Non-aqueous electrolyte secondary battery and manufacturing method thereof
A non-aqueous electrolyte secondary battery according to the present invention includes a positive electrode, a negative electrode, and a non-aqueous electrolyte solution. The negative electrode includes a coating derived from lithium bis(oxalate)borate. The coating derived from lithium bis(oxalate)borate includes a coating containing boron element and a coating containing oxalate ion. A ratio of the boron element contained in the coating derived from lithium bis(oxalate)borate to the oxalate ion is equal to or more than 5. Accordingly, it is possible to provide a non-aqueous electrolyte secondary battery capable of reliably obtaining the effect due to the formation of a coating.
1. A non-aqueous electrolyte secondary battery, comprising:
a positive electrode;
a negative electrode; and
a non-aqueous electrolyte solution, wherein
the negative electrode includes a coating,
the coating contains
a compound containing boron element, the compound being represented by the following formula:
and
an oxalate ion, and
a ratio of the boron element to the oxalate ion is equal to or more than 5.
2. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the ratio of the boron element to the oxalate ion is equal to or more than 5.9.
3. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the ratio of the boron element to the oxalate ion is equal to or more than 7.1.
4. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the ratio of the boron element to the oxalate ion is equal to or more than 10.
5. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the ratio of the boron element to the oxalate ion is equal to or more than 13.4.
6. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the non-aqueous electrolyte solution contains lithium difluorophosphate.
7. The non-aqueous electrolyte secondary battery according to claim 1 , wherein the compound containing boron element and the oxalate ion contained in the coating are products of a reductive decomposition of a lithium bis(oxalate)borate.
8. A method of manufacturing a non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte solution, the method comprising:
adding lithium bis(oxalate)borate to the non-aqueous electrolyte solution; and
performing a conditioning process for charging and discharging the non-aqueous electrolyte secondary battery to form a coating containing a compound containing boron element and oxalate ion, wherein the compound containing boron element and oxalate ion are products of the reductive decomposition of the lithium bis(oxalate)borate on the negative electrode, a ratio of boron element contained in the coating to oxalate ion contained in the coating being set to 5 or more, wherein the compound is represented by the following formula:
9. The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 8 , wherein
the conditioning process includes a process of repeating a process of charging the non-aqueous electrolyte secondary battery to a first state of charge and thereafter discharging the non-aqueous electrolyte secondary battery to a second state of charge, and
a range between the first state of charge and the second state of charge is equal to or more than 20% and equal to or less than 50%.
10. The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 9 , wherein the range between the first state of charge and the second state of charge is equal to or more than 30% and equal to or less than 50%.
11. The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 9 , wherein the range between the first state of charge and the second state of charge is 40%.
12. The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 8 , wherein lithium bis(oxalate)borate is added to the non-aqueous electrolyte solution with a concentration of lithium bis(oxalate)borate of 0.1 mol/kg or less in the non-aqueous electrolyte solution.
13. The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 8 , wherein lithium bis(oxalate)borate is added to the non-aqueous electrolyte solution with a concentration of lithium bis(oxalate)borate of 0.025 mol/kg or less in the non-aqueous electrolyte solution.
14. The method of manufacturing a non-aqueous electrolyte secondary battery according to claim 8 , wherein the non-aqueous electrolyte solution contains lithium difluorophosphate.