JP5214088B2 - Non-aqueous electrolyte battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte battery and intends to provide a non-aqueous electrolyte battery having high energy density and excellent battery performance.

  In this specification, the non-aqueous electrolyte means that the solvent contains an electrolyte salt. Here, the non-aqueous electrolyte may be liquid or solid.

A non-aqueous electrolyte battery represented by a lithium ion secondary battery is characterized in that a high voltage can be obtained in principle because it can take out a high voltage. LiCoO ₂ which is a lithium transition metal composite oxide is mainly used as a positive electrode active material for a positive electrode of a lithium ion secondary battery currently on the market. Moreover, a negative electrode active material made of a carbon material capable of occluding and releasing lithium ions is mainly used for the negative electrode.

  In recent years, the energy density of nonaqueous electrolyte batteries has been improved and improved due to improvements in electrode active material materials, thinning of various members used in batteries, progress in electrode manufacturing techniques, and the like. Currently, there is a demand for higher energy density.

  However, it has almost reached the limit for further increasing the energy density of the nonaqueous electrolyte battery. The reason for this is that the positive electrode active material and the negative electrode active material are basically not changed greatly, and the thickness of the current collector, separator, exterior body, etc. is from the viewpoint of manufacturing problems and quality assurance. In other words, it is approaching the limit of thinning.

  A typical method for manufacturing a nonaqueous electrolyte battery will be described below. The electrode (positive electrode, negative electrode) is, for example, a binder and a conductive agent added to the particulate active material (positive electrode active material, negative electrode active material) as necessary, and kneaded using a volatile solvent to form a paste, After coating on the current collector (positive electrode current collector, negative electrode current collector), an electrode mixture (positive electrode mixture, negative electrode mixture) is formed on the current collector by removing the volatile solvent. Here, in the electrode mixture, voids are provided between the active material particles. The packing density and porosity of the active material in the electrode mixture can be controlled by pressing the electrode mixture after removing the volatile solvent. After the electrode (positive electrode, negative electrode) and separator are combined to form a power generation element, the power generation element is installed in the exterior body and a nonaqueous electrolyte is injected. Thereby, a nonaqueous electrolyte is arrange | positioned in the said space | gap part. Here, by ensuring a certain degree of porosity in the mixture, the nonaqueous electrolyte can be sufficiently introduced into the voids by injection, and this enables sufficient contact between the active material particles and the nonaqueous electrolyte. The electrode reaction accompanying charging and discharging can be sufficiently advanced.

When the packing density of the active material in the electrode mixture is increased, the energy density of the nonaqueous electrolyte battery can be increased in calculation. It is easy to produce an electrode with an increased packing density of the mixture by using the common technical knowledge of those skilled in the art by adjusting the press pressure after coating and drying. However, when the packing density is increased, the porosity is inevitably lowered, and the nonaqueous electrolyte cannot be sufficiently introduced into the voids by injection, and therefore sufficient contact between the active material particles and the nonaqueous electrolyte is achieved. Since it cannot be ensured, the electrode reaction cannot proceed sufficiently. Therefore, from the viewpoint of a non-aqueous electrolyte battery with sufficient battery performance, in the current non-aqueous electrolyte battery, the positive electrode filling density in the positive electrode mixture is about 3.1 g / cm ³ and the negative electrode filling in the negative electrode mixture The density is designed to be about 1.4 g / cm ³ .

  In order to obtain a non-aqueous electrolyte battery having a higher energy density, there has been a demand for a technique capable of sufficiently disposing the non-aqueous electrolyte in the gap of the electrode even when an electrode having a high packing density is used.

As a typical nonaqueous electrolyte used for a nonaqueous electrolyte battery, LiPF which is an electrolyte salt is mixed with a mixed solvent in which ethylene carbonate which is a high dielectric constant solvent and diethyl carbonate which is a low viscosity solvent are mixed at a volume ratio of 2: 3. An example is one in which ₆ is dissolved at a concentration of 1 mol / l. Thus, by mixing a large amount of the low-viscosity solvent at a volume ratio, the viscosity of the non-aqueous electrolyte can be lowered, so that the non-aqueous electrolyte is sufficiently injected into the gap provided in the mixture. Can be arranged. However, in recent years, batteries having a flexible exterior body such as a metal resin composite film have been developed and put into practical use. However, a flexible exterior body such as a metal resin composite film can be deformed by changes in battery internal pressure. Since the low-viscosity solvent generally has a high vapor pressure, if the non-aqueous electrolyte contains a large amount of the low-viscosity solvent, there is a problem that the battery tends to swell. Therefore, there has been a demand for a technique that can provide a nonaqueous electrolyte battery having sufficient battery performance while using a nonaqueous electrolyte that does not contain a low-viscosity solvent or contains a small amount thereof.

