An anode for a secondary battery including an anode active material and a secondary battery including the anode and having improved stability and reduced resistance are disclosed. In an aspect, the anode active material includes a silicon-based active material having a specific surface area (BET) in a range from 0.5 m.sup.2/g to 5 m.sup.2/g, a first carbon-based active material having an average particle diameter (D50) in a range from 1 μm to 4 μm, and a second carbon-based active material having an average particle diameter greater than that of the first carbon-based active material.

Composites comprising an exfoliated graphite support material having a degree of graphitization g in an range of 50 to 93%, obtained by XRD Rietveld analysis, which is coated with ZnO nanoparticles. These composites are produced by three different methods: A) (syn) the method comprises the following consecutive steps: i) a Zn(II)salt is dissolved in a solvent ii) graphite and a base are added simultaneously iii) the mixture is stirred under impact of ultrasound iv) the solvent is removed from the suspension or B) (pre) the method comprises the following consecutive steps: i) graphite is suspended in a solvent and exfoliated via impact of ultrasound ii) a Zn(II)salt and a base are added simultaneously forming nano-ZnO particles iii) the mixture is stirred iv) the solvent is removed from the suspension or C) (post) the method comprises the following steps: i) a Zn(II)salt and a base are mixed in a solvent in a first reactor forming nano-ZnO particles ii) graphite is exfoliated via impact of ultrasound in a second reactor iii) both suspensions of i) and ii) are mixed together iv) after step iii) the solvent is removed from the suspension. These coated composites may be tempered in a further step and again coated and again tempered.

A negative electrode active material containing a negative electrode active material particle which includes a silicon compound particle containing a silicon compound (SiO.sub.x: 0.5≤x≤1.6). The silicon compound particle has three or more peaks in a chemical shift value ranging from −40 ppm to −120 ppm but has no peak in a chemical shift value within a range of −65±3 ppm in a spectrum obtained from .sup.29Si-MAS-NMR of the silicon compound particle. This provides a negative electrode active material capable of improving cycle characteristics when it is used as a negative electrode active material for a secondary battery.

A nonaqueous electrolyte secondary battery includes a positive electrode, a nonaqueous electrolytic solution, and a negative electrode. The negative electrode includes a negative electrode current collector and a negative electrode active material layer which is formed on the negative electrode current collector. The negative electrode active material layer has a first region and a second region. The first region is a region formed on a surface of the negative electrode current collector and contains lithium titanium composite oxide as a major component. The second region is a region including a surface of the negative electrode active material layer and contains lithium titanium composite oxide as a major component and further contains silicon oxide.

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 method for manufacturing a nonaqueous electrolyte secondary battery according to an embodiment of the present invention is a method for manufacturing a nonaqueous electrolyte secondary battery including a positive electrode plate and a negative electrode plate provided with a negative electrode mixture layer containing graphite and a silicon material and includes a step of applying positive electrode mixture slurry containing a lithium-transition metal composite oxide and polyvinylidene fluoride to a positive electrode current collector, a step of forming a positive electrode mixture layer by drying the positive electrode mixture slurry, and a step of heat-treating the positive electrode mixture layer. The temperature of heat treatment is preferably 160° C. to 350° C.

This disclosure relates to an SO.sub.2-based electrolyte for a rechargeable battery cell containing at least one conducting salt of the Formula (I) ##STR00001##
wherein M is a metal selected from the group consisting of alkali metals, alkaline earth metals, metals of group 12 of the periodic table of the elements and aluminum; x is an integer from 1 to 3; the substituents R, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from the group consisting of C.sub.1-C.sub.10 alkyl, C.sub.2-C.sub.1 alkenyl, C.sub.2-C.sub.1 alkynyl, C.sub.3-C.sub.10 cycloalkyl, C.sub.6-C.sub.14 aryl, and C.sub.5-C.sub.14 heteroaryl; and Z is aluminum or boron.

The present invention provides an anode active material and a method for preparing the same, wherein the anode active material has a core-shell structure having formula (MOx-Liy)-C (here, M is a metal (or metalloid), x is greater than 0 and less than 1.5, and y is greater than 0 and less than 4) and including a core part containing an alloy of a metal (or metalloid) oxide-Li (MOx-Liy) and a shell part containing a carbon material coated on a surface of the core part, wherein the shell part contains lithium in an amount less than 5 atm % in the surface and the inner portion thereof. The anode active material can provide high capacity, excellent cycle characteristics, excellent volume expansion control capability, and high initial efficiency.

An embodiment of the present invention relates to a silicon-based carbon composite, a preparation method therefor, and an anode active material for a lithium secondary battery, comprising same, and, more specifically, the silicon-based carbon composite of the present invention is a silicon-based carbon composite having a core-shell structure, wherein the core comprises silicon, silicon oxide compound and magnesium silicate, the shell comprises at least two carbon layers comprising a first carbon layer and a second carbon layer, and the second carbon layer is reduced graphene oxide, and thus, during application of the silicon-based carbon composite to an anode active material for a secondary battery, the charge/discharge capacity, initial charge/discharge efficiency and capacity retention of the secondary battery can be improved.

A non-aqueous electrolyte secondary battery according to an aspect of the present disclosure is provided with a negative electrode having: a negative electrode collector: a first negative electrode mixture layer provided on the surface of the negative electrode collector; and a second negative electrode mixture layer provided on the surface of the first negative electrode mixture layer. Each of the first negative electrode mixture layer and the second negative electrode mixture layer contains graphite particles. The ratio (S2/S1) of the inter-particle porosity (S2) of the graphite particles in the second negative electrode mixture layer to the inter-particle porosity (S1) of the graphite particles in the first negative electrode mixture layer is 1.1-2.0. The ratio (D2/D1) of the filling density (D2) of the second negative electrode mixture layer to the filling density (D1) of the first negative electrode mixture layer is 0.9-1.1.