JP4275060B2 - hearing aid - Google Patents

Description

  The present invention relates to a hearing aid, and more particularly to a hearing aid that is lightweight, highly safe, and has a low environmental burden.

  Currently, air batteries are generally used as power sources for hearing aids (for example, Patent Documents 1 and 2). Since the air battery uses zinc for the negative electrode and oxygen in the air is used for the positive electrode, there is no need to load the positive electrode in the battery, so there is an advantage that a large capacity can be secured for the battery size. is there.

  By the way, it is preferable that the hearing aid reduces the number of complicated battery replacement operations as much as possible because of the relatively large proportion of the elderly among the users. From such a point of view, it is common to use a relatively high capacity air battery, but it is impossible to avoid the battery replacement operation itself even though the capacity of the air battery is large. Furthermore, since zinc used for the negative electrode of the air battery contains mercury, there is also a problem of an environmental load at the time of disposal.

  From the above circumstances, there is an increasing demand for hearing aids that use a rechargeable secondary battery as a power source instead of a primary battery such as an air battery.

Japanese Patent Laid-Open No. 7-222294 Japanese Patent Laid-Open No. 9-215098

  For example, an attempt has been made to configure a hearing aid using a nickel-hydrogen storage alloy battery (hereinafter referred to as “nickel metal hydride battery”) as a power source. The air battery used in a conventional hearing aid has a voltage of around 1.4V, but the nickel-metal hydride battery has a voltage of around 1.4V, so that it can be replaced without changing the circuit configuration of the hearing aid. There is.

  However, the nickel metal hydride battery uses an alkaline aqueous solution as an electrolyte, and there is a possibility of leakage of the alkaline electrolyte, which is a phenomenon peculiar to such an aqueous battery. Of the hearing aids, those with ear-hooks or ear-holes are used in direct contact with the human body, and when an alkaline electrolyte leaks, the human body is greatly adversely affected.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a hearing aid having high safety, light weight, and low environmental load.

The hearing aid of the present invention that has achieved the above object has a coin-type non-aqueous electrolyte secondary battery including a positive electrode containing lithium titanate and a negative electrode containing amorphous carbon. Is. In the battery industry, a flat battery with a diameter larger than the height is called a coin-type battery or a button-type battery, but there is a clear gap between the coin-type battery and the button-type battery. There is no difference, and the coin-type battery according to the present invention does not exclude what is called a button-type battery, and such a battery called a button-type battery is also within the scope of the coin-type battery according to the present invention. included.

  The hearing aid of the present invention has a coin-type non-aqueous electrolyte secondary battery as a power source with little leakage problem, so it is excellent in safety and can be charged. It is substantially unnecessary, and the environmental load due to disposal of used batteries is extremely small. Furthermore, even if the coin-type non-aqueous electrolyte secondary battery is very small and light, it can have a high capacity. Therefore, the hearing aid of the present invention can also achieve a reduction in weight.

  Hearing aids usually have sound input means (such as a microphone), sound amplification means (such as an amplifier), and sound output means (such as speakers), as well as sound quality adjustment means for the input sound, and the output sound is not too loud. It has components such as output control means for controlling. The coin-type non-aqueous electrolyte battery according to the present invention is used as a power source for driving these various elements constituting the hearing aid.

  As the form of the hearing aid, there are an ear hole shape that is used by inserting the main body into the outer ear, an ear hook shape that is used by being hooked on the auricle, a glasses shape in which the glasses have a hearing aid function, a box shape, etc. Either form can be taken. However, the effect of the present invention is more effective when a small battery such as a coin-type battery is in the form of an ear hole shape, ear hook shape, or eyeglass shape, which is a particularly required form. It is very effective in the case of the ear hole shape that is required.