However, since the high dielectric constant solvent generally has a high viscosity, if a non-aqueous electrolyte containing no or a small proportion of a low-viscosity solvent is used, the non-aqueous electrolyte is placed in the gap of the electrode mixture having a high packing density. If the above-mentioned problem to be sufficiently arranged is not solved, on the contrary, it is in the direction that sufficient arrangement of the non-aqueous electrolyte becomes difficult. Furthermore, when the packing density of the positive electrode mixture is designed to exceed 3.3 g / cm ³ Or, when the packing density of the negative electrode mixture is designed to exceed 1.4 g / cm ³ , there is a problem that the non-aqueous electrolyte can hardly be arranged in the gap and the battery performance is greatly deteriorated. .

In general, as a method for sufficiently disposing a non-aqueous electrolyte in the gap of the electrode mixture, a long standing process is provided after the injection, or a high temperature is left after the injection. However, it is difficult to adopt a sufficient standing time after injecting the liquid because the manufacturing cost is greatly increased, and it is difficult to adopt the standing process at a high temperature. there were. LiPF ₆ as an electrolyte salt is typically used in a general non-aqueous electrolyte battery because it can bring out excellent electrode performance. However, LiPF ₆ is not good in thermal stability, so after injection. Leaving it at a high temperature was not the preferred method. Also, when the packing density of the positive electrode mixture is designed to exceed 3.3 g / cm ³ as described above, or when the packing density of the negative electrode mixture is designed to exceed 1.4 g / cm ³ , There is a problem that it is substantially impossible to spread the non-aqueous electrolyte sufficiently even if a method of providing a standing process for a long time after the liquid or a method of using the standing process at a high temperature is used.

  In addition, as a non-aqueous electrolyte, there is a battery using a gel electrolyte instead of a liquid non-aqueous electrolyte (electrolytic solution) (hereinafter also referred to as “gel electrolyte battery”), and in particular, a flexible exterior body such as a metal resin composite film is used. It is going to be used for many batteries. Here, as a method of disposing the non-aqueous electrolyte in the gap of the electrode mixture, polymerization that is a polymer precursor constituting the gel in the gap portion provided in the electrode mixture (positive electrode mixture, negative electrode mixture). A method of solidifying after disposing a non-aqueous electrolyte containing a monomer having a functional functional group (hereinafter also referred to as “monomer solution”) is common. Here, as a method of arranging the monomer liquid in the void portion provided in the electrode mixture, the monomer liquid is added to the active material particles to which a conductive agent is added as necessary, and is applied as a paste on the current collector and then solidified. However, since it is difficult to make the active material density of the mixture sufficiently high with this method, it is not widely used.

  Thus, in the gel electrolyte battery, since the gel after solidification does not have fluidity, if the monomer liquid cannot be sufficiently disposed in the gap of the mixture before solidification, sufficient battery performance is achieved. Therefore, the problem of sufficiently disposing the non-aqueous electrolyte in the gaps of the electrode in which the active material is arranged at a high density must be achieved more reliably. Furthermore, in order to take advantage of the fact that the gel electrolyte battery can reduce the weight of the exterior body, a flexible exterior body material is often used, and the non-aqueous electrolyte does not need to contain many low-viscosity solvents having a high vapor pressure. Is even higher. In addition, since the viscosity of a monomer solution containing a monomer is often higher than that of a non-aqueous electrolyte that does not contain a monomer, the above-described problem is even more serious.

In Patent Document 1, a lithium salt such as LiBF ₄ or LiPF ₆ as a solute and a lithium salt such as LiN (CF ₃ SO ₂ ) ₂ or LiC (CF ₃ SO ₂ ) ₃ are used as a solute. It is described that self-discharge can be suppressed, storage characteristics can be improved, the conductivity of the electrolyte can be improved, and a higher energy density non-aqueous electrolyte battery can be provided. However, this Patent Document 1 does not have a problem of sufficiently arranging the nonaqueous electrolyte in the gap of the electrode mixture.

