Abstract: A battery pack includes battery cells and a spacer. Each battery cell includes an electrode body and a case accommodating the electrode body in a state sealed by a sealing portion. The battery cells are arranged in an arrangement direction. The spacer is arranged between the case of one of the battery cells and the case of an adjacent battery cell. The battery cells are bound together in a state in which a binding pressure is applied to the battery cells. The electrode body includes a flat portion. The spacer includes a base plate and projections projecting from the base plate toward the case of the adjacent battery cell. The projections include a top projection that presses the case of the adjacent battery cell at a position located upward from an upper edge of the flat portion where the sealing portion is the closest.

Abstract: The nonaqueous electrolyte secondary battery herein disclosed includes a nonaqueous electrolyte, a wound electrode assembly, and a battery case accommodating them. The wound electrode assembly includes a pair of flat surface parts and a pair of R parts. In a state where 4.5 kN restriction pressure is added from a thickness direction so as to restrict the wound electrode assembly, when a total of outermost circumferential lengths of the pair of R parts of the wound electrode assembly on a cross section orthogonal to the winding axis of the wound electrode assembly is treated as a (mm), an outermost circumferential length of the cross section is treated as b (mm), a width of the positive electrode active material layer is treated as c (mm), and a height of the wound electrode assembly of the cross section is treated as d (mm), both 0.282<a/b and c/d<1.91 are satisfied.

Abstract: A non-aqueous electrolytic secondary battery includes a rolled electrode assembly including a positive electrode, a negative electrode and a separator, the positive electrode and the negative electrode being rolled with the separator sandwiched between the positive and negative electrodes; a non-aqueous electrolytic solution; and a quadrangular battery case accommodating the rolled electrode assembly and the non-aqueous electrolytic solution. The positive electrode includes a positive electrode active material layer containing at least a positive electrode active material and carbon nanotubes as a conductive material. The negative electrode includes a negative electrode active material layer containing a negative electrode active material. Where a void volume per unit area of the negative electrode active material layer is A (cm3/cm2) and a void volume per unit area of the positive electrode active material layer is B (cm3/cm2), the non-aqueous electrolytic secondary battery satisfies 0.6?B/A?1.2.

Abstract: A nonaqueous electrolyte rechargeable battery includes an electrode body, a nonaqueous electrolyte, and a rectangular box-shaped battery case accommodating the electrode body and the nonaqueous electrolyte. The electrode body includes a positive electrode including a positive base and a positive composite material layer, a negative electrode including a negative base and a negative composite material layer, and a porous resin separator disposed therebetween. The electrode body has a low profile when the positive electrode, the negative electrode, and the separator are laminated and rolled. When spring constant of the nonaqueous electrolyte rechargeable battery with a load of 316 to 210 N/cm2 and 95 to 74 N/cm2 is respectively referred to as spring constant H and spring constant L, the ratio L/H is 0.34 or greater and 0.41 or less. A resistance increase rate between before and after a square wave test is less than or equal to 1.17.

Abstract: A secondary battery with a reduced degree of increase in internal pressure over time, is provided. In a preferred embodiment, a secondary battery including: an electrode body, a battery case, an electrode terminal, and a gasket sandwiched between the battery case and the electrode terminal is provided. The secondary battery is configured such ghat a parameter K calculated using the following equation (1): K=Wi/(VrGH2) (1) (where Wi represents an initial capacity (Ah) of the secondary battery, Yr represents a volume (cm3) of void in the battery case, and GH2, represents an H2 gas permeability coefficient (cm3·cm)/(cm2·s·cmHg) of the gasket at 60° C.) satisfies 0.43×108 or more to 0.59×108 or less.