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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 73 records · Page 4

Tailoring solid-electrolyte interphase and solvation structure for subzero temperature, fast-charging, and long-cycle-life sodium-ion batteries

The sluggish Na + reaction kinetics with carbon materials limits the fast-charging capability, Coulombic efficiency, and cycle life of sodium-ion batteries, especially at low temperatures. Herein, free-standing carbon nanofiber films, with controllable crystallinity and surface chemistry, are used as a platform to investigate the correlation between Na + reaction kinetics, storage mechanism, and electrolyte environment. The ion solvation effect and solid-electrolyte interphase (SEI) properties determine the kinetics and storage mechanism. A strong Na + -solvent interaction, such as Na + -diglyme, tends to form a "pseudo-SEI" layer dominated by anion decomposition, enabling fast Na + -solvent co-intercalation kinetics. Tuning the SEI chemistries by pre-cycling in the weakly solvated electrolyte (e.g., ester electrolyte), the intercalation capacity rapidly disappears due to the high energy barrier for Na + transport. Finally, such mechanistic insights allow us to develop the optimal combination of electrode materials and electrolyte chemistry to achieve high initial Coulombic efficiency, ultra-long cycle life under fast charging, and excellent low-temperature performance.

25 ENERGY STORAGE↗

Kinetically Stable Oxide Overlayers on Mo 3 P Nanoparticles Enabling Lithium–Air Batteries with Low Overpotentials and Long Cycle Life

The main drawbacks of today's state-of-the-art lithium–air (Li–air) batteries are their low energy efficiency and limited cycle life due to the lack of earth-abundant cathode catalysts that can drive both oxygen reduction and evolution reactions (ORR and OER) at high rates at thermodynamic potentials. Here, inexpensive trimolybdenum phosphide (Mo 3 P) nanoparticles with an exceptional activity—ORR and OER current densities of 7.21 and 6.85 mA cm –2 at 2.0 and 4.2 V versus Li/Li + , respectively—in an oxygen-saturated non-aqueous electrolyte are reported. The Tafel plots indicate remarkably low charge transfer resistance—Tafel slopes of 35 and 38 mV dec –1 for ORR and OER, respectively—resulting in the lowest ORR overpotential of 4.0 mV and OER overpotential of 5.1 mV reported to date. Using this catalyst, a Li–air battery cell with low discharge and charge overpotentials of 80 and 270 mV, respectively, and high energy efficiency of 90.2% in the first cycle is demonstrated. Furthermore, a long cycle life of 1200 is also achieved for this cell. Density functional theory calculations of ORR and OER on Mo 3 P (110) reveal that an oxide overlayer formed on the surface gives rise to the observed high ORR and OER electrocatalytic activity and small discharge/charge overpotentials.

25 ENERGY STORAGE↗

An anode-free Li metal cell with replenishable Li designed for long cycle life

Pit corrosion of Li during stripping is an important factor responsible for poor Li cycling efficiency, a metric that determines its cycling life. When excess Li is present, it has been observed that Li tends to strip in a non-uniform fashion, forming pits that extend well past the theoretical Li depth that inevitably lead to the formation of electronically isolated “dead” Li particles. In this work, a novel cell with replenishable Li is shown to inherently mitigate the formation of this “dead” Li, as a direct result of a design in which the intrinsically more homogenous stripping behavior of anode-free cells are combined with a replenishable limited Li reservoir. These novel cells (Li|Cu||LiFePO 4 ) exhibit 25% and 34% higher cumulative capacities than the conventional cells (Cu|Li||LiFePO 4 ) in carbonate and ether electrolytes, respectively, enabling a significant increase in cycle life without impacting energy density. This improvement strategy represents a new direction in Li metal battery improvement, in which improved cycling can be achieved regardless of electrolyte chemistry.

Long cycle life↗

Enabling Ether-Based Electrolytes for Long Cycle Life of Lithium-Ion Batteries at High Charge Voltage

