Patent Description:
<CIT> discloses a dryer apparatus that dries a substrate material having a slurry coating film while conveying the substrate material. The dryer apparatus disclosed in <CIT> is equipped with a drying furnace for drying the coating film on the substrate material and an exhaust port for expelling the gas inside the drying furnace out of the drying furnace. The drying furnace includes a plurality of dry zones having different dry atmospheres from each other along a conveying direction of the substrate material. The exhaust port of the drying furnace is disposed downstream of the most upstream one of the plurality of dry zones. With such a dryer apparatus, the solvent evaporated from the slurry coating film is not exhausted in the most upstream dry zone (that is, the initial stage of drying), so the concentration of the solvent gas inside the drying furnace increases. When the concentration of the solvent gas inside the drying furnace increases, it approaches the saturation vapor pressure, so the evaporation of the solvent is inhibited. It is stated that this inhibits rapid drying of the slurry coating film at the initial stage of drying, so it is possible to prevent the migration that occurs due to rapid drying of the slurry coating film at the initial stage of drying.

<CIT> discloses a method of collecting an inorganic solvent. In cases where an organic solvent is used, the organic solvent is contained in an exhaust gas in the drying step, so it is necessary to collect the organic solvent. Methods of collecting an organic solvent include a dry type method and a wet type method. In a dry type process, for example, the exhaust gas in the drying step is cooled with a cooling water or the like by an indirect heat exchanger to condense and collect a solvent component within the exhaust gas. A wet type process involves a gas absorption method using water as an absorbent. In a wet type process, the exhaust gas is introduced into an absorption tower in which water is sprayed, to thereby cause a solvent component in the exhaust gas to be absorbed into water. The publication states that in the wet type process, the lower the temperature, the higher the efficiency in absorbing the solvent component. It is stated that, for that reason, the exhaust gas to be introduced into the absorption tower should preferably be cooled in advance and brought into gas-liquid contact with a large amount of water.

As demands for lithium-ion secondary batteries are expected to increase with the shift to EVs in vehicle industries, massive cost increases are expected in mass production of lithium-ion secondary batteries. In particular, it is considered desirable to lower the energy required in the drying step in manufacturing electrodes to reduce manufacturing costs. The present inventors believe that, for a method of collecting an organic solvent from the exhaust gas after the drying, a wet type process, which causes water to absorb the organic solvent, is advantageous over a dry type process, in which the exhaust gas needs to be cooled to a level at which the organic solvent condenses. Accordingly, the present inventors intend to reduce the manufacturing costs including the collecting of an organic solvent with a wet type process.

According to the present disclosure, an electrode manufacturing facility includes a dryer, a solvent collection device, a first pipe, an outside air inlet pipe, a heat exchanger, and a second pipe.

The dryer includes a drying furnace, a heater, and a conveyor device. Here, the heater is a device that heats the air supplied through the outside air inlet pipe and supplies the air to the drying furnace. The conveyor device is a device that conveys a sheet-shaped current collector coated with a mixture slurry in which electrode active material particles are dispersed in an organic solvent, along a predetermined conveyance passage in the drying furnace.

The solvent collection device is a device that causes the organic solvent contained in an exhaust gas expelled from the dryer to dissolve into water to collect the organic solvent. The first pipe is a pipe that sends the exhaust gas expelled from the dryer to the solvent collection device. The outside air inlet pipe is a pipe that introduces outside air and sends the outside air to the dryer. The heat exchanger is a device configured to exchange heat between the first pipe and the outside air inlet pipe. The second pipe is a pipe that is connected to a pipe to which the exhaust gas after having passed through the solvent collection device is expelled and to a portion of the outside air inlet pipe that is upstream of the heat exchanger, and sends at least a portion of the exhaust gas after having passed through the solvent collection device to the outside air inlet pipe.

In the above-described electrode manufacturing facility, the exhaust gas after having passed through the solvent collection device is mixed with the outside air in the outside air inlet pipe and further heat exchanged with the exhaust gas from the dryer by the heat exchanger. This allows the temperature of the outside air introduced to the dryer to be raised in advance, and lowers the energy required by the heater of the dryer.

In this case, the outside air inlet pipe, which sends the outside air to the dryer, may further include a heating device disposed downstream of the heat exchanger. In another embodiment of the electrode manufacturing facility, the outside air inlet pipe, which sends the outside air to the dryer, may be provided with a heating device disposed downstream of the heat exchanger without providing the second pipe.

