This disclosure provides for Olivine-type compounds, their preparation and use in cathode materials for sodium-ion batteries. The olivine-type compounds of the invention are obtained by a direct synthesis embodying a hydrothermal method.

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.

Provided are various embodiments of a positive electrode for a secondary battery, which in one embodiment includes a first positive electrode material mixture layer formed on a positive electrode collector, and a second positive electrode material mixture layer formed on the first positive electrode material mixture layer, wherein the first positive electrode material mixture layer has an operating voltage of 4.25 V to 6.0 V and includes an active material for overcharge which generates lithium and gas during charge; a method of preparing such a positive electrode for a secondary battery; and a lithium secondary battery including such a positive electrode.

Provided are various embodiments of a positive electrode for a secondary battery, which in one embodiment includes a first positive electrode material mixture layer formed on a positive electrode collector, and a second positive electrode material mixture layer formed on the first positive electrode material mixture layer, wherein the first positive electrode material mixture layer has an operating voltage of 4.25 V to 6.0 V and includes an active material for overcharge which generates lithium and gas during charge; a method of preparing such a positive electrode for a secondary battery; and a lithium secondary battery including such a positive electrode.

A positive electrode including a positive electrode current collector, an intermediate layer disposed on the positive electrode current collector and including a conductive agent and inorganic particles, and a positive electrode mixture layer disposed on the intermediate layer and including a positive electrode active material and a hydrogen phosphate salt represented by the general formula MaHbPO4 (wherein a satisfies 1≤a≤2, b satisfies 1≤b≤2, and M includes at least one element selected from alkali metals and alkaline earth metals), the positive electrode satisfying 0.5≤X≤3.0, 1.0≤Y≤7.0, and 0.07≤X/Y≤3.0 wherein X is the mass ratio (mass %) of the hydrogen phosphate salt relative to the total mass of the positive electrode active material and Y is the mass ratio (mass %) of the conductive agent relative to the total mass of the intermediate layer.

A positive-electrode material for a lithium secondary battery is provided. The material includes a lithium oxide compound or a complex oxide as reactive substance. The material also includes at least one type of carbon material, and optionally a binder. A first type of carbon material is provided as a coating on the reactive substance particles surface. A second type of carbon material is carbon black. And a third type of carbon material is a fibrous carbon material provided as a mixture of at least two types of fibrous carbon material different in fiber diameter and/or fiber length. Also, a method for preparing the material as well as lithium secondary batteries including the material is provided.

An aqueous secondary battery including: a positive electrode; a negative electrode; a separator; and an aqueous electrolytic solution including water and a metal salt represented by Chemical Formula 1 A.sub.xD.sub.y and having molality of about 5 M to about 40 M wherein in Chemical Formula 1, A is at least one metal ion selected from a sodium ion, a potassium ion, a magnesium ion, a calcium ion, a strontium ion, a zinc ion, or a barium ion, D is at least one type of atomic group ion selected from Cl.sup.−, SO.sub.4.sup.2−, NO.sub.3.sup.−, ClO.sub.4.sup.−, SCN.sup.−, CF.sub.3SO.sub.3.sup.−, C.sub.4F.sub.3SO.sub.3.sup.−, (CF.sub.3SO.sub.2).sub.2N.sup.−, AlO.sub.2.sup.−, AlCl.sub.4.sup.−, AsF.sub.6.sup.−, SbF.sub.6.sup.−, BR.sub.4.sup.−, and PO.sub.2F.sub.2.sup.−, and 0<x≤2, and 0<y≤2.

The epsilon polymorph of vanadyl phosphate, ε-VOPO.sub.4, made from the solvothermally synthesized H.sub.2VOPO.sub.4, is a high density cathode material for lithium-ion batteries optimized to reversibly intercalate two Li-ions to reach the full theoretical capacity at least 50 cycles with a coulombic efficiency of 98%. This material adopts a stable 3D tunnel structure and can extract two Li-ions per vanadium ion, giving a theoretical capacity of 305 mAh/g, with an upper charge/discharge plateau at around 4.0 V, and one lower at around 2.5 V.

Provided is an electrode material which is suitable for use as a material for forming electrodes for use in lithium ion secondary batteries, etc. and which makes it possible to heighten the rate characteristics of batteries. The electrode material is characterized by comprising a polymer having, in a side chain, a fluoflavin skeleton such as that shown by the formula and an inorganic active material, the polymer being contained in an amount of 1 mass % or less with respect to the solid components.

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