Provided are a binder resin for an electrode of a lithium secondary battery containing a solvent-soluble polyimide having a repeating unit represented by the following Formula [I], and a method of producing the binder resin for an electrode. ##STR00001## (In the formula, Z represents an aromatic or alicyclic tetracarboxylic dianhydride residue, and Ar is an aromatic diamine residue having a carboxyl group and an aromatic diamine residue having an aromatic ether bond, or an aromatic diamine residue having a phenylindan structure).

Provided are a binder resin for an electrode of a lithium secondary battery containing a solvent-soluble polyimide having a repeating unit represented by the following Formula [I], and a method of producing the binder resin for an electrode. ##STR00001## (In the formula, Z represents an aromatic or alicyclic tetracarboxylic dianhydride residue, and Ar is an aromatic diamine residue having a carboxyl group and an aromatic diamine residue having an aromatic ether bond, or an aromatic diamine residue having a phenylindan structure).

A positive-electrode active material contains a compound that has a crystal structure belonging to a space group FM3-M and contains is represented by the composition formula (1) and an insulating compound,
Li.sub.xMe.sub.yO.sub.αF.sub.β  (1)
wherein Me denotes one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr, and the following conditions are satisfied.
1.7≤x≤2.2
0.8≤y≤1.3
1≤α≤2.5
0.5≤β≤2

A positive-electrode active material contains a compound that has a crystal structure belonging to a space group FM3-M and contains is represented by the composition formula (1) and an insulating compound,
Li.sub.xMe.sub.yO.sub.αF.sub.β  (1)
wherein Me denotes one or two or more elements selected from the group consisting of Mn, Co, Ni, Fe, Al, B, Ce, Si, Zr, Nb, Pr, Ti, W, Ge, Mo, Sn, Bi, Cu, Mg, Ca, Ba, Sr, Y, Zn, Ga, Er, La, Sm, Yb, V, and Cr, and the following conditions are satisfied.
1.7≤x≤2.2
0.8≤y≤1.3
1≤α≤2.5
0.5≤β≤2

A nickel-based active material for a lithium secondary battery, a method of preparing the nickel-based active material, and a lithium secondary battery including a positive electrode including the nickel-based active material, the nickel-based active material comprising a secondary particle having an outer portion with a radially arranged structure and an inner portion with an irregular porous structure, wherein the inner portion of the secondary particle has a larger pore size than the outer portion of the secondary particle.

A nickel-based active material for a lithium secondary battery, a method of preparing the nickel-based active material, and a lithium secondary battery including a positive electrode including the nickel-based active material, the nickel-based active material comprising a secondary particle having an outer portion with a radially arranged structure and an inner portion with an irregular porous structure, wherein the inner portion of the secondary particle has a larger pore size than the outer portion of the secondary particle.

Electrodes are formed with a porous layer of particulate electrode material bonded to each of the two major sides of a compatible metal current collector. In one embodiment, opposing electrodes are formed with like lithium-ion battery anode materials or like cathode materials or capacitor materials on both sides of the current collector. In another embodiment, a battery electrode material is applied to one side of a current collector and capacitor material is applied to the other side. In general, the electrodes are formed by combining a suitable grouping of capacitor layers with un-equal numbers of anode and cathode battery layers. One or more pairs of opposing electrodes are assembled to provide a combination of battery and capacitor energy and power properties in a hybrid electrochemical cell. The cells may be formed by stacking or winding rolls of the opposing electrodes with interposed separators.

Electrodes are formed with a porous layer of particulate electrode material bonded to each of the two major sides of a compatible metal current collector. In one embodiment, opposing electrodes are formed with like lithium-ion battery anode materials or like cathode materials or capacitor materials on both sides of the current collector. In another embodiment, a battery electrode material is applied to one side of a current collector and capacitor material is applied to the other side. In general, the electrodes are formed by combining a suitable grouping of capacitor layers with un-equal numbers of anode and cathode battery layers. One or more pairs of opposing electrodes are assembled to provide a combination of battery and capacitor energy and power properties in a hybrid electrochemical cell. The cells may be formed by stacking or winding rolls of the opposing electrodes with interposed separators.

A process for preparing a titanic acid salt, titanic acid, and titanium oxide having a controllable particle size and a hierarchical structure, wherein the process includes the steps of: preparing a titanium-containing peroxo-complex solution; adding a basic metal compound to the titanium-containing peroxo-complex solution to form a mixture solution; adding one of polyvinyl alcohol, hydroxypropyl methyl cellulose, and polyethylene glycol to the mixture solution to form a precursor dispersion; and subjecting the precursor dispersion to a solvothermal reaction to obtain the titanic acid salt having a hierarchical structure. The process for preparing a titanic acid salt, titanic acid, and titanium oxide having a controllable particle size and a hierarchical structure, can not only realize the regulation of morphology and particle diameter of constituent units in the hierarchical structure, but also can achieve the regulation of particle size in the hierarchical structure.

A process for preparing a titanic acid salt, titanic acid, and titanium oxide having a controllable particle size and a hierarchical structure, wherein the process includes the steps of: preparing a titanium-containing peroxo-complex solution; adding a basic metal compound to the titanium-containing peroxo-complex solution to form a mixture solution; adding one of polyvinyl alcohol, hydroxypropyl methyl cellulose, and polyethylene glycol to the mixture solution to form a precursor dispersion; and subjecting the precursor dispersion to a solvothermal reaction to obtain the titanic acid salt having a hierarchical structure. The process for preparing a titanic acid salt, titanic acid, and titanium oxide having a controllable particle size and a hierarchical structure, can not only realize the regulation of morphology and particle diameter of constituent units in the hierarchical structure, but also can achieve the regulation of particle size in the hierarchical structure.