JP2011081960A - Nonaqueous secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous secondary battery capable of doping/dedoping lithium and having an excellent capacity and moreover excellent in input/output characteristics even in a continuous discharging exceeding 10 seconds. <P>SOLUTION: In the nonaqueous secondary battery provided with a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte solution in which lithium salt is dissolved in a nonaqueous solvent, the positive electrode contains at least an active material which can store/desorb lithium and a fiber type conductive material, and the negative electrode has an atomic ratio of hydrogen to carbon of 0.60-0.05, and moreover, has a principal composition of an insoluble/infusible substrate (A) having a face interval of crystal faces (002) of 3.6 Å or more and an average grain diameter of the insoluble/infusible substrate (A) is 2.0 μm or less and moreover a specific surface area in the BET method is less than 150 m<SP>2</SP>/g, and lithium of 500 mAh/g or more per weight of the insoluble/infusible substrate (A) is carried. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a non-aqueous secondary battery having high energy density and high input / output characteristics.

  In recent years, midnight power storage systems, home-use distributed power storage systems based on solar power generation technology, and power storage systems for electric vehicles have attracted attention from the viewpoint of the effective use of energy aimed at preserving the global environment and conserving resources. Yes. Among them, in a combination of a high-efficiency engine and a power storage system (for example, a hybrid electric vehicle) or a combination of a fuel cell and a power storage system (for example, a fuel cell electric vehicle), the engine or the fuel cell operates at maximum efficiency. In order to cope with output fluctuation or energy regeneration on the load side, high output discharge characteristics and / or high rate charging characteristics are required on the power storage system side. In order to meet this demand, in power storage systems, higher output of lithium ion batteries or higher energy density of capacitors typified by electric double layer capacitors are being studied.

  In lithium ion batteries, which are representative of high energy density secondary batteries, carbon materials such as graphite capable of being doped / undoped with lithium ions have been used for the negative electrode. As a material applicable as a negative electrode material for a lithium ion battery, graphite and an amorphous carbon material are generally used.

  On the other hand, there is a material group (generally referred to as hydrographene in Non-Patent Document 1) in which hydrogen is bonded to the periphery of the carbon hexagonal network as a material capable of doping and dedoping lithium ions. 1. A heat-treated product of an aromatic condensation polymer composed of carbon, hydrogen, and oxygen described in 1, having a hydrogen / carbon atom ratio of 0.60 to 0.15 and containing a polyacene skeleton structure There is an infusible substrate. An insoluble and infusible substrate containing a polyacene-based skeleton structure is called PAS in Non-Patent Document 2 (PAS is an abbreviation for Polyacenic Semiconductor), and its feature is that it can be doped / undoped with lithium ions about 3 times that of graphite. Is described in Non-Patent Document 3. In addition, a non-aqueous secondary battery having a high voltage and a high capacity can be obtained by using lithium in an anode (hereinafter sometimes referred to as pre-doping) using an insoluble infusible substrate containing this polyacene skeleton structure. Are described in Non-Patent Document 4, Patent Document 2, Non-Patent Document 5, and Patent Document 3, but all take advantage of the high capacity that is characteristic of insoluble and infusible substrates (PAS) containing a polyacene-based skeleton structure. In addition, there is no description regarding application to a non-aqueous lithium ion battery having a high energy density and a high output.

  Another example of a material in which hydrogen is bonded to the periphery of the carbon hexagonal network surface (hydrographene) is obtained by subjecting a raw material mainly composed of pitch to a thermal reaction, and a hydrogen / carbon atomic ratio of 0. There is a material that is 35 to 0.05, and it is described that lithium of 1000 mAh / g or more exceeding the PAS can be doped / undoped (Patent Document 4, Non-Patent Document 6). Non-Patent Document 6 and Non-Patent Document 7 refer to this material as PAHs (abbreviation of Polycyclic Aromatic Hydrocarbons), which describes that the shape of a typical carbon hexagonal mesh surface is a disk shape. Non-Patent Document 8 discloses a lithium secondary battery using the PAHs as a negative electrode, and a small secondary battery having a capacity about twice that of a commercially available lithium ion battery is obtained. This is also an approach to a high energy density type battery utilizing the high capacity that is characteristic of PAHs, and there is no description regarding application to a non-aqueous lithium ion battery having high energy density and high output.

  Recently, higher energy density of capacitors has begun to be studied, and development of lithium-type capacitors containing activated carbon for the positive electrode, materials capable of being doped / undoped with lithium ions for the negative electrode, and lithium salts in the electrolyte is also underway (Patent Literature). 5). Non-Patent Document 9 and Non-Patent Document 10 disclose capacitors using the above-mentioned PAS as a negative electrode and a lithium-based electrolyte in which lithium is supported on the negative electrode in advance. The energy density thereof is 20 Wh / L (about 12 Wh / kg), and in order to satisfy the above requirements, further higher energy density and higher output are required.

  Further, Patent Document 6 discloses that discharge can be performed at a current density of about several tens of A / g with respect to the weight of the negative electrode active material and an electrode density for realizing a device having an unprecedented high energy density and high output characteristics. A negative electrode for a non-aqueous secondary battery having a high capacity and a high capacity per weight of the negative electrode active material and a high energy density / high-power non-aqueous secondary battery using the same are disclosed. Specifically, a hydrogen atom / carbon is disclosed. In an insoluble insoluble negative electrode for a non-aqueous secondary battery whose main component is an insoluble infusible substrate having an atomic ratio of 0.60 to 0.05 and a crystal plane 002 plane spacing of 3.6 mm or more. A negative electrode for a non-aqueous secondary battery characterized in that an average particle size of a fusible substrate is 2.0 μm or less and lithium of 500 mAh / g or more per weight of an insoluble and infusible substrate is previously supported. Has been.

  The positive electrode of the lithium ion battery can be doped with lithium and dedope. For example, lithium composite metal oxides include lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide, lithium composite iron phosphate, Or various materials, such as these mixtures, are proposed.

  In order to increase the output of the lithium ion battery, the electrode current collection structure using a conductive material has been improved for the positive electrode. For example, Patent Document 7 discloses a positive electrode in which a positive electrode active material is mixed with a powdery carbon material, a scaly carbon material, and a fibrous carbon material as a conductive material. According to Examples, it is described that when the positive electrode is used and a graphite electrode is used for the negative electrode, an output density of about 2.3 kW / kg can be obtained with a dischargeable output for 10 seconds. According to Patent Document 8, a positive electrode using a conductive material made of fibrous graphite having a fiber diameter of 1 μm to 15 μm is disclosed, and the 3C discharge capacity is 95% or more of the 1C discharge capacity. Is described. However, in a lithium ion battery having an energy density of 100 Wh / L or more, there is no description of an output density of 7 kW / kg or more per weight (or 10 kW / L or more per volume) using a fibrous conductive material.

  As described above, while studying high energy density and high output of non-aqueous storage devices (batteries and capacitors) using lithium ions, technological development is also progressing with respect to the input / output evaluation method. Non-Patent Document 11 and Non-Patent Document 12 show a DC internal resistance (“current quiescent method resistance”) evaluation method by “current quiescent method” and an input / output calculation method using “current quiescent method resistance”. Unlike the conventional resistance evaluation method (AC internal resistance evaluation, DC internal resistance evaluation calculated from ΔV during charge / discharge), the “current pause method resistance” can be directly related to the input / output curve of the device. In other words, by analyzing the time dependence of the “current pause method resistance”, the input / output curve of the device can be directly calculated, and by evaluating and analyzing the time dependency of the “current pause method resistance” The device input / output characteristics can be evaluated.

    Conventionally, for example, when positive and negative electrodes having excellent input / output characteristics have been developed, the individual input / output characteristics of the positive and negative electrodes are accurately evaluated even if the battery is assembled (evaluation is performed by separating the resistance from the battery). It was extremely difficult to do. As an evaluation method for solving such a problem, Non-Patent Document 11 and Non-Patent Document 12 describe a resistance separation technique using a “quadrupole cell”. According to this method, the positive electrode resistance, the negative electrode resistance, and the separator (electrolyte) resistance of the device can be separated and evaluated, the resistance separation method using this “quadrupole cell” is used, and the above-described “current pause method” By applying “resistance”, it is possible to separate and evaluate the input / output characteristics of the positive electrode or the negative electrode easily and accurately.

JP 59-3806 JP-A-3-233860 WO98 / 33227 JP 2000-251885 A WO2002 / 41420 Publication JP 2007-294286 A JP 2000-208147 A JP 2000-133245 A

T.A. Yamabe, M .; Fujii, S .; Mori, H .; Kinoshita, S .; Yata: Synth. Met. , 145, 31 (2004) S. Yata, Y. et al. Hato, K .; Sakurai, T .; Osaki, K .; Tanaka, T .; Yamabe: Synth. Met. , 18, 645 (1987) S. Yata, H .; Kinoshita, M .; Komori, N .; Ando, T .; Kashiwamura, T .; Harada, K .; Tanaka, T .; Yamabe: Synth. Met. 62, 153 (1994) Shigeru Yada, Industrial Materials, Vol. 40, no. 5, 32 (1992) S. Yata, Y. et al. Hato, H .; Kinoshita, N .; Ando, A .; Anekawa, T .; Hashimoto, M .; Yamaguchi, K .; Tanaka, T .; Yamabe: Synth. Met. 73, 273 (1995) S. Wang, S.W. Yata, J .; Nagano, Y .; Okano, H .; Kinoshita, H .; Kikuta, T .; Yamabe: J. et al. Electrochem. Soc. , 147 (7), 2498 (2000) Shigekuni Yada et al .: Molecular Functional Materials and Device Development, 77 (2004) Shigetaka Yada et al .: Functional molecular materials and device development, 428 (2004) Nobuo Ando et al., Development of Lithium Ion Capacitor (1) “Abstracts of the 46th Battery Discussion Meeting”, November 2005, 1C12, p294 Shinichi Tazaki et al., Development of Lithium Ion Capacitors (2) “Abstracts of the 46th Battery Conference”, November 2005, 1C13, p296 Shigekuni Yada, "Practical evaluation technology for lithium-ion batteries and capacitors", Technical Information Association (2006) Shigekuni Yada, “Practical Evaluation Technology for Lithium Ion Batteries and Capacitors”, Technical Information Association (2009)

  As described in Patent Document 6, the hydrogen atom / carbon atom ratio is 0.60 to 0.05, the interplanar spacing of the crystal plane 002 is 3.6 mm or more, and the average particle size is 2.0 μm or less. By supporting lithium of 500 mAh / g or more per weight on an insoluble infusible substrate in advance, a negative electrode for non-aqueous secondary batteries having high capacity and high input / output can be obtained. It contributes to the realization of electricity storage devices. However, when the resistance separation method by the above-mentioned “quadrupole cell” is used and the “current pause method resistance” is applied and the negative electrode input / output characteristics are separated and evaluated, the “current pause method resistance” (charging or Equivalent to the input / output characteristics up to 10 seconds after the start of discharge), the resistance is significantly reduced compared to conventional graphite-based materials and amorphous carbon materials, but the “current pause method resistance” increases after 10 seconds. The problem of doing was found. In this case, for example, when applied to a lithium-ion battery for HEV, the continuous charge / discharge time is within 10 seconds, and no major problem occurs, but a plug-in considered to require continuous charge / discharge of about 30 seconds. When trying to apply to a lithium-ion battery for hybrid, etc., further improvement was necessary.