In Patent Document 2, a polymer solid electrolyte using a lithium salt having a perfluoroalkyl group such as LiN (CF ₃ SO ₂ ) ₂ or LiC (CF ₃ SO ₂ ) ₃ is applied on a positive electrode and impregnated. Then, by performing thermal polymerization (claim 1), it is possible to provide a polymer solid electrolyte battery having a higher energy density and improved contact between the positive electrode mixture and the polymer solid electrolyte (paragraph [ 0058]) is described. However, in this patent document 2, as an electrolyte salt, an inorganic anion LiPF ₆ or LiBF ₄ and an organic anion LiN (C _n F _{2n + 1} SO ₂ ) ₂ (n: an integer of 1 to 4) or LiC (C _n F _2n There is no description about using an imide salt or a methide salt represented by ₊₁ SO ₂ ) ₃ (n: an integer of 1 to 4).
Japanese Patent No. 3016447 Japanese Patent No. 3499916

  The present invention has been made in view of the above problems, and is intended to provide a non-aqueous electrolyte battery having a high energy density that can sufficiently exhibit battery performance while using an electrode having a high filling rate. To do. Another object of the present invention is to provide a nonaqueous electrolyte battery having a high energy density while using a nonaqueous electrolyte containing 60% by volume or more of a solvent having a dielectric constant of 40 or more.

  The configuration and operational effects of the present invention are as follows. However, the action mechanism includes estimation, and the success or failure of the action mechanism does not limit the present invention.

The present invention provides a nonaqueous electrolyte battery comprising a positive electrode, a negative electrode and a nonaqueous electrolyte, wherein the positive electrode contains a positive electrode active material made of a lithium transition metal composite oxide, and the positive electrode packing density of the positive electrode is 3.5 g / cm. ³ or more, the non-aqueous electrolyte includes an inorganic anion and an organic anion, the inorganic anion includes one or both of PF ₆ ⁻ and BF ₄ ⁻ , and the organic anion is (C _n F _{2n + 1} SO ₂ ) (C _m F _{2m + 1} SO ₂ ) N ⁻ (n and m are both integers of 1 to 4, and n and m may be the same or different). The molar ratio of the organic anion to the inorganic anion is not less than 1/4 and not more than 1/1, and the nonaqueous electrolyte further includes 60% by volume or more of a solvent having a dielectric constant of 40 or more. Non-aqueous electrolyte battery characterized in that A.

According to such a configuration, a non-aqueous electrolyte can be sufficiently disposed even for a positive electrode having a positive electrode filling rate of 3.5 g / cm ³ or more, and thus a non-aqueous electrolyte battery having a high energy density is provided. Can do. If the positive electrode filling density is 3.6 g / cm ³ or more, the effect of the present invention can be achieved in a positive electrode filled with higher density, and thus a non-aqueous electrolyte battery with higher energy density can be provided, which is preferable. .

In addition, the present invention is characterized in that the positive electrode packing density of the positive electrode is 3.7 g / cm ³ or less. According to such a configuration, the porosity of the positive electrode mixture can be sufficiently secured, and the possibility that the porosity becomes too low and the arrangement of the nonaqueous electrolyte in the voids becomes insufficient can be reduced.

Further, the present invention is pre SL negative electrode contains a negative electrode active material composed of carbon material, a negative electrode packing density of the negative electrode is a non-aqueous electrolyte, wherein the Ru der 1.5 g / cm ³ or more.

According to such a configuration, since the nonaqueous electrolyte can be sufficiently disposed even for the negative electrode having a negative electrode filling rate of 1.5 g / cm ³ or more, a nonaqueous electrolyte battery having a high energy density is provided. Can do. If the negative electrode filling density is 1.6 g / cm ³ or more, the effect of the present invention is exerted in the negative electrode filled with higher density, and thus a non-aqueous electrolyte battery with higher energy density can be provided. preferable.

In addition, the present invention is characterized in that the negative electrode filling density of the negative electrode is 1.8 g / cm ³ or less. According to such a configuration, the porosity of the negative electrode mixture can be sufficiently secured, and the possibility that the porosity becomes too low and the arrangement of the nonaqueous electrolyte in the voids becomes insufficient can be reduced.