According to the present disclosure, a method of manufacturing electrodes includes: a drying step of drying a sheet-shaped current collector coated with a mixture slurry in which electrode active material particles are dispersed in an organic solvent; and a solvent collecting step of collecting the organic solvent by spraying water to an exhaust gas produced in the drying step and causing the organic solvent contained in the exhaust gas to dissolve into the water. In the drying step, a portion of the exhaust gas after having been sprayed water in the solvent collecting step is mixed with outside air, heat-exchanged with the exhaust gas produced in the drying step, and introduced into the dryer. In this case, in the drying step, it is also possible that a gas in which outside air is mixed with a portion of the exhaust gas after having been sprayed with water in the solvent collecting step may be heat-exchanged with the exhaust gas produced in the drying step, thereafter further heated, and then introduced into the dryer.

In another embodiment, the method of manufacturing electrodes includes: a drying step of drying a sheet-shaped current collector coated with a mixture slurry in which electrode active material particles are dispersed in an organic solvent; and a solvent collecting step of collecting the organic solvent by spraying water to an exhaust gas produced in the drying step and causing the organic solvent contained in the exhaust gas to dissolve into the water. in the drying step, outside air is heat-exchanged with the exhaust gas produced in the drying step, further heated, and thereafter introduced into a dryer.

The electrode manufacturing methods as described above are able to raise the temperature of the outside air introduced to the dryer in advance and lower the energy required by the heater of the dryer.

Hereinbelow, the present disclosure will be described in detail. Unless otherwise stated, the present disclosure is not intended to limit the invention as set forth in the appended claims. The drawings are depicted schematically and do not necessarily accurately depict actual objects. The features and components that exhibit the same effects are designated by the same reference symbols as appropriate, and the description thereof will not be repeated.

<FIG> is a configuration diagram illustrating the configuration of an electrode manufacturing facility <NUM>. The electrode manufacturing facility <NUM> is used as, for example, manufacturing equipment for manufacturing electrode sheets for use in electricity storage devices, such as lithium-ion secondary batteries and electric double layer capacitors. The electrodes manufactured by the electrode manufacturing facility <NUM> are such that an active material layer containing electrode active material particles is formed on a sheet-shaped substrate material serving as a current collector. A method of manufacturing an electrode sheet includes the step of preparing a mixture slurry containing electrode active material particles for a battery electrode, the step of coating a substrate material with the mixture slurry (coating step), and the step of drying the coated mixture slurry (drying step).

The mixture slurry containing a battery electrode active material includes, for example, electrode active material particles, a binder, and the like that are contained in a solvent. The mixture slurry is also referred to as a mixture paste. The step of coating a substrate material with a mixture slurry involves coating the prepared mixture slurry onto a sheet-shaped substrate material. The electrode sheet substrate material may use a metal foil, such as aluminum foil or copper foil. Herein, the electrode sheet substrate material is prepared in the form of, for example, a strip-shaped sheet. In the step of applying a mixture slurry onto a substrate material, the mixture slurry is supplied through a die or the like onto an electrode sheet conveyed in a roll-to-roll process. In the step of drying the applied mixture slurry, an active material layer containing electrode active material particles is formed on the electrode sheet by drying the applied mixture slurry. In the drying step, the electrode sheet is passed through a drying furnace to dry the mixture slurry applied on the electrode sheet. The active material layer that has undergone the drying step is adjusted to have predetermined thickness and density through a pressing step and the like.

The mainstream of the positive electrode slurry for lithium-ion secondary batteries is one that uses an organic solvent. For the positive electrode slurry, for example, polyvinylidene difluoride (hereinafter referred to as PVdF) may be used as a binder for binding materials, and an organic solvent such as N-methyl-<NUM>-pyrrolidone (hereinafter referred to as NMP) may be used as a solvent. On the other hand, the mainstream of the negative electrode slurry for lithium-ion secondary batteries is a slurry that uses styrenebutadiene rubber (hereinafter SBR), which is an aqueous dispersion binder, and water as a solvent. It should be noted that the materials used for the positive electrode slurry and the negative electrode slurry are not limited to the materials exemplified herein, unless specifically stated otherwise.

The mixture slurry applied in the coating step contains a required amount of solvent. In the step of drying the applied mixture slurry, it is necessary to cause such a solvent to evaporate. This means that, in the mass production of lithium-ion secondary batteries, a large amount of heat is required in the drying step in the manufacturing of electrode sheets. Moreover, in cases where an organic solvent is used, the organic solvent is contained in an exhaust gas in the drying step. For this reason, it is necessary to collect the organic solvent.

As illustrated in <FIG>, the electrode manufacturing facility <NUM> includes a dryer <NUM>, a first pipe <NUM>, a solvent collection device <NUM>, an outside air inlet pipe <NUM>, a heat exchanger <NUM>, a second pipe <NUM>, a heating device <NUM>, and a controller <NUM>.

The dryer <NUM> is a device that dries a sheet-shaped current collector coated with a mixture slurry in which electrode active material particles are dispersed in an organic solvent. In the embodiment shown in <FIG>, the dryer includes a drying furnace 11a, a heater 11b, and a conveyor device 11c.

