A secondary battery in which heat resistance is excellent and the formation of lithium dendrite is suppressed is provided. The present invention relates to a secondary battery comprising an electrode element comprising a positive electrode, a negative electrode and a separator, wherein the negative electrode comprises a carbon material (a) capable of absorbing and desorbing lithium ions and an oxide (b) capable of absorbing and desorbing lithium ions, and the separator comprises 50% by mass or more of a non-woven fabric having a thermal melting or thermal decomposition temperature of 160° C. or more.

A rechargeable lithium battery including an electrode assembly includes a positive electrode including a positive current collector and a positive active material layer disposed on the positive current collector; a negative electrode including a negative current collector, a negative active material layer disposed on the negative current collector, and a negative electrode functional layer disposed on the negative active material layer; and a separator, wherein the positive active material layer includes a first positive active material including at least one of a composite oxide of metal selected from cobalt, manganese, nickel, and a combination thereof and lithium and a second positive active material including a compound represented by Chemical Formula 1, the negative electrode functional layer includes flake-shaped polyethylene particles, and a battery capacity is greater than or equal to about 3.5 Ah.
Li.sub.aFe.sub.1−x1M.sub.x1PO.sub.4  [Chemical Formula 1] In Chemical Formula 1, 0.90≤a≤1.8, 0≤x1≤0.7, and M is Mn, Co, Ni, or a combination thereof.

The present invention relates to a separator for a secondary battery which is capable of improving a shut-down function of a cellulose-based multilayer separator physically having high strength. The separator for a secondary battery comprises a substrate formed of cellulose-based nanofibers and polyethylene nanoparticles; and a resin layer stacked on one surface or both surfaces of the substrate, the resin being formed from a polyolefin.

A method of making a reference electrode assembly for an electrochemical cell according to various aspects of the present disclosure includes providing a subassembly including a separator layer and a current collector layer coupled to the separator layer. The method further includes providing an electrode ink including an electroactive material, a binder, and a solvent. The method further includes creating a reference electrode precursor by applying an electroactive precursor layer to the current collector layer. The electroactive precursor layer covers greater than or equal to about 90% of a superficial surface area of a surface of the current collector layer. The electroactive precursor layer includes the electrode ink. The method further includes creating the reference electrode assembly by drying the electroactive precursor layer to remove at least a portion of the solvent, thereby forming an electroactive layer. The electroactive layer is solid and porous.

The use of ion-conducting materials to protect electrodes is generally described. The ion-conducting material may be in the form of a layer that is adjacent to a polymeric layer, such as a porous separator, to form a composite. At least a portion of the pores of the polymer layer may be filled or unfilled with the ion-conducting material. In some embodiments, the ion-conducting layer is sufficiently bonded to the polymer layer to prevent delamination of the layers during cycling of an electrochemical cell.

The use of ion-conducting materials to protect electrodes is generally described. The ion-conducting material may be in the form of a layer that is adjacent to a polymeric layer, such as a porous separator, to form a composite. At least a portion of the pores of the polymer layer may be filled or unfilled with the ion-conducting material. In some embodiments, the ion-conducting layer is sufficiently bonded to the polymer layer to prevent delamination of the layers during cycling of an electrochemical cell.

Novel or improved microporous single or multilayer battery separator membranes, separators, batteries including such membranes or separators, methods of making such membranes, separators, and/or batteries, and/or methods of using such membranes, separators and/or batteries are provided. In accordance with at least certain embodiments, a multilayer dry process polyethylene/polypropylene/polyethylene microporous separator which is manufactured using the inventive process which includes machine direction stretching followed by transverse direction stretching and a subsequent calendaring step as a means to reduce the thickness of the multilayer microporous membrane, to reduce the percent porosity of the multilayer microporous membrane in a controlled manner and/or to improve transverse direction tensile strength. In a very particular embodiment, the inventive process produces a thin multilayer microporous membrane that is easily coated with polymeric-ceramic coatings, has excellent mechanical strength properties due to its polypropylene layer or layers and a thermal shutdown function due to its polyethylene layer or layers. The ratio of the thickness of the polypropylene and polyethylene layers in the inventive multilayer microporous membrane can be tailored to balance mechanical strength and thermal shutdown properties.

Novel or improved microporous single or multilayer battery separator membranes, separators, batteries including such membranes or separators, methods of making such membranes, separators, and/or batteries, and/or methods of using such membranes, separators and/or batteries are provided. In accordance with at least certain embodiments, a multilayer dry process polyethylene/polypropylene/polyethylene microporous separator which is manufactured using the inventive process which includes machine direction stretching followed by transverse direction stretching and a subsequent calendaring step as a means to reduce the thickness of the multilayer microporous membrane, to reduce the percent porosity of the multilayer microporous membrane in a controlled manner and/or to improve transverse direction tensile strength. In a very particular embodiment, the inventive process produces a thin multilayer microporous membrane that is easily coated with polymeric-ceramic coatings, has excellent mechanical strength properties due to its polypropylene layer or layers and a thermal shutdown function due to its polyethylene layer or layers. The ratio of the thickness of the polypropylene and polyethylene layers in the inventive multilayer microporous membrane can be tailored to balance mechanical strength and thermal shutdown properties.

Described herein is a multilayer microporous film or membrane that may exhibit improved properties, including improved dielectric break down and strength, compared to prior monolayer or tri-layer microporous membranes of the same thickness. The preferred multilayer microporous membrane comprises microlayers and one or more lamination barriers. Also disclosed is a battery separator or battery comprising one or more of the multilayer microporous films or membranes. The inventive battery and battery separator is preferably safer and more robust than batteries and battery separators using prior monolayer and tri-layer microporous membranes. Also, described herein is a method for making the multilayer microporous separators, membranes or films described herein.

Described herein is a multilayer microporous film or membrane that may exhibit improved properties, including improved dielectric break down and strength, compared to prior monolayer or tri-layer microporous membranes of the same thickness. The preferred multilayer microporous membrane comprises microlayers and one or more lamination barriers. Also disclosed is a battery separator or battery comprising one or more of the multilayer microporous films or membranes. The inventive battery and battery separator is preferably safer and more robust than batteries and battery separators using prior monolayer and tri-layer microporous membranes. Also, described herein is a method for making the multilayer microporous separators, membranes or films described herein.