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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 19 records

High-Energy Solid-State Lithium Batteries with Organic Cathode Materials (Final Report)

Organic materials made from abundant elements via low-energy processes are emerging as sustainable and low-cost alternatives to transition metal oxides as the electrode materials for high- energy batteries in the wake of supply chain and environmental issues associated with critical materials during the transition to clean energy. Organic insertion materials (OIMs) offer material- level energy comparable to transition metal oxides, but they have durability difficulties owing to dissolving in common liquid electrolytes. Combining ceramic-based solid electrolytes with organic electrode materials is one intriguing solution. The goal of this project is to design and synthesize high-energy OIMs, to understand the chemical dynamics and mechanical properties at the OIM-sulfide interface during electrochemical cycling, and to develop methods for constructing the optimum cathode microstructure, which will lead to improved electrochemical performance. The project team has accomplished the following over the last four years: (a) demonstrating that the mechanical softness of organic electrode materials is uniquely beneficial in suppressing crack formation at the electrode-electrolyte interface during cell operation; (b) understanding the interaction between cathode microstructure and the mechanical properties of individual components; and (c) establishing predictive control of cathode microstructure by tuning the mechanical properties of solid electrolytes and OIMs; (d) determining the chemical combability of sulfide electrolyte with high-energy OIMs and finally (f) laying out a road map toward a specific energy of 500 Wh kg -1 for solid-state lithium batteries. 14 publications resulted from this project.

25 ENERGY STORAGE↗

Trimer Quinoxalines as Organic Cathode Materials for Lithium-Ion Batteries

Due to synthetic ease, high redox potentials, low solubility in polar electrolytes, and good electric conductivity of their semiconducting crystals, discotic quinoxaline trimers (3Q) have been considered as possible candidates for 4 V organic cathodes in lithium-ion batteries. To assess their feasibility as such materials, several 3Q derivatives have been synthesized and tested in half-cells. In voltage limited cycling tests at 1.2–3.9 V vs Li/Li + , the specific discharge capacities of 40–180 mAh g -1 were obtained at a rate of 1 C, and multiple lithiation of 3Q and its derivatives was observed during discharge. However, the obtained discharge capacity was only a fraction of the theoretical capacity expected for reversible six-electron reduction; there was also rapid capacity fade. Our spectroscopic studies indicate the reversible three-electron lithiation at 2 V vs Li/Li + , but suggest instability of more highly discharged states. Finally, our conclusion is that while the 3Q derivatives combine several traits that are desirable in an organic cathode material (including negligible solubility, capacity for multiple charging, and near-100% coulombic efficiency), these materials are still impractical to use.

25 ENERGY STORAGE↗

Bipolar Organic Cathodes for Stable and Sustainable Na‐Ion and Rechargeable Al Batteries

Bipolar organic materials have emerged as promising cathode materials for rechargeable batteries because of their high voltage and high capacity. However, they suffer from poor cyclic stability and slow reaction kinetics. In this work, we designed and synthesized two bipolar organic cathode materials, containing carbonyl (n‐type) and amine (p‐type) functional groups, as well as extended conjugation structures, for Na‐ion batteries (NIBs) and rechargeable aluminum batteries (RABs). As universal electrode materials, bipolar organic materials exhibited exceptional electrochemical performance in terms of high capacity, high voltage, long cycle life, and fast rate capability. Further, the extended conjugation structures in backbones of the bipolar organic materials facilitate the π–π stacking with graphene, playing a critical role in the high performance. Furthermore, the formation of a stable and robust NaF‐rich cathode electrolyte interphase was shown to stabilize the bipolar organic cathode in NIBs. Electrochemical kinetic measurements reveal that both functional groups undergo reversible redox reactions. Specifically, the electron transfer rate constant of the p‐type amine group is one order of magnitude higher than that of the n‐type carbonyl group. These results highlight the efficacy of developing bipolar organic materials for achieving high‐performance organic cathode in NIBs and RABs.

