An electrochemical apparatus, including a positive electrode, a negative electrode, and an electrolyte, where the positive electrode includes a positive electrode active material layer, and the positive electrode active material layer has a relatively small contact angle with respect to a non-aqueous solvent. The electrochemical apparatus has improved cycling performance, rate performance, and direct-current resistance.

The power storage device comprises an electrode assembly including a positive electrode, a separator, and a negative electrode, and an electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer. The active material layer comprises a surplus region A not facing the positive electrode active material layer, an end region B facing a region in the positive electrode active material layer, the region extending from an end of the positive electrode active material layer toward a center of the positive electrode active material layer by a length of 5% of a length from the center to the end, and a center region C. A negative electrode potential VA and a negative electrode potential VC after the positive electrode and the negative electrode are short-circuited satisfy Formulas below: (1): VA≤2.0 V, (2): VC≤1.0 V, (3): VA/VC≥0.7.

An electrode for electrochemical cells including an electrically conductive cohesive membrane having a thickness defined by a first surface and a second surface opposite the first surface; ohmic impedance independent of membrane thickness; simultaneous uniform charge/discharge throughout membrane thickness; the membrane comprising open cell pores and surfaces; a current collector electrically strongly coupled to the entire membrane thickness; and pins extending through the membrane from the first surface to the second surface; the pins electrically coupled to the current collector having eliminated prior art problematical interfacial layers.

Hybrid lithium-ion electrochemical cells include a first electrode having a first polarity and a first electroactive material that reversibly cycles lithium ions having a first maximum operational voltage and a second electrode having the first polarity with a second electroactive material having a second maximum operational voltage. A difference between the second and first maximum operational voltages defines a predetermined voltage difference. Also included are at least one third electrode including a third electroactive material that reversibly cycles lithium ions having a second polarity opposite to the first polarity, a separator, and electrolyte. A voltage modification component (e.g., diode) is in electrical communication with the first and the second electrodes. In a first operational state corresponding to charging, the at least one voltage modification component is configured to induce a voltage drop corresponding to the predetermined voltage difference providing high power density and high energy density hybrid lithium-ion electrochemical cells.

Hybrid lithium-ion electrochemical cells include a first electrode having a first polarity and a first electroactive material that reversibly cycles lithium ions having a first maximum operational voltage and a second electrode having the first polarity with a second electroactive material having a second maximum operational voltage. A difference between the second and first maximum operational voltages defines a predetermined voltage difference. Also included are at least one third electrode including a third electroactive material that reversibly cycles lithium ions having a second polarity opposite to the first polarity, a separator, and electrolyte. A voltage modification component (e.g., diode) is in electrical communication with the first and the second electrodes. In a first operational state corresponding to charging, the at least one voltage modification component is configured to induce a voltage drop corresponding to the predetermined voltage difference providing high power density and high energy density hybrid lithium-ion electrochemical cells.

In an embodiment, the present disclosure pertains to a method of creating a supercapacitor. The method includes forming an anode and a cathode, each composed of a substrate having at least one of a lignin, a lignin-based composite, activated carbon, a plant extract, a cellulose by-product, biofuel waste, one or more metals, a metal oxide, a monometallic tungstate, or a bimetallic tungstate, and sandwiching an electrolyte coated separator between the anode and the cathode. In an addition embodiment, the present disclosure pertains to an electrode composed of a particle-decorated lignin. In some embodiments, the particle-decorated lignin includes particles that can include, without limitation, MnO.sub.2, NiWO.sub.4, MnO.sub.2, NiCoWO.sub.4, CoWO.sub.4, and combinations thereof. In a further embodiment, the present disclosure pertains to a supercapacitor made via the methods of the present disclosure.

In an embodiment, the present disclosure pertains to a method of creating a supercapacitor. The method includes forming an anode and a cathode, each composed of a substrate having at least one of a lignin, a lignin-based composite, activated carbon, a plant extract, a cellulose by-product, biofuel waste, one or more metals, a metal oxide, a monometallic tungstate, or a bimetallic tungstate, and sandwiching an electrolyte coated separator between the anode and the cathode. In an addition embodiment, the present disclosure pertains to an electrode composed of a particle-decorated lignin. In some embodiments, the particle-decorated lignin includes particles that can include, without limitation, MnO.sub.2, NiWO.sub.4, MnO.sub.2, NiCoWO.sub.4, CoWO.sub.4, and combinations thereof. In a further embodiment, the present disclosure pertains to a supercapacitor made via the methods of the present disclosure.

There are provided: a nonaqueous electrolytic solution for an energy storage device provided with a positive electrode, a negative electrode, a separator and a nonaqueous electrolytic solution having an electrolyte salt dissolved in a nonaqueous solvent, wherein the potential of the positive electrode in a full-charge state is 4.5 V or higher on Li basis and the nonaqueous electrolytic solution contains at least one kind of tertiary carboxylic acid esters represented by the following general formula (I); and an energy storage device using the nonaqueous electrolytic solution.

##STR00001## wherein R.sup.1 to R.sup.3 each independently represent a methyl group or an ethyl group; and R.sup.4 represents a halogenated alkyl group having 1 to 5 carbon atoms.

One aspect of the present invention is a positive electrode for an energy storage device including a positive active material layer, in which the positive active material layer includes a positive active material particle having a ratio of a secondary particle size to a primary particle size of 3 or less, and a fibrous conductive agent.

An asymmetric nanocomposite supercapacitor and a method of making the asymmetric nanocomposite supercapacitor. The asymmetric nanocomposite supercapacitor includes a negative electrode with monoclinic tungsten oxide (m-WO.sub.3) nanoplates, and a binding compound coated on one face of a substrate, and a positive electrode with a carbonaceous material and a binding compound coated on one face of a substrate. Where the face of the positive electrode and the face of the negative electrode coated with the carbonaceous material and m-WO.sub.3 nanoplates, respectively, are separated by and in direct contact with a porous separator.