An electrochemical device has an electrochemical cell provided with an electrolyte having proton conductivity, an anode provided on one side of the electrolyte, and a cathode provided on the other side of the electrolyte. The electrochemical device is configured so that a solution containing water, an artificial synthetic resin, and an acid is supplied to the anode. The electrochemical device is configured so that an oxygen-containing gas is supplied to the cathode and connecting a load between the anode and the cathode. The electrochemical device is configured so that the inert gas is supplied to the cathode and connecting the voltage application unit between the anode and the cathode.

A positive electrode active material includes a nickel-containing lithium transition metal oxide containing nickel in an amount of 60 mol % or more based on a total number of moles of transition metals excluding lithium, and a lithium-containing inorganic compound layer formed on a surface of the nickel-containing lithium transition metal oxide, wherein the positive electrode active material has a first peak in a range of 5 eV or less, a second peak in a range of 7 eV to 13 eV, and a third peak in a range of 20 eV to 30 eV when intensity is measured by X-ray photoelectron spectroscopy, and the first peak has a maximum value of 80% to 120% with respect to the third peak. A method of preparing the positive electrode active material, and a positive electrode and a lithium secondary battery are also provided.

The present invention provides a cost-effective method of synthesizing phosphate salt of a metal M such as Fe and Mn that can be used for electrode active material of a lithium secondary battery. An oxidization-precipitation reaction is carried out on metal such as Fe(II) and Mn(II) to produce phosphate salt and hydroxide of the metal oxidized e.g. Fe(III) and Mn(III). With overdosed phosphoric acid, hydroxide of the oxidized metal is then converted to a phosphate salt. The invention also provides a method of preparing wet phosphate salt nanoparticles and their application in the synthesis of a cathode material. The present invention exhibits numerous technical merits such as lower cost, easier operation, and being environmentally friendly.

A secondary battery having high electromotive force and including less lead or being free of lead is provided. The secondary battery includes a positive electrode including a positive electrode active material containing manganese oxide, a negative electrode including a negative electrode active material containing at least one selected from zinc, gallium, and tin, and an electrolytic solution containing at least one selected from phosphoric acid and organic oxoacid and having a pH of less than 7 at 25 C. This secondary battery has an open circuit voltage of more than 1.6 V in a fully charged state.

A reduction-oxidation flow battery wherein the catholyte and/or the anolyte are selected from among respective defined groups of polyoxometalate compounds.

An illustrative example fuel cell device includes a cell stack assembly of a plurality of fuel cells that each include an anode and a cathode. A pressure plate is situated near one end of the cell stack assembly. A spacer between the end of the cell stack assembly and the pressure plate has a length, a width, and a height. The height of the spacer defines a spacing between the pressure plate and the end of the cell stack assembly. The spacer has a plurality of ribs that define at least two fluid reservoirs. At least one of the ribs separates the fluid reservoirs so that fluid in one of the reservoirs is isolated from fluid in the other.

A redox flow battery includes a battery cell including a positive electrode, a negative electrode, and a membrane disposed between these two electrodes; a positive electrode electrolyte supplied to the positive electrode; and a negative electrode electrolyte supplied to the negative electrode, wherein the positive electrode electrolyte contains manganese ions and a phosphorus-containing substance, the negative electrode electrolyte contains at least one species of metal ions selected from titanium ions, vanadium ions, chromium ions, and zinc ions, and a concentration of the phosphorus-containing substance is 0.001 M or more and 1 M or less.

The present invention provides a cost-effective method of synthesizing phosphate salt of a metal M such as Fe and Mn that can be used for electrode active material of a lithium secondary battery. An oxidization-precipitation reaction is carried out on metal such as Fe(II) and Mn(II) to produce phosphate salt and hydroxide of the metal oxidized e.g. Fe(III) and Mn(III). With overdosed phosphoric acid, hydroxide of the oxidized metal is then converted to a phosphate salt. The invention also provides a method of preparing wet phosphate salt nanoparticles and their application in the synthesis of a cathode material. The present invention exhibits numerous technical merits such as lower cost, easier operation, and being environmentally friendly.

A hybrid fuel cell comprises an anode, a cathode, and a membrane electrode assembly. The membrane electrode assembly comprises a first polymeric proton exchange membrane, a second polymeric proton exchange membrane, and an acidic liquid electrolyte layer disposed between the first and second proton exchange membranes. A method of producing electricity with the fuel cell is also disclosed.

To suppress electrolysis of an aqueous electrolyte solution on a surface of an anode when an aqueous potassium-ion battery is charged/discharged, in the aqueous electrolyte solution, potassium pyrophosphate is dissolved in water so that its concentration per kilogram of the water is no less than 2 mol. It is believed that thereby, a pyrophosphate ion is decomposed on the surface of the anode when the battery is charged/discharged, and a coating is formed on a portion of a high work function on the surface of the anode. As a result, direct contact between the aqueous electrolyte solution and the surface of the anode is suppressed, and electrolysis of the aqueous electrolyte solution on the surface of the anode is suppressed when the battery is charged/discharged.