Herein, the drying furnace 11a may include a furnace chamber that is surrounded by a heat insulating material. Inside the drying furnace 11a, a dry atmosphere is formed in a closed space. The drying furnace 11a is provided with an inlet 11alinto which the current collector coated with the mixture slurry is introduced, and an outlet 11a2. Inside the drying furnace 11a, a predetermined conveyance passage is provided along which the current collector coated with the mixture slurry is to be conveyed. Inside the drying furnace 11a, a dry atmosphere is formed that is at a temperature at which the solvent contained in the mixture slurry can evaporate, for example, at higher than or equal to <NUM>.

The heater 11b is, for example, a device that heats the air supplied through the outside air inlet pipe <NUM> and supplies the air into the drying furnace 11a. The heater 11b may be composed of, for example, an electric heater. That said, the heater 11b is not limited to an electric heater but may be a gas heater or the like. When the solvent uses NMP, the heater 11b heats up the air supplied through the outside air inlet pipe <NUM> to a predetermined temperature (for example, <NUM>) and supplies the heated air to the drying furnace 11a.

The conveyor device 11c may be a device that conveys a sheet-shaped current collector coated with a mixture slurry. The current collector coated with the mixture slurry may be, for example, a strip-shaped sheet and may be conveyed along the predetermined conveyance passage inside the drying furnace 11a. The mixture slurry may be applied onto the current collector before the current collector enters the drying furnace 11a. In this embodiment, a coating device 11d for applying the mixture slurry onto the current collector is provided upstream of the inlet 11a1 of the drying furnace 11a in the current collector conveyance passage. Herein, the mixture slurry applied to the current collector may be a slurry in which electrode active material particles are dispersed in an organic solvent (for example, NMP).

The first pipe <NUM> is a pipe that sends the exhaust gas expelled from the dryer <NUM> to the solvent collection device <NUM>. Here, the exhaust gas expelled from the dryer <NUM> contains a solvent component. The organic solvent used as the solvent component, such as NMP, has a boiling point higher than water. Accordingly, the exhaust gas expelled from the dryer <NUM> has a temperature of, for example, about <NUM>. As illustrated in <FIG>, the first pipe <NUM> is arranged from the drying furnace 11a through the heat exchanger <NUM> to the solvent collection device <NUM>. In the embodiment shown in <FIG>, the first pipe <NUM> is equipped with a blower fan 12a. The exhaust gas expelled from the dryer <NUM> is forcibly sent to the solvent collection device <NUM> by the blower fan 12a. The blower fan 12a may be disposed in front of the solvent collection device <NUM>, in the first pipe <NUM>. The blower fan 12a is controlled together with a later-described blower fan 14a that is disposed in the outside air inlet pipe <NUM> so that the drying conditions in the dryer <NUM> can be optimized. The flow velocity of the exhaust gas sent from the dryer <NUM> to the solvent collection device <NUM> may be controlled by controlling the blower fan 12a. In order to ensure stability of the flow velocity, it is also possible to provide a blower fan in the middle of the first pipe <NUM> according the length of the pipe. The airflow volumes of the blower fans provided in the facility may be controlled in order to, for example, maintain the conditions in the drying furnace.

The solvent collection device <NUM> is a wet-type collection device. In the embodiment shown in <FIG>, water is supplied to the solvent collection device <NUM> through a water supply pipe 13a, and the solvent collection device <NUM> causes the organic solvent contained in the exhaust gas expelled from the dryer <NUM> to dissolve into water to collect the organic solvent. The organic solvent, such as NMP, easily dissolves into water. Therefore, when water is sprinkled in the exhaust gas expelled from the dryer <NUM>, the organic solvent contained in the exhaust gas is absorbed by water and is collected efficiently.

<FIG> is a schematic view of the solvent collection device <NUM>. The solvent collection device <NUM> includes a plurality of collection tanks 61a to 61d that are separated from each other. A pipe <NUM> in which the exhaust gas expelled from the dryer <NUM> is flowed is passed in upper portions of the collection tanks 61a to 61d. The collection tanks 61a to 61d are lined up in that order from the inlet end of the pipe <NUM> toward the outlet end thereof. Mist eliminators 62a to 62d for separating organic solvent from the exhaust gas are filled in the pipe <NUM>. The mist eliminators may be composed of, for example, a mesh material called a demister.

The water to be supplied to the solvent collection device <NUM> is supplied to each of the collection tanks 61a to 61d. The water to be supplied to the solvent collection device <NUM> may be, for example, pure water or the like such as to be adjusted to required water quality. The water is supplied so that the level of the water reserved in each of the collection tanks 61a to 61d reaches a predetermined water level. The water may be sprinkled on the mist eliminators 62a to 62d. The water reserved in the collection tanks 61a to 61d may be pumped up by pumps 63a to 63d so as to be sprinkled from the top of the collection tanks 61a to 61d. The water sprinkled from the top of the collection tanks 61a to 61d is retained in the mist eliminators 62a to 62d. The organic solvent contained in the exhaust gas expelled from the dryer <NUM> is absorbed by the water when the exhaust gas passes through the mist eliminators 62a to 62d.

