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Whittingham, M. Stanley

Publications and source records attributed to Whittingham, M. Stanley.

18 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Importance of High Valence Element Nb in Ni-Rich Layered Cathodes for High-Voltage Lithium-Metal Batteries

Ni-rich layered cathode materials have attracted extensive attention due to their higher energy density and technological maturity in commercialization. As the nickel content is raised, especially surpassing 80%, the increased energy density comes with the tradeoff of diminished thermal stability and increased electrochemical structural instability of the cathode. Compared with Co, Al, B, and Ta, the introduction of high valence element Nb significantly improved the electrochemical cycling, delivering a capacity of 202 mAh/g, corresponding to a capacity retention of 92% after 200 cycles tested at 45 °C. Further, the ex situ differential scanning calorimetry and in situ isothermal microcalorimetry demonstrate that the Nb-modified cathode has the potential to enhance the safety of ultrahigh nickel (Ni) NMCs and displays remarkable resilience to extensive cycling by inhibiting high-temperature decomposition reactions and exhibiting a lower heat flow during electrochemical cycling.

25 ENERGY STORAGE↗
DOE OSTI2024

Enhancing Cycling Stability of Lithium Metal Batteries by a Bifunctional Fluorinated Ether

Abstract The lifespan of lithium (Li) metal batteries (LMBs) can be greatly improved by the formation of inorganic‐rich electrode‐electrolyte interphases (EEIs) (including solid‐electrolyte interphase on anode and cathode‐electrolyte interphase on cathode). In this work, a localized high‐concentration electrolyte containing lithium bis(fluorosulfonyl)imide (LiFSI) salt, 1,2‐dimethoxyethane (DME) solvent and 1,2‐bis(1,1,2,2‐tetrafluoroethoxy)ethane (BTFEE) diluent is optimized. BTFEE is a fluorinated ether with weakly‐solvating ability for LiFSI so it also acts as a co‐solvent in this electrolyte. It can facilitate anion decomposition at electrode surfaces and promote the formation of more inorganic‐rich EEI layers. With an optimized molar ratio of LiFSI:DME:BTFEE = 1:1.15:3, LMBs with a high loading (4 mAh cm −2 ) lithium nickel manganese cobalt oxide (LiNi 0.8 Mn 0.1 Co 0.1 ) cathode can retain 80% capacity in 470 cycles when cycled in a voltage range of 2.8–4.4 V. The fundamental understanding on the functionality of BTFEE revealed in this work provides new perspectives on the design of practical high‐energy density battery systems.

25 ENERGY STORAGE↗
DOE OSTI2024

ε-VOPO 4 cathode for lithium ion batteries

The epsilon polymorph of vanadyl phosphate, ε-VOPO 4 , made from the solvothermally synthesized H 2 VOPO 4 , is a high density cathode material for lithium-ion batteries optimized to reversibly intercalate two Li-ions to reach the full theoretical capacity at least 50 cycles with a coulombic efficiency of 98%. This material adopts a stable 3D tunnel structure and can extract two Li-ions per vanadium ion, giving a theoretical capacity of 305 mAh/g, with an upper charge/discharge plateau at around 4.0 V, and one lower at around 2.5 V.

Siu, Carrie↗
DOE OSTI2024

Lithium inventory tracking as a non-destructive battery evaluation and monitoring method

Tracking the active lithium (Li) inventory in an electrode shows the true state of a Li battery, akin to a fuel gauge for an engine. However, non-destructive Li inventory tracking is currently unavailable. Here, in this work, we used the theoretical capacity of a transition metal oxide to convert capacity into a Li inventory analysis. The Li inventory in electrodes was tracked reliably to show how battery formulations and test methods affect performance. Contrary to capacity, Li inventory tracking reveals stoichiometric variations near the electrode–electrolyte interface. Verifiable results rationalized differences in measurements, clarifying and reducing interferences from cell formulations and experimental manipulations. By tracing four variables from formation to end-of-life, we characterize electrode and cell performance with a thermodynamic framework. Accurate rationalization of subtle differences in Li inventory utilization promises precise battery engineering, evaluation, failure analysis and risk mitigation. The method could be applicable from cell design optimization and fabrication to battery management, improving battery performance and reliability.

25 ENERGY STORAGE↗
DOE OSTI2024

VOPO 4 cathode for sodium ion batteries

An electrode comprising a space group Pna2 1 VOPO 4 lattice, capable of electrochemical insertion and release of alkali metal ions, e.g., sodium ions. The VOPO 4 lattice may be formed by solid phase synthesis of KVOPO 4 , milled with carbon particles to increase conductivity. A method of forming an electrode is provided, comprising milling a mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate; heating the milled mixture to a reaction temperature, and holding the reaction temperature until a solid phase synthesis of KVOPO 4 occurs; milling the KVOPO 4 together with conductive particles to form a conductive mixture of fine particles; and adding binder material to form a conductive cathode. A sodium ion battery is provided having a conductive NaVOPO 4 cathode derived by replacement of potassium in KVOPO 4 , a sodium ion donor anode, and a sodium ion transport electrolyte. The VOPO 4 , preferably has a volume greater than 90 Å 3 per VOPO 4 .

