Composite electrode, lithium battery and implantable medical device

Abstract

The utility model provides a composite electrode, lithium battery and implantable medical device, the composite electrode includes current collector and is provided mixed cathode material layer on the current collector at least one side surface, the mixed cathode material layer includes at least two active material layer, and the active material layer includes the current collector and the mixed cathode material layer. And the discharge platform voltages of the two adjacent active material layers are different from each other. The utility model has the advantages of high rate performance and service life indication function.

Description

Technical Field

[0001] This utility model belongs to the field of power supply technology for implantable medical devices, and relates to a composite electrode, a lithium battery, and an implantable medical device. Background Technology

[0002] Implantable medical devices often use batteries to power their devices and treat various diseases. The batteries used in these devices must provide the required energy in a specific way, depending on the type of device and its application. For example, implantable pacemakers only require low power or current (microamperes) throughout their lifespan, while implantable neurostimulators, drug pumps, and defibrillators, in addition to low-rate requirements, sometimes require short bursts of medium-power pulses (milliamperes) to high-power pulses (amperes) to provide medical care to patients.

[0003] While the power requirements, size, capacity, and configuration of batteries vary depending on the device type and treatment, there are common requirements for implantable medical batteries. These include: the battery must operate effectively for many years to minimize surgical frequency, be safe during installation and use, have predictable and reliable performance, and possess low self-discharge and high volumetric energy density to enable device miniaturization and maximize patient comfort.

[0004] CN110099716A discloses an implantable medical device comprising a battery cell, the battery cell comprising: an anode; a cathode comprising fluorinated carbon particles; a spacer between the anode and the cathode; and an electrolyte in contact with the anode, the cathode, and the spacer; wherein more than 50% by volume of the fluorinated carbon particles have a particle size in the range of 2 micrometers to 10 micrometers; and wherein more than 50% by quantity of the fluorinated carbon particles have an aspect ratio of 1:1.2 to 1:8.

[0005] CN113422104A discloses an implantable lithium-ion battery capable of discharging to zero volts, comprising: a positive electrode, a negative electrode, and an isolation-conduction module; wherein, the isolation-conduction module comprises: a separator and a liquid electrolyte, a polymer solid electrolyte separator, or a polymer-inorganic composite solid electrolyte separator; the positive electrode comprises a positive electrode active material supported on a positive electrode current collector, the positive electrode active material comprising one or more of the following materials: nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium manganese oxide, lithium cobalt oxide, and lithium vanadium phosphate; the negative electrode comprises a negative electrode active material supported on a negative electrode current collector, wherein the negative electrode current collector is made of an oxidation-resistant material or is a current collector with an anti-oxidation functional coating.

[0006] However, existing battery systems experience a sharp drop in discharge voltage at the end of their lifespan when used at high rates, making it impossible to predict the remaining lifespan of the battery. Therefore, there is a need to provide batteries that can indicate when their lifespan is exhausted, in order to avoid affecting the safe operation of electrical equipment. Utility Model Content

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a composite electrode, a lithium battery, and an implantable medical device. By employing active material layers with different discharge plateau voltages, the pulse voltage is increased, which is beneficial to improving the battery rate performance. This allows the battery voltage drop to indicate the start time of battery depletion or end-of-service (EOS), thereby ensuring the predictability, stability, and reliability of the battery.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a composite electrode, the composite electrode comprising a current collector and a mixed cathode material layer disposed on at least one side surface of the current collector, the mixed cathode material layer comprising at least two active material layers, wherein the discharge plateau voltages of adjacent active material layers are different from each other.

[0010] In this invention, the composite electrode, by setting a mixed cathode material layer, not only improves the battery rate performance but also increases the capacity in the voltage range near the battery depletion or service termination, thereby extending the time of the voltage range near EOS. This allows the battery life to be indicated by monitoring the voltage drop of the battery body, avoiding the problem of rapid voltage drop at the end of the battery life, which makes it impossible to predict its lifespan.

[0011] It should be noted that the discharge platform voltage mentioned in this utility model refers to the voltage value corresponding to a relatively gentle voltage change in the active material layer during the discharge process, while the capacity change is relatively large, under the same current conditions.

[0012] As a preferred embodiment of this utility model, the thickness of the mixed cathode material layer is 0.05~5mm, for example, it can be 0.05mm, 0.1mm, 0.2mm, 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm or 5mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] As a preferred technical solution of this utility model, the thickness of the current collector is 0.01~0.2mm, for example, it can be 0.01mm, 0.02mm, 0.05mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm or 0.2mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0014] As a preferred embodiment of the present invention, the hybrid cathode material layer includes an electrode active material layer and an auxiliary active material layer stacked sequentially. The electrode active material layer is a manganese dioxide material layer and / or a fluorinated carbon material layer, and the auxiliary active material layer is a silver vanadium oxide material layer. The electrode active material layer is disposed close to the current collector.