Lithium-ion batteries (LIBs) with high-nickel (Ni) content LiNi x Mn y Co z O 2 ( x + y + z = 1) (NMC with Ni ≥ 0.6) cathodes operated at high charge voltages have been considered as one of the most promising candidates for addressing the challenge of increasing energy density demand. Conventional LiPF 6 –organocarbonate electrolytes exhibit incompatibility with such cell chemistries under certain testing conditions because of the instability of electrode/electrolyte interphases. In response to this challenge, ether-based electrolytes with finely tuned structure and composition of solvation sheaths were developed and evaluated in graphite (Gr)∥NMC811 cell chemistry in 2.5–4.4 V, despite ethers being conventionally considered to be unfavorable electrolyte solvents for LIBs because of their anodic instability above 4.0 V and cointercalation into Gr electrodes. Furthermore, the functional ether-based electrolytes in this work enable both excellent cycle life and high rate capability of Gr∥NMC811 cells. Mechanistic studies reveal that the unique structure and composition of the solvation sheath of the functional ether electrolytes are the main reasons behind their excellent anodic stability and effective protection of the Gr electrode and, consequently, the extraordinary cell performances when operated at high charge cutoff voltages. This work also provides a feasible approach in developing highly stable functional electrolytes for high-energy density LIBs.

25 ENERGY STORAGE↗

A stable cathode-solid electrolyte composite for high-voltage, long-cycle-life solid-state sodium-ion batteries

Rechargeable solid-state sodium-ion batteries (SSSBs) hold great promise for safer and more energy-dense energy storage. However, the poor electrochemical stability between current sulfide-based solid electrolytes and high-voltage oxide cathodes has limited their long-term cycling performance and practicality. Here, we report the discovery of the ion conductor Na 3-x Y 1-x Zr x Cl 6 (NYZC) that is both electrochemically stable (up to 3.8 V vs. Na/Na + ) and chemically compatible with oxide cathodes. Its high ionic conductivity of 6.6 × 10 –5 S cm –1 at ambient temperature, several orders of magnitude higher than oxide coatings, is attributed to abundant Na vacancies and cooperative MCl 6 rotation, resulting in an extremely low interfacial impedance. A SSSB comprising a NaCrO 2 + NYZC composite cathode, Na 3 PS 4 electrolyte, and Na-Sn anode exhibits an exceptional first-cycle Coulombic efficiency of 97.1% at room emperature and can cycle over 1000 cycles with 89.3% capacity retention at 40 °C. These findings highlight the immense potential of halides for SSSB applications.

99 GENERAL AND MISCELLANEOUS↗

Perspective—Lithium Metal Nucleation and Growth on Conductive Substrates: A Multi-Scale Understanding from Atomistic, Nano-, Meso-, to Micro-Scales

Reversible lithium (Li) deposition and stripping on conductive substrates like copper is vital for long-life high-energy rechargeable Li batteries. The reversibility is believed hindered by solid electrolyte interphase (SEI) formation and Li dendritic growth. Via in situ, operando cryo-microscopy and molecular dynamics simulation, we discovered amorphous Li before a disorder-order phase transition to bcc phase. The kinetics plays a significant role in Li nucleation and morphology evolution. This perspective on Li nucleation and growth from atomistic to nano- (<20 nm), meso- (20–100 nm), and micro-scales (>100 nm) provides a practical guidance on regulating dense Li deposits reversibly for long life performance.

25 ENERGY STORAGE↗

Dual Protective Mechanism of AlPO 4 Coating on High-Nickel Cathode Material for High Energy Density and Long Cycle Life Lithium-Ion Batteries

Cathode material with high nickel content is a promising candidate for the future generation of Li-ion batteries (LIBs). However, severe structural degradation during cycling limits its practical use, especially for electric vehicles. Herein, AlPO 4 nanoparticles were synthesized and then coated onto the surface of a high-nickel layer-structured cathode via a dry coating method. The AlPO 4 nanoparticles coating significantly improved the cycling stability from 69.2% to over 80% capacity retention after 140 cycles. Furthermore, the structure and chemical composition of the AlPO 4 -coated cathode was investigated by XRD, SEM, XPS, and STEM. Compared with the non-coated cathode, we revealed a dual protective mechanism for enhanced cycling stability, where Al doping and Li 3 PO 4 coating play synergistic roles in protecting cathode material through long-term cycling. This work demonstrates a facile and environmentally friendly approach toward improving the performance of high-nickel LIB cathodes, which can be easily scaled up for industrial applications.

25 ENERGY STORAGE↗

Tritium Betavoltaic Powered Sensor Platforms: Power Augmentation with Scintillating Particles

Betavoltaics (BV) are long-life power sources that typically convert beta particle radiation into electricity. Largely, the radioactive decays within the source go unharvested by the device. This work seeks to augment the power generation of BV devices by integration of scintillating particles within the radiative getter to convert beta emission which would otherwise not leave the getter into usable light for power generation. Silica-covered barium fluoride scintillating particles were integrated into a tritiated water getter. Power generation was increased from 100s of nW to µW levels with the addition of 0.2 wt. % particles into the getter. Nanowatt-scale sensor platforms were demonstrated with the µW BV devices and the maximum possible lifetime of such platforms was estimated. As this technique enables higher power density BV devices from conventional Si semiconductors (compared to wider bandgap BVs), the further implementation may lower the barrier-to-deployment of these long-life power/sensor platforms.