Whittingham, M. Stanley↗
DOE OSTI2023

Fifty years of lithium-ion batteries and what is next?

Here, the first rechargeable lithium batteries were built 50 years ago, at the same time as the Materials Research Society was formed. Great strides have been made since then taking a dream to domination of portable energy storage. During the past two decades, the demand for the storage of electrical energy has mushroomed both for portable applications such as for the iPhone and electric vehicles and for more than 1 GWh grid applications. As storage and power demands have increased, the batteries have evolved with their chemistries being pushed to the limits. This has resulted in the energy densities almost doubling and the cost dropping by more than an order of magnitude. However, the present electrochemical systems are still too costly to penetrate major new markets, still higher performance is required, and environmentally acceptable and sustainable materials are required.

25 ENERGY STORAGE↗
DOE OSTI2023

3D–Integrated, Multi–Functional Carbon Fibers for Stable, High–Areal–Capacity Batteries

Increasing lithium-ion batteries' (LIBs) electrode areal capacity can boost energy density and lower manufacturing costs, but faces challenges in manufacturing, rate performance, and cycling stability. A conductive framework made of commercial micro-sized carbon fibers (Cfs) is presented that serves as a host for both the LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC 532) cathode and Cfs anode. The Cf framework has multiple functions that offer high electronic conductivity (270 mS cm –1 ), low tortuosity (1.7), low Li + diffusion resistance (22 Ω), and high thermal conductivity (200 W mK –1 ). Additionally, the Cf-integrated electrodes can have an extremely high mass loading of NMC 532 (70 mg cm –2 ) with a theoretical capacity of 14 mAh cm –2 . Thus, the practical full cells assembled with the Cfs-enabled electrodes exhibit an initial areal capacity of 4.1 mAh cm –2 and capacity retention of 90.4% at 500 cycles at a cycling rate of C/3, 1.5 mA cm –2 . Data collected from the operando isothermal microcalorimetry suggest that full cells utilizing the Cf anode experience less heat release from side reactions compared to cells utilizing a conventional graphite anode. Finally, this present approach is scalable and cost-effective and can fabricate practical LIBs that boast high areal capacity, rate performance, and a lengthy cycling lifetime.

25 ENERGY STORAGE↗
DOE OSTI2023

ϵ-VOPO 4 cathode for lithium ion batteries

The epsilon polymorph of vanadyl phosphate, ε-VOPO 4 , made from the solvothermally synthesized H 2 VOPO 4 , is a high density cathode material for lithium-ion batteries optimized to reversibly intercalate two Li-ions to reach the full theoretical capacity at least 50 cycles with a coulombic efficiency of 98%. This material adopts a stable 3D tunnel structure and can extract two Li-ions per vanadium ion, giving a theoretical capacity of 305 mAh/g, with an upper charge/discharge plateau at around 4.0 V, and one lower at around 2.5 V.

25 ENERGY STORAGE↗
DOE OSTI2023

Complex defect chemistry of hydrothermally-synthesized Nb-substituted β$'$-LiVOPO 4

Lithium vanadyl phosphate (LiVOPO 4 ) is a next-generation multielectron battery cathode that can intercalate up to two Li-ions per V-ion through the redox couples of V 4+ /V 3+ and V 5+ /V 4+ . However, its rate capacity is undermined by the sluggish Li-ion diffusion in the high-voltage region (4 V for V 5+ /V 4+ redox). Nb substitution was used to expand the crystal lattice to facilitate Li-ion diffusion. Here, in this work, Nb substitution was achieved via hydrothermal synthesis, which resulted in a new, lower symmetry β'-LiVOPO 4 phase with preferential Nb occupation of one of the two V sites. This phase presents complex defect chemistries, including cation vacancies and hydrogen interstitials, characterized by a combination of X-ray and neutron diffraction, elemental and thermogravimetric analyses, X-ray absorption spectroscopy, and magnetic susceptibility measurements. The Nb-substituted samples demonstrated improved capacity retention and rate capabilities in the high-voltage region, albeit an enlarged voltage hysteresis related to a partial V 4+ /V 3+ redox reaction, as evidenced by ex situ X-ray absorption spectroscopy and pair distribution function analysis. This work highlights the importance of understanding the complex defect chemistry and its consequence on electrochemistry in polyanionic intercalation compounds.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Voltage and Temperature Limits of Advanced Electrolytes for Lithium-Metal Batteries

Several advanced electrolytes (mainly ether-based) have recently demonstrated excellent electrochemical performance in high energy density lithium (Li)-metal batteries. However, the safety of these ether-based electrolytes is still unknown. This work evaluates the thermal stability of these new formulations to understand their safety limits of operation in comparison to carbonate electrolytes typically used in Li-ion batteries. Electrolyte stability is assessed in conjunction with LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode and Li-metal anode at ultra-high voltages (≤ 4.8 V) and temperatures (≤ 300°C) to trigger thermal runaway, where onset and extent of heat release are monitored via isothermal microcalorimetry and differential scanning calorimetry Most ether-based electrolytes show improved thermal resilience over commercial carbonate formulations when heated up to 300°C. The thermal behavior in presence of charged cathode and Li-metal suggests that the new electrolytes may be better at stabilizing active material surfaces than carbonate electrolytes. Although extreme voltages severely destabilize the ether-based formulations, prompting thermal runaway, a phosphate based localized high concentration electrolyte exhibits superior stability over commercial carbonate electrolytes at all tested temperatures (32°C, 45°C, and 60°C). Although thermal analysis during the first charge process (as adopted in this preliminary study) may be insufficient to conclude the long-term advantages of these electrolytes, a more stable electrolyte identified under extreme voltage and temperature conditions will provide valuable guidance for the safety of future electrolyte designs.

