Lithium titanate button secondary battery and electronic price tag

Abstract

Provided are a lithium titanate button secondary battery and an electronic price tag. The secondary battery is a button battery formed by stacking and connecting a lithium titanate composite electrode, a battery positive electrode, a separator, an electrolyte, a negative electrode casing, a positive electrode casing, a positive electrode current collector, a sealing gasket and the like. The lithium titanate composite electrode is formed by compressing a lithium titanate composite electrode material with a special structure by means of a tabletting process.

Description

Lithium titanate button secondary battery and electronic price tag

[0001] Related applications

[0002] This application claims priority to the Chinese invention patent application with application number 202311746869.6 filed on December 18, 2023, and cites the entire contents disclosed in the above patent application as part of this application. Technical Field

[0003] The present disclosure relates to a lithium titanate button-type secondary battery having a structure similar to that of a primary battery, and an electronic price tag using the lithium titanate button-type secondary battery as an energy storage device. Background Art

[0004] Electronic price tags typically rely on non-rechargeable primary batteries such as lithium-manganese button cells and lithium-manganese soft-pack batteries for screen price changes and wireless communications. Due to the limited capacity of the batteries, self-discharge, and the power consumption of the tags during continuous standby operation, the lifespan of these primary batteries is limited. When the batteries are depleted, they must be promptly replaced, requiring secondary investment in the application. Researchers are also exploring renewable energy sources such as light, vibration, and microwaves as energy sources for electronic price tags. However, these energy sources are intermittent, fluctuating, and low-energy. These energy sources alone cannot meet the needs of continuous standby operation and instantaneous screen refreshes. Therefore, energy storage devices are essential for product-level application. Currently, common consumer energy storage devices fall into three main categories: physical energy storage devices, electrochemical energy storage devices, and lithium-ion capacitors, which combine the properties of both.

[0005] Among the aforementioned energy storage devices, physical energy storage devices primarily include various types of capacitors, such as ceramic capacitors, electrolytic capacitors, or capacitors with other dielectrics, including supercapacitors. Conventional capacitors operate on the principle that charge moves in an electric field due to force. The dielectric between conductors hinders this movement, causing charge to accumulate on the conductors, resulting in charge accumulation. Supercapacitors achieve double-layer charge storage through polarized electrolytes and redox pseudocapacitive charging. The capacity of a supercapacitor depends on the distance between the electrodes and their surface area. Activated carbon is often coated on the electrodes to increase surface area and thus capacity. Charge in these capacitors is statically stored or physically adsorbed, without chemical reaction. When the external potential is removed, the charge between the two plates easily migrates due to the concentration difference, resulting in a recombination reaction, which manifests as a rapid drop in the capacitor voltage, or rapid self-discharge. Conventional capacitors have a very small capacity, ranging from a few pico-farads to several thousand micro-farads, which cannot meet the typical energy consumption of electronic price tags. Supercapacitors can achieve capacities ranging from several to several thousand farads, but their volume increases dramatically, resulting in a low volume density, posing significant challenges to the internal space and volume of electronic price tags.

