Non-aqueous electrolyte secondary battery and non-aqueous electrolyte
View Patent ↗The objective of the present invention is to prevent deterioration and expanding of anode active material and to improve charge-discharge cycle characteristics in a non-aqueous electrolyte secondary battery comprising an anode of which current collector has thereon a thin layer of an anode active material containing a metal. To solve this problem, in a non-aqueous electrolyte secondary battery wherein a thin layer of anode active material containing a metal which absorbs and discharges lithium is formed on a current collector and the thin layer of the anode active material is divided into columns by a gap formed along the thickness thereof, a compound represented by the following formula is contained in the non-aqueous electrolyte. A-N═C═O In the above formula, A represents an element or a group other than hydrogen.
1. A non-aqueous electrolyte secondary battery comprising an anode of which current collector has thereon a thin layer of an anode active material comprising a metal which absorbs and discharges lithium, a cathode comprising a cathode active material which absorbs and discharges lithium, and a non-aqueous electrolyte where a lithium salt is dissolved in a non-aqueous solvent, the thin layer of the anode active material being divided by a gap formed along the thickness thereof and shaped into columns,
wherein said non-aqueous electrolyte comprises a compound represented by the formula (III) below:
wherein R represents, independently of each other, an alkyl group or aryl group that may have substituents, and wherein more than one R may be connected to another R to form a ring, and
wherein the thin layer of an anode active material comprises at least one material selected from the group consisting of silicon, silicon alloys, tin and tin alloys.
2. A non-aqueous electrolyte secondary battery as defined in claim 1 , wherein said non-aqueous electrolyte contains 0.01 weight % or more and 20 weight % or less of the compound represented by the formula (III).
3. A non-aqueous electrolyte secondary battery as defined in claim 1 , wherein said non-aqueous electrolyte contains 0.1 weight % or more and 10 weight % or less of bis(trimethylsilyl)sulfate.
4. A non-aqueous electrolyte secondary battery as defined in claim 1 , wherein
said non-aqueous electrolyte comprises at least one solvent selected from the group consisting of cyclic carbonates, linear carbonates, lactone compounds, chained carboxylic acid esters, cyclic ethers and chain ethers, having 3 to 9 carbon atoms in total respectively, and
the total amount of the solvent, and the compound represented by the formula (III) is 70 to 100 weight % in said non-aqueous electrolyte exclusive of the lithium salt.
5. A non-aqueous electrolyte secondary battery as defined in claim 4 , wherein at least one of the cyclic carbonate and the lactone compound are present, and the total amount of the cyclic carbonate and the lactone compound is 5 weight % or more of said non-aqueous electrolyte exclusive of the lithium salt.
6. A non-aqueous electrolyte secondary battery as defined in claim 4 , wherein
the at least one solvent is selected from the group consisting of cyclic carbonates, linear carbonates, lactone compounds, and
the lactone compound is at least one selected from the group consisting of γ-butyrolactone, γ-valerolactone and δ-valerolactone,
the cyclic carbonate is at least one selected from the group consisting of ethylene carbonate, propylene carbonate and butylene carbonate, and
the linear carbonate is at least one selected from the group consisting of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate.
7. A non-aqueous electrolyte secondary battery as defined in claim 1 , wherein the lithium salt contains 5 to 100 mol % in the total amount of lithium salt of at least one selected from the group consisting of LiBF 4 and LiPF 6 .
8. A non-aqueous electrolyte secondary battery as defined in claim 1 , wherein the compound represented by formula (III) is selected from the group consisting of