  1 and 2 show an example (ear hole shape) of the hearing aid of the present invention. FIG. 1 is a perspective view schematically showing a hearing aid. 10 is a hearing aid, 11 is a hearing aid body, 12 is a battery housing cover, 13 is a volume knob, 14 is a microphone, 15 is a take-out wire, and 16 is a speaker. When the hearing aid 10 is used, the hearing aid 10 is inserted into the ear hole from the speaker 16 side, and after use, the take-out wire 15 is pulled and removed from the ear hole. The sound picked up by the microphone 14 is emitted from the speaker 16 toward the middle ear with its volume and sound quality adjusted by the sound amplifying means and sound quality adjusting means built in the hearing aid body 11. When the adjusted volume is too high, the output control means built in the hearing aid main body 11 blocks the transmission to the speaker 16. The volume knob 13 is connected to sound amplification means in the hearing aid main body 11, and the volume can be adjusted by the volume knob 13.

  FIG. 2 is a perspective view schematically showing a state in which the battery housing cover 12 of the hearing aid of FIG. 1 is opened. Battery holding means (not shown) is provided inside the battery housing lid 12 and holds a coin-type non-aqueous electrolyte secondary battery 18. Reference numeral 17 denotes a battery housing portion in which means for taking out electricity from the battery, such as a battery connection terminal, is disposed (not shown).

  Note that the shape and structure of the hearing aid is not limited to that shown in FIGS. 1 and 2, and may include, for example, a power on / off switch, a battery charging terminal, and the like. Further, the arrangement of each component is not limited to that shown in FIGS. 1 and 2, and may be changed as appropriate.

  3 and 4 show another example (ear-hook type) of the hearing aid of the present invention. FIG. 3 is a perspective view schematically showing a hearing aid, in which 20 is a hearing aid, 21 is a hearing aid body, 22 is a battery compartment, 23 is a volume knob, 24 is a microphone, 25 is a hook for ear hooks, and 27 is a switch. , 29 are rotating shafts. An earphone jack is provided at the tip of the hook 25 so that an earphone as an audio output means can be connected. When the hearing aid 20 is used, an earphone is connected to the tip of the hook 25, the switch 27 is turned on, the hook 25 is hooked on the auricle, and the earphone is inserted into the outer ear. The internal configuration of the hearing aid 20 is the same as that of the ear hole type hearing aid shown in FIG. 1, and the volume knob 23 is connected to the sound amplification means built in the hearing aid main body 21, and the output volume can be controlled by this volume knob 23. .

  FIG. 4 is a partial side view schematically showing a state in which the battery housing part 22 of the hearing aid of FIG. 3 is opened. A battery holding means (not shown) is provided in the battery housing portion 22, and the coin-type non-aqueous electrolyte secondary battery 28 is held in a state of partially protruding outward. A means for taking out electricity from the battery, such as a connection terminal of the battery, is disposed inside the end of the hearing aid main body 21 on the battery housing portion 22 side (not shown).

  Even in the case of an ear-mounted hearing aid, its shape and structure are not limited to those shown in FIGS. 3 and 4, and other components (for example, a sound quality adjustment knob, a battery charging terminal, etc.) are provided. May be. Further, the arrangement of the volume knob 23, the microphone 24, the switch 27, and the like is not limited to that shown in FIGS. 3 and 4, and may be changed as appropriate.

  In the hearing aid of the present invention, it is recommended that a coin-type non-aqueous electrolyte secondary battery as a power source is built in, and that the battery is enclosed. In an air battery widely used in conventional hearing aids, an air hole for taking air into the hearing aid is necessary in order to use oxygen in the air for the positive electrode. However, since the hearing aid is used so as to be in direct contact with the human body, moisture such as sweat may enter the hearing aid through the air holes and may have an adverse effect. In conventional hearing aids, there is a problem of how to eliminate the moisture that enters from the air holes. Incidentally, the techniques disclosed in the above-mentioned Patent Documents 1 and 2 avoid the problem derived from such moisture. Is an issue.

  However, the hearing aid of the present invention has a coin-type non-aqueous electrolyte secondary battery as a power source, and does not use air like an air battery (details of the structure will be described later). For this reason, it is not necessary to provide an air hole, and the battery can be enclosed. Thus, problems due to the presence of air holes in conventional hearing aids can be avoided.

