Provided is a lithium-supplementing additive comprising -phase lithium nitride and/or -phase lithium nitride. According to the lithium-supplementing additive provided by the present application, the comprised pure -phase lithium nitride has high lithium ion conductivity, thereby facilitating the de-intercalation of lithium ions; the comprised pure -phase lithium nitride has a high energy barrier for lithium-ion mobility and a high decomposition voltage, so that the mobility of lithium ions in a battery system is more stable; and the comprised mixed-phase lithium nitride has reduced activity and can be prevented from reacting with widely used N-methylpyrrolidone (NMP) and polyvinylidene fluoride (PVDF) during a homogenizing process, and thus has good stability.

Provided is a lithium nitride composition for a sulfide-based inorganic solid electrolyte material including -lithium nitride, wherein in a spectrum obtained by X-ray diffraction in which a CuK ray is used as a radiation source, when a diffraction intensity of a diffraction peak present at a position of a diffraction angle 2=23.00.3 is represented by I.sub. and a diffraction intensity of a diffraction peak present at a position of a diffraction angle 2=32.00.3 is represented by I.sub., a value of I.sub./I.sub. is 4.50 or lower.

Provided is a lithium nitride manufacturing device (10) for heating a lithium member (9) in a nitrogen atmosphere to nitride the lithium member (9) such that lithium nitride is manufactured, the lithium nitride manufacturing device including: a reaction tank (1) where a nitriding reaction of the lithium member (9) is performed; a heating unit (2) that heats the lithium member (9); an atmosphere control unit (3) that controls a dew point in the reaction tank (1); and an atmosphere cooling unit (4) that cools an inside of the reaction tank (1).

The invention is directed to a method of preparing NH.sub.3, and to a method of regenerating a metal M from MOR.sup.1, wherein O is oxygen and R.sup.1 is CH.sub.3 and/or C.sub.2H.sub.5. The method for preparing NH.sub.3 comprises the steps of a) reacting a metal with nitrogen gas to produce a metal nitride, wherein the metal is selected from the group consisting of Li, Be, Mg, Na, Mo, Al, Zn, Ca, Sr, and Ba, b) reacting the metal nitride obtained in step a) with R.sup.1OH to produce NH.sub.3 and MOR.sup.1, wherein R.sup.1 represents CH.sub.3 and/or C.sub.2H.sub.5, and c) regenerating the metal by electrolysing said MOR.sup.1 under formation of HCHO and/or CH.sub.3CHO. The method of regenerating a metal M from MOR.sup.1, comprises electrolysing of MOR.sup.1 under formation of HCHO and/or CH.sub.3CHO, wherein R.sup.1 represents CH.sub.3 and/or C.sub.2H.sub.5.