  Moreover, even if the problem that the “current pause method resistance” after 10 seconds is increased and a negative electrode for a non-aqueous secondary battery having high capacity and high input / output is obtained, the high capacity, high It is necessary to design not only the negative electrode but also the positive electrode according to the negative electrode characteristic in order to obtain a non-aqueous secondary battery that fully draws out the input / output characteristic and has higher performance, higher energy density and higher input / output characteristic. was there.

  Accordingly, it is an object of the present invention to provide a non-aqueous secondary battery that is excellent in capacity and excellent in input / output characteristics even during continuous charge / discharge exceeding 10 seconds.

  As a result of conducting research while paying attention to the problems of the prior art as described above, the present inventor has obtained a non-aqueous secondary battery that has excellent capacity, high energy density, and high output characteristics that have not been conventionally available. In order to obtain, (1) the positive electrode contains at least an active material capable of occluding and desorbing lithium, and a fibrous conductive material, and (2) the negative electrode has a crystal plane 002 plane spacing of 3.6 mm or more. The inventors have found that this can be achieved by using an insoluble and infusible substrate, and controlling the particle size, specific surface area, and amount of lithium supported on the insoluble and infusible substrate, and have completed the present invention. .

  That is, the present invention is characterized by having the following configuration and solves the above problems.

[1] In a non-aqueous secondary battery including a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution in which a lithium salt is dissolved in a non-aqueous solvent, the positive electrode is an active material that can occlude and desorb at least lithium, a fibrous material An insoluble infusible substrate (A) containing a conductive material, in which the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, and the interplanar spacing of the crystal plane 002 is at least 3.6 mm. As an ingredient, the insoluble infusible substrate (A) has an average particle size of 2.0 μm or less and a specific surface area by the BET method of less than 150 m ² / g, and is 500 mAh / g or more per weight of the insoluble infusible substrate (A). A non-aqueous secondary battery in which lithium is supported.

  [2] In the above [1], in the non-aqueous secondary battery, the insoluble infusible substrate (A) as a main component of the negative electrode has a pore size of 20 cm or less being 0.05 cc / g or less. The nonaqueous secondary battery as described.

[3] In the non-aqueous secondary battery, the insoluble infusible substrate (A) as the main component of the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, and a specific surface area by the BET method of 500 m ^2. Part or all of the pores of the pulverized insoluble infusible substrate (B) having an average particle size of 2.0 μm or less obtained by pulverizing the insoluble infusible substrate (B) less than / g The nonaqueous secondary battery according to [1] or [2], wherein the nonaqueous secondary battery is sealed with a material.

[4] In the non-aqueous secondary battery, the insoluble infusible substrate (A) as the main component of the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, and a specific surface area by the BET method of 500 m ^2. By heat-treating the pulverized insoluble infusible substrate (B) having an average particle diameter of 2.0 μm or less obtained by pulverizing the insoluble infusible substrate (B) of less than / g in the presence of a carbon precursor. The nonaqueous secondary battery according to any one of [1] to [3], wherein the nonaqueous secondary battery is obtained.

  [5] In the non-aqueous secondary battery, the positive electrode includes at least an active material capable of inserting and extracting lithium, a fibrous conductive material, and a non-fibrous conductive material. The non-aqueous secondary battery according to any one of the above.

  [6] The non-aqueous secondary battery according to any one of [1] to [5], wherein the fibrous conductive material contained in the positive electrode is 2 wt% or more and 13 wt% or less. Water-based secondary battery.

  [7] In the non-aqueous secondary battery, the fibrous conductive material contained in the positive electrode is 2 wt% or more and 13 wt% or less, and the total amount of the fibrous conductive material and the non-fibrous conductive material is 7 wt% or more. The nonaqueous secondary battery as described in [6] above, which is 20% by weight or less.

  [8] In any one of the above [1] to [7], in the non-aqueous secondary battery, an average particle diameter of an active material capable of inserting and extracting lithium contained in the positive electrode is 7 μm or less. The non-aqueous secondary battery described in 1.

In the non-aqueous secondary battery of the present invention, the positive electrode includes at least an active material capable of inserting and extracting lithium, and a fibrous conductive material, and the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, In addition, the insoluble infusible substrate (A) whose crystal plane 002 plane spacing is 3.6 mm or more is a main component, and the insoluble infusible substrate (A) has an average particle size of 2.0 μm or less and is insoluble. 500 mAh / g or more of lithium is supported per weight of the infusible substrate, and the specific surface area by the BET method of the insoluble infusible substrate (A) of the negative electrode is less than 150 m ² / g. It is an aqueous secondary battery. Therefore, the negative electrode using the insoluble and infusible substrate in the non-aqueous secondary battery of the present invention is a graphite-based carbon material, a non-graphitizable carbon material used in a conventional lithium ion battery (the theoretical capacity of the graphite carbon material is 372 mAh). / G) has a higher discharge capacity (500 mAh / g or more). Furthermore, the negative electrode using the insoluble and infusible substrate in the nonaqueous secondary battery of the present invention has a specific surface area of the insoluble and infusible substrate by BET method of less than 150 m ² / g. The problem that the “current quiescent resistance” after 10 seconds of the negative electrode proposed in Japanese Patent Publication (Patent Document 6) increases can be greatly improved. It has a "current pause method resistance" of 1/2 or less (resistance value of 60 seconds) and has a high output characteristic more than twice even in continuous charging or discharging exceeding 10 seconds. Furthermore, combining a negative electrode using this insoluble and infusible substrate with a positive electrode containing an active material capable of occluding and desorbing lithium and a fibrous conductive material, it has an unprecedented high energy density (high capacity) and high output. A non-aqueous secondary battery having characteristics (low resistance) can be obtained.

It is a figure explaining the relationship between the compounding ratio of the fibrous conductive material of a positive electrode of this invention, and a non-fibrous conductive material, and electrical conductivity. It is a figure explaining the structure of the quadrupole cell in the Example of this invention. It is an enlarged view of the 1st discharge rest point in Example 1 of this invention.

  An embodiment of the present invention will be described as follows.

In the nonaqueous secondary battery of the present invention, the positive electrode includes at least an active material capable of inserting and extracting lithium, and a fibrous conductive material, and the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, In addition, the insoluble infusible substrate (A) whose crystal plane 002 plane spacing is 3.6 mm or more is a main component, the insoluble infusible substrate (A) has an average particle size of 2.0 μm or less and insoluble infusible. The specific surface area of the conductive substrate by the BET method is less than 150 m ² / g, and 500 mAh / g or more of lithium is supported on the weight of the insoluble and infusible substrate.

In the non-aqueous secondary battery of the present invention, an insoluble infusible substrate having a hydrogen atom / carbon atom ratio of 0.60 to 0.05 and an interval between crystal planes 002 of 3.6 mm or more ( The insoluble infusible substrate (A) has an average particle diameter of 2.0 μm or less, a specific surface area by the BET method of less than 150 m ² / g, and the insoluble infusible substrate (A). A negative electrode characterized by supporting lithium of 500 mAh / g or more per weight is used. This insoluble infusible substrate (A) has, for example, a hydrogen atom / carbon atom ratio of 0.60 to 0.05 and an average particle size of 2.0 μm or less described in JP-A-2007-294286. It can be obtained by controlling the specific surface area of the pulverized product of the insoluble infusible substrate (B). Hereinafter, an insoluble infusible substrate (B) applicable to the negative electrode of the present invention, and a pulverized product of the insoluble infusible substrate (B) (the average particle size described in JP-A-2007-294286 is 2.0 μm or less) The insoluble and infusible substrate) will be described.

  The insoluble infusible substrate (B) can be obtained by heat-treating the following aromatic condensation polymer. The aromatic condensation polymer is a condensate of an aromatic hydrocarbon compound, for example, a condensate of an aromatic hydrocarbon compound and an aldehyde. As the aromatic hydrocarbon compound, for example, so-called phenols such as phenol, cresol, xylenol and the like are suitable. For example, it can be methylene bisphenols, or it can be hydroxy biphenyls or hydroxynaphthalenes. Of these, phenols, particularly phenol, are suitable for practical use. As the aromatic condensation polymer, a part of the aromatic hydrocarbon compound having a phenolic hydroxyl group is substituted with an aromatic hydrocarbon compound having no phenolic hydroxyl group, for example, xylene, toluene, aniline, etc. A modified aromatic condensation polymer such as a condensate of phenol, xylene and formaldehyde can also be used, and a modified aromatic condensation polymer substituted with melamine or urea can also be used. Furan resins are also suitable. As the aldehyde, aldehydes such as formaldehyde, acetaldehyde and furfural can be used, but formaldehyde is preferable. The phenol formaldehyde condensate may be either a novolak type, a resol type or a mixture thereof. It can also be obtained by heat-treating thermosetting resins such as epoxy resins, unsaturated polyesters, alkyd resins, urethane resins and ebonites, cellulosic materials such as coconut shells, wood chips and bamboo, polyimides and the like. Although the present invention is not limited to the raw material of the insoluble and infusible substrate, the insoluble and infusible substrate of the present invention is characterized in that the crystal plane 002 has a wide interplanar spacing of 3.6 mm or more. When a raw material that reaches the insoluble and infusible substrate (B) in the solid phase without being liquefied is selected, this structure is easily obtained.

  The insoluble infusible substrate (B) is obtained, for example, by thermally reacting the raw materials exemplified above and has an insoluble insoluble structure having a polyacene skeleton structure described in JP-A-59-3806. A fusible substrate is an example. The insoluble infusible substrate (B) can be produced, for example, as follows. The raw materials exemplified above are gradually heated to a suitable temperature of, for example, 400 ° C. to 800 ° C. in a non-oxidizing atmosphere (including a vacuum), whereby a hydrogen atom / carbon atom ratio (hereinafter referred to as H / C). Insoluble and infusible substrates having a value of 0.60 to 0.05 can be obtained.