[0006] In addition, electrochemical energy storage mainly includes ternary lithium batteries, lithium cobalt oxide batteries, and lithium iron phosphate batteries. These batteries are widely used in mainstream electronic products on the market. Among them, ternary lithium batteries, lithium cobalt oxide batteries, and lithium iron phosphate batteries all use graphite-based negative electrode materials. When overcharged, side reactions occur within the battery, causing battery safety issues. First, excessive lithium is embedded in the negative electrode, and lithium dendrites grow on the negative electrode surface. Lithium dendrites may puncture the separator and cause a short circuit between the positive and negative electrodes. Second, excessive lithium is released from the positive electrode, causing the positive electrode structure to collapse, releasing heat and oxygen. Oxygen accelerates the decomposition of the electrolyte, and the internal pressure of the battery continues to rise. After a certain level, the battery may rupture. The contact between the active material and air further generates more heat, leading to fire or explosion. When this type of battery is deeply over-discharged, the SEI film on the negative electrode surface will decompose, triggering a reaction between the electrolyte and the graphite negative electrode, generating heat and releasing gas. Continued over-discharge will also cause the negative electrode current collector copper foil to dissolve and further deposit on the positive electrode. Simultaneously, the structure of the positive electrode material expands due to the excessive lithium ion insertion. When a large amount of copper is deposited on the positive electrode, it will clog the surface of the positive electrode material and may puncture the separator, causing an internal short circuit, which in turn causes safety issues. For lithium-ion batteries using graphite negative electrode materials, the diffusion rate of lithium ions decreases at low temperatures, restricting the battery's charge and discharge speed. Typically, the charging temperature of such batteries must be greater than 0°C, otherwise abnormal lithium deposition may occur, and the resulting lithium dendrites will puncture the separator, causing an internal short circuit. The main negative electrode material of lithium titanate batteries is lithium titanate, not graphite. Since the electrochemical potential of lithium titanate is higher than that of pure metallic lithium, lithium dendrites are not easily generated, and the current collectors of the positive and negative electrodes are both made of aluminum foil, there will be no copper deposition during over-discharge, and the voltage will not be lower than 0V, so its safety is greatly improved in the event of overcharge or over-discharge; the lithium titanate material has a large lattice gap, and the volume strain force when lithium ions are inserted and extracted is extremely small, and the theoretical cycle performance is good; its ion diffusion coefficient is one order of magnitude higher than that of graphite materials, and it has potential large current charge and discharge capabilities and good low-temperature performance. However, its disadvantages are also obvious. The electronic conductivity of lithium titanate material is low, which limits its large current charging and discharging capabilities. At the same time, no SEI film will be formed on the surface of the negative electrode lithium titanate. During use, lithium titanate and electrolyte will continuously react and continuously release trace gases. This gas production behavior is the main factor inhibiting the application of lithium titanate. In addition, the energy density and volume density of lithium titanate batteries are much lower than those of common ternary lithium and iron lithium batteries. At present, there are only a few applications on the market in power fields such as buses and rail transit that are not sensitive to volume, space and weight. The structural forms are mainly large-size square shell batteries, cylindrical batteries, etc.

[0007] From the perspective of manufacturing technology, existing lithium-ion batteries usually use stacking or winding processes to prepare battery cells. Positive / negative current collectors need to extend from the positive / negative electrode sheets of the battery cells respectively, and the battery power is extracted by welding the current collectors to the external tabs or external poles. The process is complicated, as shown in Figures 1 and 2.

[0008] This process has the following two disadvantages:

[0009] The first disadvantage is that the metal conductive current collector and conductive electrode ears will occupy a large part of the internal volume space of the battery. The more windings there are, the larger the volume occupied by the conductive current collector, the smaller the available space for the battery's effective materials, and the lower the battery's volume energy density.

[0010] Disadvantage 2: The width of the battery electrode during winding significantly limits the thickness of the battery, making it impossible to implement thin button-type secondary batteries. For example, the thickness of button-type secondary batteries for Bluetooth headsets is typically 5.4mm or 4mm, and there is no mass production of thinner button-type secondary batteries.

[0011] In addition, lithium-ion capacitors are a type of device whose principles and performance are between capacitors and lithium-ion batteries. One pole of a lithium-ion capacitor uses activated carbon material, and the other pole is a small amount of lithium-ion battery material added to the activated carbon material. When charging, lithium ions will be embedded in the battery material, further increasing the amount of charge, so its capacity is greater than that of ordinary capacitors. The lithium-ion capacitor uses one pole of activated carbon, and its working principle is still physical adsorption. After the external potential is removed, the ions migrate under the action of the concentration difference, and the speed of the composite reaction is also faster, that is, the self-discharge level is higher. When over-discharged, lithium-ion capacitors will also have the abnormality of copper precipitation during over-discharge, causing copper to be deposited on the surface of the positive electrode material, blocking the positive electrode pores, hindering the adsorption of lithium ions, and significantly reducing the capacity.

[0012] Summary of the Invention

[0013] For electronic price tags powered by renewable energy sources (including but not limited to light energy, vibration energy, and microwave energy) with intermittent, fluctuating, and micro-energy characteristics, an energy storage solution and device are invented to achieve continuous and stable operation of the electronic price tags, with good environmental compatibility, maintenance-free performance, resistance to over-discharge, and high safety.

[0014] Specifically, the present disclosure first prepares a lithium titanate composite electrode material with anti-flatulence and high conductivity, and first coats the surface of the nano-scale lithium titanate negative electrode material with an oxide layer. The density and high energy level of the coating layer are utilized to improve the stability of the contact interface between lithium titanate and the electrolyte, and effectively suppress the gas production during use; then a layer of graphene is coated, and its ultra-high conductivity is utilized to improve the conductivity of the lithium titanate negative electrode; the present disclosure also partially draws on the structure of a primary battery, and combined with the performance advantages of the lithium titanate composite electrode in the present disclosure, realizes a lithium titanate secondary battery that is completely different from the existing secondary battery structure, and realizes the energy storage application of lithium titanate secondary batteries in electronic price tags.

