Nonaqueous electrolyte secondary battery and manufacturing method of the same
A manufacturing method according to the present invention includes: preparing a positive-electrode active material including sulfate ions by 0.04 mmol/m 2 to 0.16 mmol/m 2 per unit specific surface area; manufacturing a positive electrode by use of the positive-electrode active material including sulfate ions; manufacturing a negative electrode by use of a negative-electrode active material; assembling a battery assembly by accommodating the positive electrode, the negative electrode, and a nonaqueous electrolyte including lithium difluoro bis-oxalate phosphate in a battery outer case, wherein an additive amount (μmol) of the lithium difluoro bis-oxalate phosphate in the nonaqueous electrolyte is determined so as to satisfy Formula (I); and performing a charging process on the battery assembly at least once.
1. A method for manufacturing a nonaqueous electrolyte secondary battery, the method comprising:
preparing a positive-electrode active material including sulfate ions by not less than 0.04 mmol/m 2 but not more than 0.16 mmol/m 2 per unit specific surface area;
manufacturing a positive electrode by use of the positive-electrode active material including sulfate ions;
manufacturing a negative electrode by use of a negative-electrode active material;
assembling a battery assembly by accommodating the positive electrode, the negative electrode, and a nonaqueous electrolyte including lithium difluoro bis-oxalate phosphate in a battery outer case, wherein an additive amount X (μmol) of the lithium difluoro bis-oxalate phosphate in the nonaqueous electrolyte is determined so as to satisfy the following formula (I):
0.004
≦
X
(
Sc
·
Wc
+
Sa
·
Wa
)
≦
0.037
(
I
)
wherein in the formula (I), Sc indicates a specific surface area (m 2 /g) of the positive-electrode active material, We indicates a mass (g) of the positive-electrode active material, Sa indicates a specific surface area (m 2 /g) of the negative-electrode active material, and Wa indicates a mass (g) of the negative-electrode active material; and
performing a charging process on the battery assembly at least once, so as to form films on surfaces of the positive-electrode active material and the negative-electrode active material.
2. The method for manufacturing the nonaqueous electrolyte secondary battery, according to claim 1 , further comprising:
in the assembling of the battery assembly, adding lithium difluorophosphate to the nonaqueous electrolyte, in addition to the lithium difluoro bis-oxalate phosphate, wherein
an additive amount Y (μmol) of the lithium difluorophosphate in the nonaqueous electrolyte is determined so as to satisfy the following formula (II):
0.018
≦
Y
(
Sc
·
Wc
+
Sa
·
Wa
)
≦
0.092
(
II
)
wherein, in the formula (II), Sc, Wc, Sa, and Wa are the same as those in the formula (I).
3. The method for manufacturing the nonaqueous electrolyte secondary battery, according to claim 1 , wherein
a lithium transition metal composite oxide having a layered or spinel structure is used as the positive-electrode active material.
4. A nonaqueous electrolyte secondary battery, comprising
a battery assembly by accommodating a positive electrode, a negative electrode, and a nonaqueous electrolyte including lithium difluoro bis-oxalate phosphate in a battery outer case, wherein
the nonaqueous electrolyte secondary battery is manufactured by the manufacturing method according to claim 1 .