A method for preparing a niobium, titanium or vanadium metal oxide nanostructured material is provided. The method comprises providing an aqueous reagent comprising (i) a soluble metal oxalate, and/or (ii) oxalic acid and a metal oxide precursor, adding a buffering agent to the aqueous reagent to form a mixture, and heating the mixture under hydrothermal conditions to obtain the metal oxide nanostructured material. The metal oxide nanostructured material may also be doped with a dopant metal such as titanium to enhance capacity and cycling stability. An electrode comprising the metal oxide nanostructured material, and an electrochemical cell containing the electrode are also provided.

Disclosed herein are a multilayer electrode and a lithium secondary battery including the same. The multilayer electrode includes an electrode current collector for transmitting electrons between an external wire and an electrode active material and three or more electrode mixture layers sequentially applied to the electrode current collector, wherein each of the electrode mixture layers includes an electrode active material and a conducting agent, and wherein the content of the conducting agent of one of adjacent electrode mixture layers that is relatively close to the current collector in the direction in which the electrode mixture layers are formed is higher than that of the conducting agent of the other of the adjacent electrode mixture layers that is relatively distant from the current collector.

Disclosed is a power storage element including a positive electrode current collector layer and a negative electrode current collector layer which are arranged on the same plane and can be formed through a simple process. The power storage element further includes a positive electrode active material layer on the positive electrode current collector layer; a negative electrode active material layer on the negative electrode current collector layer; and a solid electrolyte layer in contact with at least the positive electrode active material layer and the negative electrode active material layer. The positive electrode active material layer and the negative electrode active material layer are formed by oxidation treatment.

Disclosed is a power storage element including a positive electrode current collector layer and a negative electrode current collector layer which are arranged on the same plane and can be formed through a simple process. The power storage element further includes a positive electrode active material layer on the positive electrode current collector layer; a negative electrode active material layer on the negative electrode current collector layer; and a solid electrolyte layer in contact with at least the positive electrode active material layer and the negative electrode active material layer. The positive electrode active material layer and the negative electrode active material layer are formed by oxidation treatment.

As for a secondary battery using lithium cobalt oxide as a positive electrode active material, the positive electrode active material with which a decrease in battery capacity due to repeated charge and discharge is inhibited is provided. Alternatively, a positive electrode active material particle which hardly deteriorates is provided. The positive electrode active material includes lithium, cobalt, oxygen, magnesium, aluminum, and fluorine and is a crystal represented by a layered rock-salt structure. The space group of the crystal is represented by R−3m. The concentration of fluorine in a surface portion of the crystal is higher than that inside the crystal. The concentration of magnesium in the surface portion of the crystal is higher than that inside the crystal. The atomic ratio of magnesium to aluminum in the surface portion of the crystal is higher than that inside the crystal.

An electrode including a binary metal oxide, a method for preparing an electrode including the same, and a supercapacitor are provided. The binary metal oxide includes a first metal element and a second metal element. The first metal element includes a first transition metal element with two valence states. The second metal element is different from the first metal element and is selected from one of Mn, Fe, Ni, Zn, Al, Li, Ba, and La.

An electrode including a binary metal oxide, a method for preparing an electrode including the same, and a supercapacitor are provided. The binary metal oxide includes a first metal element and a second metal element. The first metal element includes a first transition metal element with two valence states. The second metal element is different from the first metal element and is selected from one of Mn, Fe, Ni, Zn, Al, Li, Ba, and La.

Disclosed is a hybrid electrochemical cell with a first conductor having at least one portion that is both a first capacitor electrode and a first battery electrode. The hybrid electrochemical cell further includes a second conductor having at least one portion that is a second capacitor electrode and at least one other portion that is a second battery electrode. An electrolyte is in contact with both the first conductor and the second conductor. In some embodiments, the hybrid electrochemical cell further includes a separator between the first conductor and the second conductor to prevent physical contact between the first conductor and the second conductor, while facilitating ion transport between the first conductor and the second conductor.

Disclosed is a hybrid electrochemical cell with a first conductor having at least one portion that is both a first capacitor electrode and a first battery electrode. The hybrid electrochemical cell further includes a second conductor having at least one portion that is a second capacitor electrode and at least one other portion that is a second battery electrode. An electrolyte is in contact with both the first conductor and the second conductor. In some embodiments, the hybrid electrochemical cell further includes a separator between the first conductor and the second conductor to prevent physical contact between the first conductor and the second conductor, while facilitating ion transport between the first conductor and the second conductor.

A cathode material, containing a crystal with a superlattice structure, is provided. A chemical formula of the crystal is xLi.sub.2MO.sub.3.(1-x)LiNi.sub.aCo.sub.bMn.sub.(1-a-b)O.sub.2, where 0<x≤0.1, 0.8≤a<1, b≤0.1, and M is selected from one or more of Mn, Co, and Ni. A preparation method of the cathode material and a battery or a capacitor containing the cathode material are also provided.