TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The lithium secondary battery further comprises: a negative electrode including a negative active material comprising natural graphite, artificial graphite, soft carbon, hard carbon, a mesophase pitch carbonized product, fired coke, silicon oxide and/or silicon oxide coated with conductive carbon; and a non-aqueous electrolyte i.e. a mixture of ethylene carbonate, ethylmethyl carbonate and dimethyl carbonate.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The non-aqueous electrolyte comprises a supporting electrolytic salt comprising lithium hexafluorophosphate, and the supporting electrolytic salt in the non-aqueous electrolyte has a concentration of 0.5-2 M. The metal filler comprises a component comprising metal oxide, metal hydroxide, metal phosphate, metal nitrate, metal carbonate, metal sulfate, metal alkoxide and/or ceramics. The amount of metal filler is 5-80 wt.%. The high-voltage positive active material is lithium nickel manganese oxide compounds of formula (Li1+xNiyMn2-y-zMzO4+w), preferably (LiNi(0.5)Mn(1.5)O4), and/or olivine-based lithium metal phosphate. The metal filler is magnesium carbonate, barium carbonate, lithium carbonate, hydrated aluminum hydroxide, aluminum sulfate, magnesium sulfate, aluminum ethoxide, yttrium phosphate, zirconyl pyrophosphate, aluminum nitrate, a mixture of dialuminum trisulfate and aluminum ethoxide, lithium aluminate, pentalithium aluminate, magnesium oxide, magnesium aluminate, barium titanate, cobalt aluminate, lithium orthosilicate, lithium tetraborate, lithium molybdate, aluminum hydroxide, aluminum phosphate, magnesium hydroxide, a mixture of aluminum oxide and aluminum phosphate, lithium zirconate, a mixture of aluminum oxide and aluminum hydroxide, oxide compounds of formula (AM1O3) or aluminum oxide.A = Ca, Ba, Sr or Pb;M1 = Ti, Zr, Sn or Hf;x = 0-0.2;x = 0.4-0.6;z = 0-0.2;w = 0 or 0.1; andM = Al, Ti, Mg or Zn.    TECHNOLOGY FOCUS - POLYMERS - The porous substrate comprises at least one kind of polyolefin-based monolayer or multilayer, and/or polyethylene, polypropylene, polyvinylidene fluoride or its multilayer. The separator further comprises a coating layer on at least one side of the porous substrate. The coating layer comprises a polymer and a metal filler. The polymer comprises a component comprising poly(vinylidene fluoride-hexafluoropropylene) co-polymer (preferred), polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyimide, polyamic acid, polyamide imide and aramid. The coating layer has a thickness of 0.5-5 mu m. The separator has an entire thickness of 5-30 mu m. The porous substrate has a porosity of 48-60%.