  The nonaqueous electrolyte battery of the present invention is characterized in that the nonaqueous electrolyte contains 60% by volume or more of a high dielectric constant solvent having a dielectric constant of 40 or more.

  According to such a configuration, a positive electrode in which an active material is arranged at a high density while using a non-aqueous electrolyte that contains 60% by volume or more of a high dielectric constant solvent having a dielectric constant of 40 or more and a low content of a low viscosity solvent. In addition, the nonaqueous electrolyte can be sufficiently distributed to the negative electrode. Therefore, since the vapor pressure of the non-aqueous electrolyte can be lowered, it is possible to suppress the swelling of the battery using the exterior body that can be deformed by the change in the battery internal pressure such as the metal resin composite film. From this viewpoint, the ratio of the high dielectric constant solvent having a dielectric constant of 40 or more is more preferably 70% by volume or more, further preferably 85% by volume or more, and most preferably 90% by volume or more.

  In the nonaqueous electrolyte battery of the present invention, the nonaqueous electrolyte is a gel electrolyte.

  According to such a configuration, in a gel electrolyte battery in which the monomer liquid is required to be disposed on the positive electrode and the negative electrode before solidification, the electrode has a high energy density while using an electrode having a high active material filling density. A nonaqueous electrolyte battery (gel electrolyte battery) can be provided.

  The nonaqueous electrolyte battery of the present invention is characterized in that the outer package can be deformed by a change in the battery internal pressure.

  According to such a configuration, even in a battery using an exterior material that can be deformed by a change in the internal pressure of the battery such as a metal resin composite film, the increase in the internal pressure is suppressed according to the present invention, so that the expansion of the battery is suppressed. A non-aqueous electrolyte battery can be provided.

When the positive electrode having a positive electrode filling density of 3.5 g / cm ³ or more and the negative electrode having a negative electrode filling density of 1.5 g / cm ³ or more are combined, the energy density of the battery may be increased. This is preferable because it is possible.

  In the specification of the present application, “positive electrode packing density” and “negative electrode packing density” are parts of a positive electrode and a negative electrode that do not include a current collector, that is, an active material, if necessary, a conductive agent, a binder, and the like. It shall be calculated with respect to the electrode mixture part formed by mixing. The positive electrode mixture or the negative electrode mixture may be formed by forming a layer on a plate-like or foil-like current collector, and is embedded in a mesh-like, mesh-like, or fiber-like current collector. In any case, the packing density is calculated by subtracting the current collector portion. That is, the positive electrode packing density and the negative electrode packing density are obtained from the volume and weight of the electrode mixture part to be calculated. When the electrode mixture is integrated with the current collector, the volume and weight of the current collector are subtracted from the volume and weight of the positive electrode or negative electrode including the current collector, thereby filling the positive electrode and the negative electrode. The density can be determined. In calculating the “positive electrode packing density” and the “negative electrode packing density”, it is assumed that a non-aqueous electrolyte is not disposed in the electrode. When it is necessary to measure the packing density for an electrode containing a non-aqueous electrolyte, the electrode is immersed in a low boiling point solvent (for example, dimethyl carbonate) for about 1 minute, and then another low boiling point solvent (for example, dimethyl carbonate). The nonaqueous electrolyte can be substantially removed by immersing in carbonate) for about 1 minute and finally vacuum drying with a rotary pump or the like.

The positive electrode active material composed of a lithium transition metal composite oxide which can be applied to the present invention, but are not particularly limited, the general formula _{Li x Ni a Mn b Co c} O z (0 <x ≦ 1. 3, 0 ≦ a <1.0, 0 ≦ b <0.6, 0 ≦ c ≦ 1, a + b + c = 1, 1.7 ≦ z ≦ 2.3) are preferable. In addition, it has been confirmed that the effects of the present invention are surely exhibited in the above composition range. Among them, those in which the values of the coefficients a and b in the above general formula are substantially equal, such as LiCoO ₂ , LiNi _0.165 Mn _0.165 Co _0.67 O ₂ , and LiNi _0.2 Mn _0.2 Co _0.4 O ₂ are preferable. A conductive agent, a binder, or the like made of a known material can be applied to the positive electrode within the scope of common technical knowledge. If the positive electrode mixture is a positive electrode containing 85% or more of a positive electrode active material made of a lithium transition metal composite oxide, the effects of the present invention are exhibited regardless of the type and ratio of other materials such as a conductive agent and a binder.

