A stabilization process for an arsenic solution comprising thiosulfates, the process comprising: acidifying the arsenic solution to decompose the thiosulfates, to yield an acidified solution; oxidizing the acidified solution to oxidize residual As.sup.3+ to As.sup.5+ and reduced sulfur species to sulfates, to yield a slurry comprising elemental sulfur; separating elemental sulfur from the slurry to yield a liquid; oxidizing the liquid to oxidize residual reduced sulfur species, to yield an oxidized solution; and forming a stable arsenic compound from the oxidized solution.

A method for producing antimony trisulfide can inexpensively produce antimony trisulfide that has a relatively low content of lead, arsenic, and crystalline silica (i.e., impurities). The method includes charging a reaction vessel with an antimony trioxide powder and sulfur, and heating the inside of the reaction vessel to react antimony trioxide with sulfur. Since antimony trioxide is obtained by volatilization-oxidation refining, antimony trioxide has a small particle size and a large specific surface area, and exhibits good reactivity, and high-purity antimony trioxide having a low content of impurities (e.g., lead, arsenic, and crystalline silica) is easily available. It is possible to inexpensively produce antimony trisulfide having a low content of impurities by utilizing high-purity antimony trioxide as a raw material.

A process is provided for separation of at least one metal sulfide from a mixed sulfide concentrate. The process includes: subjecting the mixed sulfide concentrate to flotation in which at least one sulfide including antimony, arsenic and a first metal is floated and at least one sulfide including a second metal is depressed. The flotation yields a first metal concentrate having the at least one sulfide including antimony, arsenic and the first metal and a second metal concentrate having the at least one sulfide including the second metal. The first metal concentrate is leached to yield a further concentrate and a leach solution. The further concentrate includes the first metal and the leach solution includes soluble antimony and soluble arsenic. The process further includes oxidizing the leach solution to yield an antimony precipitate and an arsenic solution, and forming a stable arsenic compound from the arsenic solution.

The invention relates to anode materials suitable for use in batteries, such as lithium ion batteries and sodium ion batteries. In particular, the anode material is a reduced graphene oxide/metal sulfide composite. Methods for forming the reduced graphene oxide/metal sulfide composite are also disclosed.

A solid electrolyte for solid-state batteries comprises a phosphorous-free solid electrolyte having a cubic argyrodite structure. The solid electrolyte has a composition according to the molecular formula: Li.sub.6+xM.sub.xSb.sub.1yS.sub.5zR, where x=0 to 0.7; y=0 to 0.7 and z=0 to 0.7, wherein the (semi-) metal comprises M=Si, Sn, W and the halogen comprises R=I.sub.1, Cl.sub.1, Br.sub.z, Br.sub.1 and further wherein, in a case where R=I.sub.1, M=W and x>0. Furthermore, a production method is described.

A solid electrolyte for solid-state batteries comprises a phosphorous-free solid electrolyte having a cubic argyrodite structure. The solid electrolyte has a composition according to the molecular formula: Li.sub.6+xM.sub.xSb.sub.1yS.sub.5zR, where x=0 to 0.7; y=0 to 0.7 and z=0 to 0.7, wherein the (semi-) metal comprises M=Si, Sn, W and the halogen comprises R=I.sub.1, Cl.sub.1, Br.sub.z, Br.sub.1 and further wherein, in a case where R=I.sub.1, M=W and x>0. Furthermore, a production method is described.

A sulfide-based solid electrolyte with an argyrodite crystal structure is represented by the formula Li.sub.7x3ySb.sub.yPS.sub.6xHa.sub.x, where Ha is one or more halogen elements selected from F, Cl, Br, I, and their combinations, is disclosed. The sulfide-based solid electrolyte comprises a substituted antimony (Sb) element in Wyckoff position 48h of the argyrodite crystal structure instead of Li. The sulfide-based solid electrolyte exhibits a downshifted argyrodite Raman peak compared to an electrolyte without antimony substitution. The disclosed solid electrolyte may be synthesized using a ball milling process to ensure uniform distribution of staring materials and achieve a disordered crystal structure that enhances lithium ion conductivity, pellet density, and fracture strength. The disclosed solid electrolyte can be used in lithium-ion batteries, which are suitable for vehicle applications.