[0015] In this invention, the silver vanadium oxide in the auxiliary active material layer has two different discharge plateau voltages, and the discharge plateau voltages of manganese dioxide and / or carbon fluoride in the electrode active material layer are both located between the two discharge plateau voltage ranges of the silver vanadium oxide, which increases the capacity in the voltage range near EOS to provide a sloped voltage ramp and greatly improves the pulse voltage.

[0016] It should be noted that the manganese oxide, fluorinated carbon, and silver vanadium oxide are all conventional materials known to those skilled in the art and can be purchased directly. Furthermore, when the electrode active material layer consists of a manganese dioxide layer and a fluorinated carbon layer, the manganese dioxide layer and the fluorinated carbon layer are stacked sequentially, and they are independent of each other and do not affect each other.

[0017] As a preferred embodiment of this utility model, the current collector is a stainless steel sheet, aluminum foil, or titanium foil.

[0018] Secondly, this utility model provides a lithium battery, which includes a casing, an anode, the composite electrode described in the first aspect, and a liquid organic electrolyte disposed inside the casing, and at least two membrane layers are disposed between the anode and the composite electrode.

[0019] In a preferred embodiment of this invention, the anode comprises metallic lithium.

[0020] As a preferred embodiment of this utility model, at least one end of the housing is an open end, and the open end is sealed with a feeder, which is electrically connected to the composite electrode of the lithium battery.

[0021] As a preferred embodiment of this utility model, the thickness of the diaphragm layer is 0.01~0.05mm, for example, it can be 0.01mm, 0.02mm, 0.03mm, 0.04mm or 0.05mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Thirdly, this utility model provides an implantable medical device, which includes an electrically connected battery assembly and a voltage detection assembly, wherein the battery assembly includes the lithium battery described in the second aspect.

[0023] This invention indicates the start time of battery depletion or service termination by detecting a drop in the voltage of the battery assembly, thereby ensuring continuous and safe operation of the device.

[0024] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0025] This invention provides a composite electrode, lithium battery, and implantable medical device that improves the battery's pulse voltage, enabling it to indicate when the battery is about to run out of power or when service is about to terminate, ensuring the predictability of battery life, and exhibiting high rate performance, stability, and safety. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the composite electrode provided in Embodiment 1 of this utility model.

[0027] Figure 2 This is a schematic diagram of the structure of the composite electrode provided in Embodiment 3 of this utility model.

[0028] Figure 3 This is a comparison chart of the discharge curves of the lithium batteries in Embodiment 1 and Comparative Example 1 of this utility model.

[0029] Among them, 10-composite electrode; 1-current collector; 2-mixed cathode material layer; 21-electrode active material layer; 22-auxiliary active material layer. Detailed Implementation

[0030] It should be understood that in the description of this utility model, the terms "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing the utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0031] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0033] In one specific embodiment, this invention provides a composite electrode, including a current collector and a mixed cathode material layer disposed on at least one surface of the current collector. The mixed cathode material layer includes at least two active material layers, and the discharge plateau voltages of adjacent active material layers are different. Traditional lithium batteries exhibit a gradually decreasing voltage curve at low and medium rates, but a sharp drop in discharge voltage at the end of their lifespan at high rates, making it impossible to predict the remaining battery life. To address this, this invention, by designing and configuring a composite electrode with a mixed cathode material layer, can improve rate performance, extend the capacity in the voltage range near the end of the lifespan (EOS), provide a sloping voltage ramp, and reduce the voltage at the end of the lifespan, thus having an EOS (End of Service) indication function.

[0034] In some embodiments, the thickness of the hybrid cathode material layer is 0.05~5 mm.

[0035] In some embodiments, the hybrid cathode material layer includes an electrode active material layer and an auxiliary active material layer stacked sequentially. The electrode active material layer is a manganese dioxide material layer and / or a fluorinated carbon material layer, and the auxiliary active material layer is a silver vanadium oxide material layer. The electrode active material layer is disposed close to the current collector. The silver vanadium oxide material layer has two distinct discharge plateau voltages at 3.2V and 2.6V, respectively, while the discharge plateau voltage of the fluorinated carbon material layer is 2.8V, and the discharge plateau voltage of the manganese dioxide material layer is 3.0V, both located between the two discharge plateau voltages of the silver vanadium oxide material layer. Therefore, the lifetime endpoint voltage of the hybrid cathode material layer is lower than that of conventional active material layers using manganese dioxide, fluorinated carbon, or silver vanadium oxide alone (traditional Li / CFx system, Li / SVO system, or Li / MnO2 system batteries). This increases the capacity of the battery body in the voltage range near the end of discharge, and thus the lifetime indication function can be achieved by detecting the voltage drop.