In the negative electrode of the present invention, the output is not obtained by controlling the pore structure (10 to 100 Å) of a porous material such as activated carbon (the technique described in Patent Document 5), but the material structure control (molecular structure: interplanar spacing). , Particle diameter) and improved electron conductivity (semiconductor → metal transition) by lithium ion doping of 500 mAh / g or more to achieve high output. Therefore, in the present invention, the pore structure of the material is not particularly important, and it becomes difficult to pulverize the porous material to 2 μm or less and to control the specific surface area by the BET method to less than 150 m ² / g. A porous insoluble and infusible substrate obtained by mixing zinc chloride or the like with an aromatic condensation polymer and causing a thermal reaction is not preferable as the insoluble and infusible substrate (B).

Usually, the insoluble and infusible substrate (B) is obtained by thermally reacting an aromatic condensation polymer such as a plate, film, granule, powder of 5 μm or more, and is obtained after the thermal reaction. The fusible substrate (B) has a size of 2 μm or more, and the specific surface area according to the BET method when measured with particles of about 5 μm is usually 50 m ² / g or more. When this is pulverized to 2 μm or less, the BET The specific surface area measured by the method exceeds 150 m ² / g.

The insoluble infusible substrate (A) used in the negative electrode of the present invention is an insoluble infusible substrate (B) obtained by pulverizing the obtained insoluble infusible substrate (B) to an average particle size of 2 μm or less, preferably 1 μm or less. A pulverized product can be obtained as a starting material. The insoluble infusible substrate (B) is pulverized in accordance with a conventional method until the predetermined particle diameter is obtained, and the insoluble infusible substrate (B) is further pulverized with a pulverizer such as a ball mill, jet mill, or bead mill. If so, classify. By crushing to 2 μm or less, preferably 1 μm or less, the H / C value and the interplanar spacing of the crystal plane 002 are hardly changed, but the specific surface area measured by the BET method is increased. For example, when pulverized to 1 μm or less, a specific surface area value exceeding 500 m ² / g may be measured, but the pore structure is a porous material such as activated carbon described in WO2002 / 41420 (Patent Document 6). Compared to the material, when part or all of the pores are closed with a carbonaceous material, a large amount of carbonaceous material is not required.

  The insoluble infusible substrate (B) having an average particle size of 2 μm or less obtained by the above method has a high capacity and is insoluble infusible substrate (B) as described in JP-A-2007-294286. ) Is doped with 500 mAh / g or more of lithium, and a negative electrode material for a non-aqueous secondary battery exhibiting excellent input / output characteristics is obtained.

  Recently, as described in the background art, regarding the evaluation of input / output characteristics of a high-output power storage device, it has been proposed to evaluate the “current pause method resistance” obtained by the “current pause method”.

  Non-Patent Document 12, Shizukuni Yada, “Practical Evaluation Technology for Lithium Ion Batteries and Capacitors”, Technical Information Association (2009), describes as follows. “The input and output characteristics of power storage devices such as batteries and capacitors are determined by the environment in which they are used, the voltage range, and the current, but it is difficult to determine the charge / discharge curves under all conditions. It has been said that the input characteristics and output characteristics can be predicted by calculation regardless of the current condition (rate) if the resistance is measured, and certainly about 1 hour rate (1C rate) in which the battery has been used conventionally. The internal resistance played a role in the slow region, but in the extremely high rate region corresponding to charge / discharge of seconds to several tens of seconds, the conventional impedance measurement method and DC internal resistance method cannot cope. Within this short time, the DC internal resistance changes significantly with time. " Here, the “current pause method resistance” is a function of time, and the input / output curve can be calculated from this time dependency. Therefore, it is possible to evaluate the “current pause method resistance”, that is, the input / output characteristics of the storage device. Is equivalent to

  In addition, as described in the background art, by using a “quadrupole cell” and separately evaluating “current quiescent resistance” into a positive electrode, a negative electrode, and a separator (electrolyte), it has been difficult to make a clear evaluation in the past. It has become possible to individually evaluate the input / output characteristics of the positive and negative electrodes.

  The inventors of the present invention have used the above-described evaluation technique to determine the “current pause of a negative electrode for a non-aqueous secondary battery (a negative electrode including a pulverized product of an insoluble and infusible substrate (B)) having high capacity and excellent input / output characteristics. When the “resistance” is separated and evaluated by the “quadrupole cell”, the “current resting resistance” after 10 seconds increases with time, that is, the input / output decreases during continuous discharge or charging for 10 seconds or more. A new problem was discovered. The present invention solves this problem with the insoluble infusible substrate (A) in which the specific surface area of the pulverized product of the insoluble infusible substrate (B) is controlled. ).

The insoluble and infusible substrate (A) used for the negative electrode of the present invention has a hydrogen atom / carbon atom ratio (H / C) of 0.60 to 0.05 and a crystal plane 002 plane spacing of 3. An insoluble infusible substrate having an average particle size of 2.0 μm or less and a specific surface area of the insoluble infusible substrate by the BET method of less than 150 m ² / g, for example, the insoluble infusible substrate It can be produced by closing all or part of the pores of the pulverized product (B) with a carbonaceous material. That is, the insoluble infusible substrate (A) has a structure in which a carbonaceous material exists on the particle surface and / or pores of the pulverized product of the insoluble infusible substrate (B) having an average particle size of 2.0 μm or less. It is.

    A preferred example of the production method will be described but is not limited thereto. As the method, (1) when heated to 400 ° C. to 800 ° C., a substance that generates a hydrocarbon gas or the like (carbon precursor) as a carbon source in the heating process (for example, pitch, mesophase pitch, coke, tar) Etc.) and a method in which an insoluble infusible substrate (B) having an average particle size of 2.0 μm or less is simultaneously heat-treated in a non-oxidizing atmosphere (a carbon precursor such as hydrocarbon gas is generated from pitch or the like during the heating process). The insoluble infusible substrate (B) is heat-treated in the presence of the carbon precursor), (2) an inert atmosphere containing a hydrocarbon gas (carbon precursor) such as benzene, xylene and toluene Examples thereof include a method of heat-treating the insoluble and infusible substrate (B) in the middle (in the presence of a carbon precursor). Here, when heat-treating the insoluble infusible substrate (B), it is necessary to set the heat treatment temperature so as to have a predetermined hydrogen atom / carbon atom ratio, and the temperature is preferably 400 ° C to 800 ° C. Moreover, the method of vapor-depositing carbonaceous material is also possible. The insoluble infusible substrate (A) obtained by this method has a carbon precursor-derived carbonaceous material on the particle surface and / or in the pores of the pulverized product of the insoluble infusible substrate (B). Thus, all or part of the pores can be blocked. In the present invention, since the output is not obtained by controlling the pore structure (10 to 100%) of a porous material such as activated carbon (Patent Document 5), the finely divided material of the insoluble and infusible substrate (B) has The pores may be completely blocked with a carbonaceous material derived from a carbon precursor. When all or part of the pores of the pulverized product of the insoluble infusible substrate (B) is blocked, the amount of pores of 20 mm or less of the insoluble infusible substrate (A) is 0.05 cc / g or less, preferably When it is 0.02 cc / g or less and the amount of pores of 20 mm or less in the insoluble and infusible substrate (A) is large, the resistance increase of the negative electrode after 10 seconds becomes large, and it becomes difficult to obtain the effect of the present invention. Here, the amount of pores of 20 mm or less can be obtained by analyzing the isothermal adsorption curve with nitrogen gas at 77.4K by the QSDFT method.

  The hydrogen atom / carbon atom ratio (H / C) of the insoluble and infusible substrate (A) thus obtained is 0.60 to 0.05, preferably 0.50 to 0.05, more preferably 0.35. -0.05, More preferably, it is 0.35-0.1. When H / C exceeds the upper limit, since the aromatic polycyclic structure is not sufficiently developed, lithium doping and dedoping cannot be performed smoothly, and charge / discharge efficiency is also reduced. When H / C is less than or equal to the lower limit, the average interplanar spacing becomes small, so that the output that is the object of the present invention cannot be obtained sufficiently, or the energy density of the battery decreases due to a decrease in negative electrode capacity.

  According to the X-ray diffraction (Cu-Kα), the insoluble and infusible substrate (A) used for the negative electrode of the present invention has a main peak position of 25 ° or less represented by 2θ. In addition, there is another broad peak between 41 ° and 46 °. The main peak existing at 25 ° or less is derived from the crystal plane 002. The surface interval of the crystal plane 002 of the insoluble infusible substrate used in the present invention is 3.6 mm or more, and when the surface distance is less than 3.6 mm, the surface distance is narrow. It becomes difficult to obtain. Although the upper limit is not particularly limited, it is desirable to set the surface interval to 4.5 mm or less, and when it exceeds 4.5 mm, the aromatic polycyclic structure is undeveloped and it becomes difficult to dope lithium. The insoluble infusible substrate of the present invention has an amorphous structure, and the crystallite length in the C-axis direction obtained from the half-value width of the main peak is preferably 15 mm or less, and the lower limit is 5 mm or more. It is preferable that Since the insoluble and infusible substrate of the present invention has an amorphous structure as described above, lithium can be stably doped in a large amount and high output characteristics can be obtained.

  The average particle diameter of the insoluble and infusible substrate (A) used for the negative electrode of the present invention is 2 μm or less, preferably 1 μm or less. The lower limit is preferably as small as possible, but is practically 0.05 μm or more when considering current collection or molding into an electrode. Regarding the method for obtaining an insoluble infusible substrate (A) of 2 μm or less, the insoluble infusible substrate (B) having an average particle diameter of 2 μm or less, preferably 1 μm or less described in Paragraph [0036] is described in Paragraph [0043]. It is obtained by processing by the method. When treated by the method described in paragraph [0043], the primary particles of the insoluble and infusible substrate (A) having an average particle diameter of 2 μm or less, preferably 1 μm or less are partially agglomerated, or intentionally secondary In this case, the average particle size referred to in the present invention is only the particle size of the primary particles. When the primary particles of the insoluble and infusible substrate (A) having an average particle size of 2 μm or less, preferably 1 μm or less are partially agglomerated, they can be crushed as necessary.

  When the average particle diameter exceeds 2 μm, the output that is the object of the present invention cannot be sufficiently obtained. From the viewpoint of output, it is desirable that the 90% particle diameter in the particle size distribution of the insoluble and infusible substrate (A) is 10 μm or less, preferably 5 μm or less. These average particle diameter and particle size value can be measured with a commercially available laser diffraction particle size distribution analyzer. Further, when the primary particles are partially aggregated, it can be confirmed by direct observation with an electron microscope or the like. The shape of the insoluble and infusible substrate (A) in the present invention is not particularly limited, and is appropriately selected from spherical, fibrous, amorphous particles and the like. The particle size.