25 ENERGY STORAGE↗

Porous bipolar polymers as organic cathodes for sustainable sodium/potassium-ion batteries

Redox-active porous polymers are becoming promising organic electrode materials for alkali-ion batteries because of their tunable pore size, flexible chemical structure, and high thermal stability. This work presents various porous bipolar polymers as cathodes in Na-ion batteries (NIBs) and K-ion batteries (KIBs). Two structural units containing carbonyl and amine active centers, respectively, were introduced into the repeating units of the polymers by the polycondensation of N,N,N',N'-tetrakis(4-aminophenyl)-1,4-phenylenediamine (TAP) and various dianhydrides. Here, the resulting bipolar polymers undergo multi-electron redox reactions involving both cations and anions during battery charge and discharge. The impacts of extended conjugation structures and porosity on the electrochemical performances were investigated by tuning the conjugation structures in the dianhydride monomers. The bipolar polymers with extended conjugation structures and small pore size exhibit superior electrochemical performance in NIBs and KIBs in terms of high redox potentials, long cycle life, and fast-charging capability, demonstrating great promise as organic cathode materials for alkali-ion batteries.

25 ENERGY STORAGE↗

Proton-enabled biomimetic stabilization of small-molecule organic cathode in aqueous zinc-ion batteries

Small-molecule organic cathode materials offer flexible structural design features, high capacity and sustainable production. Nonetheless, the stability decrease due to the high solubility of the electrode materials especially under electrochemical cycling conditions limits their wide-range applications in energy storage technologies. Here we describe a nature-inspired strategy to address cathode stability via introduction of transient vinylogous amide hydrogen bond networks into the small-molecule organic electrode material hexaazatrianthranylene (HATA) embedded quinone (HATAQ). Thanks to the proton-enabled biomimetic mechanism, HATAQ exhibits unparalleled cycling stability, ultra-high capacity and rate capability in aqueous zinc-ion batteries, delivering 492 mA h g -1 at 50 mA g -1 and a reversible capacity of 199 mA h g -1 , corresponding to 99% retention at 20 A g -1 after 1000 cycles.

25 ENERGY STORAGE↗

Building a spontaneously formed and self-healing protective layer with an F-rich electrochemically active organic molecule for ultra-stable Li metal batteries

Additives in the electrolyte act as engineers in Li metal batteries. Inspired by the superior cycle performance of organic materials in half cells, tetrafluoro-1,4-benzoquinone (TFBQ), the main structure of which has been widely applied as an organic cathode material, is utilized for the first time as an additive for Li metal protection. By chemical and electrochemical reactions between TFBQ and the Li metal surface, an F-rich interface layer is in situ formed on the Li metal surface during the charge and discharge process. From electrochemical tests and characterization, the powerful self-healing ability of the interface layer enabled by TFBQ is revealed, making an extremely stable Li metal anode. By using a lean electrolyte with 0.1 M TFBQ, the cycle life of Li|Li symmetric cells is increased at least 6 times compared to the control group. Moreover, impressive full cell performance was achieved. Ultra-stable Li–LFP cells showed a 0.026% average degradation for 600 cycles at 1C and Li–NMC622 cells showed a 36.8% higher capacity compared to the control group over 200 cycles at 0.5C, which are among the best results reported. Furthermore, this work efficiently and conveniently provides a new research direction to Li metal protection and Li metal batteries.

25 ENERGY STORAGE↗

Understanding High-Voltage Behavior of Sodium-Ion Battery Cathode Materials Using Synchrotron X-ray and Neutron Techniques: A Review

Despite substantial research efforts in developing high-voltage sodium-ion batteries (SIBs) as high-energy-density alternatives to complement lithium-ion-based energy storage technologies, the lifetime of high-voltage SIBs is still associated with many fundamental scientific questions. In particular, the structure phase transition, oxygen loss, and cathode–electrolyte interphase (CEI) decay are intensely discussed in the field. Synchrotron X-ray and neutron scattering characterization techniques offer unique capabilities for investigating the complex structure and dynamics of high-voltage cathode behavior. In this review, to accelerate the development of stable high-voltage SIBs, we provide a comprehensive and thorough overview of the use of synchrotron X-ray and neutron scattering in studying SIB cathode materials with an emphasis on high-voltage layered transition metal oxide cathodes. We then discuss these characterizations in relation to polyanion-type cathodes, Prussian blue analogues, and organic cathode materials. Finally, future directions of these techniques in high-voltage SIB research are proposed, including CEI studies for polyanion-type cathodes and the extension of neutron scattering techniques, as well as the integration of morphology and phase characterizations.

