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We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface-functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil-in-water emulsions, from which yolk-shell and dual-shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li-ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li-ion anodes composed of 46 wt % of dual-shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm-2 achieve an overall specific capacity higher than 600 mAh g-1 , which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si-C composites for Li-ion batteries.

We report the electrochemical intercalation-extraction of aluminum (Al) in the layered TiS2 and spinel-based cubic Cu0.31Ti2S4 as the potential cathode materials for rechargeable Al-ion batteries. The electrochemical characterizations demonstrate the feasibility of reversible Al intercalation in both titanium sulfides with layered TiS2 showing better properties. The crystallographic study sheds light on the possible Al intercalation sites in the titanium sulfides, while the results from galvanostatic intermittent titration indicate that the low Al3+ diffusion coefficients in the sulfide crystal structures are the primary obstacle to facile Al intercalation-extraction.

The development of practical Mg based batteries is limited by the lack of a library of suitable electrolytes. Recently a 12-vertex closo-carborane anion based electrolyte has been shown to be the first electrolyte for Mg based batteries, which is both non-corrosive and has high electrochemical stability (+3.5 V vs. Mg0/2+). Herein we show that smaller 10-vertex closo-carborane anions also enable electrolytes for Mg batteries. Reduction of the trimethylammonium cation of [HNMe31+][HCB9H91-] with elemental Mg yields the novel magnesium electrolyte [Mg2+][HCB9H91-]2. The electrolyte displays excellent electrochemical stability, is non-nucleophilic, reversibly deposits and strips Mg, and is halide free. This discovery paves the way for the development of libraries of Mg electrolytes based on more cost effective 10-vertex closo-carborane anions.

The formation of a solid–electrolyte interphase (SEI) on the surface of Li4Ti5O12 (LTO) has become a highly controversial topic, with arguments for it and against it. However, prior studies supporting the formation of an SEI layer have typically suggested that a layer forms upon cycling of a cell, although the layer is probed after disassembling. In this study, cubic mesostructured LTO is synthesized with crystallite domain sizes between 3 and 4 nm and uniform pores with diameters ≤8 nm. The mean pore size is controlled between 4–8 nm through the use of a triblock amphipathic copolymer with a tunable hydrophobic block as template and by thermal treatment. The LTO morphology obtained is spherical and evolves upon heat treatment. These materials show excellent electrochemical performance, including high rate capability and capacity retention. The LTO material is subjected to operando small‐angle neutron scattering and X‐ray photoelectron spectroscopy experiments, which reveal that the highly debated SEI forms at potentials as high as 2.2 V, first as a LiF‐rich layer and subsequently by the growth of a carbonaceous layer. These SEI products form first on the smaller pores before forming on the mesopores. [ABSTRACT FROM AUTHOR]

Switching from organic to aqueous solvents for battery electrode processing is desirable due to both safety and cost advantages. Lithium iron phosphate (LFP) is considered a cathode material for aqueous processing due to its demonstrated chemical compatibility with water, in addition to its favorable cost, safety, electrochemical performance, and environmental advantages as a battery active material. All research on LFP stability in water has been conducted in a scenario where LFP is aged in stagnant water, or surrounded by water when confined within a composite electrode. However, a much accelerated degradation in the electrochemical performance of LFP when it is in contact with water and exposed to mechanical agitation is demonstrated. Changes to LFP are probed using a combination of materials characterization methods. Although there are no significant changes to the bulk particle structure and morphology, significant particle surface damage and compositional modifications are observed. These results suggest that the systems where LFP is exposed to agitation in an aqueous environment, such as in aqueous battery electrode processing or in aqueous slurry electrodes, need to be carefully investigated for potential changes to the LFP surface environment under relevant processing conditions. Lithium iron phosphate (LiFePO4) is considered a cathode material for aqueous processing due to demonstrated chemical compatibility with water, in addition to favorable cost, safety, electrochemical performance, and environmental advantages. However, this study demonstrates conditions under which a much‐accelerated degradation in the electrochemical performance occurs when the material is in contact with water and exposed to mechanical agitation. [ABSTRACT FROM AUTHOR]

The Chevrel phase Mo6S8 is prepared by reaction of CuCl2 and (NH4)2MoS4 in DMF (90 °C, 6 h) followed by heating of the precipitate in 5% H2/Ar atmosphere (1000 °C, 7 h). [ABSTRACT FROM AUTHOR]

TiNb 2 O 7 (TNO) is regarded as one of the promising next-generation anode materials for lithium-ion batteries (LIBs) due to its high rate capabilities, higher theoretical capacity, and higher lithiation voltage. This enables the cycling of TNO-based anodes under extreme fast charging (XFC) conditions with a minimal risk of lithium plating compared to that of graphite anodes. Here, the gas evolution in real time with TNO-based pouch cells is first reported via operando mass spectrometry. The main gases are identified to be CO 2 , C 2 H 4 , and O 2 . A solid-electrolyte interphase is detected on TNO, which continues evolving, forming, and dissolving with the lithiation and delithiation of TNO. The gas evolution can be significantly reduced when a protective coating is applied on the TNO particles, reducing the CO 2 and C 2 H 4 evolution by ∼2 and 5 times, respectively, at 0.1C in a half-cell configuration. The reduction on gas generation in full cells is even more pronounced. The surface coating also enables 20% improvement in capacity under XFC conditions.

The formation of a solid-electrolyte interphase (SEI) on the surface of Li 4 Ti 5 O 12 (LTO) has become a highly controversial topic, with arguments for it and against it. However, prior studies supporting the formation of an SEI layer have typically suggested that a layer forms upon cycling of a cell, although the layer is probed after disassembling. In this study, cubic mesostructured LTO is synthesized with crystallite domain sizes between 3 and 4 nm and uniform pores with diameters ≤8 nm. The mean pore size is controlled between 4-8 nm through the use of a triblock amphipathic copolymer with a tunable hydrophobic block as template and by thermal treatment. The LTO morphology obtained is spherical and evolves upon heat treatment. These materials show excellent electrochemical performance, including high rate capability and capacity retention. The LTO material is subjected to operando small-angle neutron scattering and X-ray photoelectron spectroscopy experiments, which reveal that the highly debated SEI forms at potentials as high as 2.2 V, first as a LiF-rich layer and subsequently by the growth of a carbonaceous layer. These SEI products form first on the smaller pores before forming on the mesopores., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report colloidal routes to synthesize silicon@carbon composites for the first time. Surface-functionalized Si nanoparticles (SiNPs) dissolved in styrene and hexadecane are used as the dispersed phase in oil-in-water emulsions, from which yolk-shell and dual-shell hollow SiNPs@C composites are produced via polymerization and subsequent carbonization. As anode materials for Li-ion batteries, the SiNPs@C composites demonstrate excellent cycling stability and rate performance, which is ascribed to the uniform distribution of SiNPs within the carbon hosts. The Li-ion anodes composed of 46 wt % of dual-shell SiNPs@C, 46 wt % of graphite, 5 wt % of acetylene black, and 3 wt % of carboxymethyl cellulose with an areal loading higher than 3 mg cm -2 achieve an overall specific capacity higher than 600 mAh g -1 , which is an improvement of more than 100 % compared to the pure graphite anode. These new colloidal routes present a promising general method to produce viable Si-C composites for Li-ion batteries., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)