A nonaqueous electrolyte secondary battery that is an aspect of the present disclosure comprises a positive electrode, a negative electrode, and a nonaqueous electrolyte solution. The negative electrode comprises a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector. The negative electrode active material layer contains graphite particles A and graphite particles B as negative electrode active materials. The graphite particles A have an internal void ratio of 5% or less. The graphite particles B have an internal void ratio of 8-20%. When the negative electrode active material layer is divided in half in the thickness direction, the region of the half to the side of the outer surface contains more graphite particles A than the region of the half to the side of the negative electrode current collector.

A solid-state battery that includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer, where the negative electrode layer includes a conductive additive containing a metal material having an elongated shape in a section view at 7% to 28% in area ratio with respect to the negative electrode layer.

A lithium secondary battery pack of the present invention includes: a lithium secondary battery including an electrode body formed of a positive electrode and a negative electrode facing each other and a separator interposed therebetween, and a non-aqueous electrolyte; a PTC element; and a protection circuit including a field effect transistor. The lithium secondary battery has an energy density per volume of 450 Wh/L or more, the lithium secondary battery has a current density of 3.0 mA/cm.sup.2 or less, and a relational expression (1) and a relational expression (2) below are established where A (mΩ) is an impedance of the lithium secondary battery and B (mΩ) is an impedance of the entire circuit unit of the lithium secondary battery pack excepting the impedance A (mΩ) of the lithium secondary battery:
A≤50 mΩ  (1)
B/A≤1  (2).

Electrodes are formed with a porous layer of particulate electrode material bonded to each of the two major sides of a compatible metal current collector. In one embodiment, opposing electrodes are formed with like lithium-ion battery anode materials or like cathode materials or capacitor materials on both sides of the current collector. In another embodiment, a battery electrode material is applied to one side of a current collector and capacitor material is applied to the other side. In general, the electrodes are formed by combining a suitable grouping of capacitor layers with un-equal numbers of anode and cathode battery layers. One or more pairs of opposing electrodes are assembled to provide a combination of battery and capacitor energy and power properties in a hybrid electrochemical cell. The cells may be formed by stacking or winding rolls of the opposing electrodes with interposed separators.

A nonaqueous electrolyte secondary battery according to one embodiment of the present disclosure comprises a positive electrode, a negative electrode and a nonaqueous electrolyte solution; the negative electrode comprises a negative electrode collector and a negative electrode active material layer that is provided on the negative electrode collector; the negative electrode active material layer contains, as negative electrode active materials, graphite particles A and graphite particles B; the graphite particles A have an internal void fraction of 5% or less; the graphite particles B have an internal void fraction of from 8% to 20%; if the negative electrode active material layer is halved in the thickness direction, a region on the half closer to the outer surface contains more graphite particles A than a region on the half closer to the negative electrode collector.

A secondary battery is provided including an electrode wound body housed in a battery can, with the electrode wound body having a structure including a band-shaped positive electrode and a band-shaped negative electrode laminated and wound with a separator interposed therebetween, where the positive electrode includes a positive electrode active material layer on both sides of a band-shaped positive electrode foil, the negative electrode includes a negative electrode active material layer on both sides of a band-shaped negative electrode foil, the electrode wound body includes a positive electrode tab at a central part of the positive electrode, includes a negative electrode tab on a winding end side of the negative electrode, and includes a foil tab in a flat plate shape on a winding start side of either one or both of the positive electrode and the negative electrode.

A negative electrode plate includes a current collector and an active substance layer provided on the current collector, where the active substance layer includes a silicon-based material, and a proportion by mass of element silicon in the active substance layer has a minimum value X1 and a maximum value X2 among different locations of a same area size, where a value of X1/X2 is M, and M≥0.7; and a weight loss rate of the active substance layer under thermogravimetric (TG) analysis within 800° C. has a minimum value Y1 and a maximum value Y2 among different locations of a same area size, where a value of Y1/Y2 is N, and N≥0.7. In this disclosure, the silicon-based material and a binder in the active substance layer are uniformly dispersed, improving C-rate performance and cycling performance of the electrochemical apparatus and reducing swelling of an electrode assembly.

The present invention relates to a negative electrode for a secondary battery which comprises a negative electrode collector, a negative electrode active material layer formed on the negative electrode collector, and a lithium metal layer, wherein an adhesive layer is disposed between the negative electrode active material layer and the lithium metal layer, and the lithium metal layer comprises lithium and metal oxide in a weight ratio of 50:50 to 99:1.

A negative electrode material for a secondary battery includes a matrix containing silicon oxide, a composite oxide of one or more doping elements selected from an alkali metal, an alkaline earth metal, and a post-transition metal, and silicon, or a mixture thereof; and silicon nanoparticles dispersed and embedded in the matrix.

A negative electrode for a lithium secondary battery, a method for preparing a negative electrode for a lithium secondary battery, and a lithium secondary battery including the negative electrode. The negative electrode for a lithium secondary battery includes a negative electrode current collector layer, a first negative electrode active material layer on one surface or both surfaces of the negative electrode current collector layer, and a second negative electrode active material layer on a surface opposite to a surface of the first negative electrode