A cathode active material for a lithium secondary battery is provided which comprises a first region and a second region. The first region is represented by Chemical Formula1 wherein M1, M2 and M3 are constant: Li.sub.a1M1.sub.x1M2.sub.y1M3.sub.z1O.sub.2+. The second region is formed around the first regions and is represented by Chemical Formula 2 Li.sub.a2M1.sub.x2M2.sub.y2M3.sub.z2M4.sub.wO.sub.2+. The concentrations of M1, M2 and M3 are changed from Chemical Formula 1. In both Chemical Formula 1 and 2, M1, M2 and M3 is selected from a group including Ni, Co, Mn and combinations thereof, M4 is selected from a group including Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B and combinations thereof, 0<a11.1, 0<a21.1, 0x11, 0x21, 0y11, 0y21, 0z11, 0z21, 0<w0.1, 0.00.02, 0<x1+y1+z11, 0<x2+y2+z21.

A cathode active material for a lithium secondary battery is provided which comprises a first region and a second region. The first region is represented by Chemical Formula1 wherein M1, M2 and M3 are constant: Li.sub.a1M1.sub.x1M2.sub.y1M3.sub.z1O.sub.2+. The second region is formed around the first regions and is represented by Chemical Formula 2 Li.sub.a2M1.sub.x2M2.sub.y2M3.sub.z2M4.sub.wO.sub.2+. The concentrations of M1, M2 and M3 are changed from Chemical Formula 1. In both Chemical Formula 1 and 2, M1, M2 and M3 is selected from a group including Ni, Co, Mn and combinations thereof, M4 is selected from a group including Fe, Na, Mg, Ca, Ti, V, Cr, Cu, Zn, Ge, Sr, Ag, Ba, Zr, Nb, Mo, Al, Ga, B and combinations thereof, 0<a11.1, 0<a21.1, 0x11, 0x21, 0y11, 0y21, 0z11, 0z21, 0<w0.1, 0.00.02, 0<x1+y1+z11, 0<x2+y2+z21.

A lithium secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, and more particularly, the positive electrode includes a positive active material including lithium-metal oxide in which at least one metal has a continuous concentration gradient from the center to the surface, and the negative electrode includes a negative active material including graphite having an average lattice distance (d.sub.002) in the range of 3.356 to 3.365 , thereby improving storage characteristics at a high temperature and lifetime characteristics.

A lithium secondary battery includes a positive electrode, a negative electrode, and a non-aqueous electrolyte, and more particularly, the positive electrode includes a positive active material including lithium-metal oxide in which at least one metal has a continuous concentration gradient from the center to the surface, and the negative electrode includes a negative active material including graphite having an average lattice distance (d.sub.002) in the range of 3.356 to 3.365 , thereby improving storage characteristics at a high temperature and lifetime characteristics.

In some examples, a primary battery comprising a cathode comprising at least one active material and at least one of a metal oxide and metal fluoride, wherein the active material exhibits a first discharge capacity and the at least one of metal oxide and metal fluoride exhibits a second discharge capacity at a voltage lower than the first discharge capacity; an anode comprising a metal as an electron source; and an electrolyte between the cathode and anode. The metal reacts with the electrolyte below a third discharge capacity at a voltage lower than the second discharge capacity to form a gas, where the metal reacts with the active material at the first discharge capacity, and, following the consumption of the active material of the cathode, the metal reacts with the at least one of metal oxide and metal fluoride of the cathode prior to reacting with the electrolyte below the third discharge capacity.

In some examples, a primary battery comprising a cathode comprising at least one active material and at least one of a metal oxide and metal fluoride, wherein the active material exhibits a first discharge capacity and the at least one of metal oxide and metal fluoride exhibits a second discharge capacity at a voltage lower than the first discharge capacity; an anode comprising a metal as an electron source; and an electrolyte between the cathode and anode. The metal reacts with the electrolyte below a third discharge capacity at a voltage lower than the second discharge capacity to form a gas, where the metal reacts with the active material at the first discharge capacity, and, following the consumption of the active material of the cathode, the metal reacts with the at least one of metal oxide and metal fluoride of the cathode prior to reacting with the electrolyte below the third discharge capacity.

A method for producing a silver nanoparticle dispersion according to the present invention includes the steps of mixing an amine compound, a resin, and a silver salt to yield a complex compound; and heating and decomposing the complex compound to form silver nanoparticles. A silver nanoparticle ink can be obtained by adding an organic solvent to the silver nanoparticle dispersion obtained by this method. The resin includes, for example, a polymer exhibiting viscosity at a temperature within the range of 20 C. to 50 C. or a high molecular weight compound exhibiting viscosity at a temperature within the range of 20 C. to 50 C.

A method for producing a silver nanoparticle dispersion according to the present invention includes the steps of mixing an amine compound, a resin, and a silver salt to yield a complex compound; and heating and decomposing the complex compound to form silver nanoparticles. A silver nanoparticle ink can be obtained by adding an organic solvent to the silver nanoparticle dispersion obtained by this method. The resin includes, for example, a polymer exhibiting viscosity at a temperature within the range of 20 C. to 50 C. or a high molecular weight compound exhibiting viscosity at a temperature within the range of 20 C. to 50 C.

A method to prepare a chloride free magnesium electrolyte salt is provided. According to the method a water stable borate or carborate anion is converted to metal salt of an alkali metal or silver by an ion exchange and then converted to a chloride free magnesium salt by another ion exchange. A chloride free magnesium salt suitable as an electrolyte for a magnesium battery and a magnesium battery containing the chloride free magnesium electrolyte are also provided.

A method to prepare a chloride free magnesium electrolyte salt is provided. According to the method a water stable borate or carborate anion is converted to metal salt of an alkali metal or silver by an ion exchange and then converted to a chloride free magnesium salt by another ion exchange. A chloride free magnesium salt suitable as an electrolyte for a magnesium battery and a magnesium battery containing the chloride free magnesium electrolyte are also provided.