[0036] In addition, the active material layer also includes conductive agents and organic binders necessary for realizing the battery function, but these are not the main improvements of this utility model. Polyvinylidene fluoride or polytetrafluoroethylene commonly used in the art can be selected as organic binders, and carbon black, conductive graphite or acetylene black can be selected as conductive agents. Those skilled in the art can add or subtract them according to the actual situation.

[0037] In some embodiments, a mixed cathode material layer is disposed on one side surface or on both sides of the current collector, and the mixed cathode material layer completely covers the surface of the current collector. The thickness of the current collector is 0.01~0.2mm, which is beneficial for improving the pulse voltage of the battery. The current collector is a stainless steel sheet, aluminum foil, or titanium foil.

[0038] In another specific embodiment, the present invention provides a lithium battery, the lithium battery including a casing, an anode, a composite electrode as described in a specific embodiment, and a liquid organic electrolyte disposed inside the casing, and at least two membrane layers disposed between the anode and the composite electrode.

[0039] In some embodiments, the housing is either a rigid housing or a soft-pack housing. The rigid housing includes, but is not limited to, a stainless steel housing, a titanium metal housing, or a titanium alloy housing. The soft-pack housing can be a pouch-type soft-pack, and its material includes, but is not limited to, plastics such as polypropylene, polybutylene terephthalate, and polybutylene succinate. At least one end of the housing is an open end with an internal cavity structure to accommodate the anode, composite electrode, and liquid organic electrolyte. A feedthrough is sealed to the open end, and the feedthrough is electrically connected to the composite electrode of the lithium battery, achieving a sealed housing and ensuring the safety of battery operation. This invention does not specifically limit the structure of the feedthrough; any feedthrough structure well known to those skilled in the art can be used, and the housing can be sealed and connected by commonly used bonding, welding, or coupling methods, preferably welding. Furthermore, the material of the feedthrough is preferably corrosion-resistant glass, which helps extend battery life.

[0040] In some embodiments, the anode comprises lithium metal, and during the battery charging and discharging process, lithium ions are inserted and extracted back and forth between the anode and the composite negative electrode, resulting in a high specific capacity. Specifically, lithium metal sheets or lithium-containing transition metal oxides well known to those skilled in the art can be used.

[0041] In some embodiments, the thickness of the membrane layer is 0.01~0.05mm, which can prevent short circuits between the positive and negative electrodes while allowing active ions to pass through. The membrane layer includes, but is not limited to, polypropylene membranes, polyethylene membranes, non-woven fabrics, ceramics, and their composite materials commonly used in the art.

[0042] In some embodiments, the liquid organic electrolyte serves to conduct active ions between the anode and the composite electrode, and typically includes a lithium salt and an organic solvent. The lithium salt includes, but is not limited to, LiClO4, LiPF6, LiAsF6, LiBF4, and mixtures thereof, which are well known to those skilled in the art; the organic solvent includes, but is not limited to, DMC (dimethyl carbonate), THF (tetrahydrofuran), EC (ethylene carbonate), PC (polycarbonate), GBL (γ-hydroxybutyrolactone), DME (ethylene glycol dimethyl ether), and mixtures thereof, which are well known to those skilled in the art.

[0043] In another specific embodiment, this invention provides an implantable medical device including an electrically connected battery assembly and a voltage detection assembly. The battery assembly includes the lithium battery described in the above-described embodiment. This invention utilizes the voltage detection assembly to detect the real-time voltage of the battery assembly, allowing the operator to promptly monitor voltage drops and indicate the warning time for battery depletion or service termination, thus estimating battery lifespan. The voltage detection assembly can employ any voltage detection instrument commonly used by those skilled in the art; this invention does not impose any specific limitations on it.

[0044] Example 1

[0045] This embodiment provides a lithium battery, including a titanium casing with one open end sealed to a feedthrough. The casing has a hollow internal structure containing an anode, a composite electrode 10, and a liquid organic electrolyte. The feedthrough is electrically connected to the composite electrode 10. The anode is a lithium metal sheet, and two 0.02mm thick polypropylene separator layers are disposed between the anode and the composite electrode 10. Figure 1 As shown, the composite electrode 10 includes a current collector 1 and a mixed cathode material layer 2 disposed on the surface of the current collector 1, with the mixed cathode material layer 2 close to the separator layer. The current collector 1 is a titanium foil with a thickness of 0.1 mm, and the mixed cathode material layer 2 has a thickness of 1 mm. The mixed cathode material layer 2 includes an electrode active material layer 21 and an auxiliary active material layer 22 stacked sequentially. The electrode active material layer 21 is a fluorinated carbon material layer, disposed close to the current collector 1, and the auxiliary active material layer 22 is a silver vanadium oxide material layer. The liquid organic electrolyte is a mixed solution of LiClO4, PC, and DME.

