Carbon material for nonaqueous electrolyte secondary battery and method for manufacturing same, and negative electrode using carbon material and nonaqueous electrolyte secondary battery

Abstract

The object of the present invention is to provide a carbonaceous material which is obtainable from plant-derived char and has a decreased specific surface area. Further, the object of the present invention is to provide a non-aqueous electrolyte secondary battery having excellent dedoping capacity (discharge capacity), non-dedoping capacity (irreversible capacity), and charge-discharge efficiency. The object can be solved by a carbonaceous material for non-aqueous electrolyte secondary batteries characterized in that the carbonaceous material is obtained by heat-treating plant-derived char which is demineralized in gas-phase, and carbon precursor (i.e. non-graphitizable carbon precursor, graphitizable carbon, or mixture thereof) or volatile organic compound under a non-oxidizing gas atmosphere; and a specific surface area determined by a BET method is 10 m 2 /g or less. Further, the object can be solved by a carbonaceous material for non-aqueous electrolyte secondary batteries characterized in that the carbonaceous material is obtained by heating plant-derived char, and hydrocarbon compound having 1 to 20 carbon atoms; and a specific surface area determined by a BET method is 15 m 2 /g or less.

1 . A carbonaceous material for non-aqueous electrolyte secondary batteries, characterized in that the carbonaceous material is obtained by subjecting 35 weight % or more of a plant-derived char demineralized in a gas-phase, which is obtained by heating plant-derived char having an average particle diameter of 100 to 10000 μm at 500° C. to 1250° C. under an inert gas atmosphere containing a halogen compound and an organic compound having a volatile-element of 10 weight % or more in an ignition treatment at 800° C., to (a) final heat-treatment at 800 to 1600° C. under a non-oxidizing gas atmosphere, or (b) pre-heat-treatment at no less than 350° C. to less than 800° C., and final heat-treatment at 800 to 1600° C. under a non-oxidizing gas atmosphere, and the carbonaceous material has a specific surface area determined by a BET method of 10 m 2 /g or less. 
     
     
         2 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 1 , wherein the organic compound is a carbon precursor. 
     
     
         3 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 2 , wherein the carbon precursor is a non-graphitizable carbon precursor, a graphitizable carbon precursor, or a mixture thereof. 
     
     
         4 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 3 , wherein the carbon precursor is at least one selected from the group consisting of infusible pitch or tar, thermosetting resins, infusible thermoplastic resins, and plant-derived organic substances. 
     
     
         5 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 3 , wherein the carbon precursor is at least one selected from the group consisting of pitch and polymer. 
     
     
         6 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 1 , wherein the organic compound is a volatile organic compound which has an actual carbon ratio of less than 5 weight % in an ignition treatment at 800° C., and is solid at ordinary temperature. 
     
     
         7 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 6 , wherein the volatile organic compound is thermoplastic resin or a low-molecular organic compound. 
     
     
         8 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 6 , wherein the volatile organic compound is at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, poly(meth)acrylic acid, poly(meth)acrylic acid ester, naphthalene, phenanthrene, anthracene, and pyrene. 
     
     
         9 . (canceled) 
     
     
         10 . A carbonaceous material for non-aqueous electrolyte secondary batteries, characterized in that the carbonaceous material is obtained by subjecting a plant-derived char demineralized in a gas-phase, which is obtained by heating plant-derived char having an average particle diameter of 100 to 10000 μm at 500° C. to 1250° C. under an inert gas atmosphere containing a halogen compound, to heat-treatment at 600 to 1000° C. in a non-oxidizing gas atmosphere containing a vaporized hydrocarbon compound having 1 to 20 carbon atoms, and subjecting the obtained plant-derived char to heat treatment at 800 to 1600° C. in a non-oxidizing gas atmosphere; and has a specific surface area determined by a BET method of 15 m 2 /g or less. 
     
     
         11 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 10 , wherein the hydrocarbon compound is an unsubstituted or substituted hydrocarbon compound having 1 to 20 carbon atoms. 
     
     
         12 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 10 , wherein the hydrocarbon compound is at least one selected from the group consisting of methane, ethane, ethylene, propylene, benzene, and toluene. 
     
     
         13 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 1 , wherein an average (002) interlayer spacing d002 determined by x-ray diffractometry is 0.360 to 0.400 nm, and a true density determined by butanol method ρ Bt  is 1.40 to 1.70 g/cm 3 . 
     
     
         14 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 1 , wherein an amount of potassium contained therein is 0.1 weight % or less, and an amount of iron contained therein is 0.02 weight % or less. 
     
     
         15 . (canceled) 
     
     
         16 . A method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries comprising the following steps:
 (1) heating plant-derived char having an average particle diameter of 100 to 10000 μm at 500° C. to 1250° C. under an inert gas atmosphere containing a halogen compound so as to demineralize the plant-derived char in a gas-phase,   (2) mixing 35 weight % or more of the plant-derived char demineralized in a gas-phase, and an organic compound having a volatile-element of 10 weight % or more in an ignition treatment at 800° C., to obtain a mixture comprising them, wherein a pulverization of the plant-derived char demineralized in a gas-phase is performed before, after, or with the mixing step, and   (3) subjecting the mixture to final heat-treatment at 800 to 1600° C. under a non-oxidizing gas atmosphere, or pre-heat-treatment at no less than 350° C. to less than 800° C., and final heat-treatment at 800 to 1600° C. under a non-oxidizing gas atmosphere, so as to obtain the carbonaceous material having a specific surface area determined by a BET method of 10 m 2 /g or less.   
     