The specific surface area according to the BET method of the insoluble and infusible substrate (A) used for the negative electrode of the present invention is less than 150 m ² / g, preferably less than 100 m ² / g, and more preferably less than 50 m ² / g. When this specific surface area is exceeded, the “current pause method resistance” after 10 seconds increases with time, and the object of the present invention cannot be achieved. The lower limit is preferably as small as possible in terms of the specific surface area according to the BET method (it is possible to block all the pores and is usually 1 m ² / g or more), but the insoluble and infusible substrate (B) is pulverized. When the ratio of the carbonaceous material existing in the particle surface of the object and / or the pores exceeds 20% with respect to the weight of the insoluble and infusible substrate (B), for example, The input / output characteristics of the original insoluble and infusible substrate (B) may be hindered. Therefore, the ratio of the carbonaceous material to the weight of the insoluble and infusible substrate (B) is preferably about 0.1% to 20%, and more preferably 5% to 20%.

Large lattice spacing, such as is used for the negative electrode of the present invention, and materials such as H / C is more than 0.1, even 5~30μm about particles normally used as a negative electrode material for batteries, 50 to 300 m ² / For particles having a specific surface area of about g and 2 μm or less, a specific surface value exceeding 200 m ² / g is usually measured. Therefore, the characteristics of particles having an average particle diameter of 2 μm or less and a specific surface area of less than 150 m ² / g as a high-power negative electrode material have been found for the first time in the present invention.

  The insoluble and infusible substrate (A) thus obtained is a high-capacity material capable of reversibly doping lithium exceeding 500 mAh / g, for example, Japanese Patent Application Laid-Open No. 2007-294286 (Patent Document 6). The problem that the “current resting method resistance” of the negative electrode proposed in 10 seconds after 10 seconds increases can be greatly improved.

  The negative electrode in the non-aqueous secondary battery of the present invention contains the insoluble and infusible substrate (A) as a main component, and is molded using a conductive material and a binder as necessary. The type of the binder is not particularly limited, and examples thereof include fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, and polyolefins such as fluorine rubber, SBR, acrylic resin, polyethylene, and polypropylene. . The amount of the binder is not particularly limited, and is appropriately determined depending on the average particle diameter, shape, etc. of the insoluble infusible substrate (A). For example, the amount of the binder is from 1% to 1% by weight of the insoluble infusible substrate (A). A ratio of about 30% is preferable. The type and amount of the conductive material are not particularly limited, but are appropriately determined depending on the average particle diameter, shape, H / C, etc. of the insoluble and infusible substrate (A). , Carbon black, acetylene black, and graphite. The amount of the conductive material is not particularly limited, and for example, a ratio of about 1% to 20% of the weight of the insoluble and infusible substrate (A) is preferable. The negative electrode used in the non-aqueous secondary battery of the present invention is a general electrode molding such as coating molding, press molding, roll molding, etc., using the above-mentioned insoluble and infusible substrate (A), if necessary, using a conductive material and a binder. Can be manufactured using the method.

The electrode density of the negative electrode (electrode mixture layer: not including the current collector) in the non-aqueous secondary battery of the present invention is appropriately determined in consideration of capacity and output, but is 0.8 g / cm ³ or more. Preferably there is. When the electrode density is less than 0.8 g / cm ³ , the energy density per volume in the non-aqueous secondary battery using this negative electrode is not preferable. The upper limit is not particularly limited, but considering the true density of the insoluble and infusible substrate, it is 1.8 g / cm ³ or less, preferably 1.4 g / cm ³ or less.

  The electrode thickness of the negative electrode in the non-aqueous secondary battery of the present invention (electrode mixture layer thickness: does not include the current collector, and if it is formed on both sides of the current collector, the thickness of one surface) takes capacity and output into consideration Although it is appropriately determined, it is preferably 30 μm or more. When the electrode thickness is less than 30 μm, it is not preferable because the energy density is lowered by increasing the volume ratio of the current collector and the separator in the non-aqueous secondary battery using this negative electrode. Moreover, although it does not specifically limit about an upper limit, When an output is considered, it is 200 micrometers or less.

  The negative electrode in the non-aqueous secondary battery of the present invention can be formed on a current collector, or an electrode formed in a sheet shape can be bonded to the current collector or bonded via a conductive layer. It is also possible to form a positive electrode layer after coating the current collector with a conductive layer mainly composed of carbon such as graphite or metal powder such as Ni on the current collector to a thickness of 10 μm or less. The material of the current collector is not particularly limited, and copper, iron, stainless steel and the like can be used. As the shape of the current collector, a metal foil or a structure capable of forming an electrode in a metal gap can be used. For example, an expanded metal, a netting material, a punching metal, or the like can be used as the current collector.

In the present invention, 500 mAh / g or more of lithium is supported on the insoluble infusible substrate (A) which is a negative electrode active material. As for the amount supported, the amount of lithium supported (pre-doped) in advance (pre-doped) on the insoluble infusible substrate (A), which is the negative electrode active material, is Cn (mAh), and is released from the positive electrode during initial charging. When the amount of lithium doped with lithium or the like is Cp (mAh) and the weight of the insoluble and infusible substrate (A) of the negative electrode is W (g), (Cn + Cp) / W is the amount of lithium supported. The amount of lithium supported here includes the amount of lithium that is not reversible. The amount of lithium supported varies depending on the initial Coulomb efficiency of the negative electrode, but is 500 mAh / g or more, preferably 550 mAh / g or more, more preferably 600 mAh / g or more, in particular, per weight of the insoluble and infusible substrate (A). 800 mAh / g or more. In addition, from the viewpoint of energy density during discharge, the insoluble infusible substrate (A) and the insoluble infusible substrate (A) are provided so that 30% or more, preferably 50% or more of the supported lithium amount can be dedoped. It is preferable to design a non-aqueous secondary battery having a negative electrode used or a negative electrode using an insoluble and infusible substrate (A). The upper limit of the amount of lithium supported is not particularly limited, but is preferably set to 1300 mAh / g or less in consideration of precipitation of lithium metal. The lithium that can be doped by being released from the positive electrode means the amount of lithium contained in the positive electrode during battery assembly and released during the charging operation and taken into the negative electrode. For example, lithium-containing composite oxides such as LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ are representative examples of lithium-containing positive electrode materials.

  The method for preliminarily supporting lithium on the negative electrode used in the non-aqueous secondary battery of the present invention (pre-doping method) is not particularly limited in the present invention, but a known method can be used. For example, the negative electrode material of the present invention can be formed electrochemically after being formed into an electrode. In the present invention, the method is not particularly limited. For example, before assembling the battery, an electrochemical system using lithium metal as a counter electrode is assembled and pre-doped in a non-aqueous electrolyte described later, and the negative electrode impregnated with the electrolyte is charged with lithium. The method of bonding a metal is mentioned. In addition, in order to pre-dope lithium after the battery is assembled, the lithium source such as lithium metal and a negative electrode are bonded together by a method such as bonding them together and injecting an electrolyte into the battery. It is possible to pre-dope lithium.

  With the above configuration, the negative electrode in the present invention has a “current quiescent resistance” (resistance value of 60 seconds) that is 1/2 or less that of a negative electrode using a graphite-based material used in a conventional lithium ion battery. The problem that the “current pause method resistance” of the negative electrode proposed in 2007-294286 (Patent Document 6) increases after 10 seconds can be greatly improved, and continuous charging or discharging exceeding 10 seconds Also has a high output characteristic more than twice. Hereinafter, it describes about the positive electrode combined with this negative electrode.

  The positive electrode in the present invention includes at least an active material capable of inserting and extracting lithium and a fibrous conductive material. The positive electrode active material capable of inserting and extracting lithium is not particularly limited as long as it can be doped and dedoped with lithium. For example, metal oxide, metal sulfide, lithium composite metal oxide Lithium composite metal oxides include lithium composite cobalt oxide, lithium composite nickel oxide, lithium composite manganese oxide, lithium composite iron phosphate, or a mixture thereof, and further to dissimilar metal elements in these composite oxides. One or more added systems can be used. In order to obtain a non-aqueous secondary battery having high energy density and high output, which is the object of the present invention, it is preferable to use an oxide having a small average particle diameter, for example, preferably 7 μm or less, more preferably 4 μm. Hereinafter, it is particularly preferably 2 μm or less. The lower limit is preferably as small as possible, but is 0.05 μm or more practically considering current collection and electrode forming. When the primary particles are secondary particles bound, the particle size referred to in the present invention is the primary particle size.

  The positive electrode in the present invention includes at least an active material capable of inserting and extracting lithium and a fibrous conductive material. Examples of the fibrous conductive material include carbon nanotubes, carbon fibers, and vapor-grown carbon fibers, and the fiber diameter is preferably 1 μm or less, more preferably 0.5 μm or less. Although the amount can be reduced, it is practically determined in consideration of dispersibility in the electrode. The length of the fibrous conductive material is desirably a length connecting several particles of the active material, and is appropriately determined. The lower limit of the length of the fibrous conductive material is preferably 5 μm or more, more preferably 8 μm or more. The upper limit is preferably 100 μm or less, more preferably 50 μm or less, and further preferably 30 μm or less. Practically, the upper limit is determined in consideration of dispersibility in the electrode.

  In addition to the active material and the fibrous conductive material, a non-fibrous conductive material can be added to the positive electrode in the present invention. Examples of the non-fibrous conductive material include carbon black, acetylene black, and graphite.

  The amount of the conductive material contained in the positive electrode is preferably 2% by weight or more and 13% by weight or less of the weight of the positive electrode of the fibrous conductive material, and more preferably 2% by weight or more of the weight of the positive electrode of the fibrous conductive material. In the case of using only the fibrous conductive material, it is preferably 5% by weight or more and 13% by weight or less of the weight of the positive electrode, and if it is less than the lower limit, it becomes difficult to ensure the electron conductivity of the electrode, and the upper limit is set. If it exceeds, the electrode density decreases, and a sufficient energy density cannot be obtained. Further, when the fibrous conductive material and the non-fibrous conductive material are used in combination, the fibrous conductive material is 2 wt% or more and 13 wt% or less of the weight of the positive electrode, and the total amount (the fibrous conductive material and the non-fibrous conductive material). The total amount of the material is preferably 7% to 20% by weight, more preferably 7% to 15% by weight, and particularly preferably 8% to 14% by weight. If it is less than the lower limit, it becomes difficult to ensure the electron conductivity of the electrode, and if it exceeds the upper limit, the electrode density is lowered and a sufficient energy density cannot be obtained.

