An electrochemical device including a positive electrode current collector; a first protruding portion including a plurality of positive electrodes in electrical contact with the positive electrode current collector, and a first dented portion disposed between each positive electrode of the plurality of positive electrodes; an electrolyte layer including a second protruding portion and a second dented portion respectively disposed on the first protruding portion including the plurality of positive electrodes and the first dented portion disposed between each positive electrode of the plurality of positive electrodes; and a negative electrode current collector layer including a third protruding portion and a third dented portion respectively disposed on the second protruding portion and the second dented portion of the electrolyte layer.

An electrochemical device including a positive electrode current collector; a first protruding portion including a plurality of positive electrodes in electrical contact with the positive electrode current collector, and a first dented portion disposed between each positive electrode of the plurality of positive electrodes; an electrolyte layer including a second protruding portion and a second dented portion respectively disposed on the first protruding portion including the plurality of positive electrodes and the first dented portion disposed between each positive electrode of the plurality of positive electrodes; and a negative electrode current collector layer including a third protruding portion and a third dented portion respectively disposed on the second protruding portion and the second dented portion of the electrolyte layer.

A stretchable electrode includes: a current collector; and, disposed on a surface of the current collector, a metal layer or an electrode active material layer, wherein the current collector includes a spiral-type coil spring and an elastic polymer, the spiral-type coil spring including a coil spring wound in a spiral pattern around a point, and wherein the elastic polymer is disposed in at least a portion of an inside of the coil spring, in at least a portion of a space between spiral coils of the spiral-type coil spring, or both.

A stretchable electrode includes: a current collector; and, disposed on a surface of the current collector, a metal layer or an electrode active material layer, wherein the current collector includes a spiral-type coil spring and an elastic polymer, the spiral-type coil spring including a coil spring wound in a spiral pattern around a point, and wherein the elastic polymer is disposed in at least a portion of an inside of the coil spring, in at least a portion of a space between spiral coils of the spiral-type coil spring, or both.

A lithium secondary battery comprises an electrode group and a nonaqueous electrolyte having lithium-ion conductivity. A negative electrode current collector has a first surface facing outward of winding of the electrode group and a second surface facing inward of the winding of the electrode group. At least the first surface or the second surface includes a first region and a second region that is closer to an innermost circumference of the winding of the electrode group than the first region. Protrusions include outer-circumference-side protrusions disposed on the first region and inner-circumference-side protrusions disposed on the second region. A first average height of the outer-circumference-side protrusions is smaller than a second average height of the inner-circumference-side protrusions.

A lithium secondary battery comprises an electrode group and a nonaqueous electrolyte having lithium-ion conductivity. A negative electrode current collector has a first surface facing outward of winding of the electrode group and a second surface facing inward of the winding of the electrode group. At least the first surface or the second surface includes a first region and a second region that is closer to an innermost circumference of the winding of the electrode group than the first region. Protrusions include outer-circumference-side protrusions disposed on the first region and inner-circumference-side protrusions disposed on the second region. A first average height of the outer-circumference-side protrusions is smaller than a second average height of the inner-circumference-side protrusions.

A flexible secondary battery includes an electrode support; a sheet-type internal electrode wound helically outside of the electrode support; a sheet-type first solid electrolyte layer wound helically outside of the internal electrode; a sheet-type bipolar electrode wound helically outside of the first solid electrolyte layer; a sheet-type second solid electrolyte layer wound helically outside of the bipolar electrode; and a sheet-type external electrode wound helically outside of the second solid electrolyte layer, wherein each of the first and second solid electrolyte layers include an organic solid electrolyte, the internal electrode is provided with insulation coating portions at both longitudinal ends of one surface facing the first solid electrolyte layer, the external electrode is provided with insulation coating portions at both longitudinal ends of one surface facing the second solid electrolyte layer, and the bipolar electrode is provided with insulation coating portions at both longitudinal ends of both surfaces.

A flexible secondary battery includes an electrode support; a sheet-type internal electrode wound helically outside of the electrode support; a sheet-type first solid electrolyte layer wound helically outside of the internal electrode; a sheet-type bipolar electrode wound helically outside of the first solid electrolyte layer; a sheet-type second solid electrolyte layer wound helically outside of the bipolar electrode; and a sheet-type external electrode wound helically outside of the second solid electrolyte layer, wherein each of the first and second solid electrolyte layers include an organic solid electrolyte, the internal electrode is provided with insulation coating portions at both longitudinal ends of one surface facing the first solid electrolyte layer, the external electrode is provided with insulation coating portions at both longitudinal ends of one surface facing the second solid electrolyte layer, and the bipolar electrode is provided with insulation coating portions at both longitudinal ends of both surfaces.

A thread battery that includes: a thread-like solid electrolyte that extends in a longitudinal direction between a first end and a second end that face each other in the longitudinal direction; a first electrode on a first part of an outer peripheral surface of the solid electrolyte along the longitudinal direction; a second electrode on a second part of the outer peripheral surface of the solid electrolyte along the longitudinal direction, wherein the first electrode and the second electrode do not contact each other; a first current collector on an outer peripheral surface of the first electrode along the longitudinal direction; and a second current collector on an outer peripheral surface of the second electrode along the longitudinal direction.

A battery cell, including a first electrode plate, a second electrode plate, and a separator located between the first electrode plate and the second electrode plate. The first electrode plate and the second electrode plate include a first current collector and a second current collector respectively, the first current collector includes a first uncoated region, and the second current collector includes a second uncoated region facing the first uncoated region. In a width direction of the battery cell, the first uncoated region and the second uncoated region are both located on lateral parts of the battery cell. The battery cell and a battery including the battery cell are capable of improving abuse performance of the battery cell and avoiding energy density loss.