An effectively solvent-free alkali metal or alkali earth metal closo-borate salt is prepared in the presence of a non-aqueous solvent where the solvent can be removed to levels below one mole percent of the salt. The process involves the exchange of cations with a closo-borate anion via an acid-base process or a metathesis process. The solvent is removed from the alkali metal or alkali earth metal closo-borate salt by heating. The temperature can be greater than the melting point of the salt but lower than temperatures where decomposition occurs.

An effectively solvent-free alkali metal or alkali earth metal closo-borate salt is prepared in the presence of a non-aqueous solvent where the solvent can be removed to levels below one mole percent of the salt. The process involves the exchange of cations with a closo-borate anion via an acid-base process or a metathesis process. The solvent is removed from the alkali metal or alkali earth metal closo-borate salt by heating. The temperature can be greater than the melting point of the salt but lower than temperatures where decomposition occurs.

Apparatuses and methods for extracting desired chemical species and/or impurities from input material. An aspect of the present disclosure comprises a continuous flow system using solvents and other reactants to assist in conversion and extraction of the desired output material and/or removal of specific impurities from the input material through pressure, temperature, and volume control within the extraction system.

Apparatuses and methods for extracting desired chemical species and/or impurities from input material. An aspect of the present disclosure comprises a continuous flow system using solvents and other reactants to assist in conversion and extraction of the desired output material and/or removal of specific impurities from the input material through pressure, temperature, and volume control within the extraction system.

A sulfide solid electrolyte containing lithium, phosphorus, sulfur; and one or more of elements X selected from the group consisting of halogen elements and chalcogen elements excluding sulfur, wherein the sulfide solid electrolyte includes an argyrodite-type crystal structure, and wherein a molar ratio of the lithium to the phosphorus, a (Li/P), a molar ratio of the sulfur to the phosphorus, b (S/P), and a molar ratio of the element X to the phosphorus, c (X/P), satisfy formulas (1) to (3): 5.0≤a≤7.1 (1) 1.0<a−b≤1.5 (2) 6.5≤a+c<7.1 (3) wherein b>0 and c>0 are satisfied.

A positive electrode for an all-solid secondary battery, comprising a positive electrode active material expressed by A.sub.2S.AX, wherein

A is an alkali metal; and

X is selected from I, Br, Cl, F, BF.sub.4, BH.sub.4, SO.sub.4, BO.sub.3, PO.sub.4, O, Se, N, P, As, Sb, PF.sub.6, AsF.sub.6, ClO.sub.4, NO.sub.3, CO.sub.3, CF.sub.3SO.sub.3, CF.sub.3COO, N(SO.sub.2F).sub.2 and N(CF.sub.3SO.sub.2).sub.2.

A positive electrode for an all-solid secondary battery, comprising a positive electrode active material expressed by A.sub.2S.AX, wherein

A is an alkali metal; and

X is selected from I, Br, Cl, F, BF.sub.4, BH.sub.4, SO.sub.4, BO.sub.3, PO.sub.4, O, Se, N, P, As, Sb, PF.sub.6, AsF.sub.6, ClO.sub.4, NO.sub.3, CO.sub.3, CF.sub.3SO.sub.3, CF.sub.3COO, N(SO.sub.2F).sub.2 and N(CF.sub.3SO.sub.2).sub.2.

A sulfide-based solid electrolyte particle having a crystal phase of a cubic argyrodite-type crystal structure composed of Li, P, S and a halogen (Ha), wherein good contact between the sulfide-based solid electrolyte particles and positive or negative electrode active material particles is secured and improvements in the rate characteristic and the cycle characteristic are attained. The ratio (Z.sub.Ha2/Z.sub.Ha1) of an element ratio Z.sub.Ha2 of the halogen (Ha) at the position of 5 nm in depth from the particle surface to an element ratio Z.sub.Ha1 of the halogen (Ha) at the position of 100 nm in depth from the particle surface is 0.5 or lower and the ratio (Z.sub.O2/Z.sub.A2) of an element ratio Z.sub.O2 of oxygen to the total Z.sub.A2 of element ratios of P, S, O, and the halogen (Ha) at the position of 5 nm in depth from the particle surface is 0.5 or higher, as measured by XPS.

The present invention relates to an oxide active material surface-treated with a lithium compound, a method for preparing the same, and an all-solid lithium secondary battery capable of effectively suppressing an interface reaction in a solid electrolyte by adopting the same. In the all-solid lithium secondary battery comprising an electrode containing a positive electrode active material and a sulfide-based solid electrolyte, the positive electrode active material according to the present invention can significantly improve battery characteristics since a coating layer formed of a lithium compound is formed while surrounding a particle surface to act as a functional coating layer which suppresses the interface reaction of the sulfide-based solid electrolyte and the electrode. In addition, in cases where the active material is synthesized and coated with a lithium compound at the same time, a lithium salt and a transition metal salt are dissolved in a solvent through stirring, to prepare a solution, followed by drying and heat treatment, and here, the prepared active material has a form in which a mixture generated from an excessive amount of lithium salt which is synthesized and then remains on the particle surface having a structure capable of absorbing and releasing lithium is coated on the particle surface to form a coating layer. In addition, in cases where the previously synthesized active material is coated with a lithium compound, the active material and a lithium salt are dissolved in a solvent through stirring, followed by drying and heat-treatment, and here, the prepared active material has a form in which a mixture generated from an excessive amount of lithium salt which is synthesized and then remains on the particle surface having a structure capable of absorbing and releasing lithium is coated on the particle surface to for m a coating layer.

The present invention relates to a multi-layer structured lithium metal electrode and a method for manufacturing the same and, specifically, to a multi-layer structured lithium metal electrode comprising: a buffer layer of lithium nitride (Li3N) formed on a lithium metal plate; and a protective layer of LiBON formed on the buffer layer, and to a method for manufacturing a multi-layer structured lithium metal electrode by continuously forming a lithium nitride buffer layer and a LiBON protective layer on a lithium metal plate through continuous reactive sputtering multi-layer structured lithium metal electrode multi-layer structured lithium metal electrode lithium metal plate multi-layer structured lithium metal electrode lithium metal plate. The multi-layer structured lithium metal electrode of the present invention can protect the reactivity of the lithium metal from moisture or an environment within a battery, and prevent the formation of dendrites, by forming the protective layer.