25 ENERGY STORAGE↗

Supramolecular Self-Assembled Multi-Electron-Acceptor Organic Molecule as High-Performance Cathode Material for Li-Ion Batteries

Organic electrode materials possess many advantages such as low toxicity, sustainability, and chemical/structural tunability toward high energy density. However, to compete with inorganic-based compounds, crucial aspects such as redox potential, capacity, cycling stability, and electronic conductivity need to be improved. Herein, a comprehensive strategy on the molecular design of small organic electron-acceptor-molecule—hexaazatrianthranylene (HATA) embedded quinone (HATAQ) is reported. By introducing conjugated quinone moieties into the electron-deficient hexaazatriphenylene-derivative core, HATAQ with highly extended π-conjugation can yield extra-high capacity for lithium storage, delivering a capacity of 426 mAh g -1 at 200 mA g -1 (0.4C). At an extremely high rate of 10 A g -1 (19C), a reversible capacity of 209 mAh g -1 corresponding to nearly 85% retention is obtained after 1000 cycles. A unique network of unconventional lock-and-key hydrogen bonds in the solid-state facilitates favorable supramolecular 2D layered arrangement, enhancing cycling stability. To the best of the authors’ knowledge, the capacity and rate capability of HATAQ are found to be the best ever reported for organic small-molecule-based cathodes. Finally, these results together with density functional theory studies provide proof-of-concept that the design strategy is promising for the development of organic electrodes with exceptionally high energy density, rate capability, and cycling stability.

25 ENERGY STORAGE↗

Electrochemical Potential of the Metal Organic Framework MIL-101(Fe) as Cathode Material in Li-Ion Batteries

We discuss the characteristic factors that determine the electrochemical potentials in a metal-organic framework used as cathode for Li-ion batteries via density functional theory-based simulations. Our focus is on MIL-101(Fe) cathode material. Our study gives insight into the role of local atomic environment and structural deformations in generating electrochemical potential.

Keshavarz, Fatemeh↗

A nitrogen- and carbonyl-rich conjugated small-molecule organic cathode for high-performance sodium-ion batteries

Organic-based cathode materials have attracted considerable attention for sustainable Na-ion batteries due to their great promise to overcome the issues arising from the insertion of large Na + into the rigid structures of conventional transition-metal-containing inorganic electrodes. The structural flexibility as a result of weak intermolecular interactions and simple electron- and ion-storage mechanisms found in organic compounds ensure facile and reversible transport of Na ions. In order to address the general drawbacks of small-molecule organic electrodes such as material dissolution in commonly used organic electrolytes and poor electronic conductivity, we report the use of a nitrogen- and carbonyl-rich highly extended π-conjugated small molecule, hexaazatrianthranylene (HATA) embedded quinone (HATAQ), as a cathode for sodium-ion batteries. The unique hydrogen bonds between highly functionalized conjugated HATAQ molecules allow supramolecular graphite-like 2D layered arrangements in the solid state which help facilitate the structural stability during long-term cycling and promote charge transfer. The compound delivers a capacity as high as 460 mA h g -1 at 500 mA g -1 and an excellent capacity retention of 99% (~138 mA h g -1 ) after 5000 cycles at an extremely high rate of 60 A g -1 . The reaction kinetics and redox mechanism of the material have been elucidated by several characterization techniques together with density functional theory (DFT) studies. The insights gained in this work could pave the way for ultra-high-performance small-molecule organic cathodes for sustainable energy storage.