42 ENGINEERING↗

Halting Oxygen Evolution to Achieve Long Cycle Life in Sodium Layered Cathodes

Oxygen redox chemistries at high voltage have materialized as a revolutionary paradigm for cathodes with high-energy density; however, they are plagued by the challenges of labile oxygen loss and rapid degradations upon cycling, even after concerted endeavors from the research community. Here we propose a multi-concentration stratagem propelled by entropy reinforcement to enhance the electronic structure disorder (ESD) at high desodiation states for impeding undesired oxygen mobility and ensuring controlled oxygen activity, elucidated by density functional theory calculations. The increased disorder strengthens the reversible electrochemistry of lattice oxygen redox, leading to effectively suppressed P−O structural evolution and highly stable localized TMO 6 octahedral environments, as demonstrated by soft/hard X-ray absorption spectroscopy. Furthermore, through a comparative analysis of sodium-layered cathodes with different configuration entropy, we reveal that a high-entropy state induced by cationic disordering has the capacity to perturb cationic redox boundaries, significantly restraining the formation of detrimental O′3 phases. As a consequence, the high-voltage cycling stability has been greatly upgraded, up to 4.4 V versus Na + /Na, with an impressive 90.1 % capacity retention at 1 C over 100 cycles and 76.1 % capacity retention at 2 C over 300 cycles. In conclusion, the resilient oxygen redox, enabled through the control of ESD, broadens the horizons for entropy engineering and lays the foundation for advancements in high-energy, long-cycling, and safe batteries.

25 ENERGY STORAGE↗

A weakly ion pairing electrolyte designed for high voltage magnesium batteries

High-voltage rechargeable magnesium batteries (RMBs) are potential alternatives to lithium-ion batteries owing to the low cost and high abundance of magnesium. However, the parasitic reactions of the latter with many electrolytes greatly hinders the stability and kinetics of Mg plating/stripping. Here we report a new and easily accessible solvent-designed electrolyte, which effectively solves the difficulty of ion pair dissociation and facilitates fast nanoscale Mg nucleation/growth using simple Mg(TFSI)2 as the salt, enabling a facile interfacial charge transfer process. Dendrite-free Mg plating/stripping is maintained for over 7000 hours (∼10 months) at a practical areal capacity of 2 mA h cm−2. The high-voltage stability of these electrolytes is demonstrated by benchmarking with polyaniline||Mg full cells with an operating voltage up to 3.5 V that exhibit stable cycling at a 2C rate with 99% coulombic efficiency after 400 cycles. This work opens up new frontiers in coupling low-cost electrolytes with next-generation high-voltage cathode materials for fast-charging RMBs with long life and high energy densities.

Li, Chang↗

Rational designs to enable 10-min fast charging and long cycle life in lithium-ion batteries

A daunting challenge in the design of lithium ion batteries (LiBs) is enabling 10-min extreme fast charging (XFC) while achieving appreciable charge acceptance and cycle life. This desirable outcome requires both a comprehensive understanding of LiB operation and aging behavior at different length scales and careful optimization. Lithium plating has been a critical bottleneck because, at XFC rates, it consumes cyclable lithium causing distinct aging and safety concerns even in moderate-loading LiBs. Here, we propose combining multiple solutions, including materials-to-electrode design-to-charging protocols, that are intended to overcome limitations in lithium-ion transport in the electrolyte phase, thus enabling 10-min XFC in LiBs. Some implemented strategies include cathode chemistry, optimized carbon binder domain in the cathode, dual layer anode design, improved separator and advanced electrolyte. Further, innovative charging protocols in moderately loading (~3 mAh/cm 2 anode/2.7 mAh/cm 2 cathode) single-layer pouch cells are proposed, together with demonstrated 10-min XFC with higher charge acceptance between 87.3 and 92.1% (or 2–2.1 mAh/cm 2 ) for 600 cycles without lithium plating. This methodical study with well-defined cells shows promise in combining multiple solution strategies to enable 10-min XFC, charting a pathway to achieve XFC in higher-loading energy-optimized LiBs.