The water that has absorbed the organic solvent is collected in the collection tanks 61a to 61d. The water collected in the collection tanks 61a to 61d is sent in sequence from the collection tank 61d that is near the outlet end toward the collection tank 61a that is near the inlet end. This means that the concentration of the organic solvent is higher toward the collection tank 61a that is near the inlet end. For example, each of the collection tanks 61a to 61d measures the concentration of the organic solvent in the water collected the respective collection tanks 61a to 61d, and when the concentration of the organic solvent reaches a predetermined concentration based on the measured values, a valve is opened to send the water to the next one of the collection tanks. The collection tank 61a that is near the inlet end has a higher concentration of organic solvent, and the water is discharged one after another from the solvent collection device <NUM>.

The water that has absorbed the organic solvent may be distilled by a reprocessing facility 13b or the like, as illustrated in <FIG>, so that it can be separated into organic solvent and water. The water separated from the organic solvent may be used again in the solvent collection device <NUM>. The separated organic solvent may be refined again so that it can be reused. The exhaust gas after the organic solvent has been absorbed by water in the solvent collection device <NUM> is expelled through a pipe 13c. The pipe 13c in which the exhaust gas expelled from the solvent collection device <NUM> is flowed is connected to the second pipe <NUM>, as will be described later. In the example shown in <FIG>, the reprocessing facility 13b is provided within the factory. It is also possible that the reprocessing facility 13b may be provided outside the factory, for example. When this is the case, a reserve tank for reserving the water that has absorbed the organic solvent may be provided, and the water may be transported with a tank truck or the like to the reprocessing facility 13b outside the factory, where the organic solvent is reprocessed.

The outside air inlet pipe <NUM> is a pipe that introduces outside air and sends it to the dryer <NUM>. The outside air inlet pipe <NUM> is arranged so as to pass through the heat exchanger <NUM> and reach the dryer <NUM>. The embodiment shown in <FIG> is configured so that a portion of the exhaust gas expelled from the solvent collection device <NUM> is supplied through the second pipe <NUM> to the outside air inlet pipe <NUM>. The outside air inlet pipe <NUM> is provided with a blower fan 14a in front of the heat exchanger <NUM>. Such a blower fan 14a enables outside air to be sent forcibly from the outside air inlet pipe <NUM> to the heat exchanger <NUM>. The flow velocity of the outside air sent from the outside air inlet pipe <NUM> to the heat exchanger <NUM> may be controlled by controlling the blower fan 14a. In addition, the outside air inlet pipe <NUM> is also provided with a blower fan 14b in front of the dryer <NUM>. The blower fan 14b enables outside air to be sent forcibly from the outside air inlet pipe <NUM> to the dryer <NUM>. The flow velocity of the outside air sent from the outside air inlet pipe <NUM> to the dryer <NUM> may be controlled by controlling the blower fan 14b.

The heat exchanger <NUM> is configured to exchange heat between the first pipe <NUM> and the outside air inlet pipe <NUM>. Such heat exchanger <NUM> enables exchange of heat between the exhaust gas expelled from the dryer <NUM>, which flows through the first pipe <NUM>, and the outside air that is introduced from the outside air inlet pipe <NUM>. This allows the temperature of the outside air introduced to the dryer <NUM> to be raised in advance. In addition, the exhaust gas expelled from the dryer <NUM>, which flows through the first pipe <NUM>, is passed through the heat exchanger <NUM> and supplied to the solvent collection device <NUM>. The heat exchanger <NUM> lowers the temperature of the exhaust gas expelled from the dryer <NUM>. In the solvent collection device <NUM>, the lower the temperature of the exhaust gas expelled from the dryer <NUM>, the more easily the solvent contained in the exhaust gas condenses, so the more efficiently the organic solvent can be absorbed by water.

The second pipe <NUM> is connected to the pipe 13c in which the exhaust gas expelled from the solvent collection device <NUM> is flowed, and to a portion of the outside air inlet pipe <NUM> that is upstream of the heat exchanger <NUM>. The second pipe <NUM> is a pipe that sends at least a portion of the exhaust gas after having passed through the solvent collection device <NUM> to the outside air inlet pipe <NUM>. The second pipe <NUM> allows a portion of the exhaust gas after having passed through the solvent collection device <NUM> to be introduced into the outside air inlet pipe <NUM>, then passed through the heat exchanger <NUM>, and supplied to the dryer <NUM>. Because the second pipe <NUM> allows a portion of the exhaust gas after having passed through the solvent collection device <NUM> to be introduced into the outside air inlet pipe <NUM>, it is possible to stabilize the temperature of the air supplied to the heat exchanger <NUM>.

