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We studied the intercalation chemistry of graphitic carbon nitride (gCN), combining theory and experimental methods. A series of new alkali-ethylenediamine-gCN products were prepared using a one-po...

A sodium-ethylenediamine graphite intercalation compound (Na(ethylenediamine)C15: "GIC") made from graphite flakes was used to study the microwave absorption performance of a GIC for the first time. Compared with the pristine graphite flakes, the neighboring layers in this GIC are pillared by Na(ethylenediamine)+ and possess a larger layer distance and improved electrical conductivity. Owing to the electrical conductivity of this GIC, only half of the loading content, compared to graphite flakes, is needed to achieve an outstanding absorption of -75.6 dB at 9.25 GHz (10.0 wt % GIC in paraffin in a 4.0 mm thick sample), but for graphite, 20.0 wt % is required for an absorption of -37.6 dB.

Although substrate composition can influence the chemical reactivity of graphene, substrate lattice orientation provides a valuable alternative. The effect of Cu surface orientation on the reactivi...

Presenting a versatile method to make soft, deformable, functional metallic “putty” from liquid gallium and nonmetallic fillers., We report a versatile method to make liquid metal composites by vigorously mixing gallium (Ga) with non-metallic particles of graphene oxide (G-O), graphite, diamond, and silicon carbide that display either paste or putty-like behavior depending on the volume fraction. Unlike Ga, the putty-like mixtures can be kneaded and rolled on any surface without leaving residue. By changing temperature, these materials can be stiffened, softened, and, for the G-O–containing composite, even made porous. The gallium putty (GalP) containing reduced G-O (rG-O) has excellent electromagnetic interference shielding effectiveness. GalP with diamond filler has excellent thermal conductivity and heat transfer superior to a commercial liquid metal–based thermal paste. Composites can also be formed from eutectic alloys of Ga including Ga-In (EGaIn), Ga-Sn (EGaSn), and Ga-In-Sn (EGaInSn or Galinstan). The versatility of our approach allows a variety of fillers to be incorporated in liquid metals, potentially allowing filler-specific “fit for purpose” materials.

The first structural and compositional details of a low-stage graphite interaction compound (GIC) containing Mg are reported, with the GIC obtained by combining magnesium metal and graphite powder in ethylenediamine (en) at 100 °C under an inert atmosphere. Thermal analyses indicate the bottle-green stage 1 product has a composition of [Mg(en)1.0]C13. X-ray diffraction shows a c-axis expansion of 0.55 nm, indicating the presence of intercalate monolayers with the en cointercalate oriented perpendicular to the encasing graphene layers. Redox titration indicates two electrons are transferred per Mg. A structural model is proposed with dimeric [Mg2(en)2]2+ intercalate species.

Diffusion of alkali metals in graphite layers is significant for the chemical and electrochemical properties of graphite intercalation compounds (GICs). Crown ethers co-intercalate into graphite with alkali metal (Na and K) cations and form ternary GICs. The structures and molecular dynamics of 15-crown-5 and 18-crown-6 ether coordinating to Na+ or K+ in GICs were investigated by DFT calculations and 1H solid state NMR analyses. DFT calculations suggest a stacked structure of crown ether–metal complex with some offset. 1H NMR shows two kinds of molecular motions at room temperature: isotropic rotation with molecular diffusion and axial rotation with fluctuation of the axis. The structure and dynamics of crown ether molecules in GIC galleries are strongly affected by the geometry of the crown ether molecules and the strength of the interaction between alkali metal and ligand molecules.

New graphite intercalation compounds (GICs) containing 1-alkyl-2,3-dimethyl imidazolium cations (Im1-1-a, a = alkyl length) are obtained from [Na(ethylenediamine)1.0]C15 by cation exchange. Exchange reactions occur rapidly, but require higher temperature than for substituted alkylammoniums. Powder X-ray diffraction, thermogravimetry and structural modeling indicate that [Im1-1-4]C47 is a stage-2 GIC with 0.36 nm monolayer galleries and cations oriented parallel to graphene sheets. [Im1-1-12]C44 is a stage-1 GIC with a gallery expansion of 0.40 nm. The lower sheet charge density for [Im1-1-12]C44 is commensurate with its larger intercalate. Imidazolium cations without alkyl substitution at the imidazolium ring C2 do not form stable GICs by this route.

