capability. The advent of aqueous symmetric sodium-ion battery with high safety and low cost may provide a solution for large-scale stationary energy storage.

25 ENERGY STORAGE↗
DOE OSTI2017

Strain Coupling of Conversion-type Fe 3 O 4 Thin Films for Lithium Ion Batteries

Lithiation/delithiation induces significant stresses and strains into the electrodes for lithium ion batteries, which can severely degrade their cycling performance. Moreover, this electrochemically induced strain can interact with the local strain existing at solid–solid interfaces. It is not clear how this interaction affects the lithiation mechanism. The effect of this coupling on the lithiation kinetics in epitaxial Fe 3 O 4 thin film on a Nb-doped SrTiO 3 substrate is investigated. In-situ and ex-situ transmission electron microscopy (TEM) results show that the lithiation is suppressed by the compressive interfacial strain. At the interface between the film and substrate, the existence of Li x Fe 3 O 4 rock-salt phase during lithiation consequently restrains the film from delamination. 2D phase-field simulation verifies the effect of strain. This work provides critical insights of understanding the solid–solid interfaces of conversion-type electrodes.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2017

Effects of macromolecular configuration of thermally sensitive binder in lithium‐ion battery

ABSTRACT In order to suppress heat generation of nail‐penetrated lithium‐ion battery (LIB) cell, thermally sensitive binders (TSB) based on poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride‐ co ‐hexafluoropropylene) (PVDF‐HFP) were investigated. The testing data showed that with appropriate treatment, TSB could efficiently reduce the peak temperature associated with internal shorting, and did not influence the cycling performance of LIB. The molecular weight of TSB was not a vital factor, while crosslinking was critical. This technology can be used to mitigate thermal runaway of LIB, enabling safe and robust large‐scale energy storage. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45078.

Le, Anh V.↗
DOE OSTI2017

Mitigating thermal runaway of lithium‐ion battery by using thermally sensitive polymer blend as cathode binder

ABSTRACT Thermally sensitive binder (TSB) is developed as an internal safety mechanism of lithium‐ion battery (LIB). The TSB is a polymer blend of poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride‐ co ‐hexafluoropropylene) (PVDF‐HFP). Compared with regular PVDF binder, the softening and swelling of TSB are more pronounced when temperature is above 110 °C. With the TSB, the cycling performance of LIB cell is not affected; upon nail penetration, the heat generation rate is significantly reduced. The crystallinity of TSB is an important factor. This technology may lead to the development of thermal‐runaway‐mitigating LIB cells. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 45737.

Le, Anh V.↗
DOE OSTI2019

Polymer Binders Constructed through Dynamic Noncovalent Bonds for High-Capacity Silicon-Based Anodes

Silicon (Si) is a promising candidate for high-capacity anode materials owing to its high theoretical capacity (3579 mAh g -1 ), low working voltage, and wide natural abundance, although its huge volume variation during charge/discharge processes always results in a short cycling life. Polymer binders play a vital role in improving the cycling performance of Si-based anodes, although traditional polyvinylidene difluoride cannot fulfill the requirements owing to its weak van der Waals forces with the Si surface. Recently, polymer binders constructed by dynamic bonds have been developed, which are reported to allow high-energy-density electrodes with improved electrochemical performance. With dynamic bonds including hydrogen bonding, ionic bonding, and host–guest interactions, these polymer binders possess self-healing capabilities and enhanced mechanical performance, achieving a tremendous advance in addressing the capacity fading of Si-based anodes. In this study, we will summarize the research progress of polymer binders constructed with dynamic bonds, and the challenges for their real applications in advanced Li-ion batteries will also be discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Phosphate‐functionalized Zirconium Metal–Organic Frameworks for Enhancing Lithium–Sulfur Battery Cycling

Abstract Lithium–sulfur batteries are promising candidates for next‐generation energy storage devices due to their outstanding theoretical energy density. However, they suffer from low sulfur utilization and poor cyclability, greatly limiting their practical implementation. Herein, we adopted a phosphate‐functionalized zirconium metal–organic framework (Zr‐MOF) as a sulfur host. With their porous structure, remarkable electrochemical stability, and synthetic versatility, Zr‐MOFs present great potential in preventing soluble polysulfides from leaching. Phosphate groups were introduced to the framework post‐synthetically since they have shown a strong affinity towards lithium polysulfides and an ability to facilitate Li ion transport. The successful incorporation of phosphate in MOF‐808 was demonstrated by a series of techniques including infrared spectroscopy, solid‐state nuclear magnetic resonance spectroscopy, and X‐ray pair distribution function analysis. When employed in batteries, phosphate‐functionalized Zr‐MOF (MOF‐808‐PO4) exhibits significantly enhanced sulfur utilization and ion diffusion compared to the parent framework, leading to higher capacity and rate capability. The improved capacity retention and inhibited self‐discharge rate also demonstrate effective polysulfide encapsulation utilizing MOF‐808‐PO4. Furthermore, we explored their potential towards high‐density batteries by examining the cycling performance at various sulfur loadings. Our approach to correlate structure with function using hybrid inorganic–organic materials offers new chemical design strategies for advancing battery materials.

