A negative electrode used in a nickel metal hydride secondary battery includes a negative electrode core body and a negative electrode mixture carried on the negative electrode core body. The negative electrode mixture includes hydrogen storage alloy powder which is an aggregate of hydrogen storage alloy particles, a binder, and a thickener. The hydrogen storage alloy particles have a volume mean particle size of 40 μm or less and a concentration of chlorine of not less than 180 ppm to not more than 780 ppm.

A secondary battery in which an insulation sheet is inserted between a cap-up and a case, thereby increasing safety, is provided. The secondary battery includes: an electrode assembly; a case for receiving the electrode assembly; a cap assembly coupled to an upper part of the case; and a gasket interposed between the cap assembly and the case. The cap assembly includes: a cap-up; a safety vent installed at a lower part of the cap-up and extending to an upper part of the cap-up so as to surround a periphery of the cap-up; and an insulation sheet positioned at an upper part of the safety vent extending to the upper part of the cap-up.

A method of producing a porous carbon is provided that can change type of functional groups, amount of functional groups, or ratio of functional groups while inhibiting its pore structure from changing. A method of producing a porous carbon includes: a first step of carbonizing a material containing a carbon source and a template source, to prepare a carbonized product; and a second step of immersing the carbonized product into a template removing solution, to remove a template from the carbonized product, and the method is characterized by changing at least two or more of the following conditions: type of the material, ratio of the carbon source and the template source, size of the template, and type of the template removal solution, to thereby control type, amount, or ratio of functional groups that are present in the porous carbon.

An open cabin electric wheeled vehicle includes a large-capacity driving battery having a volume energy density higher than the volume energy density of a lead storage battery, the large-capacity driving battery being configured to supply electric power to a driving electric motor. The vehicle also includes a fuel-type electric power generation apparatus that generates electric power using a fuel. As seen from a leftward direction or a rightward direction, between the large-capacity driving battery and the fuel-type electric power generation apparatus, a recess overlaps with a passage region which allows people or baggage to pass through of an entrance and exit opening portion having no door, so that a bottom end of a front wall portion, a bottom end of a rear wall portion, and a bottom portion are located further downward than a top end of the large-capacity driving battery which has a volume energy density higher than the volume energy density of a lead storage battery, and a top end of the fuel-type electric power generation apparatus.

A power storage device includes an electricity storage element, a case, and a sealing member which includes an elastic member. The elastic member contains an elastic polymer and a hindered phenol compound. The hindered phenol compound having a phenol skeleton includes a first hindered group and a second hindered group. The first hindered group is bonded to a first substitution site of the phenol skeleton, and the second hindered group is bonded to a second substitution site of the phenol skeleton. Each of the first substitution site and second substitution site is adjacent to a substitution site of the phenol skeleton to which a phenolic hydroxy group is bonded. One of one or more tertiary carbon atoms in the first hindered group and one of one or more tertiary carbon atoms in the second hindered group are bonded to the first substitution site and the second substitution site, respectively.

An electrical energy power source comprises a casing made by micro-bonding an upper ceramic wafer and a lower ceramic wafer to the opposed surfaces of a ceramic ring. The upper and lower ceramic wafers have respective first and second conductive pathways extends therethrough. A first current collector supporting a first active material layer contacts the upper ceramic wafer and the first conductive pathway, and a second current collector supporting a second, opposite polarity active material layer contacts the lower ceramic wafer and the second conductive pathway. A separator resides between the first and second active materials, and an electrolyte filled into the casing through a fill port activates the active materials. The first and second conductive pathways serve as opposite polarity terminals for the power source.

A button cell includes a housing having a cell cup, the cell cup having a flat bottom area, a cell cup casing, and a bottom edge forming a transition between the flat bottom area and the cell cup casing, and a cell top, the cell top having a flat top area and a cell top casing. An electrode-separator assembly winding is disposed within the housing, the electrode-separator assembly winding including a multi-layer assembly that is wound in a spiral shape about an axis, the multi-layer assembly including a separator disposed between a positive electrode and a negative electrode, and a first output conductor. An insulator is disposed between an end face of the electrode-separator assembly winding and the first output conductor, wherein the first output conductor is welded to the first of the flat bottom area or the flat top area.

A button cell includes a housing having a cell cup, the cell cup having a flat bottom area, a cell cup casing, and a bottom edge forming a transition between the flat bottom area and the cell cup casing, and a cell top, the cell top having a flat top area and a cell top casing. An electrode-separator assembly winding is disposed within the housing, the electrode-separator assembly winding including a multi-layer assembly that is wound in a spiral shape about an axis, the multi-layer assembly including a separator disposed between a positive electrode and a negative electrode, and a first output conductor. An insulator is disposed between an end face of the electrode-separator assembly winding and the first output conductor, wherein the first output conductor is welded to the first of the flat bottom area or the flat top area.

A battery system includes a nickel hydride battery and an electronic control unit. The electronic control unit is configured to store data indicating a corresponding relationship between an elapsed time from start of use of the nickel hydride battery and a memory quantity. The data are data determined in a classified manner individually for each of conditions of use that are defined in such a manner as to include an open circuit voltage and a temperature. The electronic control unit is configured to sequentially calculate, with reference to the data, the memory quantity within a time when classification of the conditions of use does not change. The memory quantity is a quantity indicating an amount of change in voltage resulting from a memory effect. The electronic control unit is configured to estimate a current memory quantity of the nickel hydride battery by integrating the calculated memory quantity.

A nickel-hydrogen secondary battery includes an electrode group comprising a separator, a positive electrode, and a negative electrode, and the positive electrode contains a positive electrode active material including a base particle comprising a nickel hydroxide particle containing Mn in solid solution and a conductive layer comprising a Co compound and covering the surface of the base particle, wherein the X-ray absorption edge energy of Mn detected within 6500 to 6600 eV by measurement with an XAFS method is 6548 eV or higher.