A method for producing a microporous material comprising the steps of: providing an ultrahigh molecular weight polyethylene (UHMWPE); providing a filler; providing a processing plasticizer; adding the filler to the UHMWPE in a mixture being in the range of from about 1:9 to about 15:1 filler to UHMWPE by weight; adding the processing plasticizer to the mixture; extruding the mixture to form a sheet from the mixture; calendering the sheet; extracting the processing plasticizer from the sheet to produce a matrix comprising UHMWPE and the filler distributed throughout the matrix; stretching the microporous material in at least one direction to a stretch ratio of at least about 1.5 to produce a stretched microporous matrix; and subsequently calendering the stretched microporous matrix to produce a microporous material which exhibits improved physical and dimensional stability properties over the stretched microporous matrix.

Disclosed herein is a battery separator comprising two porous or microporous layers and a heat-resistant layer between the two porous or microporous layers. The heat-resistant layer may be a ceramic layer or a layer containing a high melt integrity polymer. In some embodiments, the battery separator may further comprise one or more adhesive layers between the two porous or microporous layers. The resulting battery separator may be safer, have more integrity, and/or have shutdown function.

Disclosed herein is a battery separator comprising two porous or microporous layers and a heat-resistant layer between the two porous or microporous layers. The heat-resistant layer may be a ceramic layer or a layer containing a high melt integrity polymer. In some embodiments, the battery separator may further comprise one or more adhesive layers between the two porous or microporous layers. The resulting battery separator may be safer, have more integrity, and/or have shutdown function.

A multilayer porous membrane with two exterior layers and at least one interior layer. The average pore size of the interior layer is greater than that of either of the two exterior layers. The multilayer porous membrane may be used, for example, as or as part of a battery separator. Compared to prior multilayer porous membranes for battery separators, the multilayer porous membrane herein may exhibit at least one of improved thermal properties, improved anti-metal contamination properties, improved ease of manufacture, and combinations thereof.

A multilayer porous membrane with two exterior layers and at least one interior layer. The average pore size of the interior layer is greater than that of either of the two exterior layers. The multilayer porous membrane may be used, for example, as or as part of a battery separator. Compared to prior multilayer porous membranes for battery separators, the multilayer porous membrane herein may exhibit at least one of improved thermal properties, improved anti-metal contamination properties, improved ease of manufacture, and combinations thereof.

Provided is an LDH-like compound separator including a porous substrate made of a polymeric material; and a layered double hydroxide (LDH)-like compound with which pores of the porous substrate are plugged. A central region along the thickness of the LDH-like compound separator has a lower mean porosity than peripheral regions along the thickness of the LDH-like compound separator.

Provided is an LDH-like compound separator including a porous substrate made of a polymeric material; and a layered double hydroxide (LDH)-like compound with which pores of the porous substrate are plugged. A central region along the thickness of the LDH-like compound separator has a lower mean porosity than peripheral regions along the thickness of the LDH-like compound separator.

This application discloses a secondary battery and a device containing the secondary battery. A positive active material of the secondary battery includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and a modified material thereof. A negative active material of the secondary battery includes a silicon-oxygen compound and graphite. A separator of the secondary battery includes a substrate and a coating layer. The secondary battery satisfies:

[00001]$7.5\le \frac{3460}{ED}-\left(D50-D_{C}50\times 0.75-\frac{T}{18}\right)\le 11.5,$

where ED≥270 Wh/Kg, 11 μm≤D50≤18.5 μm, 11 μm≤D.sub.C50≤20 μm. The secondary battery according to this application achieves relatively high cycle performance while achieving a relatively high energy density concurrently.

This application discloses a secondary battery and a device containing the secondary battery. A positive active material of the secondary battery includes one or more of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and a modified material thereof. A negative active material of the secondary battery includes a silicon-oxygen compound and graphite. A separator of the secondary battery includes a substrate and a coating layer. The secondary battery satisfies:

[00001]$7.5\le \frac{3460}{ED}-\left(D50-D_{C}50\times 0.75-\frac{T}{18}\right)\le 11.5,$

where ED≥270 Wh/Kg, 11 μm≤D50≤18.5 μm, 11 μm≤D.sub.C50≤20 μm. The secondary battery according to this application achieves relatively high cycle performance while achieving a relatively high energy density concurrently.

A secondary battery includes an electrode body, a battery case, and an electrode terminal. The electrode body has a foil collecting portion. The electrode terminal corresponding to at least one of a positive electrode and a negative electrode is electrically connected to the foil collecting portion via a current collector terminal. The current collector terminal is joined to the foil collecting portion. The foil collecting portion has a joining mark composed of a plurality of recesses on a surface on an opposite side of the foil collecting portion from a surface joined to the current collector terminal. The joining mark has two corners on an inner side of the electrode body and two corners on an outer side of the electrode body, and only the two corners on the inner side of the electrode body have a chamfered shape.