25 ENERGY STORAGE↗

Polyimide as a durable cathode for all-solid-state Li(Na)–organic batteries with boosted cell-level energy density

The integration of organic electrode materials (OEMs) with solid-state electrolytes (SSEs) is expected to build an all-solid-state battery (ASSB) with long-term sustainability, high safety, and high energy density. Despite this great promise, the cell-level energy density is still far from practically applicable, which stems from the ultrathick SSE layer and thin cathode layer used in a pellet-type ASSB design. Here, a cost-effective polyimide (PI) material was first exploited as an organic cathode for sulfide-based ASSBs. A capacity of ~190 mAh g -1 was delivered with almost no capacity decay over 300 cycles. Moreover, for the first time, a dry-film approach was introduced to manufacture a sheet-type Li–organic ASSB with an ultrathin SSE layer and a high-areal-loading PI cathode. Notably, PI is a perfect candidate for dry-film technology due to its high thermal stability and extraordinary chemical inertness toward sulfide SSEs. Remarkably, the free-standing SSE membrane was merely 46 μm thick, and an ultralow areal resistance of 3.3 Ω cm 2 was achieved, more than tenfold lower than that of reported SSE pellets. One order of magnitude boost in the cell-level energy density was achieved. This work presents a significant leap in transferring organic ASSB technology from laboratory research to factory manufacturing.

25 ENERGY STORAGE↗

High-Energy, High-Power Sodium-Ion Batteries from a Layered Organic Cathode

Sodium-ion batteries (SIBs) attract significant attention due to their potential as an alternative energy storage solution, yet challenges persist due to the limited energy density of existing cathode materials. In principle, redox-active organic materials can tackle this challenge because of their high theoretical energy densities. However, electrode-level energy densities of organic electrodes are compromised due to their poor electron/ion transport and severe dissolution. Here, we report the use of a low-bandgap, conductive, and highly insoluble layered metal-free cathode material for SIBs. It exhibits a high theoretical capacity of 355 mAh g –1 per formula unit, enabled by a four-electron redox process, and achieves an electrode-level energy density of 606 Wh kg –1 electrode (90 wt % active material) along with excellent cycling stability. It allows for facile two-dimensional Na+ diffusion, which enables a high intrinsic rate capability. Growth of the active cathode material in the presence of as little as 2 wt % carboxyl-functionalized carbon nanotubes improves charge transport and charge transfer kinetics and further enhances the power performance. Altogether, these allow the construction of SIB cells built from an affordable, sustainable organic small molecule, which provide a cathode energy density of 472 Wh kg –1 electrode when charging/discharging in 90 s and a top specific power of 31.6 kW kg –1 electrode .

36 MATERIALS SCIENCE↗

Practically Accessible All-Solid-State Batteries Enabled by Organosulfide Cathodes and Sulfide Electrolytes

The combination of organic electrode materials and sulfide electrolytes is expected to enable the development of all-solid-state organic batteries featuring high energy density and long-term sustainability. In this work, thiuram hexasulfide is reported as a low-cost and high-capacity organic cathode for solid-state batteries based on sulfide electrolytes, delivering a capacity of ~600 mAh g -1 and retaining 80.8 % capacity after 500 cycles. An electrochemically reversible change of the cathode interface was revealed upon cycling. Full cell displays an oscillating stress change up to 0.6 MPa during cycling, predominated by the anode side. The energy density is 1140 Wh kg -1 at the material level and 376 Wh kg -1 at the electrode level, which are among the best-reported organic cathodes to date. A high areal capacity of 10.4 mAh cm -2 is reached with a high mass loading cathode. A dry-film approach is further explored to manufacture sheet-type cells. Free-standing electrolyte film is merely ~48 μm thick and demonstrates an ultralow areal resistance of 3.9 Ω cm 2 , significantly boosts the cell-level energy density and reduces the cell internal resistance.

25 ENERGY STORAGE↗

Solution–Processable Thermally Crosslinked Organic Radical Polymer Battery Cathodes

Organic radical polymers are promising cathode materials for next-generation batteries because of their rapid charge transfer and high cycling stability. However, these organic polymer electrodes gradually dissolve in the electrolyte, resulting in capacity fade. Several crosslinking methods have been developed to improve the performance of these electrodes, but they are either not compatible with carbon additives or compromise the solution processability of the electrodes. A one-step post-synthetic, carbon-compatible crosslinking method was developed to effectively crosslink an organic polymer electrode and allow for easy solution processing. The highest electrode capacity of 104 mAh g –1 (vs. a theoretical capacity of 111 mAh g –1 ) is achieved by introducing 1 mol % of the crosslinker, whereas the highest capacity retention (99.6 %) is obtained with 3 mol % crosslinker. In addition, mass transfer was observed in situ by using electrochemical quartz crystal microbalance with dissipation monitoring. Furthermore, these results may guide future electrode design toward fast-charging and high-capacity organic electrodes.