  From the viewpoint of avoiding the problem due to moisture infiltration to a higher degree, for example, in the hearing aid of the form shown in FIG. 1, the battery housing lid 12 and the hearing aid body 11 are used. In the hearing aid of the form shown in FIG. It is preferable that the battery housing portion 22 and the hearing aid main body 21 have waterproof means such as a configuration in which the battery housing portion 22 and the hearing aid main body 21 are fitted through a packing made of resin or rubber. Further, in any of these types of hearing aids, the volume knobs 13 and 23, the switch 27, and the hearing aid body 11 and 21 are waterproofed by waterproof means such as packing (O-ring or the like). desirable.

  In addition, the battery which the hearing aid of this invention has is a secondary battery as above-mentioned, and can be charged. As charging methods, there are a contact type and a non-contact type, and any method may be adopted in the present invention. However, in the case of the contact type, a charging terminal is required outside the hearing aid. If moisture such as sweat adheres to this terminal, it may corrode, so in the present invention, it is desirable to employ a non-contact charging method. Specifically, a charger equipped with an oscillating circuit and a primary coil connected to the oscillating circuit is installed with a hearing aid equipped with a secondary coil and a rectifying and smoothing circuit that supplies the output of the secondary coil to the battery, By causing the primary coil of the charger to oscillate with alternating current, an alternating current is generated in the secondary coil by electromagnetic induction, thereby enabling non-contact charging.

  As the coin-type non-aqueous electrolyte secondary battery included in the hearing aid of the present invention, a lithium ion battery is suitable because it is lightweight and highly safe.

  The coin-type nonaqueous electrolyte secondary battery preferably has a voltage of around 1.4V. This is because the air battery used in the conventional hearing aid has a high compatibility because the voltage is around 1.4 V, and the same configuration as the conventional one can be adopted for the hearing aid circuit and the like.

In the present invention, a “lithium titanate-carbon battery” having a positive electrode containing lithium titanate and a negative electrode containing a carbon material is used as a lithium ion battery having a voltage of around 1.4 V.

The positive electrode of the above “lithium titanate-carbon battery” contains lithium titanate represented by the general formula Li _x Ti _y O ₄ as an active material. In the above general formula, x and y each preferably have a stoichiometric number of 0.8 ≦ x ≦ 1.4 and 1.6 ≦ y ≦ 2.2, particularly x = 1.33, Those having a stoichiometric number of y = 1.67 (specifically, Li ₄ Ti ₅ O ₁₂ ) are preferable. Such lithium titanate can be obtained, for example, by heat treating titanium oxide and a lithium compound at 760 to 1100 ° C. As the titanium oxide, either anatase type or rutile type can be used. As the lithium compound, for example, lithium hydroxide, lithium carbonate, lithium oxide or the like can be used.

  As a positive electrode of a lithium titanate-carbon battery, a positive electrode mixture prepared by mixing lithium titanate represented by the above general formula, a conductive additive, and a binder is preferable. Examples of the conductive aid include flaky graphite, acetylene black, carbon black, ketjen black, and the like. In particular, ketjen black is preferable because it has a greater effect of improving conductivity than other conductive aids. Moreover, as a binder, a fluororesin is used suitably, Specifically, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF) etc. are mentioned, for example.

  The composition ratio of each component constituting the positive electrode, that is, the composition ratio of the positive electrode mixture is, for example, 70 to 90% by mass of lithium titanate represented by the above general formula as the positive electrode active material, and 5% of the conductive auxiliary. It is preferable that it is -20 mass% and a binder is 1-10 mass%.

Moreover, the negative electrode of a lithium titanate-carbon battery contains a carbon material as an active material. Amorphous carbon is used as the carbon material. Thereby, in the battery, a stable voltage gradient in the period from the initial discharge to the end of discharge can be obtained.

Suitable examples of the amorphous carbon include amorphous coke and an amorphous carbon material obtained from a phenol resin. And as a physical property of this amorphous carbon, it is preferable that the space | interval of (002) plane is 0.3-0.5 nm and a true density is 1.2-2.0 g / cm < ² >, for example. That is, if the surface spacing of the (002) plane of amorphous carbon is the above value and the true density of amorphous carbon is the above value, the period from the beginning of discharge to the end of discharge The voltage gradient at is particularly stable, the amount of impurities in the carbon is small, and the battery characteristics are particularly good.