25 ENERGY STORAGE↗

Calcium-Doped High-Voltage Spinel Cathode for Long Cycle Life Lithium-Ion Batteries

With the promises of low cost, high operating voltage, and excellent rate capability, the high-voltage spinel material with the formula of LiNi 0.5 Mn 1.5 O 4 (LNMO) has been considered as one of the most promising cathode materials for nextgeneration lithium-ion batteries (LIBs). However, the adoption of LNMO into practical LIBs is greatly hindered due to its rapid capacity decay associated with its bulk structural instability and interfacial side reactions. To address these issues, we proposed to use the cost-effective calcium (Ca) element as a dopant to stabilize the oxygen framework and surface of the LNMO crystal. The experimental results showed that, with moderate Ca doping, the obtained cathode (Ca 0.05 LNMO) retained a specific capacity of ∼121 mAh/g (∼94.4% capacity retention) after 500 cycles at 0.5 C, compared to ∼73% for the baseline bare sample. Furthermore, the Ca 0.05 LNMO cathode retained ∼84% of its initial capacity, vs the baseline with ∼69%, after 150 cycles at the high temperature of 55 °C. The excellent battery performance of the moderately Ca-doped LNMO cathode is ascribed to its structural and kinetic advantages.

25 ENERGY STORAGE↗

Calcium Gradient-Doped LiNi 0.5 Mn 1.5 O 4 Cathode for Long Cycle Life Lithium-Ion Batteries

High-voltage spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) has attracted considerable attention as a cathode material for next-generation lithium-ion batteries due to its high operating voltage and intrinsically fast lithium-ion diffusion kinetics. However, the practical implementation of LNMO remains limited by its rapid capacity decay, primarily associated with bulk structural instability and parasitic interfacial reactions. To address these issues, we innovatively introduced calcium (Ca) as a dopant to enhance both the oxygen framework and surface stabilities of the LNMO crystal through gradient doping. Observations from the electronic microscopies, X-ray diffraction, and the elemental analysis confirmed that Ca is preferentially enriched at the particle surface, and a disordered crystal phase is preserved in the bulk in the gradient-doped LNMO cathodes. As cathodes in LIBs, the Ca gradient-doped (Ca gr) LNMO materials delivered formation capacities of ∼126−130 mAh/g and exhibited Coulombic efficiencies of 88−95%, which are consistently higher than those of the uniform-doped samples at the same doping level and undoped sample. Especially, the Ca gr 0.05 LNMO cathode demonstrated significantly improved rate capability with ∼113 mAh/g preserved at 10 C, while ∼92 mAh/g and ∼110 mAh/g for undoped and Ca uniform 0.05 LNMO, respectively, and excellent cycling stability, retaining ∼124.1 mAh/g (∼96.3% capacity retention) after 500 cycles. The analysis of cyclic voltammetry, differential capacity, and electrochemical impedance revealed that the excellent electrochemical performance is attributed to the structural and morphological advantages of gradient-doped LNMO cathodes with a disordered bulk structure for fast Li + diffusion and a Ca-enriched surface for minimizing the Mn dissolution.

25 ENERGY STORAGE↗

An inorganic-rich but LiF-free interphase for fast charging and long cycle life lithium metal batteries

Abstract Li metal batteries using Li metal as negative electrode and LiNi 1-x-y Mn x Co y O 2 as positive electrode represent the next generation high-energy batteries. A major challenge facing these batteries is finding electrolytes capable of forming good interphases. Conventionally, electrolyte is fluorinated to generate anion-derived LiF-rich interphases. However, their low ionic conductivities forbid fast-charging. Here, we use CsNO 3 as a dual-functional additive to form stable interphases on both electrodes. Such strategy allows the use of 1,2-dimethoxyethane as the single solvent, promising superior ion transport and fast charging. LiNi 1-x-y Mn x Co y O 2 is protected by the nitrate-derived species. On the Li metal side, large Cs + has weak interactions with the solvent, leading to presence of anions in the solvation sheath and an anion-derived interphase. The interphase is surprisingly dominated by cesium bis(fluorosulfonyl)imide, a component not reported before. Its presence suggests that Cs + is doing more than just electrostatic shielding as commonly believed. The interphase is free of LiF but still promises high performance as cells with high LiNi 0.8 Mn 0.1 Co 0.1 O 2 loading (21 mg/cm 2 ) and low N/P ratio (~2) can be cycled at 2C (~8 mA/cm 2 ) with above 80% capacity retention after 200 cycles. These results suggest the role of LiF and Cs-containing additives need to be revisited.

36 MATERIALS SCIENCE↗