New graphite intercalation compounds (GICs) containing N,N-n-alkyl substituted pyrrolidinium cation intercalates (Pyn.m, n, m = alkyl chain lengths) are obtained via cationic exchange from stage-1 donor-type GIC [Na(ethylenediamine)1.0]C15. Powder X-ray diffraction and thermogravimetric analyses are used to determine the GIC structures and compositions. [Py4.8]C47·0.71DMSO and [Py8.8]C48 with intercalate monolayers are obtained as stage-1 GICs with gallery expansions of 0.48 nm, whereas [Py1.18]C47 and [Py12.12]C80·0.25DMSO form stage-1 GICs with intercalate bilayers and gallery expansions of 0.81 nm. The gallery dimensions require that alkyl chain substituents orient parallel to the encasing graphene sheets. Smaller intercalate cations such as Py1.4, Py4.4, and Py1.8 either form high-stage GICs or do not form stable intercalation compounds. These results, along with those reported for graphite intercalation of other quaternary ammonium cations, indicate trends in graphite chemistry where larger intercala...

The electric vehicle and energy storage industries will generate over one-million tons per annum of lithium-ion for recycling in the next decade. There are significant technology gaps in the recovery of lithium-ion battery materials that threaten the sustainability of these industries. Cathode healing is introduced here as a new approach to produce low cost (i.e.

Crown ethers are well established as cointercalates in many layered hosts, but there are no reports of crown ethers incorporated into graphite. Here, we describe the preparation of the first graphite intercalation compounds (GICs) containing crown ethers. These GICs are obtained either by reductive intercalation of an alkali metal-amine complex followed by cointercalate exchange or by the direct reaction of graphite with a crown ether, alkali metal, and an electrocatalyst. Structural and compositional characterization of these new GICs using powder X-ray diffraction, thermal analysis, and GC/MS indicates the formation of well-ordered, stage-1 bilayer galleries.

Layered host-polymer nanocomposites comprising polymeric guests between inorganic sheets have been prepared with many inorganic hosts, but there is limited evidence for the incorporation of polymeric guests into graphite. Here we report for the first time the preparation, and structural and compositional characterization of graphite intercalation compounds (GICs) containing polyether bilayers. The new GICs are obtained by either (1) reductive intercalation of graphite with an alkali metal in the presence of an oligo or polyether and an electrocatalyst, or (2) co-intercalate exchange of an amine for an oligo or polyether in a donor-type GIC. Structural characterization of products using powder X-ray diffraction, Raman spectroscopy, and thermal analyses supports the formation of well-ordered, first-stage GICs containing alkali metal cations and oligo or polyether bilayers between reduced graphene sheets.

There has been a major effort recently to develop new rechargeable sodium-ion electrodes. In lithium ion batteries, LiC6 forms from graphite and desolvated Li cations during the first charge. With sodium ions, graphite only shows a significant capacity when Na+ intercalates as a solvated complex, resulting in ternary graphite intercalation compounds (GICs). Although this chemistry has been shown to be highly reversible and to support high rates in small test cells, these GICs can require >250% volume expansion and contraction during cycling. Here we demonstrate the first example of GICs that reversibly sodiate/desodiate without any significant volume change. These pillared GICs are obtained by electrochemical reduction of graphite in an ether/amine co-solvent electrolyte. The initial gallery expansion, 0.36 nm, is less than half of that in diglyme-based systems, and shows a similar capacity. Thermal analyses suggest the pillaring phenomenon arises from stronger co-intercalate interactions in the GIC galleries.