To improve the reliability of a power storage device. A granular active material including carbon is used, and a net-like structure is formed on part of a surface of the granular active material. In the net-like structure, a carbon atom included in the granular active material is bonded to a silicon atom or a metal atom through an oxygen atom. Formation of the net-like structure suppresses reductive decomposition of an electrolyte solution, leading to a reduction in irreversible capacity. A power storage device using the above active material has high cycle performance and high reliability.

To improve the reliability of a power storage device. A granular active material including carbon is used, and a net-like structure is formed on part of a surface of the granular active material. In the net-like structure, a carbon atom included in the granular active material is bonded to a silicon atom or a metal atom through an oxygen atom. Formation of the net-like structure suppresses reductive decomposition of an electrolyte solution, leading to a reduction in irreversible capacity. A power storage device using the above active material has high cycle performance and high reliability.

The invention provides process for producing a stable Si or Ge electrode structure comprising cycling a Si or Ge nanowire electrode until a structure of the Si nanowires form a continuous porous network of Si or Ge ligaments.

The invention provides process for producing a stable Si or Ge electrode structure comprising cycling a Si or Ge nanowire electrode until a structure of the Si nanowires form a continuous porous network of Si or Ge ligaments.

A battery and a method of constructing a battery are disclosed in which a first conductive substrate portion has a first face and a second conductive substrate portion has a second face opposed to the first face. A first electrode material is disposed in electrical contact with the first face, an electrolyte material is disposed in contact with the first electrode material, a second electrode material is disposed in contact with the electrolyte material, and a conductive tab disposed in contact with the second electrode material. The first conductive substrate portion, the first electrode material, and the conductive tab extend outward beyond a particular edge of the second conductive substrate portion.

A battery and a method of constructing a battery are disclosed in which a first conductive substrate portion has a first face and a second conductive substrate portion has a second face opposed to the first face. A first electrode material is disposed in electrical contact with the first face, an electrolyte material is disposed in contact with the first electrode material, a second electrode material is disposed in contact with the electrolyte material, and a conductive tab disposed in contact with the second electrode material. The first conductive substrate portion, the first electrode material, and the conductive tab extend outward beyond a particular edge of the second conductive substrate portion.

A composite containing phosphorus, lithium, iron, sulfur, and carbon as constituent elements wherein lithium sulfide (Li.sub.2S) is present in an amount of 90 mol % or more, and wherein the crystallite size calculated from the half-width of a diffraction peak based on the (111) plane of Li.sub.2S as determined by X-ray powder diffraction measurement is 80 nm or less. The composite exhibits a high capacity (in particular, a high discharge capacity) useful as an electrode active material for a lithium-ion secondary battery (in particular, a cathode active material for a lithium-ion secondary battery), without the need for stepwise pre-cycling treatment.

A composite containing phosphorus, lithium, iron, sulfur, and carbon as constituent elements wherein lithium sulfide (Li.sub.2S) is present in an amount of 90 mol % or more, and wherein the crystallite size calculated from the half-width of a diffraction peak based on the (111) plane of Li.sub.2S as determined by X-ray powder diffraction measurement is 80 nm or less. The composite exhibits a high capacity (in particular, a high discharge capacity) useful as an electrode active material for a lithium-ion secondary battery (in particular, a cathode active material for a lithium-ion secondary battery), without the need for stepwise pre-cycling treatment.

Various embodiments of the present disclosure describe energy storage devices. In one example, an energy storage device includes an anode having a plurality of active material particles, a cathode having a transition metal oxide material, and an electrolyte including a room temperature ionic liquid to couple the anode to the cathode. Each of the plurality of anode active material particles have a particle size of between about one micrometer and about fifty micrometers. One or more of the plurality of anode active material particles are enclosed by and in contact with a membrane coating permeable to lithium ions.

Various embodiments of the present disclosure describe energy storage devices. In one example, an energy storage device includes an anode having a plurality of active material particles, a cathode having a transition metal oxide material, and an electrolyte including a room temperature ionic liquid to couple the anode to the cathode. Each of the plurality of anode active material particles have a particle size of between about one micrometer and about fifty micrometers. One or more of the plurality of anode active material particles are enclosed by and in contact with a membrane coating permeable to lithium ions.