Liu, Bingqian↗
DOE OSTI2016

Nitrogen‐Doped Nanoporous Graphenic Carbon: An Efficient Conducting Support for O 2 Cathode

Abstract Herein, we synthesize a nanoporous N‐doped graphenic carbon with high surface area and a higher graphenization/graphitic degree by further developing the metallothermic reduction of gaseous CO 2 by adding N 2 into the gas flow. The N‐doped nanoporous carbon is composed of both a highly porous graphenic and non‐graphitic matrix and homogeneously dispersed ordered graphitic nanodomains, which constitute a very unique composite carbon structure. The resulting N‐doped graphenic carbon exhibits much more favorable reactivity as a carbon conducting support in the O 2 cathode of Li‐O 2 batteries, increasing the specific capacity of the GC electrode from 5300 to 9600 mAh g −1 . The N‐doped carbon also exhibits lower overpotentials during initial cycling for the charging process as well as an enhanced cycling performance compared to the undoped carbon. These results demonstrate that N‐doping has a strong correlation with the enhanced performance of O 2 cathode of Li‐O 2 batteries.

Xing, Zhenyu↗
DOE OSTI2020

Structural Stabilization of P2-type Sodium Iron Manganese Oxides by Electrochemically Inactive Mg Substitution: Insights of Redox Behavior and Voltage Decay

Layered P2-type Na 0.8 Mn 0.5 Fe 0.5 O 2 cathode material is a promising candidate for next-generation sodium-ion batteries due to the economical and environmentally benign characteristics of Mn and Fe. The poor cycling stability of the material, however, is still a problem that must be solved. To address the problem, here, electrochemically inactive Mg 2+ was introduced into the structure by substituting some of the Fe ions. It was shown that Mg substitution led to a smoother voltage profile with improved cycling performance and rate capability. These observations were attributed to the suppressed structural changes during electrochemical processes. Detailed redox mechanisms, associated local structural changes, and phase transitions were investigated by X-ray absorption spectroscopy and X-ray diffraction. From the detailed analysis of electrochemical behaviors, it was also identified how the redox reactions and structural disordering occurred in the high-and low-voltage regions and how Mg substitution stabilized the structure.

25 ENERGY STORAGE↗
DOE OSTI2024

Chemical and Electrochemical Characterization of Hot–Pressed Li 6 PS 5 Cl Solid State Electrolyte: Operating Pressure–Invariant High Ionic Conductivity

Sulfide solid state electrolytes (SSE) are among the most promising materials in the effort to replace liquid electrolytes, largely due to their comparable ionic conductivities. Among the sulfide SSEs, Argyrodites (Li 6 PS 5 X, X=Cl, Br, I) further stand out due to their high theoretical ionic conductivity (~1×10 –2 S cm –1 ) and interfacial stability against reactive metal anodes such as lithium. Generally, solid state electrolyte pellets are pressed from powder feedstock at room temperature, however, pellets fabricated by cold pressing consistently result in low bulk density and high porosity, facilitating interfacial degradation reactions and allowing dendrites to propagate through the pores and grain boundaries. Here, we demonstrate the mechanical and electrochemical implications of hot-pressing standalone LPSCl SSE pellets with near-theoretical ionic conductivity, superior cycling performance, and enhanced mechanical stability. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and x-ray diffraction spectroscopy (XRD) analysis reveal no chemical changes to the Argyrodite surface after hot pressing up to 250°C. Furthermore, we use electrochemical impedance spectroscopy (EIS) to understand mechanical stability of Argyrodite SSE pellets as a function of externally applied pressure, demonstrating for the first time pressed standalone Argyrodite pellets with near-theoretical conductivities at external pressures below 14 MPa.

25 ENERGY STORAGE↗
DOE OSTI2023

A Hydrogen Iron Flow Battery with High Current Density and Long Cyclability Enabled Through Circular Water Management

The hydrogen‐iron (HyFe) flow cell has great potential for long‐duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries. However, its operation at high current density (high power) and over continuous cycling testing has yet to be demonstrated. In this paper, we discuss our design and demonstration of a water management strategy that supports high current and long cycling performance of a HyFe flow cell. Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm −2 during the charge process. At higher charge current density, more aggressive measures must be taken to counter back‐diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes. Our water management approach is based on water vapor feeding in the hydrogen electrode, and water evaporation in the iron electrode, thus enabling the high current density operation of 300 mA cm −2 .

