An electrochemical device, including a positive electrode. The positive electrode includes a positive current collector and a positive active material layer. The positive active material layer includes particles A and particles B. A circularity of a particle A is R.sub.A, a cross-sectional area of the particle A is S.sub.A, a circularity of a particle B is R.sub.B, a cross-sectional area of the particle B is S.sub.B, where R.sub.B<0.4≤R.sub.A and S.sub.B<20 μm.sup.2≤S.sub.A. Based on a total area of a cross section of the positive electrode in a direction perpendicular to the positive current collector, a ratio of a total area percent of the particles A to a total area percent of the particles B is 1:9 to 8:2. The electrochemical device exhibits excellent electrochemical performance, especially reduces the amount of generated gas and improves cycle stability of the electrochemical device.

A solid electrolyte material according to the present disclosure includes Li, DC, Y, Sm, and X. The DC is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn. The X is at least one selected from the group consisting of F, Cl, Br, and I. A battery according to the present disclosure includes a positive electrode, a negative electrode, and an electrolyte layer provided between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer includes the solid electrolyte material according to the present disclosure.

A solid electrolyte material according to the present disclosure includes Li, DC, Y, Sm, and X. The DC is at least one selected from the group consisting of Mg, Ca, Sr, Ba, and Zn. The X is at least one selected from the group consisting of F, Cl, Br, and I. A battery according to the present disclosure includes a positive electrode, a negative electrode, and an electrolyte layer provided between the positive electrode and the negative electrode. At least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer includes the solid electrolyte material according to the present disclosure.

There is provided a sulfide solid electrolyte containing elemental lithium (Li), elemental phosphorus (P), elemental sulfur (S), and an elemental halogen (X). The mole ratio of the elemental lithium (Li) to the elemental phosphorus (P), Li/P, satisfies 3.7<Li/P<5.4. The mole ratio of the elemental sulfur (S) to the elemental phosphorus (P), S/P, satisfies 3.9<S/P<4.1. The mole ratio of the elemental halogen (X) to the elemental phosphorus (P), X/P, satisfies 0.7<X/P<2.4. The sulfide solid electrolyte includes a crystalline phase having an argyrodite-type crystal structure.

There is provided a sulfide solid electrolyte containing elemental lithium (Li), elemental phosphorus (P), elemental sulfur (S), and an elemental halogen (X). The mole ratio of the elemental lithium (Li) to the elemental phosphorus (P), Li/P, satisfies 3.7<Li/P<5.4. The mole ratio of the elemental sulfur (S) to the elemental phosphorus (P), S/P, satisfies 3.9<S/P<4.1. The mole ratio of the elemental halogen (X) to the elemental phosphorus (P), X/P, satisfies 0.7<X/P<2.4. The sulfide solid electrolyte includes a crystalline phase having an argyrodite-type crystal structure.

An electrochemical device includes electrode plates and a separation layer formed on a surface of an electrode plate. The separation layer includes a porous layer formed on the surface of the electrode plate. The porous layer includes nanofibers. It takes 15 seconds or less for an electrolytic solution to infiltrate into the separation layer. The separation layer exhibits functions of a separator. Therefore, the electrochemical device achieves at least a relatively high energy density without using a stand-alone separator.

An electrochemical device includes electrode plates and a separation layer formed on a surface of an electrode plate. The separation layer includes a porous layer formed on the surface of the electrode plate. The porous layer includes nanofibers. It takes 15 seconds or less for an electrolytic solution to infiltrate into the separation layer. The separation layer exhibits functions of a separator. Therefore, the electrochemical device achieves at least a relatively high energy density without using a stand-alone separator.

A battery cell, comprising a first electrode plate, an separator and a second electrode plate, the first electrode plate, the separator and the second electrode plate are stacked in sequence along a first direction, the battery cell also includes a first side surface and a second side surface which are disposed along the first direction and adjacent to each other, the first side surface and the second side surface are connected through a first connection region, the battery cell further includes an adhesive film, and the adhesive film is disposed in the first connection region, and is bonded to the first electrode plate, the separator and the second electrode plate, thereby improving safety of the battery cell.

There is provided an inorganic solid electrolyte-containing inorganic solid electrolyte-containing composition, a dispersion medium, and a polymer binder, where a component constituting the polymer binder contains a soluble polymer having a combination of specific functional groups or partial structures. There are also provided a sheet for an all-solid state secondary battery and an all-solid state secondary battery, in which this inorganic solid electrolyte-containing composition is used, as well as manufacturing methods for a sheet for an all-solid state secondary battery, and an all-solid state secondary battery.

A negative electrode plate includes: a current collector; and a negative electrode framework located on the current collector, where the negative electrode framework includes at least a first negative electrode framework layer and a second negative electrode framework layer, the first negative electrode framework layer is located between the current collector and the second negative electrode framework layer, and a porosity of the first negative electrode framework layer is higher than a porosity of the second negative electrode framework layer. With this design, side reactions between lithium metal and an electrolyte can be reduced, formation of lithium dendrites can be inhibited, and drastic swelling and contraction of the negative electrode plate in volume due to intercalation and deintercalation of lithium ions can be greatly alleviated or even eliminated, thereby improving safety and stability of the electrochemical apparatus.