[0015] Specifically, the present disclosure provides the following technical solutions:

[0016] The present disclosure provides a lithium titanate button-type secondary battery, wherein:

[0017] The secondary battery is a button-type battery formed by stacking and connecting the following components:

[0018] Components include:

[0019] A lithium titanate composite electrode, which is used as the negative electrode of the battery;

[0020] The positive electrode of the battery;

[0021] a separator disposed between the positive electrode and the negative electrode;

[0022] An electrolyte, which fills the positive electrode, negative electrode, and / or separator pores inside the battery;

[0023] negative electrode housing;

[0024] positive electrode shell;

[0025] a positive electrode current collector disposed between the positive electrode and the positive electrode casing of the battery; and

[0026] The sealing rubber ring is an elastic filling medium filled between the positive and negative electrode shells of the battery.

[0027] Lithium titanate composite electrode is formed by pressing lithium titanate composite electrode material.

[0028] The lithium titanate composite electrode material is composed of lithium titanate composite particles, which contain: nano-scale lithium titanate; an oxide layer covering the nano-scale lithium titanate; and a graphene layer covering the oxide layer.

[0029] In the lithium titanate button-type secondary battery disclosed herein, the oxide constituting the oxide layer may be at least one selected from aluminum oxide, zinc oxide, and titanium dioxide, wherein aluminum oxide may be exemplarily selected.

[0030] In the lithium titanate button-type secondary battery disclosed herein, the positive electrode may be a lithium iron phosphate electrode.

[0031] The lithium titanate button-type secondary battery disclosed herein may further include a sealing adhesive, which is a sealing coating located at the sealing end of the battery.

[0032] In the lithium titanate button-type secondary battery disclosed herein, the sealing adhesive may be an epoxy-based low-temperature curing insulating sealant.

[0033] In the lithium titanate button-type secondary battery disclosed herein, the positive electrode current collector is a current collecting net or aluminum foil, and the current collecting net can be an aluminum mesh grid.

[0034] In the lithium titanate button-type secondary battery disclosed herein, the lithium titanate composite electrode may be in direct contact with the negative electrode housing to conduct electricity.

[0035] In the lithium titanate button-type secondary battery disclosed herein, a negative electrode shell conductive adhesive may be further provided between the negative electrode and the negative electrode shell of the battery.

[0036] In the lithium titanate button-type secondary battery disclosed herein, the negative electrode shell conductive adhesive may be a graphite conductive adhesive.

[0037] In the lithium titanate button-type secondary battery of the present disclosure, a negative electrode current collector may be further provided between the negative electrode and the negative electrode case of the battery.

[0038] In the lithium titanate button-type secondary battery disclosed herein, the negative electrode current collector may be a current collecting mesh.

[0039] In the lithium titanate button-type secondary battery disclosed herein, the current collecting mesh serving as the negative electrode current collector may be an aluminum mesh grid.

[0040] In the lithium titanate button-type secondary battery of the present disclosure, the negative electrode current collector may be an aluminum foil.

[0041] The present disclosure also provides an electronic price tag, which is a rechargeable electronic price tag, wherein the lithium titanate button secondary battery disclosed above is used as an energy storage device.

[0042] The electronic price tag of the present disclosure may include an electronic price tag main circuit and an electronic price tag charging management module.

[0043] In the electronic price tag disclosed herein, a voltage conversion circuit may not be used between the electronic price tag charging management module and the battery output terminal and the electronic price tag main circuit.

[0044] In the electronic price tag of the present disclosure, the electronic price tag charging management module may include a constant voltage and current limiting circuit, an electrical isolation circuit, and a power switch, wherein a battery protection circuit may not be used.

[0045] In the electronic price tag of the present disclosure, the lithium titanate secondary battery body or battery module used in the electronic price tag may not include a battery over-discharge protection circuit.

[0046] Effects of the Invention

[0047] The present disclosure can provide a lithium titanate button-type secondary battery with anti-flatulence and high conductivity, and an electronic price tag using the lithium titanate button-type secondary battery as an energy storage device, thereby providing a maintenance-free energy storage battery device for the electronic price tag. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic diagram of battery assembly with internal lamination and external soft package packaging.

[0049] Figure 2 is a schematic diagram of battery assembly with internal winding and external cylindrical packaging.

[0050] FIG3 is a schematic diagram of the assembly of a lithium titanate button-type secondary battery with anti-flatulence performance.

[0051] FIG4 is a schematic diagram of the microstructure of a lithium titanate composite electrode material having anti-flatulence properties and high electrical conductivity.

