A solid electrolyte is constituted by lithium phosphorus oxynitride (LiPON). A multiplication value obtained by multiplying a ratio of a peak intensity of nitrogen atoms having a single bond with one P atom and having a double bond with another P atom to a peak intensity of an N.sub.2 state in a Raman spectroscopy spectrum by a ratio of a content amount of N atoms to a content amount of P atoms is greater than or equal to 0.40.

A solid electrolyte is constituted by lithium phosphorus oxynitride (LiPON). A multiplication value obtained by multiplying a ratio of a peak intensity of nitrogen atoms having a single bond with one P atom and having a double bond with another P atom to a peak intensity of an N.sub.2 state in a Raman spectroscopy spectrum by a ratio of a content amount of N atoms to a content amount of P atoms is greater than or equal to 0.40.

To provide a method for producing a phosphoryl imide salt represented by the following general formula (1) at a satisfactory yield by cation exchange. The method comprises the step of performing cation exchange by bringing a phosphoryl imide salt represented by the following general formula (2) into contact with a cation exchange resin having M.sup.1 n+ or a metal salt represented by the general formula (4) in an organic solvent having a water content of 0.3% by mass or less. ##STR00001##

Provided is a nitride phosphor having two or more maximum absorption points in a range of 3,200 to 3,300 cm.sup.1 in an infrared absorption (FT-IR) spectrum. The nitride phosphor of the present invention has excellent emission characteristics and is highly reliable when used in devices.

Provided is a nitride phosphor having two or more maximum absorption points in a range of 3,200 to 3,300 cm.sup.1 in an infrared absorption (FT-IR) spectrum. The nitride phosphor of the present invention has excellent emission characteristics and is highly reliable when used in devices.

To provide a method for producing a phosphoryl imide salt represented by the following general formula (1) at a satisfactory yield by cation exchange. The method comprises the step of performing cation exchange by bringing a phosphoryl imide salt represented by the following general formula (2) into contact with a cation exchange resin having M.sup.1 n+ or a metal salt represented by the general formula (4) in an organic solvent having a water content of 0.3% by mass or less.

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A method for preparing a negative electrode active material, a negative electrode active material prepared using the same, and a lithium secondary battery, and in particular, to a method for preparing a negative electrode active material including the steps of (a) preparing a coating composition including a precursor of metal-phosphorous-oxynitride; (b) forming a precursor layer on a negative electrode active material with the coating composition of (a) using a solution process; and (c) forming a metal-phosphorous-oxynitride protective layer on the negative electrode active material by heat treating the negative electrode active material having the precursor layer formed thereon. The method for preparing a negative electrode active material uses a solution process, which is advantageous in terms of simplifying the whole process and reducing costs, and high capacity, high stabilization and long lifetime are obtained as well by the formed protective layer having excellent properties.

A method for preparing a negative electrode active material, a negative electrode active material prepared using the same, and a lithium secondary battery, and in particular, to a method for preparing a negative electrode active material including the steps of (a) preparing a coating composition including a precursor of metal-phosphorous-oxynitride; (b) forming a precursor layer on a negative electrode active material with the coating composition of (a) using a solution process; and (c) forming a metal-phosphorous-oxynitride protective layer on the negative electrode active material by heat treating the negative electrode active material having the precursor layer formed thereon. The method for preparing a negative electrode active material uses a solution process, which is advantageous in terms of simplifying the whole process and reducing costs, and high capacity, high stabilization and long lifetime are obtained as well by the formed protective layer having excellent properties.

A method for preparing a positive electrode active material, a positive electrode active material prepared using the same, and a lithium secondary battery, and in particular, to a method for preparing a positive electrode active material comprising the steps of (a) preparing a coating composition including a precursor of metal-phosphorous-oxynitride; (b) forming a precursor layer on a positive electrode active material with the coating composition of (a) using a solution process; and (c) forming a metal-phosphorous-oxynitride protective layer on the positive electrode active material by heat treating the positive electrode active material having the precursor layer formed thereon. The method for preparing a positive electrode active material uses a solution process, which is advantageous in terms of simplifying the whole process and reducing costs, and high capacity, high stabilization and long lifetime are obtained as well by the formed protective layer having excellent properties.

A method for preparing a positive electrode active material, a positive electrode active material prepared using the same, and a lithium secondary battery, and in particular, to a method for preparing a positive electrode active material comprising the steps of (a) preparing a coating composition including a precursor of metal-phosphorous-oxynitride; (b) forming a precursor layer on a positive electrode active material with the coating composition of (a) using a solution process; and (c) forming a metal-phosphorous-oxynitride protective layer on the positive electrode active material by heat treating the positive electrode active material having the precursor layer formed thereon. The method for preparing a positive electrode active material uses a solution process, which is advantageous in terms of simplifying the whole process and reducing costs, and high capacity, high stabilization and long lifetime are obtained as well by the formed protective layer having excellent properties.