[0046] Example 2

[0047] This embodiment provides a lithium battery, including a titanium casing with one open end sealed to a feedthrough. The casing has a hollow structure containing an anode, a composite electrode 10, and a liquid organic electrolyte. The feedthrough is electrically connected to the composite electrode 10. The anode is a lithium metal sheet, and three 0.01mm thick non-woven fabric separator layers are disposed between the anode and the composite electrode 10. The composite electrode 10 includes a current collector 1 and mixed cathode material layers 2 disposed on both sides of the current collector 1. The current collector 1 is made of 0.05mm thick aluminum foil, and the mixed cathode material layer 2 is 0.8mm thick. The mixed cathode material layer 2 includes an electrode active material layer 21 and an auxiliary active material layer 22 stacked sequentially. The electrode active material layer 21 is a manganese dioxide material layer disposed close to the current collector 1, and the auxiliary active material layer 22 is a silver vanadium oxide material layer. The liquid organic electrolyte is a mixed solution of LiBF4, DMC, and EC.

[0048] Example 3

[0049] This embodiment provides a lithium battery, including a soft-pack casing. One end of the casing is open, and a feedthrough is sealed to the open end. The casing has a hollow structure, inside which an anode, a composite electrode 10, and a liquid organic electrolyte are disposed. The feedthrough is electrically connected to the composite electrode 10. The anode is a lithium metal sheet, and two 0.02mm thick polyethylene separator layers are disposed between the anode and the composite electrode 10. Figure 2 As shown, the composite electrode 10 includes a current collector 1 and a mixed cathode material layer 2 disposed on the surface of the current collector 1, close to the diaphragm layer. The current collector 1 is made of stainless steel sheet with a thickness of 0.05 mm, and the mixed cathode material layer 2 has a thickness of 2 mm. The mixed cathode material layer 2 includes an electrode active material layer 21 and an auxiliary active material layer 22 stacked sequentially. The electrode active material layer 21 consists of a fluorinated carbon material layer and a manganese dioxide material layer stacked sequentially, with the fluorinated carbon material layer disposed close to the current collector 1. The auxiliary active material layer 22 is a silver vanadium oxide material layer. The liquid organic electrolyte is a mixed solution of LiPF6, DMC, and PC.

[0050] Comparative Example 1

[0051] This comparative example provides a lithium battery that differs from Example 1 in that its cathode current collector surface is coated with a conventional active material layer, which includes an electrode active material layer but does not contain an auxiliary active material layer; the rest of the structure is the same as in Example 1.

[0052] This invention applies a 22mA / cm pressure to the lithium batteries of Example 1 and Comparative Example 1, respectively. 2 A pulsed current was used for discharge, and the resulting discharge curve was recorded. The results are as follows: Figure 3 As shown.

[0053] Depend on Figure 3 It is easy to see that, compared with Comparative Example 1, the composite electrode used in Example 1 increases the pulse voltage by setting a mixed cathode material layer, thereby improving the rate performance. In addition, the capacity in the voltage region near the end of the discharge is also increased, which can better indicate the lifetime by voltage reduction.

[0054] The applicant declares that the above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A composite electrode, characterized by, The composite electrode comprises a current collector and a mixed cathode material layer arranged on at least one side surface of the current collector, wherein the mixed cathode material layer comprises at least two active material layers, and the discharge platform voltage of adjacent two active material layers is different.

2. The composite electrode according to claim 1, wherein The thickness of the mixed cathode material layer is 0.05-5 mm.

3. The composite electrode of claim 1, wherein The thickness of the current collector is 0.01-0.2 mm.

4. The composite electrode of claim 1, wherein The mixed cathode material layer comprises electrode active material layers and auxiliary active material layers arranged in sequence, the electrode active material layer is a manganese dioxide material layer and / or a carbon fluoride material layer, the auxiliary active material layer is a silver vanadium oxide material layer, and the electrode active material layer is arranged close to the current collector.

5. The composite electrode of claim 1, wherein The current collector is a stainless steel sheet, an aluminum foil or a titanium foil.

6. A lithium battery, characterized by The lithium battery comprises a shell, an anode, the composite electrode according to any one of claims 1-5 and a liquid organic electrolyte, the anode and the composite electrode are arranged with at least two diaphragm layers therebetween.

7. The lithium battery of claim 6, wherein, The anode comprises metallic lithium.

8. The lithium battery of claim 6, wherein, At least one end of the shell is an open end, and a feedthrough is sealingly connected to the open end, the feedthrough is electrically connected to the composite electrode of the lithium battery.

9. The lithium battery of claim 6, wherein, The thickness of the diaphragm layer is 0.01-0.05 mm.

10. An implantable medical device, comprising: The implantable medical device comprises an electrically connected battery assembly and a voltage detection assembly, the battery assembly comprises the lithium battery according to any one of claims 6-9.

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