Herein, the temperature of the outside air introduced into the outside air inlet pipe <NUM> is assumed to be an annual average of about <NUM>. The temperature of the outdoor air introduced into the outdoor air inlet pipe <NUM> varies depending on the season and time of day. For example, the temperature of the outdoor air can be as high as about <NUM> during daytime in summer. On the other hand, the temperature of the outdoor air can be as low as about -<NUM> during nighttime in winter. Thus, the outside air introduced into the outside air inlet pipe <NUM> is unstable throughout the year. On the other hand, the exhaust gas expelled from the dryer <NUM> is at about <NUM>.

Although the temperature of the exhaust gas lowers in the solvent collection device <NUM> because the exhaust gas is mixed with the sprinkled water, the exhaust gas expelled from the solvent collection device <NUM> is kept at about <NUM>, which is higher than the temperature of the outside air. Because a portion of the exhaust gas after having passed through the solvent collection device <NUM> is introduced into the outside air inlet pipe <NUM> through the second pipe <NUM>, the temperature of the outside air that is introduced into the dryer <NUM> can be raised, so it is expected to reduce the amount of heat required for heating the outside air with the heater 11b of the dryer <NUM>.

For example, it is assumed that, when the temperature of the outside air introduced into the outside air inlet pipe <NUM> is <NUM> and the temperature of the exhaust gas expelled from the dryer <NUM> is <NUM>, the exhaust gas from the solvent collection device <NUM> is not introduced from the second pipe <NUM> and the outside air is heat-exchanged with the heat exchanger <NUM> as it is. In this case, the temperature of the outside air having passed through the heat exchanger <NUM> may become about <NUM>. This air needs to be turned to be hot air at about <NUM> in the dryer <NUM>, so the heater 11b of the dryer <NUM> requires a considerable amount of heat to heat the outside air.

In contrast, when the exhaust gas from the solvent collection device <NUM> is introduced from the second pipe <NUM> to the outside air introduced to the outside air inlet pipe <NUM>, the temperature of the air supplied to the heat exchanger <NUM> can be raised to <NUM>. Then, the temperature of the air can be raised to <NUM> through the heat exchanger <NUM>. This air needs to be turned to be hot air at about <NUM> in the dryer <NUM>. However, because the exhaust gas from the solvent collection device <NUM> is introduced from the second pipe <NUM> to the outside air introduced to the outside air inlet pipe <NUM>, the temperature of the introduced air is higher by about <NUM>. Thus, it is expected to reduce the amount of heat required for the heater 11b of the dryer <NUM> to heat the outside air.

As described above, outside air is introduced into the outside air inlet pipe <NUM>, mixed in the outside air inlet pipe <NUM> with the exhaust gas after having passed through the solvent collection device <NUM> that is supplied from the second pipe <NUM>, and further heat exchanged with the exhaust gas from the dryer <NUM> by the heat exchanger <NUM>. This makes it possible to use the heat of the exhaust gas from the dryer <NUM> and to raise the temperature of the outside air to be introduced to the dryer <NUM> in advance. This lowers the energy required by the heater 11b of the dryer <NUM>. Moreover, because the temperature of the exhaust gas expelled from the solvent collection device <NUM> is stable throughout the year, it is possible to stabilize the temperature of the outside air supplied by the outside air inlet pipe <NUM>.

Herein, the exhaust gas after having passed through the solvent collection device <NUM> is highly humid. The electrode manufacturing facility <NUM> may further include a regulator valve 16a for regulating the flow rate of the second pipe <NUM>. Because the second pipe <NUM> is provided with the regulator valve 16a, it is possible to regulate the exhaust gas after having passed through the solvent collection device <NUM> that is introduced to the outside air inlet pipe <NUM>. This makes it possible to control the temperature and dew point of the gas that flows through the outside air inlet pipe <NUM>.

For example, a controller <NUM> may be configured to detect at least one of the temperature and dew point of a gas flowing in the outside air inlet pipe <NUM> at a part of the second pipe <NUM> that is downstream of the outside air inlet pipe <NUM> and upstream of the heat exchanger <NUM>, and execute a process of controlling the degree of opening of the regulator valve 16a based on the detected value. This makes it possible to regulate the amount of the exhaust gas introduced to the outside air inlet pipe <NUM> through the second pipe <NUM> while feeding back at least one of the temperature and dew point of the gas flowing in the outside air inlet pipe <NUM>.

