Lithium secondary battery and liquid electrolyte for the battery
AssigneeHitachi, Ltd.
InventorJuichi Arai
Life of this patent
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Abstract
A lithium secondary battery comprising a negative electrode, a positive electrode, a separator and a non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte having an electrical conductivity of 0.05 mS/cm or more and no such a flash point as specified by JIS-K2265 flash point test and comprising an ion nonconductive solvent and a lithium ion conductive solvent, is non-flammable and safe even at high temperatures.
Claims24
A lithium secondary battery, which comprises a non-aqueous liquid electrolyte containing a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), having an electrical conductivity of 0.05 mS/cm or more.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium salt-containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte comprising a mixed solution of (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), and (II) a lithium ion conductive solvent.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium-salt containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte containing at least 20% by volume of (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), and (II) a lithium ion conductive solvent in total.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium salt-containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte comprising a mixed solution of (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), and (II) a lithium ion conductive solvent, and the lithium ion conductive solvent having a dipole moment of not more than 3 debyes.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium salt-containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte comprising a mixed solution of (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), and (II) a lithium ion conductive solvents, and having an electrical conductivity of 0.1 to 3 mS/cm.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium salt-containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte comprising a mixed solution of (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), and (II) a lithium ion conductive solvent, and the lithium ion conductive solvent has a dipole moment of not more than 3 debyes.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium salt-containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte comprising:
- (a) 60 to 95% by volume of a fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4),
- (b) 5 to 40% by volume of a low dipole moment solvent having a dipole moment of less than 3 debyes obtained by molecular orbital calculation, and
- (c) 0.1 to 10% by volume of a high dipole moment solvent having a dipole moment of not less than 3 debyes obtained by molecular orbital calculation.
A lithium secondary battery, which comprises a lithium-storable and releasable negative electrode, a lithium-storable and releasable positive electrode, a separator and a lithium salt-containing non-aqueous liquid electrolyte, the non-aqueous liquid electrolyte comprising (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/14), and (II) a lithium ion conductive solvent, the lithium salt including an organic lithium salt and an inorganic lithium salt.
A non-aqueous liquid electrolyte for lithium secondary batteries, which comprises (I) a non-flammable fluorinated solvent which is a fluorinated ether represented by the following formula (1):
- CmF2m+1—O—CnH2n+1 (1)
- where m is an integer of 2 to 8, n is an integer of 1 to 5 and m and n are in such a relation as m≧((6n+1)/4), and (II) a lithium ion conductive solvent, and having an electrical conductivity of 0.1 mS/cm or more.
A non-aqueous liquid electrolyte for lithium secondary batteries, which comprises at least 80% by volume of methyl perfluorobutyl ether as a fluorinated solvent, less than 20% by volume of at least one of dimethyl carbonate, ethyl methyl carbamate and diethyl carbonate as a low dipole moment solvent, 0.1 to 10% by volume of at least one of ethylene carbonate, propylene carbonate, trifluoropropylene carbonate, chloroethylene carbonate, vinylene carbonate, butylene carbonate and dimethylvinylene carbonate as a high dipole moment solvent, 0.2 to 1.2 moles/l of LiN(SO2CF2CF3)2 as an organic lithium salt and 0.005 to 0.5 moles/l of LiPF6 as an inorganic lithium salt.
Dependencies are inferred from the claim text.