Electrolyte Optimization of a Substituted-LiCo 1-x Fe x PO 4 Cathode

Lithium cobalt phosphate (LiCoPO 4 ) is an attractive cathode material due to its high discharge potential (4.8 V vs. Li/Li + ) and specific capacity (167 mAh g -1 ), resulting in an impressive specific energy of ~802 Wh kg -1 . The development of LCP has proven difficult owing to the instability of the electrode and the tendency of the electrolyte to perpetually decompose (oxidize), leading to a highly resistive passivation layer. In this report, a substituted lithium cobalt iron phosphate (s-LiCo 1-x Fe x PO 4 or s-LCFP) cathode material was tested with various solvents and additives to find an optimized electrolyte that limits electrode polarization and improves cycle life. The s-LCFP cathode performed best with a 1M LiPF 6 solution of EC/EMC (3/7 wt%) with 2% of additive ARL1. Comparing ARL1 to the baseline electrolyte, the fade rate was reduced from 0.014% per cycle to 0.005% per cycle and the shift in charge voltage (due to polarization) was reduced from 39mV to 19mV through 50 cycles

Anion Coordination Interactions in Solvates with the Lithium Salts LiDCTA and LiTDI

Lithium 4,5-dicyano-1,2,3-triazolate (LiDCTA) and lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI) are two salts proposed for lithium battery electrolyte applications, but little is known about the manner in which the DCTA^– and TDI^– anions coordinate Li⁺ cations. To explore this in depth, crystal structures are reported here for two solvates with LiDCTA(G2)₁:LiDCTA and (G1)₁:LiDCTAwith diglyme and monoglyme, respectively; and seven solvates with LiTDI(G1)₂:LiTDI, (G2)₂:LiTDI, (G3)₁:LiTDI, (THF)₁:LiTDI, (EC)₁:LiTDI, (PC)₁:LiTDI, and (DMC)_1/2:LiTDIwith monoglyme, diglyme, triglyme, tetrahydrofuran, ethylene carbonate, propylene carbonate, and dimethyl carbonate, respectively. These latter solvate structures are compared with the previously reported acetonitrile (AN)₂:LiTDI structure. The solvates indicate that the LiTDI salt is much less associated than the LiDCTA salt and that the ions in LiTDI, when aggregated in solvates, have a very similar TDI^–···Li⁺ cation mode of coordination through both the anion ring and cyano nitrogen atoms. Such coordination facilitates the formation of polymeric ion aggregates, instead of dimers. Insight into such ion speciation is instrumental for understanding the electrolyte properties of aprotic solvent mixtures with these salts

Intramolecular Hydroalkoxylation and Hydroamination of Alkynes Catalyzed by Cu(I) Complexes Supported by <i>N</i>‑Heterocyclic Carbene Ligands

Intramolecular addition of O–H and N–H bonds across carbon–carbon triple bonds to form 5- or 6-membered rings with exocyclic methylene groups for ether products and exocyclic methyl groups for imine products is catalyzed by (IPr)­Cu­(Me) (IPr = 1,3-bis­(2,6-diisopropylphenyl)-imidazol-2-ylidene). In a competition study, the cyclization of primary amines was found to be faster than that of alcohols. Kinetic studies for the conversion of 4-pentyn-1-ol reveal that the catalytic reaction is first-order in copper catalyst and zero-order in alkynyl alcohol, and an Eyring analysis yields Δ<i>H</i>^‡ = 18.7(4) kcal/mol and Δ<i>S</i>^‡ = −26(1) eu. The reaction of 5-phenyl-4-pentyn-1-ol provides (<i>Z</i>)-2-benzylidene-tetrahydrofuran in high yield and with quantitative stereoselectivity. Results from combined experimental and DFT studies are consistent with a mechanism that involves alkyne insertion into a Cu–O_alkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol

Intramolecular Hydroalkoxylation and Hydroamination of Alkynes Catalyzed by Cu(I) Complexes Supported by <i>N</i>‑Heterocyclic Carbene Ligands

Intramolecular addition of O–H and N–H bonds across carbon–carbon triple bonds to form 5- or 6-membered rings with exocyclic methylene groups for ether products and exocyclic methyl groups for imine products is catalyzed by (IPr)­Cu­(Me) (IPr = 1,3-bis­(2,6-diisopropylphenyl)-imidazol-2-ylidene). In a competition study, the cyclization of primary amines was found to be faster than that of alcohols. Kinetic studies for the conversion of 4-pentyn-1-ol reveal that the catalytic reaction is first-order in copper catalyst and zero-order in alkynyl alcohol, and an Eyring analysis yields Δ<i>H</i>^‡ = 18.7(4) kcal/mol and Δ<i>S</i>^‡ = −26(1) eu. The reaction of 5-phenyl-4-pentyn-1-ol provides (<i>Z</i>)-2-benzylidene-tetrahydrofuran in high yield and with quantitative stereoselectivity. Results from combined experimental and DFT studies are consistent with a mechanism that involves alkyne insertion into a Cu–O_alkoxide bond followed by protonolysis upon reaction with free alkynyl alcohol