  The negative electrode of the lithium titanate-carbon battery can be obtained by molding a negative electrode mixture containing the above carbon material and a binder by an appropriate means. For example, the negative electrode mixture is pressure-molded, or the negative electrode mixture is dispersed in a solvent to prepare a negative electrode mixture-containing paste, and the negative electrode mixture-containing paste serves as a current collector It is produced by passing through a process of applying to and drying. However, the method for manufacturing the negative electrode is not limited to the above-described method, and other methods may be used. As the binder, a fluororesin such as PVDF or PTFE, styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), or the like is suitable.

  As described above, when the negative electrode is composed of a pressure-formed body of the negative electrode mixture, the composition of the negative electrode mixture is 80 to 95% by mass of the carbon material of the negative electrode active material and 5 to 20% by mass of the binder. Preferably there is.

  In the case of a lithium titanate-carbon battery, the positive and negative electrodes do not have lithium that serves as mobility, so lithium that can be used for charging and discharging is separately introduced. This lithium can be introduced, for example, by attaching a metal lithium foil to the positive electrode or the negative electrode.

The coin-type non-aqueous electrolyte secondary battery preferably has high capacity and excellent heavy load characteristics due to the characteristics of the hearing aid, and also reduces the battery mass and makes the hearing aid lighter. The lithium titanate-carbon battery described above is particularly preferable. Moreover, these various batteries may be used individually by 1 type, but you may use as an assembled battery comprised combining 2 or more types in parallel or in series.

  The structure of the coin-type non-aqueous electrolyte secondary battery according to the present invention will be described with reference to FIG. FIG. 5 is a cross-sectional view schematically showing an example of a coin-type non-aqueous electrolyte secondary battery according to the present invention. In FIG. 5, 31 is a positive electrode, 32 is a negative electrode, 33 is a separator, 34 is a positive electrode can, 35 is a negative electrode can, and 36 is an annular gasket. In addition, an electrolytic solution is injected into the battery of FIG. 5 (not shown).

  In the coin-type non-aqueous electrolyte secondary battery of FIG. 5, a negative electrode can 35 having a negative electrode 32 embedded in an opening of a positive electrode can 34 having a positive electrode 31 and a separator 33 embedded therein is an annular gasket 36 having an L-shaped cross section. And the opening end of the positive electrode can 34 is tightened inward, whereby the annular gasket 36 abuts on the negative electrode can 35, thereby sealing the opening of the positive electrode can 34 and the inside of the battery. Has a sealed structure. That is, in the coin-type non-aqueous electrolyte secondary battery of FIG. 5, the power generation element including the positive electrode 31, the negative electrode 32, and the separator 33 in the space (sealed space) formed by the positive electrode can 34, the negative electrode can 35 and the annular gasket 36. Is loaded.

  The contact surface between the inner surface of the positive electrode can 34 and the positive electrode 31 and the contact surface between the inner surface of the negative electrode can 35 and the negative electrode 32 are preferably bonded with a conductive adhesive. As the conductive adhesive, for example, carbon paste, silver paste, or the like can be used. From the viewpoint of cost, carbon paste is more preferable. For example, the carbon paste is obtained by dispersing graphite in water using water glass and a dispersant, and the water glass plays a role as an adhesive by reaction with carbon dioxide in the air.

  As the positive electrode can 34 and the negative electrode can 35, for example, those made of stainless steel or those made of iron and nickel-plated on the surface are preferable.

  As the separator 33, for example, a polypropylene nonwoven fabric or a microporous film can be used.

  Examples of the annular gasket 36 include those made of polypropylene or nylon (such as nylon 66), and for heat resistance, fluorine resins such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyphenylene ether, and the like. (PPE), polysulfone (PSF), polyarylate (PAR), polyethersulfone (PES), polyphenylene sulfide (PPS), polyether ether ketone (PEEK), etc. made of heat-resistant resin having a melting point exceeding 240 ° C. Can be used.