25 ENERGY STORAGE↗
DOE OSTI2022

KVOPO 4 cathode for sodium ion batteries

An electrode comprising: NaVOPO 4 having orthorhombic crystalline symmetry and space group Pna2 1 , as an active intercalation host material, wherein the electrode is capable of electrochemical insertion and release of greater than one sodium ion per vanadium, wherein the NaVOPO 4 is formed by a solid phase synthesis process from a heated powdered mixture of ammonium metavanadate, ammonium phosphate monobasic, and potassium carbonate, to yield NaVOPO 4 having corner-sharing VO 6 octahedra and PO 4 tetrahedra, defining two types of tunnels comprising a first type of tunnel formed of rings of two PO 4 tetrahedra and a second type of tunnel formed of rings of three PO 4 tetrahedra and three VO 6 octahedra, followed by substitution of the potassium ions with sodium ions.

Whittingham, M. Stanley↗
DOE OSTI2022

Isoxazole-Based Electrolytes for Lithium Metal Protection and Lithium-Sulfurized Polyacrylonitrile (SPAN) Battery Operating at Low Temperature

A new electrolyte system using isoxazole as the salt dissolving solvent has been developed and studied for lithium metal batteries. By using fluoroethylene carbonate (FEC) as an additive and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent for localized high concentration electrolyte (LHCE), isoxazole-based electrolytes were successfully implemented in lithium metal batteries, demonstrating excellent lithium metal protection capability. Utilizing several advanced characterization techniques (including synchrotron-based X-ray absorption spectroscopy and photoelectron spectroscopy), the solid electrolyte interphase (SEI) formed on the Li-metal anode after employing these electrolytes was thoroughly investigated. The high ionic conductivity of isoxazole at low temperature and the low impedance of SEI formed in LHCE significantly improved the low-temperature performance of Li-sulfurized polyacrylonitrile (SPAN) batteries, delivering 273.8 mAh g −1 capacity at −30 °C with 99.85% capacity retention after 50 cycles.

25 ENERGY STORAGE↗
DOE OSTI2022

ϵ-VOPO 4 cathode for lithium ion batteries

The epsilon polymorph of vanadyl phosphate, ε-VOPO 4 , made from the solvothermally synthesized H 2 VOPO 4 , is a high density cathode material for lithium-ion batteries optimized to reversibly intercalate two Li-ions to reach the full theoretical capacity at least 50 cycles with a coulombic efficiency of 98%. This material adopts a stable 3D tunnel structure and can extract two Li-ions per vanadium ion, giving a theoretical capacity of 305 mAh/g, with an upper charge/discharge plateau at around 4.0 V, and one lower at around 2.5 V.

25 ENERGY STORAGE↗
DOE OSTI2022

Battery500 Consortium: Development of High-Capacity Cathodes and Robust Solid Electrolytes

The goal off this EERE-BMR-Battery 500 consortium project was to provide the supporting science and to lead the Keystone 1 project. Key findings include: identification of 1st cycle loss of high nickel NMC materials as a major opportunity to increase the capacity of these cathode materials. The selective use of substituents and surface coatings was identified as a potential way of decreasing the 1st cycle loss and in increasing capacity retention. Niobium at around the 1% level was found to be optimum. In addition, operando DSC was utilized to scope out the stability range of electrolytes developed by the Battery 500 team.

25 ENERGY STORAGE↗
DOE OSTI2022

Oxygen Loss in Layered Oxide Cathodes for Li-Ion Batteries: Mechanisms, Effects, and Mitigation

Layered lithium transition metal oxides derived from LiMO 2 (M = Co, Ni, Mn, etc.) have been widely adopted as the cathodes of Li-ion batteries for portable electronics, electric vehicles, and energy storage. Oxygen loss in the layered oxides is one of the major factors leading to cycling-induced structural degradation and its associated fade in electrochemical performance. Herein, we review recent progress in understanding the phenomena of oxygen loss and the resulting structural degradation in layered oxide cathodes. We first present the major driving forces leading to the oxygen loss and then describe the associated structural degradation resulting from the oxygen loss. Here, we follow this analysis with a discussion of the kinetic pathways that enable oxygen loss, and then we address the resulting electrochemical fade. Finally, we review the possible approaches toward mitigating oxygen loss and the associated electrochemical fade as well as detail novel analytical methods for probing the oxygen loss.

36 MATERIALS SCIENCE↗