The controller <NUM> may be configured to detect the temperature or dew point of the gas flowing in the outside air inlet pipe <NUM> with a sensor 14c provided in the outside air inlet pipe <NUM> after the exhaust gas after having passed through the solvent collection device <NUM> has been introduced through the second pipe <NUM>, and to regulate the degree of opening of the regulator valve 16a provided in the second pipe <NUM>. The amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM> may be regulated taking the temperature or dew point of the gas flowing in the outside air inlet pipe <NUM> into consideration.

Here, the gas flowing in the outside air inlet pipe <NUM> is sent to the dryer <NUM>. The higher the temperature of the gas flowing in the outside air inlet pipe <NUM>, the better, but the lower the humidity of the gas flowing in the outside air inlet pipe <NUM>, the better. The exhaust gas introduced to the outside air inlet pipe <NUM> through the second pipe <NUM> has a high humidity. For this reason, the amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM> may be regulated taking the dew point of the gas flowing in the outside air inlet pipe <NUM> into consideration, in addition to the temperature thereof. It is more preferable that the regulator valve 16a for regulating the flow rate of the second pipe <NUM> be controlled based on the temperature and the dew point of the gas flowing in the outside air inlet pipe <NUM>.

For example, when the dew point of the gas flowing in the outside air inlet pipe <NUM> is lower than a predetermined dew point, the degree of opening of the regulator valve 16a may be adjusted so as to increase the amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM>. When the dew point of the gas flowing in the outside air inlet pipe <NUM> is higher than a predetermined dew point, the degree of opening of the regulator valve 16a may be adjusted so as to decrease the amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM>. It is also possible that when the dew point of the gas flowing in the outside air inlet pipe <NUM> becomes higher than a predetermined dew point, the regulator valve 16a may be adjusted to be closed.

It is also possible that when the temperature of the gas flowing in the outside air inlet pipe <NUM> is lower than a predetermined temperature, the degree of opening of the regulator valve 16a may be adjusted so as to increase the amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM>. When the temperature of the gas flowing in the outside air inlet pipe <NUM> is higher than a predetermined temperature, the degree of opening of the regulator valve 16a may be adjusted so as to decrease the amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM>. It is also possible that when the temperature of the gas flowing in the outside air inlet pipe <NUM> becomes higher than a predetermined temperature, the regulator valve 16a may be adjusted to be closed.

The controller <NUM> may be configured to detect the concentration of the organic solvent contained in the exhaust gas flowing in the second pipe <NUM> at a part of the second pipe <NUM> that is downstream of the outside air inlet pipe <NUM> and upstream of the heat exchanger <NUM>, and execute a process of controlling the degree of opening of the regulator valve 16a based on the concentration of the organic solvent that has been detected. This makes it possible to adjust the amount of the exhaust gas to be introduced into the outside air inlet pipe <NUM> through the second pipe <NUM> while monitoring the concentration of the organic solvent in the outside air inlet pipe <NUM>.

The controller <NUM> may be configured to detect the concentration of the organic solvent in the gas flowing in the outside air inlet pipe <NUM> with the sensor 14c provided in the outside air inlet pipe <NUM> after the exhaust gas after having passed through the solvent collection device <NUM> has been introduced through the second pipe <NUM>, and to regulate the degree of opening of the regulator valve 16a provided in the second pipe <NUM>. Here, when the concentration of the organic solvent exceeds a predetermined concentration in the outside air introduced into the dryer <NUM>, the drying of the mixture slurry in the dryer <NUM> is slowed down. The concentration of the organic solvent in the outside air to be introduced into the dryer <NUM> may be restricted to such a level as not to slow down the drying of the mixture slurry in the dryer <NUM>. In addition, because the organic solvent is in many cases a hazardous material, it is also possible that the regulator valve 16a provided in the second pipe <NUM> may be shut off when the concentration exceeds a predetermined concentration from the viewpoint of safety.

Thus, the degree of opening of the regulator valve 16a provided in the second pipe <NUM> may be configured to be adjusted based on the concentration of the organic solvent and at least one of the temperature and dew point of the gas flowing in the outside air inlet pipe <NUM>, after the exhaust gas after having passed through the solvent collection device <NUM> is introduced through the second pipe <NUM>. This makes it possible to control the temperature, the dew point, and the organic solvent concentration of the outside air that is introduced into the dryer <NUM> through the outside air inlet pipe <NUM>. For example, the regulator valve 16a provided in the second pipe <NUM> may be controlled in such a manner that the degree of opening of the regulator valve 16a is adjusted based on at least one of the temperature and dew point and the regulator valve 16a is closed when the concentration of the organic solvent exceeds a predetermined concentration. It is also possible that the regulating valve 16a may be controlled with two factors, temperature and dew point. For example, it is also possible that while the degree of opening of the regulator valve 16a is controlled based on the temperature, the degree of opening of the regulator valve 16a may be prevented from increasing when the dew point exceeds a certain value. This can prevent the degree of opening of the regulator valve 16a from increasing, for example, when the dew point exceeds a certain value even in the case where the temperature of the gas flowing in the outside air inlet pipe <NUM> is lower than a predetermined value because of temperature control after the exhaust gas after having passed through the solvent collection device <NUM> is introduced through the second pipe <NUM>. This can prevent the dew point of the gas flowing in the outside air inlet pipe <NUM> from increasing above a certain value. Thus, the degree of opening of the regulator valve 16a and the like may be controlled so that the quality of the gas flowing in the outside air inlet pipe <NUM> that is measured with the sensor 14c can be adjusted to predetermined quality.

