A first electrode current collector is joined to a multilayer of a positive electrode core in a part including no positive electrode active material layer of the first electrode core, by ultrasonic welding in a joint area. The joint area, at which the multilayers of the first electrode core where the first electrode cores are stacked is joined to the first electrode current collector by ultrasonic welding, includes a plurality of core recesses. A core projection is formed between each adjacent pair of the plurality of core recesses of the multilayer of the first electrode core with the first electrode core flexed in a convex shape. A gap in an arc shape is formed between the adjacent pair of the layers of the first electrode core forming the core projection. The gap has a length decreasing from an apex to a bottom of the core projection.

A negative electrode material includes a composite of a silicon-based material (1), a polymer (2), and carbon nanotubes (3), where the polymer (2) contains a first group and a second group, the first group is chemically bonded to the carbon nanotubes (3), and the second group is chemically bonded to the silicon-based material (1). Both the carbon nanotubes (3) and the polymer (2) containing two groups are applied to surfaces of particles of the silicon-based material (1). The two groups of the polymer (2) are chemically bonded to the silicon-based material (1) and the carbon nanotubes (3) respectively, so that bonding force between the silicon-based material (1) and the carbon nanotubes (3) is enhanced and a uniform carbon nanotube (3) coating layer is formed. This can significantly improve conductive performance of the silicon-based material (1), thereby improving cycling performance and rate performance of an electrochemical apparatus.

A porous titanium-based sintered body, having a porosity of 45% to 65%, an average pore diameter of 5 μm to 15 μm, and a bending strength of 100 MPa or more. According to the present invention, a porous titanium-based sintered body having good pore diameter and porosity that are compatible with each other and having a high strength can be provided.

A porous titanium-based sintered body, having a porosity of 45% to 65%, an average pore diameter of 5 μm to 15 μm, and a bending strength of 100 MPa or more. According to the present invention, a porous titanium-based sintered body having good pore diameter and porosity that are compatible with each other and having a high strength can be provided.

A battery module including: a battery stack of battery cells having opposite ends to which a plurality of electrode tabs are connected; end-side bus bar assemblies formed at opposite ends of the battery stack, respectively, and electrically connecting the electrode tabs of the battery cells; and a case accommodating the battery stack and the end-side bus bar assemblies.

A lithium secondary battery includes: a metal anode capable of being doped and dedoped with lithium ions; a cathode capable of being doped and dedoped with the lithium ions; and an electrolyte disposed between the metal anode and the cathode, in which the metal anode has a plate shape, and is composed of lithium and a base material in which the lithium is solid-dissolved, the metal anode in a discharged state has a layer of a substitutional solid solution, the substitutional solid solution has a structure in which a part of a crystal lattice of a metal constituting the base material is substituted with the lithium, and the layer is located on a surface of the metal anode opposite to a surface facing the cathode or inside the metal anode.

A lithium secondary battery includes: a metal anode capable of being doped and dedoped with lithium ions; a cathode capable of being doped and dedoped with the lithium ions; and an electrolyte disposed between the metal anode and the cathode, in which the metal anode has a plate shape, and is composed of lithium and a base material in which the lithium is solid-dissolved, the metal anode in a discharged state has a layer of a substitutional solid solution, the substitutional solid solution has a structure in which a part of a crystal lattice of a metal constituting the base material is substituted with the lithium, and the layer is located on a surface of the metal anode opposite to a surface facing the cathode or inside the metal anode.

Additives for energy storage devices comprising nitrogen-containing compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, where at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, and an electrolyte composition. Nitrogen-containing compounds may serve as additives to the first electrode, the second electrode, and/or the electrolyte, as well as the separator.

Additives for energy storage devices comprising nitrogen-containing compounds are disclosed. The energy storage device comprises a first electrode and a second electrode, where at least one of the first electrode and the second electrode is a Si-based electrode, a separator between the first electrode and the second electrode, and an electrolyte composition. Nitrogen-containing compounds may serve as additives to the first electrode, the second electrode, and/or the electrolyte, as well as the separator.

Provided are methods for solid state pretreatment of active materials (e.g., prelithiation of silicon monoxide) while forming treated negative active material structures. Also provided are the formed structures, negative electrodes comprising these structures, and electrochemical cells comprising these electrodes. In some examples, silicon monoxide structures are mixed with lithium hydroxide structures or some other lithium-containing structures. The mixture is heated in an inert environment to form treated negative active material structures. These treated structures comprise various lithium-containing components, some of which trap lithium. When an electrochemical cell, formed with these treated negative active material structures, is initially charged and additional new lithium ions are introduced into the negative electrodes (e.g., from the positive electrode), a larger portion of these new lithium ions forms reversible components (rather than irreversible components) in the negative electrode than, for example, in a conventional cell without any such treatment.