The negative electrode active material made of a carbon material that can be applied to the present invention is not particularly limited, and those commonly known as carbon materials capable of occluding and releasing lithium that can be used for the negative electrode of a lithium battery are generally applied. Is possible. For example, the lattice spacing (d ₀₀₂ ) is 0.333 to 0.350 nm, the crystallite size (La) in the a-axis direction is 20 nm or more, and the crystallite size (Lc) in the c-axis direction is 20 nm or more. A material having a true density of 2.00 to 2.25 g / cm ³ is a suitable material. A binder made of a known material can be applied to the negative electrode within the scope of common technical knowledge. If the negative electrode mixture is a negative electrode containing 90% or more of a carbon material, the effects of the present invention can be achieved regardless of the type and ratio of other materials such as a binder.

Aqueous PF electrolyte inorganic anions ₆ ^- and BF ₄ ^- to intended to include either or both Of, accomplished by dissolving either or both of LiPF ₆ and LiBF ₄ in a non-aqueous solvent it can. Further, the nonaqueous electrolyte is an organic anion _{(C n F 2n + 1 SO} 2) (C m F 2m + 1 SO 2) N - (n, m are both an integer of 1 to 4, n and m are as Or may be different from each other), a lithium salt of the organic anion, specifically, LiN (CF ₃ SO ₂ ) ₂ , LiN ( This can be achieved by selecting one or more of C ₂ F ₅ SO ₂ ) ₂ , LiN (CF ₃ SO ₂ ) (C ₄ F ₉ SO ₂ ), etc. and dissolving them.

  The amount of the organic anion in the non-aqueous electrolyte is not particularly limited, but the molar ratio of the organic anion to the inorganic anion is 1 in order to sufficiently arrange the non-aqueous electrolyte in the gap in the electrode mixture. / 99 or more is preferable, and 1/4 or more is more preferable. Moreover, in order to reduce the possibility that the internal resistance of the battery increases, the molar ratio of the organic anion to the inorganic anion is preferably 2/3 or less, and more preferably 1/1 or less.

The solvent having a dielectric constant of 40 or more constituting the nonaqueous electrolyte of the present invention is not particularly limited as long as it can dissolve a lithium salt suitably, but propylene carbonate, ethylene carbonate, butylene carbonate, γ- Bed Ji Rorakuton, dimethyl sulfoxide, .gamma.-valerolactone, sulfolane and the like. Especially, it is preferable to use propylene carbonate 40 volume% or more of the whole solvent, and it is more preferable to use propylene carbonate 50 volume% or more of the whole solvent.

In addition, by setting the standing step after the injection to 30 ° C. or higher, the nonaqueous electrolyte can be quickly spread into the gaps of the electrode mixture, and chemical conversion (initial charging) is started in a short time. Therefore, it is possible to provide a non-aqueous electrolyte battery having a high energy density while keeping the manufacturing cost low. In addition, when LiPF ₆ is used as an electrolyte salt, battery performance can be improved. On the other hand, a non-aqueous electrolyte using LiPF ₆ alone does not have good thermal stability. By using a mixture, the thermal stability of the non-aqueous electrolyte is improved. Therefore, the nonaqueous electrolyte used in the present invention preferably contains at least PF ₆ ⁻ as an inorganic anion, so that the effects of the present invention can be effectively exhibited.

According to Claims 1 and 2, even when the positive electrode packing density of the positive electrode mixture is 3.5 g / cm ³ or more, the non-aqueous electrolyte is sufficiently distributed inside the voids, whereby a non-aqueous electrolyte having a high energy density is obtained. An electrolyte battery can be provided.

According to Claims 3 and 4, even when the negative electrode filling density of the negative electrode mixture is 1.5 g / cm ³ or more, the non-aqueous electrolyte is sufficiently distributed inside the voids, whereby a non-aqueous electrolyte having a high energy density is obtained. An electrolyte battery can be provided.

  According to claim 5, it is possible to provide a non-aqueous electrolyte battery having a high energy density while using a non-aqueous electrolyte containing 60% by volume or more of a high dielectric constant solvent having a dielectric constant of 40 or more, which is deformed by a change in battery internal pressure. In this case, it is possible to suppress the swelling of the battery.

  According to the sixth aspect, a gel electrolyte battery having a high energy density can be provided.