  The positive electrode used in the non-aqueous secondary battery of the present invention uses the above-described positive electrode active material and the above conductive material, if necessary, using a general electrode molding method such as coating molding, press molding, roll molding, etc. using a binder. Can be manufactured. The type of the binder for the positive electrode in the present invention is not particularly limited, but fluorine resins such as polyvinylidene fluoride and polytetrafluoroethylene, polyolefins such as fluororubber, SBR, acrylic resin, polyethylene, and polypropylene. Etc. are exemplified. The amount of the binder is not particularly limited, and is appropriately determined depending on the average particle diameter, shape, and the like of the positive electrode active material. For example, the binder amount is preferably about 1% to 30% of the weight of the positive electrode active material. .

The electrode electrical conductivity of the positive electrode used in the non-aqueous secondary battery of the present invention is determined from the electrode active material species, the electrode composition, the electrode density, the electrode thickness, and the like. It is preferably 0 × 10 ⁻² S / cm or more, preferably 1.0 × 10 ⁻¹ S / cm or more, and more preferably 2.0 × 10 ⁻¹ S / cm or more. The upper limit is not particularly limited.

The electrode density of the positive electrode used in the non-aqueous secondary battery of the present invention (electrode mixture layer: not including the current collector) is appropriately determined in consideration of capacity and output. It is 40% or more, and the upper limit is preferably 75% or less. Specifically, in the case of spinel type LiMn ₂ O ₄ (true density 4.3 g / cm ³ ), it is preferably 1.7 g / cm ³ or more, more preferably 2.0 g / cm ³ or more. Yes, and the upper limit is preferably 3.2 g / cm ³ or less. When the electrode density is less than the lower limit, the energy density tends to decrease in the non-aqueous secondary battery using this positive electrode, and when the upper limit is exceeded, the amount of the electrolyte in the electrode decreases and sufficient input / output characteristics are obtained. I can't.

  The electrode thickness of the positive electrode used in the non-aqueous secondary battery of the present invention (electrode mixture layer thickness: does not include the current collector, and if it is formed on both sides of the current collector, the thickness of one surface thereof) is the capacity / output. Although appropriately determined in consideration, it is preferably 30 μm or more, more preferably 50 μm or more. When the electrode thickness is less than 30 μm, the energy density is lowered by increasing the volume ratio of the current collector and the separator in the non-aqueous secondary battery using this positive electrode, which is not preferable. Moreover, although it does not specifically limit about an upper limit, when an output is considered, it is 200 micrometers or less.

  The positive electrode used in the non-aqueous secondary battery of the present invention can be formed on a current collector, or an electrode formed into a sheet shape can be bonded to the current collector or bonded via a conductive layer. It is also possible to form a positive electrode layer after coating the current collector with a conductive layer mainly composed of carbon such as graphite or metal powder such as Ni on the current collector to a thickness of 10 μm or less. The material of the current collector is not particularly limited, and aluminum, iron, stainless steel, etc. can be used. As the shape of the current collector, a metal foil or a structure capable of forming an electrode in a metal gap can be used. For example, an expanded metal, a netting material, a punching metal, or the like can be used as the current collector.

The non-aqueous secondary battery of the present invention uses a non-aqueous electrolyte solution in which a lithium salt is dissolved in a non-aqueous solvent. As the non-aqueous electrolyte solution used in the present invention, a non-aqueous electrolyte solution containing a lithium salt can be used. According to the use conditions such as the type of the positive electrode material, the property of the negative electrode material, the charging voltage, etc. It is determined. Examples of the non-aqueous electrolyte containing a lithium salt include lithium salts such as LiPF ₆ , LiBF ₄ , LiClO ₄ , propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, dimethoxyethane, γ-butyrolactone, acetic acid. What was melt | dissolved in the organic solvent which consists of 1 type, or 2 or more types, such as methyl and methyl formate, can be used. The concentration of the electrolytic solution is not particularly limited, but generally about 0.5 to 2 mol / l is practical. As a matter of course, it is preferable to use an electrolytic solution having a water content of 100 ppm or less.

  The separator of the non-aqueous secondary battery in the present invention is not particularly limited, and a polyethylene microporous film, a polypropylene microporous film, or a laminated film of polyethylene and polypropylene, cellulose, glass fiber, polyaramid fiber, polyacrylonitrile fiber, etc. There are woven fabrics, nonwoven fabrics, and the like, which can be appropriately determined according to the purpose and situation.

  The shape of the nonaqueous secondary battery of the present invention is not particularly limited, and can be appropriately determined according to the purpose, such as a coin shape, a cylindrical shape, a square shape, and a film shape.

  EXAMPLES Examples will be shown below to further clarify the features of the present invention, but the present invention is not limited to the examples.

(Preparation of positive electrode)
The positive electrode active material is LiMn ₂ O ₄ having an average particle size of 6.0 μm, and the fibrous conductive material is vapor-grown carbon fiber (manufactured by Showa Denko: VGCF <registered trademark> -H), non-fibrous. As the conductive material, acetylene black (Denka Black (registered trademark) manufactured by Denki Kagaku Kogyo) was used. The positive electrode was produced by the following method. First, in a mixing ratio described in Table 1, a positive electrode active material, a fibrous conductive material, a non-fibrous conductive material, PVDF (polyvinylidene fluoride) as a binder is mixed with NMP (N-methyl-2-pyrrolidone), A positive electrode mixture slurry was obtained. Next, a 20 μm aluminum foil with a conductive paint made of graphite applied in a thickness of 4 μm in advance is prepared. On the surface of the current collector on which the conductive paint is applied, the positive electrode mixture is prepared. The slurry was applied, dried, and then pressed to obtain a positive electrode. Table 1 shows the thickness, density, and electrode conductivity of the obtained positive electrode mixture layer. FIG. 1 shows the relationship between the blending ratio of the fibrous conductive material and the non-fibrous conductive material and the electrode electrical conductivity.

The non-aqueous secondary battery according to the present invention is an insoluble infusible substrate in which the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05 and the interplanar spacing of the crystal plane 002 is 3.6 mm or more. The insoluble infusible substrate (A) has an average particle diameter of 2.0 μm or less and a specific surface area by the BET method of less than 150 m ² / g, the main component of (A), and the weight of the insoluble infusible substrate (A) It is possible to provide a non-aqueous secondary battery that has excellent input / output characteristics even in continuous discharge exceeding 10 seconds if a lithium conductor of 500 mAh / g or more is supported and the positive electrode contains a fibrous conductor. However, in order to provide a higher performance non-aqueous secondary battery, it is most preferable to combine the following positive electrode and the negative electrode.
As it is evident from Table 1, when used in combination fibrous conductive material and a non-fibrous conductive material as the conductive material of the positive electrode, sufficient electric conductivity for obtaining a high output characteristic (e.g., 1.0 × 10 ^{- In} order to obtain an electrical conductivity of ¹ S / cm, it is understood that 2% or more of the fibrous conductive material is necessary, and that the electrode density decreases when the fibrous conductive material exceeds 13%. Further, when only the fibrous conductive material is used as the conductive material for the positive electrode, 5% or more is necessary, and it is necessary to use a larger amount of fibrous conductive material than when the fibrous conductive material and the non-fibrous conductive material are used in combination. is there. Furthermore, in the case where a fibrous conductive material and a non-fibrous conductive material are used in combination, a total of 7% or more is necessary, and the positive electrode 1, the positive electrode 2, and the positive electrode 3 correspond to this. In the positive electrode 5 and the positive electrode 6 in which the fibrous conductive material is reduced from the positive electrode 3 (fibrous conductive material 2.0%, non-fibrous conductive material 5.7%), for example, 6% of non-fibrous conductive material is blended. However, sufficient electrical conductivity cannot be obtained (positive electrodes 4, 5). In addition, the positive electrode 9 in which the fibrous conductive material exceeds 13% has sufficient electric conductivity, but the electrode density is decreased, and the capacity per volume of the positive electrode 1, the positive electrode 2, and the positive electrode 3 is decreased.
As described above, from the results of the positive electrode examples in Table 1, as the most preferable positive electrode, when only the fibrous conductive material is used as the positive electrode conductive material, the conductive material contained in the positive electrode is 5 wt% or more and 13 wt% or less. When the fibrous conductive material and the non-fibrous conductive material are used in combination as the positive electrode conductive material, the fibrous conductive material contained in the positive electrode is 2 wt% or more and 13 wt% or less, and the fibrous conductive material It can be seen that the total amount of the non-fibrous conductive material is 7 wt% or more and 20 wt% or less.

  Hereinafter, in Examples 1 and 2 and Comparative Examples 1 and 2, only the negative electrode is changed (using the same positive electrode 1, separator, and electrolytic solution), and the negative electrode resistance is evaluated by a quadrupole cell, whereby the nonaqueous secondary of the present invention is used. The difference of the negative electrode performance in the battery was clarified.

Example 1
(Prototype of insoluble infusible substrate (B-1) pulverized product)
320 g of the phenolic resin cured body was placed in a stainless steel dish, and the dish was placed in a square furnace (400 × 400 × 400 mm) and subjected to a thermal reaction. The thermal reaction was performed in a nitrogen atmosphere, and the nitrogen flow rate was 5 liters / minute. The thermal reaction was performed at a rate of 1 ° C./minute until the furnace temperature was raised from room temperature to 630 ° C., held at that temperature for 4 hours, then cooled to 60 ° C. by natural cooling, and the dish was removed from the furnace. Taking out, the insoluble infusible substrate (B-1) of the present invention was obtained. The yield was 192g.

The obtained insoluble and infusible substrate (B-1) was pulverized to an average particle size of 0.7 μm using a ball mill. About the obtained insoluble infusible substrate (B-1) pulverized product, elemental analysis (measurement machine: elemental analyzer “PE2400 series II, CHNS / O” manufactured by PerkinElmer Co., Ltd.) and specific surface area (measurement) by BET method Used machine: “NOVA1200” manufactured by Quantachrome) was measured. In addition, the crystal structure was analyzed by an XRD (X-ray diffraction) method (measurement machine: fully automatic X-ray diffractometer “MXP ³ ” manufactured by Mac Science Co., Ltd., and generated X-rays are Cu—Kα rays). Insoluble infusible substrate having H / C of 0.24, specific surface area by BET method of 594 m ² / g, crystal plane 002 plane spacing of 3.74 mm, and crystallite length in the C-axis direction of 12.3 mm (B-1) A pulverized product. Further, when the isothermal adsorption curve by nitrogen gas at 77.4 K was analyzed by the QSDFT method, the amount of pores of 20 mm or less was 0.18 cc / g.

