A solid conductor including: a compound represented by Formula 1, a compound represented by Formula 2, or a combination thereof

Li.sub.1+x+yzTa.sub.2-xM.sub.xP.sub.1-yQ.sub.yO.sub.8-zX.sub.z Formula 1

wherein, in Formula 1, M is an element having an oxidation number of +4, Q is an element having an oxidation number of +4, X is a halogen, a pseudohalogen, or a combination thereof, and 0x2, 0y<1, and 0z2, except that cases i) x and y and z are simultaneously 0, ii) M is Hf, X is F, x is 1 , y is 0, and z is 1, iii) M is Hf, X is Cl, x is 2, y is 0, and z is 2, and iv) M is Hf, X is F, x is 2, y is 0, and z is 2,

Li.sub.1+x+yzTa.sub.2-xM.sub.xP.sub.1-yQ.sub.yO.sub.8-zLiX Formula 2

wherein, in Formula 2, M is an element having an oxidation number of +4, Q is an element having an oxidation number of +4, X is a halogen, a pseudohalogen, or a combination thereof, and 0)(2, 0y<1, and 0z2, except that cases i) x and y and z are simultaneously 0, ii) M is Hf, X is F, x is 1 , y is 0, and z is 1, iii) M is Hf, X is Cl, x is 2, y is 0, and z is 2, and iv) M is Hf, X is F, x is 2, y is 0, and z is 2.

Provided are method for producing alkali metal hexafluorophosphate, alkali metal hexafluorophosphate powder, method for producing electrolyte concentrate comprising alkali metal hexafluorophosphate, and method for producing secondary battery. The method for preparing alkali metal hexafluorophosphate includes a step of obtaining an alkali metal hexafluorophosphate by reacting phosphorus pentafluoride with alkali metal fluoride in a haloformate solvent.

Disclosed is a method for purifying a difluorophosphate, the method including mixing a difluorophosphate containing an impurity with at least one treatment agent selected from the group consisting of carbonates, hydroxides, and halides of alkali metals or alkali earth metals and amines to isolate the impurity. It is preferable that the method further include filtering off, by filtration, a salt or a complex that has been formed by allowing the impurity to be mixed with the treatment agent. Preferably, a carbonate, a hydroxide, or a halide of an alkali metal is used as the treatment agent, and more preferably a carbonate, a hydroxide, or a halide of lithium is used as the treatment agent.

Disclosed is a method for purifying a difluorophosphate, the method including mixing a difluorophosphate containing an impurity with at least one treatment agent selected from the group consisting of carbonates, hydroxides, and halides of alkali metals or alkali earth metals and amines to isolate the impurity. It is preferable that the method further include filtering off, by filtration, a salt or a complex that has been formed by allowing the impurity to be mixed with the treatment agent. Preferably, a carbonate, a hydroxide, or a halide of an alkali metal is used as the treatment agent, and more preferably a carbonate, a hydroxide, or a halide of lithium is used as the treatment agent.

A method of reducing the amount propylene chlorohydrin produced in a reaction to make a hydroxypropylated/crosslinked starch comprising removing residual propylene oxide from alkaline slurry. The residual propylene oxide is removed by the dewatering the alkaline slurry or by washing the starch in slurry at a pH of around 10. The starch is then neutralized in an acid solution and recovered from the second slurry and may or may not be washed, depending on whether the slurry while at pH around 10 to make a hydroxypropylated/crosslinked starch having less than 1 ppm propylene chlorohydrin.

Lithium oxide argyrodites having the formula Li.sub.(6y)PS.sub.4O.sub.(1y)X.sub.(1+y) where X is a halide anion and y is a number between 0 and 0.8, inclusive, are provided herein. Also provided are methods of synthesizing the lithium oxide argyrodites and composites including the lithium oxide argyrodites, as well as other alkali metal oxide argyrodites and related methods and composites.

Methods and compositions are provided for treatment of an apatite-based resin from which retained solutes have been eluted by an elution buffer that contains an alkali metal salt with solutions of calcium ion, phosphate ion, and hydroxide separately from any sample loading and elution buffers. The treatment solutions restore the resin, reversing the deterioration that is caused by the alkali metal salt in the elution buffer.

Methods and compositions are provided for treatment of an apatite-based resin from which retained solutes have been eluted by an elution buffer that contains an alkali metal salt with solutions of calcium ion, phosphate ion, and hydroxide separately from any sample loading and elution buffers. The treatment solutions restore the resin, reversing the deterioration that is caused by the alkali metal salt in the elution buffer.

The present invention provides a nonaqueous electrolytic solution that provides an electric double layer capacitor having excellent durability. The nonaqueous electrolytic solution of the present invention is a nonaqueous electrolytic solution for electric double layer capacitors prepared by dissolving a quaternary ammonium salt as an electrolyte in a nonaqueous solvent, and the nonaqueous electrolytic solution has an alkali metal cation concentration of 0.1 to 30 ppm.

The present invention provides a nonaqueous electrolytic solution that provides an electric double layer capacitor having excellent durability. The nonaqueous electrolytic solution of the present invention is a nonaqueous electrolytic solution for electric double layer capacitors prepared by dissolving a quaternary ammonium salt as an electrolyte in a nonaqueous solvent, and the nonaqueous electrolytic solution has an alkali metal cation concentration of 0.1 to 30 ppm.