An electrolytic cell includes a liquid metal cathode, an anode, and a molten salt electrolyte in contact with the liquid metal cathode and the anode. The molten salt electrolyte includes carbonate ions, and the electrolytic cell is configured to reduce the carbonate ions at the surface of the cathode or in the vicinity of the cathode to yield a carbon material and oxide ions. Producing a carbon material in the electrolytic cell includes providing carbonate ions to the electrolytic cell, reducing the carbonate ions at the liquid metal cathode to yield the carbon material, and removing the carbon material from the electrolytic cell.

An electrolytic cell includes a liquid metal cathode, an anode, and a molten salt electrolyte in contact with the liquid metal cathode and the anode. The molten salt electrolyte includes carbonate ions, and the electrolytic cell is configured to reduce the carbonate ions at the surface of the cathode or in the vicinity of the cathode to yield a carbon material and oxide ions. Producing a carbon material in the electrolytic cell includes providing carbonate ions to the electrolytic cell, reducing the carbonate ions at the liquid metal cathode to yield the carbon material, and removing the carbon material from the electrolytic cell.

In some aspects, the present disclosure pertains to methods for the electrochemical production of calcium silicate compounds in an electrochemical cell that comprises (a) a Ca-based electrode that comprises calcium metal or an inorganic calcium material, (b) an SiO.sub.x-based electrode that comprises a SiO.sub.x material, where x ranges from 1 to 2, and (c) a liquid electrolyte disposed between the Ca-based electrode and the SiO.sub.x-based electrode. In these methods, the electrochemical cell is operated under conditions such that calcium cations are produced at the Ca-based electrode and one or more calcium silicate (Ca—Si-oxide) compounds are produced at the SiO.sub.x-based electrode. In other aspects, the present disclosure pertains to systems for the electrochemical production of calcium silicate compounds.

In some aspects, the present disclosure pertains to methods for the electrochemical production of calcium silicate compounds in an electrochemical cell that comprises (a) a Ca-based electrode that comprises calcium metal or an inorganic calcium material, (b) an SiO.sub.x-based electrode that comprises a SiO.sub.x material, where x ranges from 1 to 2, and (c) a liquid electrolyte disposed between the Ca-based electrode and the SiO.sub.x-based electrode. In these methods, the electrochemical cell is operated under conditions such that calcium cations are produced at the Ca-based electrode and one or more calcium silicate (Ca—Si-oxide) compounds are produced at the SiO.sub.x-based electrode. In other aspects, the present disclosure pertains to systems for the electrochemical production of calcium silicate compounds.

Disclosed are a carbon dioxide utilization system capable of producing electricity, hydrogen, and bicarbonate by utilizing carbon dioxide, which is a greenhouse gas, through a spontaneous electrochemical reaction without a separate external power source, and producing magnesium hydrogen carbonate by reacting the hydrogen carbonate ions with magnesium ions generated at an anode.

Known phosphorus recovery methods from liquid phases proceed from the presence of ammonia or nitrate, and phosphate, in the liquid phase. Wastewater that is supposed to be freed of nitrate and phosphate pollution in sewage treatment facilities can be used as the liquid phase. In electrochemical methods, a magnesium electrode is used as a sacrificial anode, and ammonium and phosphate together are bound to the magnesium to form struvite, which in turn can be used in agriculture as a fertilizer, in useful manner. In an alternative method of procedure, first, only phosphates are removed from a liquid phase that occurs from the filtration of products of hydrothermal carbonization. A magnesium electrode is used as the cathode, so that the resulting magnesium phosphate does not go into solution and first must be precipitated, but rather is removed from the electrolysis cell directly with the cathode, after the reaction occurs.

Known phosphorus recovery methods from liquid phases proceed from the presence of ammonia or nitrate, and phosphate, in the liquid phase. Wastewater that is supposed to be freed of nitrate and phosphate pollution in sewage treatment facilities can be used as the liquid phase. In electrochemical methods, a magnesium electrode is used as a sacrificial anode, and ammonium and phosphate together are bound to the magnesium to form struvite, which in turn can be used in agriculture as a fertilizer, in useful manner. In an alternative method of procedure, first, only phosphates are removed from a liquid phase that occurs from the filtration of products of hydrothermal carbonization. A magnesium electrode is used as the cathode, so that the resulting magnesium phosphate does not go into solution and first must be precipitated, but rather is removed from the electrolysis cell directly with the cathode, after the reaction occurs.

Provided is a magnesium secondary battery including a positive electrode member 23 including at least a positive electrode active material layer 23B, a separator 24 disposed facing the positive electrode member 23, a negative electrode member 25 containing magnesium or a magnesium compound disposed facing the separator 24, and an electrolytic solution containing a magnesium salt. The positive electrode active material layer 23B includes magnesium sulfide having a zinc blende type crystal structure.

The embodiments provide an eco-friendly carbon dioxide fixation method and a system for carrying out the method. The carbon dioxide fixation method according to the embodiment includes: immersing a magnesium alloy in an aqueous solvent; blowing carbon dioxide-containing gas into the aqueous solvent; and electrically energizing and thereby subjecting the aqueous solvent to electrolysis treatment so as to produce precipitates containing magnesium carbonate. This method can be carried out in a system having: a treating bath for storing a magnesium alloy and an aqueous solvent to treat a magnesium alloy in which said magnesium alloy is treated, a gas-introducing unit for blowing carbon dioxide-containing gas into the aqueous solvent, a pair of electrodes for applying voltage to the aqueous solvent so as to conduct electrolysis treatment, and a power control unit connected to the electrodes.

The embodiments provide an eco-friendly carbon dioxide fixation method and a system for carrying out the method. The carbon dioxide fixation method according to the embodiment includes: immersing a magnesium alloy in an aqueous solvent; blowing carbon dioxide-containing gas into the aqueous solvent; and electrically energizing and thereby subjecting the aqueous solvent to electrolysis treatment so as to produce precipitates containing magnesium carbonate. This method can be carried out in a system having: a treating bath for storing a magnesium alloy and an aqueous solvent to treat a magnesium alloy in which said magnesium alloy is treated, a gas-introducing unit for blowing carbon dioxide-containing gas into the aqueous solvent, a pair of electrodes for applying voltage to the aqueous solvent so as to conduct electrolysis treatment, and a power control unit connected to the electrodes.