(Prototype of insoluble and infusible substrate (A-1))
10.1 g of the obtained insoluble and infusible substrate (B-1) pulverized product was placed in a stainless steel mesh basket and placed on a stainless steel dish containing 106.1 g of isotropic pitch (softening point: 270 ° C.). And placed in a square furnace (400 × 400 × 400 mm) for heat treatment. The heat treatment was performed in a nitrogen atmosphere, and the nitrogen flow rate was 5 liters / minute. In the heat treatment, the pitch was raised to 680 ° C., held at the same temperature for 4 hours, subsequently cooled to 60 ° C. by natural cooling, and then taken out from the furnace. Since some aggregation was observed, it was crushed with a mortar to obtain an insoluble and infusible substrate (A-1). The yield is 11.65 g (15.3% weight increase), and this weight increase is caused by carbon precursors such as hydrocarbon gas generated in the process of heating the pitch to 680 ° C. by the heat treatment, This is because it becomes a carbonaceous material on the surface and / or pores of the insoluble and infusible substrate (B-1).

The insoluble and infusible substrate (A-1) obtained had an average particle diameter of 0.7 μm, H / C of 0.16, a specific surface area by BET method of 41 m ² / g, and a plane spacing of 002 crystal planes of 3 The crystallite length in the C-axis direction was 13.4 mm. In addition, when the isothermal adsorption curve by nitrogen gas at 77.4K was analyzed by the QSDFT method, the amount of pores of 20 mm or less was 0.02 cc / g, which was significantly lower than before heat treatment (0.18 cc / g). . This is because heat treatment is performed on the insoluble infusible substrate (B-1) in the presence of the carbon precursor so that the pores of the pulverized insoluble infusible substrate (B-1) are blocked with the carbonaceous material. It depends on being removed.

  Next, 75 parts by weight of the insoluble and infusible substrate (A-1), 15 parts by weight of a conductive material (acetylene black) and 10 parts by weight of a binder (polyvinylidene fluoride: PVDF) were added to NMP (N-methyl-2-pyrrolidone). And a negative electrode mixture slurry was obtained. Prepare a 4 μm thick conductive paint made of graphite on one side of an 18 μm copper foil, and apply the negative electrode mixture slurry on the surface of the current collector on which the conductive paint is applied. After drying, press working was performed to obtain an electrode.

The electrode obtained above was used as a working electrode, lithium metal was used as a counter electrode, and LiPF ₆ was added at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methylethyl carbonate were mixed at an electrolyte ratio of 3: 7 (volume ratio). An electrochemical cell was made in a dry box using the dissolved solution. After applying a constant voltage of 1 mV to the lithium potential at a current of 60 mA / g per weight of the insoluble infusible substrate (A-1) for 12 hours, the capacity when discharged to 2.5 V at a current of 60 mA / g is It has a high capacity of 730 mAh / g.

The negative electrode (electrode area: 14 × 20 mm) having a thickness of 43 μm and a density of 1.0 g / cm ³ obtained as described above was used as a working electrode, lithium metal was used as a counter electrode, and ethylene carbonate and methyl ethyl carbonate were used as electrolytes. An electrochemical cell was prepared in a dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent mixed at 7 (volume ratio). 509 mAh / g of lithium per weight of insoluble infusible substrate (A-1) was pre-doped at a current of 60 mA / g per weight of insoluble infusible substrate (A-1).

The negative electrode predoped with lithium and the positive electrode 1 (electrode area: 14 × 20 mm) having a thickness of 67 μm and a density of 2.1 g / cm ³ obtained above were combined, and 3 ethylene carbonate and methyl ethyl carbonate were used as the electrolyte. : A quadrupole cell for separation evaluation of the current resting method resistance of the negative electrode using a solution obtained by dissolving LiPF ₆ in a concentration of 1 mol / l in a solvent mixed at 7 (volume ratio) (Non-patent Documents 11 and 12) Reference) was prepared in a dry room. The structure of the produced quadrupole cell is shown in FIG. The separator 5 is made of 8 non-woven fabrics of glass fiber (thickness 190 μm, porosity 90%). The positive reference electrode 3 and the negative reference electrode 4 are made of lithium on both sides of a stainless steel plate having a width of 0.03 mm and a thickness of 0.03 mm. Was obtained by electrochemical deposition in the cell.

  Between the positive and negative electrodes of the obtained quadrupole cell, a constant current (0.71 mA) / constant voltage charge of 4.2 V-8 hours was carried out for 8 hours, and discharged to 2.3 V with a constant current of 0.71 mA. The charge capacity is 3.48 mAh, the amount of lithium doped from the positive electrode in the initial charge is 383 mAh / g per weight of the insoluble infusible substrate (A-1), and the insoluble infusible substrate totaled with the pre-doping amount ( A-1) The amount of lithium supported per weight was 892 mAh / g. The discharge capacity was 3.29 mAh.

  By applying the above-mentioned quadrupole cell to a current value of 1.65 mA and a voltage range of 2.3 V to 4.2 V at 25 ° C. by a “current pause method” (see Non-Patent Document 11 and Non-Patent Document 12), By repeating the pause for 60 seconds, the battery was charged and discharged, and the current pause method resistance was measured. An enlarged view of the discharge first rest point of the potential between the negative electrode and the negative reference electrode is shown in FIG. The negative electrode potential immediately before the pause is 0.1510 V, the potential after 1 second of the pause is 0.1472 V, the potential after 10 seconds of the pause is 0.1460 V, and the potential after 60 seconds of the pause is 0.1437 V, which decreases with time. I understand that. By dividing the difference between the negative electrode potential immediately before the pause and the negative electrode potential at a predetermined time by the applied current value of 1.65 mA, the current pause method resistance of the negative electrode (excluding the separator resistance obtained from the potential change between the positive reference electrode and the negative reference electrode) ) The current quiescent resistance of the negative electrode separated by the quadrupole cell is 1.11Ω with a current quiescent resistance of up to 1 second, 1.84 Ω with a current quiescent resistance of up to 10 seconds, and a current quiescent method of up to 60 seconds The resistance was 3.24Ω. Similarly, a current quiescent resistance of the positive electrode (excluding the separator resistance obtained from the potential change between the positive reference electrode and the negative reference electrode) was obtained. The current quiescent resistance of the positive electrode separated by a quadrupole cell is 1.35Ω with a current quiescent resistance of up to 1 second, 1.84 Ω with a current quiescent resistance of up to 10 seconds, and a current quiescent method of up to 60 seconds. The resistance was 2.81Ω.

(Example 2)
(Prototype of insoluble infusible substrate (B-2) pulverized product)
367 g of a cured phenol resin was placed in a stainless steel dish, and the dish was placed in a square furnace (400 × 400 × 400 mm) and subjected to a thermal reaction. The thermal reaction was performed in a nitrogen atmosphere, and the nitrogen flow rate was 5 liters / minute. The thermal reaction was performed at a rate of 1 ° C./min until the temperature in the furnace reached from room temperature to 680 ° C., held at that temperature for 4 hours, then cooled to 60 ° C. by natural cooling, and the dish was removed from the furnace. The insoluble and infusible substrate (B-2) of the present invention was obtained. The yield was 226g.

The resulting insoluble and infusible substrate (B-2) was pulverized to a mean particle size of 0.8 μm using a ball mill. About the obtained insoluble infusible substrate (B-2) pulverized product, elemental analysis (measurement use machine: elemental analysis device “PE2400 series II, CHNS / O” manufactured by PerkinElmer Co., Ltd.) and specific surface area by BET method (measurement use) Machine: “NOVA1200” manufactured by Quantachrome) was measured. In addition, the crystal structure was analyzed by an XRD (X-ray diffraction) method (measurement machine: fully automatic X-ray diffractometer “MXP ³ ” manufactured by Mac Science Co., Ltd., and generated X-rays are Cu—Kα rays). H / C is 0.19, specific surface area by BET method is 385 m ² / g, crystal plane 002 plane spacing is 3.73 mm, crystal plane 002 plane crystallite length is 13.4 mm insoluble It was an infusible substrate (B-2) pulverized product. Further, when the isothermal adsorption curve by nitrogen gas at 77.4 K was analyzed by the QSDFT method, the amount of pores of 20 mm or less was 0.14 cc / g.

(Prototype of insoluble and infusible substrate (A-2))
16.0 g of the pulverized product of the obtained insoluble and infusible substrate (B-2) was placed in a stainless steel mesh basket and placed on a stainless steel dish containing 17.6 g of isotropic pitch (softening point: 270 ° C.). And placed in a square furnace (400 × 400 × 400 mm) for heat treatment. The heat treatment was performed in a nitrogen atmosphere, and the nitrogen flow rate was 5 liters / minute. In the heat treatment, the pitch is raised to 680 ° C., held at the same temperature for 4 hours, subsequently cooled to 60 ° C. by natural cooling, and then taken out from the furnace to obtain an insoluble and infusible substrate (A-2). It was. Yield was 17.6 g (10.0% weight gain).

The insoluble and infusible substrate (A-2) obtained had an average particle size of 0.8 μm, H / C of 0.13, a specific surface area by BET method of 15 m ² / g, and a plane spacing of the crystal plane 002 of 3 The crystallite length in the C-axis direction was 13.2 mm. Further, when the isothermal adsorption curve by nitrogen gas at 77.4K was analyzed by the QSDFT method, the amount of pores of 20 mm or less was 0.005 cc / g.

  Next, 75 parts by weight of the above insoluble and infusible substrate (A-2), 15 parts by weight of conductive material acetylene black and 10 parts by weight of PVdF (polyvinylidene fluoride) were mixed with NMP (N-methyl-2-pyrrolidone), A negative electrode mixture slurry was obtained. Prepare a 4 μm thick conductive paint made of graphite on one side of an 18 μm copper foil, and apply the negative electrode mixture slurry on the surface of the current collector on which the conductive paint is applied. After drying, press working was performed to obtain an electrode.

The electrode obtained above was used as a working electrode, lithium metal was used as a counter electrode, and LiPF ₆ was added at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methylethyl carbonate were mixed at an electrolyte ratio of 3: 7 (volume ratio). An electrochemical cell was made in a dry box using the dissolved solution. After applying a constant voltage of 1 mV to the lithium potential at a current of 60 mA / g per weight of the insoluble infusible substrate (A-2) for 12 hours, the capacity when discharged to 2.5 V at a current of 60 mA / g is It has a high capacity of 755 mAh / g.

The negative electrode (electrode area: 14 × 20 mm) having a thickness of 44 μm and a density of 0.94 g / cm ³ obtained above was used as a working electrode, lithium metal was used as a counter electrode, and ethylene carbonate and methyl ethyl carbonate were used as electrolytes. An electrochemical cell was prepared in a dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent mixed at 7 (volume ratio). Pre-doped 483 mAh / g lithium per insoluble infusible substrate (A-2) weight at a current of 60 mA / g per insoluble infusible substrate (A-2) weight.