     
         17 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 16 , wherein the organic compound is a carbon precursor, and the mixture comprising the plant-derived char demineralized in a gas-phase and a carbon precursor of 95:5 to 45:55 in a ratio by weight is obtained in the mixing step (2). 
     
     
         18 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 17 , wherein the carbon precursor is a non-graphitizable carbon precursor, graphitizable carbon precursor, or mixture thereof. 
     
     
         19 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 18 , wherein the non-graphitizable carbon precursor is at least one selected from the group consisting of infusible pitch or tar, thermosetting resins, infusible thermoplastic resins, or plant-derived organic substances. 
     
     
         20 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 16 , wherein the organic compound is a graphitizable carbon precursor or a mixture of non-graphitizable carbon precursor and graphitizable carbon precursor, and the mixture comprising the plant-derived char demineralized in a gas-phase and a carbon precursor (the graphitizable carbon precursor or the mixture of non-graphitizable carbon precursor and graphitizable carbon precursor) of 95:5 to 42.5:57.5 in a ratio by weight is obtained in the mixing step (2). 
     
     
         21 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 16 , wherein the organic compound is a graphitizable carbon precursor, and the mixture comprising the plant-derived char demineralized in a gas-phase and the graphitizable carbon precursor of 96.5:3.5 to 40:60 in a ratio by weight is obtained in the mixing step (2). 
     
     
         22 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 18 , wherein the graphitizable carbon precursor is at least one selected from the group consisting of pitch and a polymer. 
     
     
         23 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 16 , wherein the organic compound is a volatile organic compound which has an actual carbon ratio of less than 5 weight % in an ignition treatment at 800° C., and is solid at ordinary temperature; and the mixture comprising the plant-derived char demineralized in a gas-phase and the volatile organic compound (which has an actual carbon ratio of less than 5 weight % in an ignition treatment at 800° C., and is solid at ordinary temperature) of 97:3 to 40:60 in a ratio by weight is obtained in the mixing step (2). 
     
     
         24 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 23 , wherein the volatile organic compound is thermoplastic resin or a low-molecular organic compound. 
     
     
         25 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 23 , wherein the volatile organic compound is at least one selected from the group consisting of polystyrene, polyethylene, polypropylene, poly(meth)acrylic acid, poly(meth)acrylic acid ester, naphthalene, phenanthrene, anthracene, and pyrene. 
     
     
         26 . (canceled) 
     
     
         27 . A method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries comprising the following steps:
 (1) heating plant-derived char having an average particle diameter of 100 to 10000 μm at 500° C. to 1250° C. under an inert gas atmosphere containing a halogen compound so as to demineralize a plant-derived char in a gas-phase,   (2) pulverizing a plant-derived char demineralized in a gas-phase and subjecting the plant-derived char demineralized in a gas-phase to heat treatment at 600 to 1000° C. in a non-oxidizing gas atmosphere containing a vaporized hydrocarbon compound having 1 to 20 carbon atoms, so as to obtain the carbonaceous material having a specific surface area determined by a BET method of 15 m 2 /g or less, and   (3) subjecting the obtained plant-derived char to heat-treatment at 800 to 1600° C. in a non-oxidizing gas atmosphere.   
     
     
         28 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 27 , wherein the hydrocarbon compound is an unsubstituted or substituted hydrocarbon compound having 1 to 20 carbon atoms. 
     
     
         29 . The method for manufacturing a carbonaceous material for a negative electrode of non-aqueous electrolyte secondary batteries according to  claim 27 , wherein the hydrocarbon compound is at least one selected from the group consisting of methane, ethane, ethylene, propylene, benzene, and toluene. 
     
     
         30 . (canceled) 
     
     
         31 . A negative electrode for non-aqueous electrolyte secondary batteries comprising the carbonaceous material according to  claim 1 . 
     
     
         32 . A non-aqueous electrolyte secondary battery comprising the negative electrode according to  claim 31 . 
     
     
         33 . A vehicle comprising the non-aqueous electrolyte secondary battery according to  claim 32 . 
     
     
         34 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 10 , wherein an average (002) interlayer spacing d002 determined by x-ray diffractometry is 0.360 to 0.400 nm, and a true density determined by butanol method ρ Bt  is 1.40 to 1.70 g/cm 3 . 
     
     
         35 . The carbonaceous material for non-aqueous electrolyte secondary batteries according to  claim 10 , wherein an amount of potassium contained therein is 0.1 weight % or less, and an amount of iron contained therein is 0.02 weight % or less. 
     
     
         36 . A negative electrode for non-aqueous electrolyte secondary batteries comprising the carbonaceous material according to  claim 10 .