  Moreover, the organic electrolyte prepared by dissolving lithium salt in an organic solvent is used for the electrolyte of the coin-type non-aqueous electrolyte secondary battery regardless of the type of the battery. Examples of the organic solvent constituting the electrolytic solution include cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; acyclic carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; 1,2-dimethoxyethane, 1, 2, -Ethers such as diethoxyethane, dimethoxypropane, 1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran; and the like can be used singly or in combination of two or more. In particular, a mixed solvent of two or more containing a cyclic carbonate and an acyclic carbonate is preferable.

The lithium salt electrolyte of the electrolytic solution, for _{example, LiN (CF 3 SO 2)} 2, LiClO 4, LiPF 6, LiBF 4, LiAsF 6, LiSbF 6, LiCF 3 SO 3, LiCF 3 CO 2, LiC n F 2n + 1 SO ₃ (n ≧ 2), LiN (CF ₃ CF ₂ SO ₂ ) _{2 and the} like. Among them, LiN (CF ₃ SO ₂ ) ₂ , LiPF ₆ , LiCF ₃ SO ₃ , LiBF _{4 and the} like are particularly preferably used because they have high conductivity and are thermally stable. The concentration of these lithium salts in the electrolytic solution is not particularly limited, but is usually preferably about 0.1 to 2 mol / l, and particularly preferably about 0.4 to 2 mol / l.

  The size of such a coin-type non-aqueous electrolyte secondary battery is not particularly limited, and may be adjusted to the size required for the hearing aid. However, the smaller the battery size, the smaller the hearing aid, which is preferable. Specifically, the outer diameter of the battery is preferably 8 mm or less, more preferably 6 mm or less. With such a size, it can sufficiently cope with an ear hole type hearing aid that is required to be smaller. . On the other hand, if the battery size is too small, the battery capacity becomes small. For example, it is recommended that the lower limit of the battery size be 4 mm in terms of the battery outer diameter. Moreover, the thickness of the battery is generally about 1 to 6 mm, for example.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

Reference example 1
First, lithium titanate used as a positive electrode active material was synthesized as follows. That is, anatase type titanium oxide is used, and 2 mol of this anatase type titanium oxide and 1 mol of lithium hydroxide are mixed, and titanium is fired at 800 ° C. for 8 hours in an air atmosphere using an electric furnace. Lithium acid was synthesized. When the obtained lithium titanate was subjected to elemental analysis by atomic absorption spectrometry, it was Li _1.33 Ti _1.67 O ₄ (that is, Li ₄ Ti ₅ O ₁₂ ).

Obtained lithium titanate (Li _1.33 Ti _1.67 O ₄ ): 85 parts by mass, Ketjen black (conducting aid): 10 parts by mass, PVDF (binder): 5 parts by mass, N- A positive electrode mixture is prepared by mixing in methyl-2-pyrrolidone, and the dried positive electrode mixture is pressure-molded into pellets having a diameter of 3.5 mm and a thickness of 1.5 mm, and this is a far-infrared dryer. The positive electrode was produced by drying at 150 ° C. for 1 hour and dehydrating.

  Apart from the above, artificial graphite: 95 parts by mass, SBR and CMC mixed at 1: 1 (mass ratio) (binder): 5 parts by mass are mixed in pure water to prepare a negative electrode mixture. The negative electrode mixture after drying was pressed into pellets having a diameter of 4 mm and a thickness of 0.8 mm, and this was dried at 70 ° C. for 12 hours using a vacuum dryer and dehydrated, whereby the negative electrode was removed. Produced. Prior to battery assembly, this negative electrode was adhered to the inner surface of the negative electrode can with a carbon paste as a conductive adhesive.