This lithium pre-doped negative electrode and a positive electrode 1 (electrode area: 14 × 20 mm) having a thickness of 69 μm and a density of 2.1 g / cm ³ are combined, and the same quadrupolar cell as in Example 1 (Non-patent Documents 11 and Non-patent Documents) 12) was prepared in a dry room.

  Between the positive and negative electrodes of the obtained quadrupole cell, a constant current (0.73 mA) / constant voltage charge of 4.2 V-8 hours was carried out for 8 hours, and discharged to 2.3 V with a constant current of 0.73 mA. The charge capacity is 3.53 mAh, and the amount of lithium doped from the positive electrode in the initial charge is 405 mAh / g per weight of the insoluble infusible substrate (A-2). A-2) The amount of lithium supported per weight was 888 mAh / g. The discharge capacity was 3.32 mAh.

  By applying the above-mentioned quadrupole cell to a current value of 1.66 mA and a voltage range of 2.3 V to 4.2 V at 25 ° C. by a “current pause method” (see Non-Patent Document 11 and Non-Patent Document 12), Charging and discharging were performed by repeating the pause for 60 seconds, and the pause method resistance was measured. From the first discharge point of discharge of the potential between the negative electrode and the negative reference electrode, the current pause method resistance of the negative electrode (excluding the separator resistance determined from the change in potential between the positive reference electrode and the negative reference electrode) was determined in the same manner as in Example 1. The current quiescent resistance of the negative electrode separated by the quadrupole cell is 0.71Ω with a current quiescent resistance of up to 1 second, 1.37 Ω with a current quiescent resistance of up to 10 seconds, and a current quiescent method of up to 60 seconds. The resistance was 2.64Ω. Similarly, a current quiescent resistance of the positive electrode (excluding the separator resistance obtained from the potential change between the positive reference electrode and the negative reference electrode) was obtained. The current quiescent resistance of the positive electrode separated by a quadrupole cell is 1.25 Ω with a current quiescent resistance of up to 1 second, 1.79 Ω with a current quiescent resistance of up to 10 seconds, and a current quiescent method of up to 60 seconds The resistance was 2.70Ω. As a matter of course, since the equivalent positive electrode 1 is used, the current quiescent resistance of the separated positive electrode is equivalent to that of Example 1.

(Comparative Example 1)
A negative electrode was prototyped using the pulverized product of the insoluble and infusible substrate (B-1) obtained in the examples. 75 parts by weight of an insoluble infusible substrate (B-1), 15 parts by weight of a conductive material (acetylene black) and 10 parts by weight of a binder (polyvinylidene fluoride: PVDF) were mixed with NMP (N-methyl-2-pyrrolidone), A negative electrode mixture slurry was obtained. This slurry was applied to one side of a 18 μm thick copper foil, dried, and then pressed to obtain an electrode.

The electrode obtained above was used as a working electrode, lithium metal was used as a counter electrode, and LiPF ₆ was added at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methylethyl carbonate were mixed at an electrolyte ratio of 3: 7 (volume ratio). An electrochemical cell was made in a dry box using the dissolved solution. After applying a constant voltage of 1 mV to the lithium potential at a current of 60 mA / g per weight of the insoluble infusible substrate (B-1) for 12 hours, the capacity when discharged to 2.5 V at a current of 60 mA / g is It has a high capacity of 540 mAh / g.

The negative electrode obtained above with a thickness of 52 μm and a density of 0.80 g / cm ³ is used as a working electrode, lithium metal is used as a counter electrode, and ethylene carbonate and methyl ethyl carbonate are mixed as an electrolyte in a ratio of 3: 7 (volume ratio). An electrochemical cell was produced in a dry box using a solution of LiPF ₆ dissolved in the solvent at a concentration of 1 mol / l. 490 mAh / g of lithium per weight of insoluble infusible substrate (B-1) was pre-doped at a current of 60 mA / g per weight of insoluble infusible substrate (B-1).

The lithium pre-doped negative electrode and the positive electrode 1 having a thickness of 69 μm and a density of 2.1 g / cm ³ (electrode area: 14 × 20 mm) were combined, and the same quadrupole cell as in Example 1 (Non-patent Document 11, Non-patent) Reference 12) was prepared in a dry room.

  Between the positive and negative electrodes of the obtained quadrupole cell, a constant current (0.71 mA) / constant voltage charge of 4.2 V-8 hours was carried out for 8 hours, and discharged to 2.3 V with a constant current of 0.71 mA. The charge capacity is 3.53 mAh, and the amount of lithium doped from the positive electrode in the initial charge is 405 mAh / g per weight of the insoluble infusible substrate (B-1). B-1) The amount of lithium supported per weight was 895 mAh / g. The discharge capacity was 3.32 mAh.

  By applying the above-mentioned quadrupole cell to a current value of 1.65 mA and a voltage range of 2.3 V to 4.2 V at 25 ° C. by a “current pause method” (see Non-Patent Document 11 and Non-Patent Document 12), By repeating the pause for 60 seconds, the battery was charged and discharged, and the current pause method resistance was measured. From the first discharge point of discharge of the potential between the negative electrode and the negative reference electrode, the current pause method resistance of the negative electrode (excluding the separator resistance determined from the potential change between the positive reference electrode and the negative reference electrode) was determined in the same manner as in Example 1. The current quiescent resistance of the negative electrode separated by the quadrupole cell is 1.69 Ω with a current quiescent resistance of up to 1 second, 2.61 Ω with a current quiescent resistance of up to 10 seconds, and a current quiescent method of up to 60 seconds The resistance was 4.59Ω.

(Comparative Example 2)
(Prototype of insoluble infusible substrate (A-3 comparison))
A stainless steel dish in which 8.21 g of the insoluble and infusible substrate (B-2) obtained in Example 1 was placed in a stainless steel mesh basket and 1.25 g of an isotropic pitch (softening point: 270 ° C.) was added. And placed in a square furnace (400 × 400 × 400 mm) for heat treatment. The heat treatment was performed in a nitrogen atmosphere, and the nitrogen flow rate was 5 liters / minute. In the heat treatment, the pitch was raised to 680 ° C., held at the same temperature for 4 hours, subsequently cooled to 60 ° C. by natural cooling, and then taken out from the furnace. Since some agglomeration was observed, it was crushed in a mortar to obtain an insoluble and infusible substrate (A-3 comparison). Yield was 8.34 g (1.6% weight gain).

The obtained insoluble and infusible substrate (A-3 comparison) has an average particle size of 0.8 μm, H / C of 0.13, a specific surface area by the BET method of 271 m ² / g, and a crystal plane of 002. The interplanar spacing was 3.77 mm and the crystallite length in the C-axis direction was 13.3 mm. Further, when the isothermal adsorption curve by nitrogen gas at 77.4 K was analyzed by the QSDFT method, the amount of pores of 20 mm or less was 0.116 cc / g.

  Next, 75 parts by weight of the above insoluble infusible substrate (A-3 comparison), 15 parts by weight of conductive material acetylene black and 10 parts by weight of PVDF (polyvinylidene fluoride) were mixed with NMP (N-methyl-2-pyrrolidone). A negative electrode mixture slurry was obtained. Prepare a 4 μm thick conductive paint made of graphite on one side of an 18 μm copper foil, and apply the negative electrode mixture slurry on the surface of the current collector on which the conductive paint is applied. After drying, press working was performed to obtain an electrode.

The electrode obtained above was used as a working electrode, lithium metal was used as a counter electrode, and LiPF ₆ was added at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methylethyl carbonate were mixed at an electrolyte ratio of 3: 7 (volume ratio). An electrochemical cell was made in a dry box using the dissolved solution. Insoluble infusible substrate (A-3 comparison) Capacity when a constant voltage of 1 mV is applied to the lithium potential at a current of 60 mA / g per weight for 12 hours and then discharged to 2.5 V at a current of 60 mA / g Has a high capacity of 630 mAh / g.

The negative electrode (electrode area: 14 × 20 mm) having a thickness of 44 μm and a density of 0.95 g / cm ³ obtained as described above was used as a working electrode, lithium metal was used as a counter electrode, and ethylene carbonate and methyl ethyl carbonate were used as electrolytes. An electrochemical cell was prepared in a dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent mixed at 7 (volume ratio). The insoluble infusible substrate (A-3 comparison) was predoped with 489 mAh / g of lithium per weight of the insoluble infusible substrate (A-3 comparison) at a current of 60 mA / g.

This lithium pre-doped negative electrode and a positive electrode 1 (electrode area: 14 × 20 mm) having a thickness of 70 μm and a density of 2.1 g / cm ³ are combined, and the same quadrupole cell as in Example 1 (Non-patent Documents 11 and Non-patent Documents) 12) was prepared in a dry room.

  Between the positive and negative electrodes of the obtained quadrupole cell, a constant current (0.72 mA) / constant voltage charge for 4.2 V-8 hours was performed for 8 hours, and the battery was discharged to 2.3 V with a constant current of 0.72 mA. The charge capacity is 3.48 mAh, the amount of lithium doped from the positive electrode in the initial charge is 394 mAh / g per weight of the insoluble infusible substrate (A-3 comparison), and the insoluble infusible substrate totaled with the pre-doping amount (A-3 comparison) The amount of lithium supported per weight was 884 mAh / g. The discharge capacity was 3.30 mAh.

  By applying the above-mentioned quadrupole cell to a current value of 1.66 mA and a voltage range of 2.3 V to 4.2 V at 25 ° C. by a “current pause method” (see Non-Patent Document 11 and Non-Patent Document 12), By repeating the pause for 60 seconds, the battery was charged and discharged, and the current pause method resistance was measured. From the first discharge point of discharge of the potential between the negative electrode and the negative reference electrode, the current pause method resistance of the negative electrode (excluding the separator resistance determined from the potential change between the positive reference electrode and the negative reference electrode) was determined in the same manner as in Example 1. The current quiescent resistance of the negative electrode separated by the quadrupole cell is 1.25 Ω with a current quiescent resistance of up to 1 second, 2.10 Ω with a current quiescent resistance of up to 10 seconds, and a current quiescent method of up to 60 seconds The resistance was 3.86Ω.

