The synthesis and characterization of novel materials for use in secondary lithium-ion batteries

Poly(ethylene oxide) (PEO), {dollar}rm (CHsb2CHsb2O)sb{lcub}n{rcub},{dollar} is utilized as a polymer host for polymer electrolytes containing lithium salts. The polymer electrolytes {dollar}rm PEOsb{lcub}x{rcub}LiSOsb3CFsb2SFsb5{dollar} and {dollar}rm PEOsb{lcub}x{rcub}LiSOsb3CFHSFsb5{dollar} (where x reflects the mole ratio of etheric oxygens in PEO to lithium) are synthesized and characterized by impedance spectroscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The {dollar}rm PEOsb{lcub}x{rcub}LiSOsb3CFsb2SFsb5{dollar} complexes show significantly suppressed crystallinity. The {dollar}rm PEOsb4LiSOsb3CFsb2SFsb5{dollar} complex has a bulk ionic conductivity ({dollar}sigma{dollar}) near {dollar}rm 10sp{lcub}-5{rcub} (Omega cm)sp{lcub}-1{rcub}{dollar} at 30{dollar}spcirc{dollar}C, comparable to conductivities obtained with PEO complexes of other known plasticizing salts. The role of the anion in plasticizing is discussed by considering the common features of known plasticizers. Unlike the {dollar}rm PEOsb{lcub}x{rcub}LiSOsb3CFsb2SFsb5{dollar} complexes, a plasticizing effect for the {dollar}rm PEOsb{lcub}x{rcub}LiSOsb3CFHSFsb5{dollar} complexes is absent. This observation is discussed in terms of hydrogen bonding between {dollar}rm SFsb5CFHSOsb3sp-{dollar} anions.; The polymer electrolytes {dollar}rm PEOsb{lcub}x{rcub}lbrack LiSOsb3(CFsb2)sb{lcub}n{rcub}SOsb3Lirbrack {dollar} where n = 1 to 4, and {dollar}rm PEOsb{lcub}x{rcub}lbrack LiSOsb3CFsb2CFsb2OCFsb2CFsb2SOsb3Lirbrack {dollar} are synthesized and characterized by impedance spectroscopy. The {dollar}rm PEOsb{lcub}64{rcub}LiSOsb3CFsb2CFsb2OCFsb2CFsb2SOsb3Li{dollar} complex was found to have the highest conductivity: {dollar}sigma{dollar} is near {dollar}rm 5 times 10sp{lcub}-6{rcub} (Omega cm)sp{lcub}-1{rcub}{dollar} at 100{dollar}spcirc{dollar}C.; The polymer electrolytes {dollar}rm PEOsb{lcub}x{rcub}LiCH(SOsb2CFsb3)sb2{dollar} are synthesized and characterized by impedance spectroscopy, DSC, TGA, and cyclic voltammetry. The complexes show ionic conductivities as high as, or higher than, those derived from other plasticizing salts, with {dollar}sigma{dollar} reaching {dollar}rm 10sp{lcub}-4{rcub} (Omega cm)sp{lcub}-1{rcub}{dollar} at 30{dollar}spcirc{dollar}C.; The electrical and thermal properties of ternary solutions containing PEO, {dollar}rm LiN(SOsb2CFsb3)sb2,{dollar} and {dollar}rm LiSOsb2Csb8Fsb{lcub}17{rcub}{dollar} are described. For the equimolar concentration of salts, {dollar}rm PEOsb{lcub}x{rcub}lbrack LiN(SOsb2CFsb3)sb2rbrack sb{lcub}y{rcub}lbrack LiSOsb3Csb8Fsb{lcub}17{rcub}rbrack sb{lcub}z{rcub}{dollar} (y = z = 1), a conductivity maximum of {dollar}rm 10sp{lcub}-4{rcub} (Omega cm)sp{lcub}-1{rcub}{dollar} at 30{dollar}spcirc{dollar}C occurs at x = 16 The compositional range {dollar}rm PEOsb{lcub}16{rcub}lbrack LiN(SOsb2CFsb3)sb2rbrack sb{lcub}y{rcub}lbrack LiSOsb3Csb8Fsb{lcub}17{rcub}rbrack sb{lcub}z{rcub},{dollar} (y = {dollar}rm 2 - z){dollar} is fully evaluated and a conductivity maximum of {dollar}rm 2.5 times 10sp{lcub}-3{rcub} (Omega cm)sp{lcub}-1{rcub}{dollar} at 80{dollar}spcirc{dollar}C occurs at y = 1.75. Thermal data indicate decreasing melting transition temperatures, and increasing glass transition temperatures, as y increases from 0 to 2.