Disclosed are lithium difluoro-bis(oxalate)phosphate, a preparation method therefor, and an application thereof. The preparation method comprises the following steps: (1) mixing oxalyl chloride and lithium hexafluorophosphate with a nonaqueous solvent, adding siloxane, and reacting to obtain a lithium difluoro-bis(oxalate)phosphate solution; and (2) adding a poor solvent into the lithium difluoro-bis(oxalate)phosphate solution for crystallization treatment to obtain the lithium difluoro-bis(oxalate)phosphate. According to the present application, raw materials such as lithium hexafluorophosphate, oxalyl chloride, and hexamethyldisiloxane are used for preparing the difluoro-bis(oxalate)phosphate, and the method of the present application is few in side reaction, few in impurities, high in product purity, and suitable for industrial production.

A nonaqueous electrolyte secondary battery includes a positive electrode, a negative electrode, and a nonaqueous electrolyte. The positive electrode includes a positive electrode active material, and the positive electrode active material includes a lithium-transition metal composite oxide containing Ni, Mn, and Al. The proportions of Ni, Mn, and Al in metal elements other than Li contained in the lithium-transition metal composite oxide are, respectively, Ni: 50 atm % or more, Mn: 10 atm % or less, and Al: 10 atm % or less. When the lithium-transition metal composite oxide contains Co, the proportion of Co in the metal elements other than Li is 1.5 atm % or less. The nonaqueous electrolyte contains an oxalate compound, and the oxalate compound contains a lithium cation and an oxalate complex anion.

A compound according to an embodiment of the present disclosure is represented by Formula 1. An electrolyte for a lithium secondary battery according to an embodiment of the present disclosure may include the compound, and a lithium secondary battery according to an embodiment of the present disclosure may include the electrolyte.

The invention relates to novel and improved halogen-free flame retardant compounds having the structure of Formula (I): wherein: R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1-C.sub.6 alkyl, P(O)(OR.sup.3).sub.2, P(O)OR.sup.3R.sup.4, or P(O)R.sup.3.sub.2, wherein R.sup.3 and R.sup.4 are independently C.sub.1-C.sub.4 alkyl, C.sub.6-C.sub.12 aryl, C.sub.7-C.sub.15 aralkyl or C.sub.7-C.sub.15 alkaryl; or R.sup.1 and R.sup.2 taken together form an unsaturated cyclic ring, which is optionally substituted by an alkyl group; each k is independently an integer from 1 to 2; each X is independently oxygen (O) or sulphur (S); v is 0 or 1; each Y is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene, C.sub.7-C.sub.15 alkarylene, oxygen (O), nitrogen (NR), wherein R is H or C.sub.1-C.sub.4 alkyl; n is 0, 1 or 2 with the proviso that n is 1 when Y is oxygen (O) or nitrogen (NR); each Z is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene or C.sub.7-C.sub.15 is alkarylene; m is independently 0, 1 or 2; with the proviso that when Y is oxygen (O) or nitrogen (N), m cannot be 0; each Q is independently C.sub.1-C.sub.4 alkylene; t is an integer from 1 to 2; W is oxygen (O) or sulphur (S). The compounds are particularly suited as flame retardant additives for thermoplastic polyesters.

Spirocyclic compounds, including chiral spiro diamine, chiral spiro amino naphthol, chiral spiro bis(indole), chiral spiro diaryl diol, chiral spiro diaryl diamine, chiral spiro amino naphthol, chiral spiro diaryl diindole, and chiral spiro phospholane useful as chiral ligands and chiral organocatalysts and methods of preparation and methods of use thereof. Owing to the molecular shape and three-dimensional orientation, the chiral diamine and chiral amino naphthol molecules provide a skeleton for use as ligands and organocatalysts.

The invention relates to novel and improved halogen-free flame retardant compounds having the structure of Formula (I): wherein: R.sup.1 and R.sup.2 are independently hydrogen, C.sub.1-C.sub.6 alkyl, P(O)(OR.sup.3).sub.2, P(O)OR.sup.3R.sup.4, or P(O)R.sup.3.sub.2, wherein R.sup.3 and R.sup.4 are independently C.sub.1-C.sub.4 alkyl, C.sub.6-C.sub.12 aryl, C.sub.7-C.sub.15 aralkyl or C.sub.7-C.sub.15 alkaryl; or R.sup.1 and R.sup.2 taken together form an unsaturated cyclic ring, which is optionally substituted by an alkyl group; each k is independently an integer from 1 to 2; each X is independently oxygen (O) or sulphur (S); v is 0 or 1; each Y is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene, C.sub.7-C.sub.15 alkarylene, oxygen (O), nitrogen (NR), wherein R is H or C.sub.1-C.sub.4 alkyl; n is 0, 1 or 2 with the proviso that n is 1 when Y is oxygen (O) or nitrogen (NR); each Z is independently C.sub.1-C.sub.4 alkylene, C.sub.6 arylene, C.sub.7-C.sub.15 aralkylene or C.sub.7-C.sub.15 is alkarylene; m is independently 0, 1 or 2; with the proviso that when Y is oxygen (O) or nitrogen (N), m cannot be 0; each Q is independently C.sub.1-C.sub.4 alkylene; t is an integer from 1 to 2; W is oxygen (O) or sulphur (S). The compounds are particularly suited as flame retardant additives for thermoplastic polyesters.

Provided are an electrolyte additive for lithium secondary battery including a compound represented by Formula 1 below, an electrolyte for lithium secondary battery including the same, and a lithium secondary battery including the electrolyte. ##STR00001## wherein, in Formula 1, R.sub.1 to R.sub.3 are as defined in the detailed description.

According to an embodiment of the present inventive concept, an electrolyte additive represented by the compounds of Chemical Formulas 1 to 4 may be provided. In addition, according to another embodiment of the present inventive concept, a method for preparing an electrolyte additive of the compounds of Chemical Formulas 1 to 4 may be provided, wherein the method for preparing the electrolyte additive includes reacting hexafluorophosphate and 2-monofluoromalonic acid, further adding an HF scavenger to the mixed solution produced by the reaction, and concentrating and drying the reaction solution obtained therefrom.

A method for preparing lithium iron phosphate includes: mixing iron phosphate, a lithium source, a carbon source, a dispersant, and a solvent to make a precursor slurry; sintering the precursor slurry to make lithium iron phosphate, where the dispersant includes an ammonium salt compound represented by Formula (1), in which R.sub.1 is a carbon-containing organic group.