As is apparent from the examples so far, the insoluble and infusible substrate (A) used for the negative electrode of the nonaqueous secondary battery of the present invention can be reversibly doped with lithium exceeding 500 mAh / g. It is a high-capacity material, and has a higher discharge capacity than a negative electrode using a graphite-based carbon material and a non-graphitizable carbon material (theoretical capacity of graphite carbon material is 372 mAh / g) used in conventional lithium ion batteries. I understand that. Further, by controlling to the structure of the insoluble and infusible substrate (A) (specific surface area of 150 m ² / g or less), as is apparent from Table 2, the materials described in JP-A-2007-294286 ( The “current quiescent resistance” at 60 seconds, which was a problem of Comparative Example 1), can be greatly reduced, and can be set to a value of ½ or less of a negative electrode using a graphite-based material. In addition, about the "current resting method resistance" isolate | separated with the quadrupole cell of the negative electrode using a graphite-type material, the value described in the nonpatent literature 12 is shown according to Table 2 as a reference value. The examples described so far have clarified the effect of the negative electrode in the nonaqueous secondary battery of the present invention. Further, the features of the nonaqueous secondary battery of the present invention will be described in Example 3 to further clarify the energy density and output characteristics.

(Example 3)
An electrode having a thickness of 43 μm and a density of 1.0 g / cm ³ obtained in Example 1 mainly composed of an insoluble infusible substrate (A-1) was used as a working electrode, lithium metal was used as a counter electrode, and an electrolyte solution was used. An electrochemical cell was produced in a dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a ratio of 3: 7 (volume ratio). Lithium doping is performed at a current of 54 mA / g per weight of the insoluble and infusible substrate (A-1) at 1 mV or more with respect to the lithium potential, and 544 mAh / g doping per weight of the insoluble and infusible substrate (A-1). The negative electrode which carried lithium beforehand was obtained.

The negative electrode on which lithium is previously supported, the positive electrode 1 having a thickness of 67 μm and a density of 2.1 g / cm ³ , and a cellulose-based separator (thickness: 30 μm) are combined, and ethylene carbonate and methyl ethyl carbonate are used as an electrolytic solution. A lithium ion battery for evaluation (single-layer cell: one positive electrode and one negative electrode) in a dry box using a solution in which LiPF ₆ was dissolved in a solvent mixed at 3: 7 (volume ratio) to a concentration of 1 mol / l. It was produced with.

  The amount of lithium doped from the positive electrode in the initial charge is 359 mAh / g per weight of the insoluble infusible substrate (A-1), and lithium per weight of the insoluble infusible substrate (A-1) combined with the pre-doping amount. The supported amount was 903 mAh / g.

The resistance of the battery was evaluated by the “current pause method” at 25 ° C. with a current value of 1.5 mA and a voltage range of 2.5 V to 4.2 V while periodically pausing for 60 seconds. . The pause method resistance up to 1 second of the first discharge rest point is 2.27Ω per 2.8 cm ² , the pause method resistance up to 10 seconds is 3.60Ω, and the pause method resistance up to 60 seconds is 5. It was 60Ω.

When the battery was charged and discharged at a current of 0.7 mA between a voltage of 4.2 V and 2.5 V, the discharge capacity was 3.25 mAh. Moreover, the average voltage at the time of this discharge was 3.45V. An electrode unit volume of 0.0456 cc was obtained from the electrode area 2.8 cm ² , the thickness of the positive electrode, the thickness of the negative electrode, and the thickness of the separator used in this evaluation lithium ion battery (single layer cell: one positive electrode, one negative electrode). . However, the current collector thickness was calculated with a positive electrode current collector of 10 μm and a negative electrode current collector of 9 μm, because the thickness of the current collector was half-coated in an actual battery. From the discharge capacity, the average voltage during discharge, and the electrode unit volume, the energy density per electrode unit volume was 245 Wh / L.

With the method described in Non-Patent Document 12, using the discharge curve at a voltage of 4.2 V to 2.5 V and a current of 0.7 mA in the charge / discharge as a basic line, the output curve from the time dependence of the current pause method resistance Was calculated. With an output at 160 mA current equivalent to 50 CA, output of 24.9 seconds is possible between a voltage of 4.2 V and 3.0 V, and at an output of 320 mA current equivalent to 100 CA, a voltage between 4.2 V and 3.0 V is 4 Output of 6 seconds was possible.
(Comparative Example 3)

An electrode having a thickness of 43 μm and a density of 1.0 g / cm ³ obtained in Example 1 mainly composed of an insoluble infusible substrate (A-1) was used as a working electrode, lithium metal was used as a counter electrode, and an electrolyte solution was used. An electrochemical cell was produced in a dry box using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent in which ethylene carbonate and methyl ethyl carbonate were mixed at a ratio of 3: 7 (volume ratio). Lithium doping is performed at a current of 54 mA / g per weight of the insoluble and infusible substrate (A-1) at 1 mV or more with respect to the lithium potential, and 544 mAh / g doping per weight of the insoluble and infusible substrate (A-1). The negative electrode which carried lithium beforehand was obtained.

The negative electrode preliminarily supporting lithium, the positive electrode 4 having a thickness of 52 μm and a density of 2.3 g / cm ³ (not including a fibrous conductive material), and a cellulose-based separator are combined, and ethylene carbonate and methyl ethyl are used as an electrolyte solution. A lithium ion battery for evaluation (single-layer cell: one positive electrode and one negative electrode) was prepared using a solution obtained by dissolving LiPF ₆ at a concentration of 1 mol / l in a solvent mixed with carbonate at a ratio of 3: 7 (volume ratio). Made in a dry box.

  The amount of lithium doped from the positive electrode in the initial charge is 345 mAh / g per weight of the insoluble infusible substrate (A-1), and lithium per weight of the insoluble infusible substrate (A-1) combined with the pre-doping amount. The supported amount was 889 mAh / g.

The single-layer cell was evaluated by the “current pause method” at 25 ° C., with a current value of 1.5 mA and a voltage range of 2.5 V to 4.2 V, while periodically pausing for 60 seconds while evaluating the battery resistance. went. The resting method resistance (including separator) up to 1 second of the first resting point of discharge is 3.20Ω per 2.8 cm ² , and the resting method resistance (including separator) up to 10 seconds is 4.80Ω, 60 seconds. The resting method resistance until (including the separator) was 6.93Ω.

When the battery was charged and discharged at a current of 0.7 mA between a voltage of 4.2 V and 2.5 V, the discharge capacity was 3.14 mAh. Moreover, the average voltage at the time of this discharge was 3.45V. An electrode unit volume of 0.0426 cc was obtained from the electrode area 2.8 cm ² , the thickness of the positive electrode, the thickness of the negative electrode, and the thickness of the separator used in this evaluation lithium ion battery (single layer cell: one positive electrode, one negative electrode). . However, the thickness of the current collector was calculated by taking the case of double-sided coating into half the thickness and using a positive electrode current collector of 10 μm and a negative electrode current collector of 9 μm. From the discharge capacity, the average voltage during discharge, and the electrode unit volume, the energy density per electrode unit volume was 255 Wh / L.

  The output was calculated from the current pause method resistance as in Example 3 using the discharge at a voltage of 4.2 V to 2.5 V in the charging / discharging at a current of 0.7 mA as a basic line (see Non-Patent Document 12). With an output at 160 mA current equivalent to 50 CA, an output of 16.6 seconds is possible at a voltage between 4.2 V and 3.0 V, and at an output at 320 mA current equivalent to 100 CA, it is 1 between 4.2 V and 3.0 V. Output of 6 seconds was possible. Compared with Example 3, when the positive electrode which does not contain a fibrous conductive material is used, it turns out that the duration in continuous discharge falls.

  Examples of the use of the non-aqueous secondary battery of the present invention include use of an output storage device in a hybrid electric vehicle, a fuel cell electric vehicle, and the like. In particular, this non-aqueous secondary battery can achieve both high energy density and unprecedented high output, and contributes to the reduction in size and weight of the output power storage device.

DESCRIPTION OF SYMBOLS 1 Positive electrode layer 1 'Positive electrode collector 2 Negative electrode layer 2' Negative electrode collector 3 Positive reference electrode 3 'Positive reference electrode lead 4 Negative reference electrode 4' Negative reference electrode lead 5 Separator (including electrolyte)

Claims (8)

In a non-aqueous secondary battery comprising a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte solution in which a lithium salt is dissolved in a non-aqueous solvent, the positive electrode contains at least an active material capable of inserting and extracting lithium, and a fibrous conductive material. And the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05 and an insoluble infusible substrate (A) having a crystal plane 002 plane spacing of 3.6 mm or more as a main component, The insoluble infusible substrate (A) has an average particle size of 2.0 μm or less, a specific surface area by the BET method of less than 150 m ² / g, and lithium of 500 mAh / g or more per weight of the insoluble infusible substrate (A). A non-aqueous secondary battery, which is supported.   2. The non-aqueous secondary battery according to claim 1, wherein in the non-aqueous secondary battery, pores of 20 μm or less of the insoluble infusible substrate (A) which is a main component of the negative electrode are 0.05 cc / g or less. Secondary battery. In the non-aqueous secondary battery, the insoluble infusible substrate (A) which is the main component of the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, and a specific surface area by the BET method of less than 500 m ² / g. Part or all of the pores of the pulverized insoluble infusible substrate (B) having an average particle size of 2.0 μm or less obtained by crushing the insoluble infusible substrate (B) is filled with a carbonaceous material. The non-aqueous secondary battery according to claim 1, wherein the non-aqueous secondary battery is a non-aqueous secondary battery. In the non-aqueous secondary battery, the insoluble infusible substrate (A) which is the main component of the negative electrode has a hydrogen atom / carbon atom ratio of 0.60 to 0.05, and a specific surface area by the BET method of less than 500 m ² / g. The insoluble infusible substrate (B) pulverized product having an average particle size of 2.0 μm or less obtained by pulverizing the insoluble infusible substrate (B) is obtained by heat treatment in the presence of a carbon precursor. The non-aqueous secondary battery according to claim 1, wherein the non-aqueous secondary battery is a non-aqueous secondary battery.   5. The non-aqueous secondary battery according to claim 1, wherein the positive electrode includes at least an active material capable of inserting and extracting lithium, a fibrous conductive material, and a non-fibrous conductive material. Non-aqueous secondary battery.   6. The non-aqueous secondary battery according to claim 1, wherein the fibrous conductive material contained in the positive electrode is 2 wt% or more and 13 wt% or less in the non-aqueous secondary battery. .   In the non-aqueous secondary battery, the fibrous conductive material contained in the positive electrode is 2 wt% or more and 13 wt% or less, and the total amount of the fibrous conductive material and the non-fibrous conductive material is 7 wt% or more and 20 wt%. The nonaqueous secondary battery according to claim 6, wherein:   8. The non-aqueous secondary battery according to claim 1, wherein the active material capable of occluding and desorbing lithium contained in the positive electrode has an average particle size of 7 μm or less. 9. Water-based secondary battery.

Images