Superconcentrated Electrolytes Widens Insertion Electrochemistry to Soluble Layered Halides

Insertion compounds provide the fundamental basis of today’s commercialized Li-ion batteries. Throughout history, intense research has focus on the design of stellar electrodes mainly relying on layered oxides or sulfides, and leaving aside the corresponding halides because of solubility issues. This is no longer true. In this work, we show for the first time the feasibility to reversibly intercalate electrochemically Li⁺ into VX₃ compounds (X = Cl, Br, I) via the use of superconcentrated electrolytes, (5 M LiFSI in dimethyl carbonate), hence opening access to a novel family of Li_xVX₃ phases. Moreover, through an electrolyte engineering approach we unambiguously prove that the positive attribute of superconcentrated electrolytes against solubility of inorganic compounds is rooted in a thermodynamic rather than a kinetic effect. The mechanism and corresponding impact of our findings enrich the fundamental understanding of superconcentrated electrolytes and constitute a crucial step in the design of novel insertion compounds with tunable properties for a wide range of applications beyond Li-ion batteries.

Superconcentrated Electrolytes Widens Insertion Electrochemistry to Soluble Layered Halides

Insertion compounds provide the fundamental basis of today’s commercialized Li-ion batteries. Throughout history, intense research has focus on the design of stellar electrodes mainly relying on layered oxides or sulfides, and leaving aside the corresponding halides because of solubility issues. This is no longer true. In this work, we show for the first time the feasibility to reversibly intercalate electrochemically Li⁺ into VX₃ compounds (X = Cl, Br, I) via the use of superconcentrated electrolytes, (5 M LiFSI in dimethyl carbonate), hence opening access to a novel family of Li_xVX₃ phases. Moreover, through an electrolyte engineering approach we unambiguously prove that the positive attribute of superconcentrated electrolytes against solubility of inorganic compounds is rooted in a thermodynamic rather than a kinetic effect. The mechanism and corresponding impact of our findings enrich the fundamental understanding of superconcentrated electrolytes and constitute a crucial step in the design of novel insertion compounds with tunable properties for a wide range of applications beyond Li-ion batteries.

Structural insights into the formation and voltage degradation of lithium- and manganese-rich layered oxides

One major challenge in the field of lithium-ion batteries is to understand the degradation mechanism of high-energy lithium- and manganese-rich layered cathode materials. Although they can deliver 30 % excess capacity compared with today’s commercially- used cathodes, the so-called voltage decay has been restricting their practical application. In order to unravel the nature of this phenomenon, we have investigated systematically the structural and compositional dependence of manganese-rich lithium insertion compounds on the lithium content provided during synthesis. Structural, electronic and electrochemical characterizations of LixNi0.2Mn0.6Oy with a wide range of lithium contents (0.00 ≤ x ≤ 1.52, 1.07 ≤ y < 2.4) and an analysis of the complexity in the synthesis pathways of monoclinic-layered Li[Li0.2Ni0.2Mn0.6]O2 oxide provide insight into the underlying processes that cause voltage fading in these cathode materials, i.e. transformation of the lithium-rich layered phase to a lithium-poor spinel phase via an intermediate lithium-containing rock-salt phase with release of lithium/oxygen.

Characterization of LiCoO2 nanoparticle suspensions by single collision events

Transient electrochemical experiments associated with the collisions between hydrothermally synthesized LiCoO2 (LCO) nanoparticles/aggregates of different sizes and a polarized gold ultramicroelectrode (UME) were used as a new additive-free analytical tool applied to characterize Li ion insertion compounds.

Noble gas insertion compounds of hydrogenated and lithiated hyperhalogens

Based on density functional theory (DFT) calculations, hydrogenated hyperhalogen HM(BO2)2, lithiated hyperhalogen LiM(BO2)2 (M = Cu, Ag, Au), and their compounds with xenon were studied.

OBCN isomerization and noble gas insertion compounds of identical valence electron number species: stability and bonding

A series of new noble gas (Ng) insertion compounds of the general type XNgX, XNgY and XNgY+ has been theoretically studied using ab initio and DFT methods herein.