NEGATIVE ELECTRODE AND NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY USING THE SAME
A rolled foil of surface roughened copper as thick as 26 μm for example having a surface formed into an irregular shape with copper precipitated thereon by an electrolytic method is prepared as a negative electrode collector. Tin (Sn) or germanium (Ge) is deposited on the rolled foil described above, so that a negative electrode active material layer is formed. Note that the deposited tin or germanium is amorphous. The arithmetic mean roughness Ra in the surface-roughened rolled foil described above is preferably not less than 0.1 μm nor more than 10 μm. A non-aqueous electrolyte is produced by adding sodium hexafluorophosphate as an electrolyte salt in a concentration of 1 mol/l to a non-aqueous solvent produced by mixing ethylene carbonate and diethyl carbonate in the ratio of 50:50 by volume.
1 . A non-aqueous electrolyte secondary battery, comprising a negative electrode, a positive electrode, and a non-aqueous electrolyte including sodium ions, said negative electrode including elemental tin or elemental germanium.
2 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein said negative electrode further includes a collector including a metal, and
said elemental tin and elemental germanium are formed into a thin film state on said collector.
3 . The non-aqueous electrolyte secondary battery according to claim 2 , wherein said collector has a roughened surface.
4 . The non-aqueous electrolyte secondary battery according to claim 2 , wherein the arithmetic mean roughness of the surface of said collector is not less than 0.1 μm nor more than 10 μm.
5 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein said non-aqueous electrolyte includes sodium hexafluorophosphate.
6 . The non-aqueous electrolyte secondary battery according to claim 1 , wherein said non-aqueous electrolyte includes one or more selected from the group consisting of a cyclic carbonate, a chain carbonate, esters, cyclic ethers, chain ethers, nitrites, and amides.
7 . (canceled)