SECONDARY BATTERY AND METHOD OF MANUFACTURING THE SAME, BATTERY PACK, ELECTRIC VEHICLE, ELECTRIC POWER STORAGE SYSTEM, ELECTRIC POWER TOOL, AND ELECTRONIC APPARATUS
There is provided a secondary battery including a cathode, an anode including an anode active material layer and a coating film, and an electrolytic solution. The anode active material layer includes a titanium-containing compound, and a surface of the anode active material layer is coated with the coating film. The electrolytic solution includes one or more of unsaturated cyclic carbonate esters. Porosity of a portion of the anode active material layer measured with use of a mercury intrusion technique is within a range from 30% to 50% both inclusive. The portion of the anode active material layer is cut together with a portion of the coating film from a surface of the coating film to a depth of 10 μm.
1 . A secondary battery, comprising:
a cathode;
an anode including an anode active material layer and a coating film, the anode active material layer including a titanium-containing compound, and a surface of the anode active material layer being coated with the coating film; and
an electrolytic solution including one or more of respective unsaturated cyclic carbonate esters represented by the following formulas (11) to (13),
wherein porosity of a portion of the anode active material layer measured with use of a mercury intrusion technique is within a range from 30% to 50% both inclusive, and the portion of the anode active material layer is cut together with a portion of the coating film from a surface of the coating film to a depth of 10 μm,
where each of R11 and R12 is one of a hydrogen group and an alkyl group, each of R13 to R16 is one of a hydrogen group, an alkyl group, a vinyl group, and an allyl group, one or more of R13 to R16 are one of the vinyl group and the allyl group, R17 is a group represented by >CR171R172, and each of R171 and R172 is one of a hydrogen group and an alkyl group.
2 . The secondary battery according to claim 1 , wherein a peak is detected by analysis of the coating film with use of Fourier transform infrared spectroscopy in each of a wave number range smaller than 1000 cm −1 , and a wave number range larger than 2000 cm −1 , and a peak is not detected in a wave number range from 1000 cm −1 to 2000 cm −1 both inclusive.
3 . The secondary battery according to claim 1 , wherein the titanium-containing compound includes one or more of a titanium oxide represented by the following formula (1) and respective lithium-titanium composite oxides represented by the following formulas (2) to (4),
TiO w (1)
where w satisfies 1.85≦w2.15.
Li[Li x M1 (1−3x)/2 Ti (3+x)/2 ]O 4 (2)
where M1 is one or more of magnesium (Mg), calcium (Ca), copper (Cu), zinc (Zn), and strontium (Sr), and “x” satisfies 0≦x≦1/3,
Li[Li y M2 1-3y Ti 1+23 ] O 4 (3)
where M2 is one or more of aluminum (Al), scandium (Sc), chromium (Cr), manganese (Mn), iron (Fe), germanium (Ga), and yttrium (Y), and “y” satisfies 0≦y≦1/3, and
Li[Li 1/3 M3 z Ti (5/3)-z ]O 4 (4)
where M3 is one or more of vanadium (V), zirconium (Zr), and niobium (Nb), and “z” satisfies 0≦z≦2/3.
4 . The secondary battery according to claim 1 , wherein the unsaturated cyclic carbonate esters include vinylene carbonate.
5 . The secondary battery according to claim 1 , wherein a content of the unsaturated cyclic carbonate esters in the electrolytic solution is within a range from 0.01 wt % to 5 wt % both inclusive.
6 . The secondary battery according to claim 1 , wherein a thickness of the coating film is 100 nm or less.
7 . The secondary battery according to claim 1 , wherein a capacity retention ratio after 500 cycles of charge and discharge are performed in an environment at 45° C. is 60% or more.
8 . The secondary battery according to claim 1 , wherein electrochemical impedance of the anode measured with use of an alternate-current impedance method is 57 Ω or less.
9 . The secondary battery according to claim 1 , wherein a volume change ratio after the secondary battery is continuously charged in an environment at 45° C. until charge time reaches 500 hours is 85% or less.
10 . The secondary battery according to claim 1 , wherein the secondary battery is a lithium-ion secondary battery.
11 . A method of manufacturing a secondary battery, comprising:
fabricating a secondary battery including a cathode, an anode, and an electrolytic solution, the anode including an anode active material layer that includes a titanium-containing compound, and the electrolytic solution including one or more of respective unsaturated cyclic carbonate esters represented by the following formulas (11) to (13);
charging and discharging the secondary battery to form a coating film, a surface of the anode active material layer being coated with the coating film; and
performing heat treatment on the secondary battery, in which the coating film is formed on the surface of the anode active material layer, at a treatment temperature ranging from 45° C. to 60° C. both inclusive for treatment time ranging from 12 hours to 100 hours both inclusive in a state of charge ranging from 25% to 75% both inclusive,
where each of R11 and R12 is one of a hydrogen group and an alkyl group, each of R13 to R16 is one of a hydrogen group, an alkyl group, a vinyl group, and an allyl group, one or more of R13 to R16 are one of the vinyl group and the allyl group, R17 is a group represented by >CR171R172, and each of R171 and R172 is one of a hydrogen group and an alkyl group.
12 . An electronic apparatus comprising a secondary battery as an electric power supply source, the secondary battery including
a cathode,
an anode including an anode active material layer and a coating film, the anode active material layer including a titanium-containing compound, and a surface of the anode active material layer being coated with the coating film, and
an electrolytic solution including one or more of respective unsaturated cyclic carbonate esters represented by the following formulas (11) to (13),
wherein porosity of a portion of the anode active material layer measured with use of a mercury intrusion technique is within a range from 30% to 50% both inclusive, and the portion of the anode active material layer is cut together with a portion of the coating film from a surface of the coating film to a depth of 10 μm,
where each of R11 and R12 is one of a hydrogen group and an alkyl group, each of R13 to R16 is one of a hydrogen group, an alkyl group, a vinyl group, and an allyl group, one or more of R13 to R16 are one of the vinyl group and the allyl group, R17 is a group represented by >CR171R172, and each of R171 and R172 is one of a hydrogen group and an alkyl group.