Battery module

1 . A battery module comprising: a plurality of cylindrical batteries each comprising:

a shaft core; a set of wound electrodes comprising an electrode stack wound around the shaft core and comprising a positive electrode, a negative electrode, and an electrolyte provided between the positive and negative electrodes stacked; a first fastener provided at a first axial end of the shaft core; a second fastener provided at a second axial end of the shaft core; and an exterior member surrounding the set of wound electrodes,

adjacent ones of the cylindrical batteries being fastened together with the first and second fasteners,

wherein the cylindrical batteries each further comprise: a first cap disposed at the first axial end and electrically connected to one of the positive and negative electrodes; and a second cap disposed at the second axial end and electrically connected to another of the positive and negative electrodes,

wherein the first and second caps each have a slope region that is substantially symmetrically inclined with respect to the shaft core,

wherein the positive electrode includes a positive electrode current collector, and the negative electrode includes a negative electrode current collector,

wherein the positive electrode current collector has an extension portion extending from a first axial end of the set of wound electrodes,

wherein the negative electrode current collector has an extension portion extending from a second axial end of the set of wound electrodes,

wherein the extension portion of one of the positive and negative electrode current collectors has parts gathered and electrically connected to the shaft core, and

wherein the extension portion of another of the positive and negative electrode current collectors has parts gathered and electrically connected to the exterior member.

2 . The battery module according to claim 1 ,

wherein one of the first and second fasteners is an external thread,

wherein another of the first and second fasteners is an internal thread, and

wherein the external thread and the shaft core are parts of a single piece.

3 . The battery module according to claim 2 ,

wherein the first fastener is electrically connected to one of the positive and negative electrodes, and

wherein the second fastener is electrically connected to another of the positive and negative electrodes.

4 . The battery module according to claim 1 , wherein the slope region of one of the first and second caps that is electrically connected to the extension portion electrically connected to the exterior member is inclined at a larger angle than the slope region of another of the first and second caps that is electrically connected to the extension portion electrically connected to the shaft core.

5 . The battery module according to claim 1 , wherein the first and second caps each have a conical shape.

6 . The battery module according to claim 1 ,

wherein the first cap is electrically connected to one of the positive and negative electrode current collectors, and

wherein the second cap is electrically connected to another of the positive and negative electrode current collectors.

7 . The battery module according to claim 1 ,

wherein the extension portion of one of the positive and negative electrode current collectors is at least partially not surrounded by the exterior member, and

wherein the extension portion of another of the positive and negative electrode current collectors is surrounded by the exterior member.

8 . The battery module according to claim 1 ,

wherein the positive electrode includes a resin sheet and a positive electrode material mixture layer, the resin sheet is at least attached to a part of one surface of the positive electrode current collector, the part of one surface does not form the extension portion, the positive electrode material mixture layer is provided on a part of another surface of the positive electrode current collector, and the part of another surface does not form the extension portion, and

wherein the negative electrode includes a resin sheet and a negative electrode material mixture layer, the resin sheet is at least attached to a part of one surface of the negative electrode current collector, the part of one surface does not form the extension portion, the negative electrode material mixture layer is provided on a part of another surface of the negative electrode current collector, and the part of another surface does not form the extension portion.

9 . The battery module according to claim 8 ,

wherein the resin sheet is also attached to a part of the extension portion of the one surface of the positive electrode current collector, and

wherein the resin sheet is also attached to a part of the extension portion of the one surface of the negative electrode current collector.

10 . The battery module according to claim 1 , wherein the cylindrical batteries are each a solid-state battery.

11 . The battery module according to claim 10 , wherein the electrode stack includes a solid electrolyte layer provided between the positive and negative electrodes stacked.