  According to the seventh aspect of the present invention, it is possible to provide a non-aqueous electrolyte battery having a high energy density in which swelling of the battery using the outer package that can be deformed by a change in battery internal pressure is suppressed.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, these do not limit this invention at all.

(Nonaqueous electrolyte A)
In a mixed solvent in which ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) were mixed at a volume ratio of 5: 4: 1, LiPF _{6 having} a concentration of 0.5 mol / liter and 0.5 mol were mixed. LiN (C ₂ F ₅ SO ₂ ) ₂ having a concentration of 1 / liter was dissolved.

(Nonaqueous electrolyte B)
LiPF ₆ having a concentration of 1.0 mol / liter was dissolved in a mixed solvent in which ethylene carbonate (EC), propylene carbonate (PC) and diethyl carbonate (DEC) were mixed at a volume ratio of 5: 4: 1.

(Nonaqueous electrolyte C)
To 85 parts by weight of the non-aqueous electrolyte A, 12 parts by weight of methyl methacrylate (MMA) and 3 parts by weight of ethylene glycol dimethacrylate (EGDMA) were added and mixed uniformly to obtain an appropriate amount of azobisisobutyronitrile (AIBN). Was added to make non-aqueous electrolyte C.

(Preparation of positive electrode)
LiCoO ₂ (positive electrode active material), acetylene black and polyvinylidene fluoride (PVdF) are mixed at a weight ratio of 90: 5: 5, and N-methylpyrrolidone is added as a dispersion medium and kneaded and dispersed to obtain a paste-like coating solution. Was prepared. In addition, PVdF converted into solid weight using the liquid by which solid content was melt | dissolved and disperse | distributed. The coating solution was applied to both sides of a positive electrode current collector made of an aluminum foil having a thickness of 15 μm, dried, and pressed to produce a positive electrode in which a positive electrode mixture was formed on the positive electrode current collector. Here, the positive electrode filling density is adjusted to 3.1 g / cm ³ , 3.3 g / cm ³ , 3.4 g / cm ³ , 3.5 g / cm ³ , 3.6 g / cm ³ by appropriately adjusting the pressing pressure. And positive electrodes of 3.7 g / cm ³ respectively.

(Preparation of negative electrode)
A paste-like aqueous coating solution in which graphite (negative electrode active material), carboxymethylcellulose, and styrene-butadiene rubber were mixed at a weight ratio of 97: 1.5: 1.5 was prepared. The coating solution was applied to both sides of a negative electrode current collector made of a copper foil having a thickness of 10 μm, dried, and pressed to prepare a negative electrode in which a negative electrode mixture was formed on the negative electrode current collector. Here, by appropriately adjusting the press pressure, a negative electrode packing density of ^{1.4g / cm 3, 1.5g / cm} 3, 1.6g / cm 3, 1.7g / cm 3 and 1.8 g / cm ³ The negative electrode which is each of these was produced.

  The nonaqueous electrolyte battery is assembled according to the following formulation. A positive electrode lead terminal and a negative electrode lead terminal are attached to the positive electrode current collector and the negative electrode current collector, respectively. A positive electrode and a negative electrode are laminated via a polypropylene separator (porosity 50%), and the electrode group is formed by winding flatly. The electrode group is housed in a bag-shaped exterior body made of a metal resin composite film (aluminum laminate film), and the opening of the exterior body is sealed except for the liquid injection hole. Next, a nonaqueous electrolyte is injected from the liquid injection hole under a reduced pressure environment to seal the liquid injection hole. Next, after passing through a standing process, a non-aqueous electrolyte battery is completed through an initialization process consisting of five cycles of initial charge / discharge. The charge condition in the initialization process is a constant current / constant voltage charge of 0.1 ItmA at a temperature of 20 ° C., a voltage of 4.2 V, 15 hours, and a discharge condition is a constant current discharge of a current of 0.2 ItmA, a final voltage of 3.0 V. A 30-minute pause is provided for each discharge change. The discharge capacity at the fifth cycle of initialization is defined as the initial capacity of the battery. The dimensions of the nonaqueous electrolyte batteries produced in this example and the comparative example are all about 4 mm thick, 35 mm wide, and 62 mm high.

