Power storage device
A power storage device with reduced initial irreversible capacity is provided. The power storage device includes a positive electrode including a positive electrode current collector and a positive electrode active material layer, a negative electrode including a negative electrode current collector and a negative electrode active material layer, and an electrolyte solution. In the negative electrode active material layer, the content percentage of a carbon material with an R value of 1.1 or more is less than 2 wt %. The R value refers to a ratio of a peak intensity I 1360 to a peak intensity I 1580 (I 1360 /I 1580 ). The peak intensity I 1360 and the peak intensity I 1580 are observed by Raman spectrometry at a Raman shift of 1360 cm −1 and a Raman shift of 1580 cm −1 , respectively. The electrolyte solution contains a lithium ion and an ionic liquid composed of an organic cation and an anion.
1. A power storage device comprising:
a positive electrode including a positive electrode current collector and a positive electrode active material layer;
a negative electrode including a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer including at least a carbon material with an R value of 1.1 or more; and
an electrolyte solution containing a lithium ion and an ionic liquid composed of an organic cation and an anion,
wherein the ionic liquid is a quaternary ammonium cation having at least one ring,
wherein the at least one ring is a five-membered ring or a six-membered ring,
wherein the at least one ring has at least one substituent,
wherein a content percentage of the carbon material with the R value of 1.1 or more is less than 2 wt % in the negative electrode active material layer, and
wherein the R value is a ratio of a peak intensity I 1360 to a peak intensity I 1580 (I 1360/ I 1580 ), the peak intensity I 1360 and the peak intensity I 1580 are observed by Raman spectrometry at a Raman shift of 1360 cm −1 and a Raman shift of 1580 cm −1 , respectively.
2. The power storage device according to claim 1 , wherein the at least one substituent is an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, a methoxyethyl group, or a hydrogen atom.
3. The power storage device according to claim 1 , wherein a maximum current density of the ionic liquid measured by a cyclic voltammetry method at a scan rate of 0.1 mV/sec is lower than or equal to 2 mA/g at a voltage within a range of 1.0 V to 1.5 V (vs. Li/Li + ).
4. The power storage device according to claim 1 ,
wherein the ionic liquid is represented by a General Formula (G1),
wherein R 1 to R 6 separately represent an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, a methoxyethyl group, or a hydrogen atom,
wherein at least one of R 2 to R 5 represent an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, or a methoxyethyl group, and
wherein A 31 represents a monovalent amide anion, a monovalent methide anion, a fluorosulfonate anion, a perfluoroalkylsulfonate anion, tetrafluoroborate, perfluoroalkylborate, hexafluorophosphate, or perfluoroalkylphosphate.
5. The power storage device according to claim 1 ,
wherein the ionic liquid is represented by a General Formula (G2),
wherein R 7 to R 13 separately represent an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, a methoxyethyl group, or a hydrogen atom,
wherein at least one of R 8 to R 12 represent an alkyl group having 1 to 20 carbon atoms, a methoxy group, a methoxymethyl group, or a methoxyethyl group, and
wherein A 31 represents a monovalent amide anion, a monovalent methide anion, a fluorosulfonate anion, a perfluoroalkylsulfonate anion, tetrafluoroborate, perfluoroalkylborate, hexafluorophosphate, or perfluoroalkylphosphate.
6. The power storage device according to claim 1 ,
wherein the ionic liquid includes two aliphatic rings and is represented by a General Formula (G3),
wherein n and m are greater than or equal to 1 and less than or equal to 3,
wherein α is greater than or equal to 0 and less than or equal to 4 when n is 1, α is greater than or equal to 0 and less than or equal to 5 when n is 2, and α is greater than or equal to 0 and less than or equal to 6 when n is 3,
wherein β is greater than or equal to 0 and less than or equal to 4 when m is 1, β is greater than or equal to 0 and less than or equal to 5 when m is 2, and β is greater than or equal to 0 and less than or equal to 6 when m is 3,
wherein “α or β is 0” means that at least one of the two aliphatic rings is unsubstituted, and a case where both α and β are 0 is excluded,
wherein X or Y is a substituent which is a straight chain or lateral chain alkyl group having 1 to 4 carbon atoms, a straight chain or lateral chain alkoxy group having 1 to 4 carbon atoms, or a straight chain or lateral chain alkoxyalkyl group having 1 to 4 carbon atoms, and
wherein A 31 represents a monovalent amide anion, a monovalent methide anion, a perfluoroalkylsulfonate anion, tetrafluoroborate, perfluoroalkylborate, hexafluorophosphate, or perfluoroalkylphosphate.
7. A power storage device comprising:
a positive electrode including a positive electrode current collector and a positive electrode active material layer;
a negative electrode including a negative electrode current collector and a negative electrode active material layer, the negative electrode active material layer including at least a carbon material with an R value of less than 1.1; and
an electrolyte solution containing a lithium ion and an ionic liquid composed of an organic cation and an anion,
wherein the R value is a ratio of a peak intensity I 1360 to a peak intensity I 1580 (I 1360 /I 1580 ), the peak intensity I 1360 and the peak intensity I 1580 are observed by Raman spectrometry at a Raman shift of 1360 cm −1 and a Raman shift of 1580 cm −1 , respectively, and
wherein the ionic liquid includes two aliphatic rings and is represented by a General Formula (G3),
wherein n and m are greater than or equal to 1 and less than or equal to 3,
wherein α is greater than or equal to 0 and less than or equal to 4 when n is 1, α is greater than or equal to 0 and less than or equal to 5 when n is 2, and α is greater than or equal to 0 and less than or equal to 6 when n is 3,
wherein β is greater than or equal to 0 and less than or equal to 4 when m is 1, α is greater than or equal to 0 and less than or equal to 5 when m is 2, and β is greater than or equal to 0 and less than or equal to 6 when m is 3,
wherein “α or β is 0” means that at least one of the two aliphatic rings is unsubstituted, and a case where both α and β are 0 is excluded,
wherein X or Y is a substituent which is a straight chain or lateral chain alkyl group having 1 to 4 carbon atoms, a straight chain or lateral chain alkoxy group having 1 to 4 carbon atoms, or a straight chain or lateral chain alkoxyalkyl group having 1 to 4 carbon atoms, and
wherein A − represents a monovalent amide anion, a monovalent methide anion, a perfluoroalkvlsulfonate anion, tetrafluoroborate, perfluoroalkvlborate, hexafluorophosphate, or perfluoroalkylphosphate.
8. The power storage device according to claim 7 , wherein the carbon material is one or more of natural graphite, artificial graphite, a mesophase pitch-based carbon fiber, an isotropic pitch-based carbon fiber, and graphene.
9. The power storage device according to claim 7 , wherein the carbon material is a scaly particle, an agglomerate particle, a fiber particle, a whisker particle, a spherical particle, a flaky particle, or a granular particle.
10. The power storage device according to claim 7 , wherein a maximum current density of the ionic liquid measured by a cyclic voltammetry method at a scan rate of 0.1 mV/sec is lower than or equal to 2 mA/g at a voltage within a range of 1.0 V to 1.5 V (vs. Li/Li + ).