  The carbon paste used for the above bonding was “Bunny Height IV-174” (trade name) manufactured by Nippon Graphite Industry Co., Ltd., and its components were graphite: 26 mass%, water glass: 15.5 mass%, dispersant: 2% by mass, ion-exchanged water: 56.5% by mass, and since the carbon paste was applied to the entire surface of the negative electrode can contacting the inner surface of the negative electrode can and the negative electrode was adhered to the inner surface of the negative electrode can, the inner surface of the negative electrode can It is considered that 95% by area or more of the contact surface between the electrode and the negative electrode is bonded with a conductive adhesive.

As the electrolytic solution, a solution obtained by dissolving LiPF ₆ at a concentration of 1.6 mol / l in a mixed solvent of ethylene carbonate and dimethyl carbonate in a volume ratio of 1: 4 was used.

  A coin-type nonaqueous electrolyte secondary battery (lithium titanate-carbon battery) having an outer diameter of 7.9 mm and a height of 3.6 mm having the structure shown in FIG. did.

In FIG. 5, the positive electrode 31 uses lithium titanate (Li _1.33 Ti _1.67 O ₄ ) as an active material as described above, and the lithium titanate, ketjen black (conducting aid), and PVDF (binder). Is contained in a positive electrode can 34 made of stainless steel. The negative electrode 32 is composed of a pressure-molded body of a negative electrode mixture containing artificial graphite as an active material as described above and containing the artificial graphite, SBR, and CMC (binder). As described above, the negative electrode 32 is assembled into a battery. Prior to this, the inner surface of the negative electrode can 35 was adhered using carbon paste. In addition, the negative electrode 32 has metallic lithium corresponding to 85% of the electric capacity of the positive electrode 31 at the time of battery assembly disposed on the side facing the separator 33, and the artificial graphite as the negative electrode active material is the electrolyte solution after the battery is assembled. Lithium ions can be doped / undoped in the presence.

  And between the positive electrode 31 and the negative electrode 32, the separator 33 which consists of a polypropylene nonwoven fabric with the thickness of 0.15mm and a diameter of 5.5mm is arrange | positioned, and these positive electrode 31, the negative electrode 32, the separator 33, and electrolyte solution are positive electrode cans. 4, the negative electrode can 5, and an annular gasket 36 made of polypropylene, and the inside of the battery is sealed by tightening the opening end of the positive electrode can 34 inward. Yes.

  Using the coin-type non-aqueous electrolyte secondary battery thus obtained and the hearing aid body excluding the battery part, a commercially available ear hole type hearing aid body having the structure shown in FIGS. 1 and 2 is used. A hearing aid was constructed.

Comparative Example 1
The positive electrode was produced as follows. Nickel hydroxide powder: 100 parts by mass of cobalt hydroxide powder: 1 part by mass, CMC powder: 0.2 parts by mass and 60% by mass of PTFE dispersion: 1 part by mass Adjusted. The paste is dried at 85 ° C. and then pulverized to prepare a positive electrode mixture having an average particle size of 200 μm, and the dried positive electrode mixture is pressed into pellets having a diameter of 4.2 mm and a thickness of 2.0 mm. Thus, a positive electrode was produced.

The negative electrode was produced as follows. Each sample of commercially available misch metal (Mm) (containing La, Ce, Nd, and Pr), Ni, Co, Mn, and Al (all having a purity of 99% or more) was replaced with MmNi _3.9 Co _0.6 Mn _{0. Then} , the mixture was heated and melted in a high-frequency melting furnace to obtain a composition of _.35 Al _0.25 to obtain a hydrogen storage alloy. This hydrogen storage alloy was mechanically pulverized to obtain a hydrogen storage alloy powder having an average particle size of 35 μm. Dispersion of this hydrogen storage alloy powder: 100 parts by mass, carbonyl nickel powder: 1 part by mass, 5% by mass poly-N-vinylacetamide aqueous solution: 10 parts by mass and 40% by mass styrene-2-ethylhexyl acrylate copolymer ( Dispersion medium: water): 1.7 parts by mass were added and mixed to prepare a negative electrode mixture-containing paste. This paste was dried at 85 ° C., and the dried negative electrode mixture was pressure-molded into pellets having a diameter of 4.2 mm and a thickness of 1.0 mm to produce a negative electrode.