  As shown in Table 1, a positive electrode and a negative electrode were combined, and nonaqueous electrolyte batteries A to C were used for each combination, and nonaqueous electrolyte batteries were assembled according to the above formulation. Next, it was left in a 20 ° C. environment for 1 day as a standing step. Table 1 also shows the discharge capacity per volume of the electrode mixture in the battery based on the value of the initial capacity confirmed by the initialization. The volume of the electrode mixture in the battery is the volume occupied by the positive electrode mixture and the negative electrode mixture, and the portion other than the electrode mixture, such as the positive electrode current collector, the negative electrode current collector, the separator, and the outer package. Does not include volume.

As shown in Table 1, each of the batteries 1 to 10 uses a positive electrode having a positive electrode packing density of 3.1 g / cm ³ and a negative electrode packing density of 1.4 to 1.8 g / cm ^3. It is a non-aqueous electrolyte battery prepared by the above formulation using a non-aqueous electrolyte A or B in combination with a negative electrode. These results show the following.

In the batteries 6 to 10 using the non-aqueous electrolyte B using LiPF ₆ alone as the electrolyte salt, the negative electrode filling density is 1 as compared with the battery 6 using the negative electrode having a negative electrode filling density of 1.4 g / cm ³ . The discharge capacity of the battery 7 using the negative electrode of 5 g / cm ³ is improved. This is because the energy density of the battery 7 is improved by using a negative electrode having a higher negative electrode packing density. However, although the batteries 8 to 10 use the negative electrode having a higher negative electrode packing density, the discharge capacity is decreased. This is presumably because the negative electrode packing density was too high and the non-aqueous electrolyte B was not sufficiently disposed in the gap of the negative electrode. As a result, the battery 7 has the highest energy density among the batteries 6 to 10 having the same volume.

Battery 1 using batteries 1 to 5 using nonaqueous electrolyte A using LiPF ₆ and LiN (C ₂ F ₅ SO ₂ ) ₂ as electrolyte salts, and using a negative electrode having a negative electrode packing density of 1.4 g / cm ³ discharge of the discharge capacity is of the same order as the battery 6, the battery 2-5 using the anode of the negative electrode packing density is 1.5g / cm ³ ~1.8g / cm ³ are all of the battery 7 The capacity is exceeded. This is considered to be due to the fact that the non-aqueous electrolyte A was sufficiently distributed even to the negative electrode having a high negative electrode packing density, and as a result, a non-aqueous electrolyte battery having a higher volumetric energy density was obtained.

Each of the batteries 11 to 20 uses a negative electrode having a negative electrode filling density of 1.5 g / cm ³ and is combined with a positive electrode having a positive electrode filling density of 3.3 to 3.7 g / cm ^3. Or it is the nonaqueous electrolyte battery created by the said prescription using B. These results show the following.

In batteries 16 to 20 using nonaqueous electrolyte B using LiPF ₆ alone as an electrolyte salt, compared with the battery 16 using the positive electrode the positive electrode packing density of 3.3 g / cm ^3, a positive electrode packing density 3. The discharge capacity of the battery 17 using the negative electrode of 4 g / cm ³ is improved. This is because the energy density was improved by using the positive electrode having a higher positive electrode packing density in the battery 17. However, although the battery 18 uses a positive electrode with a higher positive electrode packing density, the discharge capacity is almost the same as that of the battery 17, and the batteries 19 and 20 using a positive electrode with a higher positive electrode packing density have a higher discharge capacity. Conversely, it is falling. This is presumably because the non-aqueous electrolyte B was sufficiently spread within the voids of the positive electrode because the positive electrode packing density was too high and the porosity of the positive electrode was low. As a result, among the batteries 16 to 20 , the battery 17 had the highest energy density.

In the batteries 11 to 15 using the non-aqueous electrolyte A using LiPF ₆ and LiN (C ₂ F ₅ SO ₂ ) ₂ as the electrolyte salt, the positive electrode packing density is 3.3 g / cm ³ or 3.4 g / cm ³ . Batteries 11 and 12 using a positive electrode have the same discharge capacity as batteries 16 and 17, respectively, but a battery using a positive electrode having a positive electrode packing density of 3.5 g / cm ³ or 3.6 g / cm ^3. 13 to 14 all exceed the discharge capacity of the battery 17. This is considered to be due to the fact that the non-aqueous electrolyte was sufficiently distributed even to the negative electrode having a high positive electrode packing density. As a result, a non-aqueous electrolyte battery having a higher volumetric energy density was obtained. The discharge capacity of the battery 15 using the positive electrode having a positive electrode packing density of 3.7 g / cm ³ is about the same as that of the battery 12, but the use of an electrode having a high electrode packing density enables the active capacity that can be accommodated in the same volume. Since the amount of substances increases, there is an advantage that a battery having a larger discharge capacity can be obtained by making and comparing batteries having the same volume.

