Publications by authors named "Romain Dubey"

Article Synopsis
  • Ultrafast (UF) sintering is a novel technique for creating LiLaZrO (LLZO) solid-state electrolytes, crucial for the development of solid-state batteries.
  • This study investigates the surface chemistry of UF-sintered LLZO and finds significant contamination, particularly from LiO, which affects electrochemical performance.
  • An additional heat treatment at 900 °C post-UF sintering effectively reduces this contamination, leading to better performance in Li/LLZO/Li symmetric cells.
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Ultrafast sintering (UFS) is a compelling approach for fabricating LiLaZrO (LLZO) solid-state electrolytes (SSEs), paving the way for advancing and commercializing Li-garnet solid-state batteries. Although this method is commonly applied to the sintering of LLZO ceramics, its use for producing dense, phase-pure LLZO SSEs has thus far been primarily limited to millimeter-thick pellets, which are unsuitable for commercial solid-state batteries. This study presents ultrafast sintering as a highly effective approach for fabricating self-standing, dense, 45 µm-thick LLZO membranes.

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Silicon oxycarbide (SiOC) has recently regained attention in the field of Li-ion batteries, owing to its effectiveness as a host matrix for nanoscale anode materials alloying with Li. The SiOC matrix, itself providing a high Li-ion storage capacity of 600 mA h g-1, assists in buffering volumetric changes upon lithiation and largely suppresses the formation of an unstable solid-electrolyte interface. Herein, we present the synthesis of homogeneously embedded Sb nanoparticles in a SiOC matrix with the size of 5-40 nm via the pyrolysis of a preceramic polymer.

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Tin-based materials are an emerging class of Li-ion anodes with considerable potential for use in high-energy-density Li-ion batteries. However, the long-lasting electrochemical performance of Sn remains a formidable challenge due to the large volume changes occurring upon its lithiation. The prevailing approaches toward stabilization of such electrodes involve embedding Sn in the form of nanoparticles (NPs) in an active/inactive matrix.

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One strategy to overcome the slow kinetics associated with electrochemical magnesium ion storage is to employ a permanently porous, capacitive cathode material together with magnesium metal as the anode. This strategy has begun to be employed, for example, using framework solids like Prussian blue analogues or porous carbons derived from metal-organic frameworks, but the cycling stability of an ordered, bottom-up synthesized, three-dimensional carbon framework toward magnesiation and demagnesiation in a shuttle-type battery remains unexplored. Zeolite-templated carbons (ZTCs) are a class of ordered porous carbonaceous framework materials with numerous superlative properties relevant to electrochemical energy storage.

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Rechargeable magnesium batteries are appealing as safe, low-cost systems with high-energy-density storage that employ predominantly dendrite-free magnesium metal as the anode. While significant progress has been achieved with magnesium electrolytes in recent years, the further development of Mg-ion batteries, however, is inherently limited by the lack of suitable cathode materials, mainly due to the slow diffusion of high-charge-density Mg-ions in the intercalation-type host structures and kinetic limitations of conversion-type cathodes that often causes poor cyclic stability. Nanostructuring the cathode materials offers an effective means of mitigating these challenges, due to the reduced diffusion length and higher surface areas.

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Dual-ion batteries (DIBs) are electrochemical energy storage devices that operate by the simultaneous participation of two different ion species at the anode and cathode and rely on the use of an electrolyte that can withstand the high operation potential of the cathode. Under such conditions at the cathode, issues associated with the irreversible capacity loss and the formation of solid-electrolyte interphase at the surface of highly porous electrode materials are far less significant than at lower potentials, permitting the exploration of high surface area, permanently porous framework materials as effective charge storage media. This concept is investigated herein by employing zeolite-templated carbon (ZTC) as a cathode in a dual-ion battery based on a potassium bis(fluorosulfonyl)imide (KFSI) electrolyte.

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Molecular catalysts offer tremendous advantages for stereoselective polymerization because their activity and selectivity can be optimized and understood mechanistically using the familiar tools of organometallic chemistry. Yet, this exquisite control over selectivity comes at an operational price that is generally not justifiable for the large-scale manufacture of polyfolefins. In this report, we identify Co-MFU-4l, prepared by cation exchange in a metal-organic framework, as a solid catalyst for the polymerization of 1,3-butadiene with high stereoselectivity (>99% 1,4-cis).

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