25 ENERGY STORAGE↗
DOE OSTI2023

A Hydrogen Iron Flow Battery with High Current Density and Long Cyclability Enabled Through Circular Water Management

The hydrogen‐iron (HyFe) flow cell has great potential for long‐duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries. However, its operation at high current density (high power) and over continuous cycling testing has yet to be demonstrated. In this article, we discuss our design and demonstration of a water‐management strategy that supports high current and long‐cycling performance of a HyFe flow cell. Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm −2 during the charge process. At higher charge current density, more aggressive measures must be taken to counter back‐diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes. Our water‐management approach is based on water vapor feeding in the hydrogen electrode and water evaporation in the iron electrode, thus enabling high current density operation of 300 mA cm −2 .

Yan, Litao↗
DOE OSTI2015

Lithium-Rich Nanoscale Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 Cathode Material Prepared by Co-Precipitation Combined Freeze Drying (CP-FD) for Lithium-Ion Batteries

Nanoscale Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 material is synthesized by a co-precipitation combined freeze drying (CP-FD) method, and compared with a conventional co-precipitation method combined vacuum drying (CP-VD). With the combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM), it is found that the sample from CP-FD method consists of a pure phase with good crystallinity and small, homogenous particles (100-300 nm) with uniform particle size distribution. Inductively coupled plasma spectroscopy (ICP) shows that the sample has a stoichiometric ratio of n((Li)): n((Mn)): n((Ni)): n((Co))=9: 4: 1: 1; and its Brunauer-Emmett-Teller (BET) specific surface area is 5.749 m(2)g(-1). This sample achieves excellent electrochemical properties: its initial discharge capacities are 298.9 mAhg(-1) at 0.1C (20 mAg(-1)), 246.1 mAhg(-1) at 0.5C, 215.8 mAhg(-1) at 1C, and 154.2 mAhg(-1) at 5C (5C charge and 5C discharge), as well as good cycling performance. In addition, the Li+ chemical diffusion coefficient of Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by the CP-FD method is 4.59 x 10(-11) cm(2) s(-1), which is higher than that of the Li1.2Mn0.54Ni0.13Co0.13O2 material prepared by CP-VD. This phenomenon illustrates the potential for Li1.2Mn0.54Ni0.13Co0.13O2 with good rate performance synthesized by CP-FD method.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Accessing a high‐voltage nonaqueous hybrid flow battery with a sodium‐methylphenothiazine chemistry and a sodium‐ion solid electrolyte

Abstract The development of redox flow batteries (RFBs) with nonaqueous electrolytes offers the possibility of accessing a high cell‐operation voltage (no restrain of hydrogen evolution and oxygen evolution potentials) and a low operation temperature (can be operated below the freezing point of water). Therefore, nonaqueous RFBs have recently garnered increasing attention. However, the cross‐mixing of liquid electrode/electrolyte materials has been plaguing the progress of the nonaqueous RFBs. Herein, we present a crossover‐free, high voltage nonaqueous hybrid flow battery (HFB) with a novel sodium‐methylphenothiazine (MPT) chemistry and a single‐ion solid‐electrolyte separator. The Na‐MPT redox couple delivers a high voltage of ~2.6 V when the cell was operated at a medium current density. A NASICON‐type solid electrolyte membrane (Na 3 Zr 2 Si 2 PO 12 ) could circumvent the crossover of the liquids between the positive and negative electrodes, and meanwhile could maintain a single‐ion (Na + ‐ion) conduction between the two electrodes to sustain the electrochemical reactions. Under such an electrochemical mechanism, the nonaqueous Na‐MPT HFB shows remarkable cycling performance.

Yu, Xingwen↗
DOE OSTI2021

High Interfacial-Energy and Lithiophilic Janus Interphase Enables Stable Lithium Metal Anodes

The stability of solid electrolyte interphase (SEI) layers is critical for developing lithium (Li) metal batteries. However, the fabrication of stable SEI layers is plagued by un-controlled structures, properties, and functions. In this work a controllable design of an ordered LiF-rich and lithiophilic hybrid Janus interphase (LiF-HJI) is reported using organic fluorination reagent as a functional SEI precursor. The LiF-HJI with a lower crystalline LiF layer and an upper Li organosulfide layer provides high interfacial energy with the Li metal and strong Li-ion affinity, allows homogenous Li-ion distribution, fast and uniform Li-ion transport, and excellent mechanical and passivation properties, enabling stable Li metal anodes under harsh conditions, such as high deposition capacities (6 mA h cm -2 ), current densities (10 mA cm -2 ), and rates (5 C). Stable LiF-HJI@Li greatly improves cycling stability and capacity retention (80.1% after 300 cycles) of Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 cells at a commercial-level areal capacity (≈4.2 mA h cm -2 ). Even under a lean-electrolyte condition of 3 g Ah -1 , 80% capacity retention can be maintained after 100 cycles, demonstrating excellent cycling performance under such harsh conditions.

25 ENERGY STORAGE↗