(Example 2)
A nonaqueous electrolyte battery was assembled according to the above formulation with the same electrode combination as in Example 5 and Example 15, except that nonaqueous electrolyte C (monomer solution) was used as the nonaqueous electrolyte. Next, after standing in a 60 ° C. environment for 1 day as a standing step, it was left at 20 ° C. for 10 hours. By this step, the nonaqueous electrolyte C is solidified to become a gel electrolyte. These batteries are referred to as a battery 21 and a battery 22, respectively.

  The initial capacity values of the battery 21 and the battery 22 were almost the same as those of the battery 5 and the battery 15, respectively. Thus, methyl methacrylate or ethylene glycol dimethacrylate is added, and even in the case of a monomer liquid (nonaqueous electrolyte C) that is considered to have a higher viscosity than the nonaqueous electrolyte A, the active material is filled with an active material at a high density. It was found that it can be sufficiently arranged in the gap. Thus, even when the electrode with the highest packing density was selected from among the positive electrode and the negative electrode prepared this time, the same battery performance as in Example 1 was confirmed, so an electrode with a lower packing density was used. It can be seen that the present invention can be applied without any problem. Therefore, the present invention can be effectively applied to a gel electrolyte battery in which the nonaqueous electrolyte is not expected to further spread into the voids after the standing step. In addition, when the battery was disassembled after initialization and the positive electrode and the negative electrode were examined, it was found that a gel electrolyte having no fluidity or exudation property was disposed in the space between the positive electrode mixture and the negative electrode mixture. confirmed.

  In the above example, in order to independently confirm the effect on the positive electrode side and the effect on the negative electrode side, one electrode having a packing density in the conventional range was used. It goes without saying that it is optimal to use electrodes with a packing density in the range.

The case where LiCoO ₂ is used as the positive electrode active material has been described above as an example, but the same effect was confirmed when LiNi _0.165 Mn _0.165 Co _0.67 O ₂ was used. Moreover, although the case where LiN (C ₂ F ₅ SO ₂ ) ₂ and LiPF ₆ were mixed and used as a lithium salt was described as an example, LiN (CF ₃ SO ₂ ) ₂ and LiPF ₆ were mixed and used. In such a case, the same effect was confirmed when LiN (C ₂ F ₅ SO ₂ ) ₂ , LiPF ₆ and LiBF ₄ were mixed and used.

Claims (6)

In a nonaqueous electrolyte battery comprising a positive electrode, a negative electrode, and a nonaqueous electrolyte, the positive electrode contains a positive electrode active material made of a lithium transition metal composite oxide, and the positive electrode has a positive electrode filling density of 3.5 g / cm ³ or more. the non-aqueous electrolyte comprises an inorganic anions and organic anions, the inorganic anions are PF ₆ ^- and BF ₄ ^- includes either or both of the organic anion is _{(C n F 2n + 1 SO} 2) _{(C m F 2m + 1 SO} 2) n - (n, m are both an integer of 1 to 4, n and m may be different even in the same) one or represented by In addition to the above, the molar ratio of the organic anion to the inorganic anion is 1/4 or more and 1/1 or less, and the non-aqueous electrolyte contains 60% by volume or more of a solvent having a dielectric constant of 40 or more. Non-aqueous electrolyte battery. The nonaqueous electrolyte battery according to claim 1, wherein a positive electrode filling density of the positive electrode is 3.7 g / cm ³ or less. The non-aqueous electrolyte battery according to claim 1, wherein the negative electrode contains a negative electrode active material made of a carbon material, and a negative electrode filling density of the negative electrode is 1.5 g / cm ³ or more. The nonaqueous electrolyte battery according to claim ^3, wherein a negative electrode filling density of the negative electrode is 1.8 g / cm ³ or less. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte is a gel electrolyte. The nonaqueous electrolyte battery according to any one of claims 1 to 5, wherein the exterior body is deformable by a change in battery internal pressure.