In the embodiment shown in <FIG>, the outside air inlet pipe <NUM> further includes a heating device <NUM>. The heating device <NUM> is disposed at a portion of the outside air inlet pipe <NUM>, which sends the outside air to the dryer <NUM>, that is downstream of the heat exchanger <NUM>. The heating device <NUM> is a device that heats up the gas sent to the dryer <NUM> through the outside air inlet pipe <NUM> at the portion downstream of the heat exchanger <NUM>. In this embodiment, the heating device <NUM> includes a heat pump <NUM> and a heat exchange coil <NUM>. The heat exchange coil <NUM> is disposed in the middle of the outside air inlet pipe <NUM>, and may be a plate type heat exchanger or the like that has sufficient capability of raising the temperature of the outside air inlet pipe <NUM> to higher than a certain value. The heat pump <NUM> may be a hot water heat pump unit. The hot water heat pump unit is, for example, a heat pump unit equipped with a heat transfer medium circulation system including a heat absorbing part and a heat dissipating part. The hot water heat pump unit receives heat from a water heat source or an air heat source outside the system by the heat absorbing part and dissipates the heat to a heat transfer system that circulates between the heat pump <NUM> and the heat exchange coil <NUM> from the heat dissipating part. This makes it possible to supply required hot water to the heat exchange coil <NUM>.

The heat exchange coil <NUM> is supplied with hot water, for example, at about <NUM> from the heat pump <NUM> to heat the gas flowing in the outside air inlet pipe <NUM>. Then, the outside air heated by the heat exchange coil <NUM> is supplied to the dryer <NUM>. When the temperature of the gas flowing in the outside air inlet pipe <NUM> that is expelled from the heat exchanger <NUM> is about <NUM>, the temperature of the outside air supplied to the dryer <NUM> can be raised to about <NUM> by heating the gas flowing in the outside air inlet pipe <NUM> through the heating device <NUM>. The heat pump <NUM> is able to utilize a large amount of heat energy with a small amount of input energy. Thus, the heating device <NUM> enables the outside air to be further heated and thereafter supplied to the device, so it is possible to significantly reduce the energy required by the heater 11b of the dryer <NUM>.

For example, the electrode manufacturing facility <NUM> may be configured to detect the temperature of the gas flowing in the outside air inlet pipe <NUM> with a sensor <NUM> provided downstream of the heating device <NUM> and to control the degree of opening of a regulator valve <NUM> provided in the heat pump <NUM>. By controlling the degree of opening of the regulator valve <NUM> based on the temperature of the gas flowing in the outside air inlet pipe <NUM>, the amount of heat transfer medium circulating in the heat pump <NUM> is controlled so that the gas flowing in the outside air inlet pipe <NUM> can be heated to a stable temperature. The amount of heat exchanged with the gas flowing in the outside air inlet pipe <NUM> may be adjusted in the heat exchange coil <NUM> in this way. This makes it possible to adjust the temperature of the outside air supplied to the dryer <NUM>. In addition, the heat pump <NUM> is able to cool other heat transfer media. For example, the heat pump <NUM> may use water as the heat transfer medium. The use of water as the heat transfer medium makes it possible to obtain cold water at about <NUM>, so that it is possible to obtain, as by-products, cooling water for air conditioning or for machines that needs to consume energy to be cooled in external facilities. This provides advantageous effects of further energy reduction.

An example of the heating device <NUM> herein illustrates an embodiment in which a heat pump and a heat exchange coil that can heat the gas flowing in the outside air inlet pipe <NUM> efficiently are used. It is sufficient that the heating device <NUM> may be, but is not limited to, a device that heats up the gas sent to the dryer <NUM> through the outside air inlet pipe <NUM> at a location downstream of the heat exchanger <NUM>.

