Embodiments of this application provide a battery separator, including a polyolefin-based porous separator, where the polyolefin-based porous separator includes polyethylene resin, an elongation rate of the polyolefin-based porous separator in an MD direction is greater than 120%, an elongation rate in a TD direction is greater than 120%, and for the polyolefin-based porous separator, crystallinity at a first-time temperature rise of polyethylene that is measured by using a differential scanning calorimeter is less than 65%, crystallinity at a second-time temperature rise is less than 55%, and a difference between the crystallinity at the first-time temperature rise and the crystallinity at the second-time temperature rise is less than 12%. The battery separator features a high elongation rate and a low temperature of closing a pore.

A separator for a secondary battery, including a porous polymer substrate; a porous coating layer on at least one surface of the porous polymer substrate. The porous coating layer includes a plurality of inorganic particles and a first binder polymer that interconnects and fixes the inorganic particles; and an adhesive layer on a surface of the porous coating layer opposite to the porous polymer substrate. The adhesive layer includes a second binder polymer, and the adhesive layer includes a first layer in contact with the surface of the porous coating layer opposite to the porous polymer substrate, and a second layer integrated with the first layer and the second layer faces an electrode. The second layer has an average pore size larger than the average pore size of the first layer. The separator for a secondary battery can improve the problem related with resistance, while ensuring adhesion to an electrode.

A separator for a secondary battery, including a porous polymer substrate; a porous coating layer on at least one surface of the porous polymer substrate. The porous coating layer includes a plurality of inorganic particles and a first binder polymer that interconnects and fixes the inorganic particles; and an adhesive layer on a surface of the porous coating layer opposite to the porous polymer substrate. The adhesive layer includes a second binder polymer, and the adhesive layer includes a first layer in contact with the surface of the porous coating layer opposite to the porous polymer substrate, and a second layer integrated with the first layer and the second layer faces an electrode. The second layer has an average pore size larger than the average pore size of the first layer. The separator for a secondary battery can improve the problem related with resistance, while ensuring adhesion to an electrode.

A negative electrode for a lithium secondary battery, a lithium secondary battery including the negative electrode, and a method for manufacturing the lithium secondary battery, where the negative electrode includes a negative electrode current collector; and a negative electrode active material layer on at least one surface of the negative electrode current collector. The negative electrode active material layer includes a Si-containing negative electrode active material, a conductive material and a first binder polymer. The Si-containing negative electrode active material has cracks formed after activation, and a second binder polymer is present in the cracks. The first binder polymer and the second binder polymer are heterogeneous (e.g., different from each other). The lithium secondary battery shows improved life characteristics.

A negative electrode for a lithium secondary battery, a lithium secondary battery including the negative electrode, and a method for manufacturing the lithium secondary battery, where the negative electrode includes a negative electrode current collector; and a negative electrode active material layer on at least one surface of the negative electrode current collector. The negative electrode active material layer includes a Si-containing negative electrode active material, a conductive material and a first binder polymer. The Si-containing negative electrode active material has cracks formed after activation, and a second binder polymer is present in the cracks. The first binder polymer and the second binder polymer are heterogeneous (e.g., different from each other). The lithium secondary battery shows improved life characteristics.

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 calendering 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.

An energy storage device according to one aspect of the present invention includes: a negative electrode including a negative electrode substrate and a negative active material layer layered directly or indirectly on a surface of the negative electrode substrate; and a positive electrode. The negative active material layer contains a negative active material. The negative active material contains non-graphitizable carbon. In one direction of the negative electrode substrate, at least one end edge side of the negative active material layer is thicker than a central portion present between the one end edge side and the other end edge side facing the one end edge side. When a true density of the non-graphitizable carbon is A [g/cm.sup.3], an amount of charge B [mAh/g] of the negative electrode in a fully charged state satisfies the following formula 1.

[1]$-173\text{XA+1588}\le \text{B}\le \text{-830A+1800}$

An energy storage device according to one aspect of the present invention includes: a negative electrode including a negative electrode substrate and a negative active material layer layered directly or indirectly on a surface of the negative electrode substrate; and a positive electrode. The negative active material layer contains a negative active material. The negative active material contains non-graphitizable carbon. In one direction of the negative electrode substrate, at least one end edge side of the negative active material layer is thicker than a central portion present between the one end edge side and the other end edge side facing the one end edge side. When a true density of the non-graphitizable carbon is A [g/cm.sup.3], an amount of charge B [mAh/g] of the negative electrode in a fully charged state satisfies the following formula 1.

[1]$-173\text{XA+1588}\le \text{B}\le \text{-830A+1800}$

An electrochemical device which includes an electrode plate and a porous layer formed on a surface of the electrode plate. The porous layer includes nanofibers and inorganic particles. The nanofibers and the inorganic particles are bonded together by a crosslinker. In addition, an electronic device, which includes this electrochemical device.

An electrochemical device which includes an electrode plate and a porous layer formed on a surface of the electrode plate. The porous layer includes nanofibers and inorganic particles. The nanofibers and the inorganic particles are bonded together by a crosslinker. In addition, an electronic device, which includes this electrochemical device.