25 ENERGY STORAGE↗

Sustainable recycling of cathode scraps via Cyrene-based separation

Separation of cathode materials from the current collector remains a challenging task for the recycling of both spent lithium-ion batteries and cathode scraps. Dissolving the organic binder polyvinylidene difluoride (PVDF) with an organic solvent to recover both cathode materials and Al foils is an efficient and promising method. However, the use of toxic solvents limits their practical application in recycling large amounts of cathode scraps generated during the manufacturing process. Cyrene, a bioderived green solvent, is proposed here for a solvent-based separation process. This study investigated a closed-loop recovery process to reclaim cathode materials, Al foils, and PVDF binder from cathode scraps. Furthermore, the reuse of the Cyrene solvent led to a circular recycling process. Additionally, the Cyrene-based separation process embraces a sustainable electrode recovery and reuse platform and paves the way for battery recycling.

25 ENERGY STORAGE↗

Recent Progress on Dominant Sulfide‐Type Solid‐State Na Superionic Conductors for Solid‐State Sodium Batteries

Abstract Over the past decade, solid‐state batteries have garnered significant attentions due to their potentials to deliver high energy density and excellent safety. Considering the abundant sodium (Na) resources in contrast to lithium (Li), the development of sodium‐based batteries has become increasingly appealing. Sulfide‐based superionic conductors are widely considered as promising solid eletcrolytes (SEs) in solid‐state Na batteries due to the features of high ionic conductivity and cold‐press densification. In recent years, tremendous efforts have been made to investigate sulfide‐based Na‐ion conductors on their synthesis, compositions, conductivity, and the feasibility in batteries. However, there are still several challenges to overcome for their practical applications in high performance solid‐state Na batteries. This article provides a comprehensive update on the synthesis, structure, and properties of three dominant sulfide‐based Na‐ion conductors (Na 3 PS 4 , Na 3 SbS 4 , and Na 11 Sn 2 PS 12 ), and their families that have a variety of anion and cation doping. Additionally, the interface stability of these sulfide electrolytes toward the anode is reviewed, as well as the electrochemical performance of solid‐state Na batteries based on different types of cathode materials (metal sulfides, oxides, and organics). Finally, the perspective and outlook for the development and practical utilization of sulfide‐based SE in solid‐state batteries are discussed.

Guo, Xiaolin↗

Significance of a Solid Electrolyte Interphase on Separation of Anode and Cathode Materials from Spent Li-Ion Batteries by Froth Flotation

The separation of electrode active materials from spent Li-ion batteries (LIBs) by froth flotation is challenging due to the changes in surface properties of electrode active materials from cycling as well as the presence of organic binders. In this work, the froth flotation separation of aged anode and cathode composite materials from spent LIBs was systematically investigated after the materials were heat treated. The results show that aged anode and cathode materials from spent LIBs can be well separated from each other after a heating process in air at 400 degrees C and at which some of the PVDF binder remains intact. The underlying mechanism was investigated by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDX). The results from the XPS and contact angle measurements show that there is a hydrophilic and oxygen-rich layer on the surface of aged anode materials. This hydrophilic surface, associated with the solid electrolyte interface (SEI) layer, impacts the froth flotation process significantly. The results also show that both the SEI layers and PVDF binder residues on the surface are removed at 400 degrees C for an hour, restoring the hydrophobicity of the anode materials, which, in turn, benefits the separation of anode and cathode materials. The STEM/EDX elemental analysis data confirms that there are 20 nm-thick oxygen-rich SEI layers on the surfaces, which can be removed after a heating process. The present result illustrates the significance of the SEI layers in flotation separation of electrode materials and sheds new lights into the future development of the recycling processes for the separation of anode and cathode composite materials from spent Li-ion batteries.

25 ENERGY STORAGE↗