Thus, by introducing the exhaust gas from the solvent collection device <NUM> into the outside air inlet pipe <NUM>, it is possible to raise the temperature of the outside air to be introduced into the dryer <NUM> through the outside air inlet pipe <NUM>. This serves to reduce the energy required by the heater 11b of the dryer <NUM>. Moreover, the energy required by the heater 11b of the dryer <NUM> is reduced significantly by heating the outside air supplied to the dryer <NUM> through the heat exchanger <NUM> by the heating device <NUM>. From the viewpoint of reducing the energy required by the heater 11b of the dryer <NUM>, merely introducing the exhaust gas from the solvent collection device <NUM> into the outside air inlet pipe <NUM> and merely heating the gas with the heating device <NUM> are both effective. The capacity required for the heating device <NUM> can be further reduced by introducing the exhaust gas from the solvent collection device <NUM> into the outside air inlet pipe <NUM> through the second pipe <NUM>, moreover heating the gas through the heat exchanger <NUM>, and further heating the gas with the heating device <NUM>. This makes it possible to reduce the size of the heating device <NUM>, and also reduces equipment costs and running costs.

Here, a method of manufacturing an electrode includes a drying step and a solvent collecting step. The drying step is a step of drying a sheet-shaped current collector coated with a mixture slurry in which electrode active material particles are dispersed in an organic solvent. In the electrode manufacturing facility <NUM> described above, the drying step is implemented by the dryer <NUM>. The solvent collecting step is a step of collecting the organic solvent by spraying water to an exhaust gas produced in the drying step and causing the organic solvent contained in the exhaust gas to dissolve into the water. In the electrode manufacturing facility <NUM> described above, the solvent collecting step is implemented by the solvent collection device <NUM>. In the drying step, a portion of the exhaust gas after having been sprayed water in the solvent collecting step may be mixed with outside air, heat-exchanged with the exhaust gas produced in the drying step, and thereafter introduced into the dryer <NUM>. This raises the temperature of the outside air introduced to the dryer <NUM>. This makes it possible to lower the energy required by the heater 11b of the dryer <NUM>.

The amount of a portion of the exhaust gas sprayed with water that is mixed with the outside air in the solvent collecting step may be adjusted based on the dew point of the gas after having been mixed. Alternatively, the amount of a portion of the exhaust gas sprayed with water that is mixed with the outside air in the solvent collecting step may be adjusted based on the concentration of the organic solvent in the gas after having been mixed. The amount of a portion of the exhaust gas sprayed with water that is mixed with the outside air in the solvent collecting step may be adjusted based on the dew point of the gas after having been mixed and the concentration of the organic solvent in the gas after having been mixed. For example, the amount of a portion of the exhaust gas sprayed with water that is mixed with the outside air in the solvent collecting step may be adjusted based on the temperature of the gas after having been mixed. The amount of a portion of the exhaust gas sprayed with water that is mixed with the outside air in the solvent collecting step may be adjusted based on the temperature of the gas after having been mixed and the concentration of the organic solvent in the gas after having been mixed. The amount of a portion of the exhaust gas sprayed with water that is mixed with the outside air in the solvent collecting step may be adjusted based on the temperature, dew point, and organic solvent concentration of the gas after having been mixed.

The method of manufacturing electrodes may involve heat-exchanging of the outside air with the exhaust gas produced in the drying step, further heating the outside air, and introducing the outside air into the dryer. This makes it possible to lower the energy required by the heater 11b of the dryer <NUM>. For example, in the drying step, it is also possible that a gas in which outside air is mixed with a portion of the exhaust gas after having been sprayed with water in the solvent collecting step may be heat-exchanged with the exhaust gas produced in the drying step, thereafter further heated, and then introduced into the dryer. This significantly lowers the energy required by the heater 11b of the dryer <NUM>.

Claim 1:
An electrode manufacturing facility (<NUM>) comprising:
a dryer (<NUM>);
a solvent collection device (<NUM>) causing an organic solvent contained in an exhaust gas expelled from the dryer (<NUM>) to dissolve into water to collect the organic solvent;
a first pipe (<NUM>) for sending the exhaust gas expelled from the dryer to the solvent collection device (<NUM>);
an outside air inlet pipe (<NUM>) for introducing outside air and sending the air to the dryer (<NUM>);
a heat exchanger (<NUM>) configured to exchange heat between the first pipe (<NUM>) and the outside air inlet pipe (<NUM>); and
a second pipe (<NUM>), being connected to a pipe to which the exhaust gas after having passed through the solvent collection device (<NUM>) is expelled and to a portion of the outside air inlet pipe that is upstream of the heat exchanger (<NUM>), for sending at least a portion of the exhaust gas after having passed through the solvent collection device (<NUM>) to the outside air inlet pipe (<NUM>), wherein:
the dryer (<NUM>) includes:
a drying furnace (11a);
a heater (11b) for heating the air supplied through the outside air inlet pipe (<NUM>) and supplying the air into the drying furnace (11a); and
a conveyor device (11c) conveying a sheet-shaped current collector coated with a mixture slurry in which electrode active material particles are dispersed in an organic solvent, along a predetermined conveyance passage in the drying furnace (11a).