As the electrolytic solution, an aqueous solution obtained by adding 17 g of LiOH and 33 g of zinc oxide to 1 liter of a 30 mass% potassium hydroxide aqueous solution and mixing them was used. A coin-type nickel metal hydride battery having a structure similar to that of Reference Example 1 shown in FIG. In addition, the nylon nonwoven fabric was used for the separator between a positive electrode and a negative electrode. A hearing aid was constructed in the same manner as in Reference Example 1 except that the above coin-type nickel metal hydride battery was used.

Comparative Example 2
A hearing aid was constructed in the same manner as in Reference Example 1 using a commercially available PR41 battery as the air battery.

For the hearing aids of Reference Example 1 and Comparative Examples 1 and 2, the mass was measured and the continuous use time until the battery was required was determined by continuously using the discharge current at 1 ° C. at 20 ° C. Here, for the batteries of Reference Example 1 and Comparative Example 1, the capacity discharged by use (4 mAh) is charged and used every 4 hours of continuous use, and the time required for charging is excluded from the continuous usable time. Asked. Moreover, about each hearing aid, the liquid leakage state of the battery at the time of storing for 12 days in 60 degreeC and 90% of humidity conditions was confirmed visually. These results are shown in Table 1. In the hearing aid of Comparative Example 2, the battery used was an air battery, and the battery itself was not hermetically sealed and was not worthy of evaluating liquid leakage. .

In Table 1, “continuous usable time until battery replacement” in the hearing aids of Reference Example 1 and Comparative Example 1 is the time from the start of use until the hearing aid cannot be driven even if it is charged further. Means.

  As can be seen from Table 1, the hearing aid of Reference Example 1 (the hearing aid using a non-aqueous electrolyte secondary battery) is a hearing aid of Comparative Example 1 that does not require short-term battery replacement in terms of the mass of the hearing aid. It was possible to reduce the weight by about 7% compared to the hearing aid used. Moreover, it was possible to reduce the weight of the hearing aid using the air battery that has been conventionally used in Comparative Example 2. Furthermore, in the hearing aid of Reference Example 1, the continuous usable time until battery replacement is significantly improved as compared with the hearing aid of Comparative Example 2 using an air battery as a primary battery, and charging is necessary. It has become possible to reduce the environmental impact of battery disposal. In addition, battery leakage during storage did not occur in the hearing aid of Reference Example 1, but occurred in the hearing aid of Comparative Example 1, and the safety improvement was achieved in the hearing aid of Reference Example 1. .

It is a perspective view which shows roughly an example of the hearing aid (ear hole shape) of this invention. It is a perspective view which shows a mode that the battery accommodating part cover of the hearing aid of FIG. 1 was opened. It is a perspective view which shows roughly an example of the hearing aid (ear-hook type) of this invention. It is a partial side view which shows a mode that the battery accommodating part of the hearing aid of FIG. 3 was opened. It is sectional drawing which shows roughly an example of the coin-type nonaqueous electrolyte secondary battery which concerns on this invention.

Explanation of symbols

10 20 Hearing Aid 11 21 Hearing Aid Main Body 12 Battery Storage Lid 17 22 Battery Storage 18 28 Coin Type Nonaqueous Electrolyte Secondary Battery 31 Positive Electrode 32 Negative Electrode 33 Separator 34 Positive Electrode Can 35 Negative Electrode Can 35 Negative Gasket 36 Annular Gasket

Claims (4)

A hearing aid comprising a coin-type non-aqueous electrolyte secondary battery including a positive electrode containing lithium titanate and a negative electrode containing amorphous carbon . The amorphous carbon contained in the negative electrode of the coin-type non-aqueous electrolyte secondary battery has a (002) plane spacing of 0.3 to 0.5 nm and a true density of 1.2 to 2.0 g / The hearing aid according to claim 1, which is cm ³ . The hearing aid according to claim 1 or 2 , wherein the hearing aid has an ear hole shape. The hearing aid according to any one of claims 1 to 3 , wherein the coin-type non-aqueous electrolyte secondary battery is enclosed inside.

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