[0052] FIG5 is a schematic diagram of the internal microstructure of a negative electrode prepared using a lithium titanate composite electrode material having anti-flatulence properties and high conductivity.

[0053] FIG6 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which the positive electrode uses a current collector and the negative electrode has no current collector.

[0054] FIG7 is a schematic diagram of a stack of lithium titanate button-type secondary batteries with aluminum foil as the positive electrode current collector and no negative electrode current collector.

[0055] FIG8 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which both the positive and negative electrodes use current collecting grids for current collection.

[0056] FIG9 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which both the positive and negative electrodes are collected using aluminum foil.

[0057] FIG10 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which the positive electrode uses a current collecting net for current collection and the negative electrode shell is coated with a conductive adhesive.

[0058] FIG11 is a schematic diagram of a stack of lithium titanate button-type secondary batteries with aluminum foil as the positive electrode current collector and conductive adhesive applied to the negative electrode shell.

[0059] FIG12 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which both the positive and negative electrodes use current collecting nets for current collection and the negative electrode shell is coated with conductive glue.

[0060] FIG13 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which aluminum foil is used for current collection at both the positive and negative electrodes and the negative electrode shell is coated with conductive adhesive.

[0061] Figure 14 is a diagram of the hardware architecture of an electronic price tag using lithium titanate batteries.

[0062] FIG15 is a curve of charge and discharge data of the HT2016 lithium titanate button secondary battery after three cycles. DETAILED DESCRIPTION

[0063] In order to achieve the above-mentioned object, the present disclosure provides a lithium titanate button-type secondary battery, wherein:

[0064] The secondary battery is a button-type battery formed by stacking and connecting the following components, including:

[0065] A lithium titanate composite electrode, which is used as the negative electrode of the battery;

[0066] The positive electrode of the battery;

[0067] a separator disposed between the positive electrode and the negative electrode;

[0068] An electrolyte, which fills the positive electrode, negative electrode, and / or separator pores inside the battery;

[0069] negative electrode housing;

[0070] A positive electrode shell, which is matched and snap-fitted with a negative electrode shell; and

[0071] The positive electrode current collector is placed between the positive electrode and the positive electrode shell of the battery.

[0072] Lithium titanate composite electrode is formed by pressing lithium titanate composite electrode material.

[0073] The lithium titanate composite electrode material is composed of lithium titanate composite particles, which contain: nano-sized lithium titanate; an oxide layer coating the nano-sized lithium titanate; and a graphene layer coating the oxide layer. Figure 3 shows a typical stacking diagram and assembly diagram of the lithium titanate button-type secondary battery disclosed herein. The following describes the components of the lithium titanate button-type secondary battery disclosed herein.

[0074] (1) Lithium titanate composite electrode

[0075] The lithium titanate composite electrode disclosed herein is used as the negative electrode of the battery for lithium ion embedding and extraction, has anti-flatulence performance and high conductivity, can be in direct contact with the negative electrode shell to conduct electricity to realize the extraction of battery power, and does not require a negative electrode current collector, welding between the current collector and the tab, or welding between the tab and the external conductive electrode column.

[0076] The lithium titanate composite electrode disclosed in the present invention can be obtained by forming the lithium titanate composite electrode material through a simple sheeting process. Its manufacturing process is simple. The sheeting process replaces the existing coating process of the secondary battery electrode sheet, and can achieve the absence of a negative electrode current collector and related welding processes. The one-time molding and sealing process of the mold replaces the existing hot pressing packaging of soft-pack secondary batteries or the welding packaging of square / cylindrical secondary batteries, which can greatly reduce the production cost of the battery.

[0077] First, the lithium titanate composite electrode material forming the lithium titanate composite electrode of the present disclosure will be described.

[0078] The particles constituting the lithium titanate composite electrode material of the present disclosure include: nano-sized lithium titanate; an oxide layer covering the nano-sized lithium titanate; and a graphene layer covering the oxide layer.

[0079] The structure of the particles of the lithium titanate composite electrode material disclosed in the present invention is shown in FIG4 , which has a core-shell structure with nano-scale lithium titanate as the core, an oxide modification layer coated on the periphery of the nano-scale lithium titanate, and a graphene layer coated on the periphery of the modification layer.

[0080] Specifically, in the synthesis of the lithium titanate composite electrode material disclosed herein, first, the surface of the nano-scale lithium titanate negative electrode material is coated with an oxide layer. The density and higher energy level of the coating layer are utilized to improve the stability of the contact interface between lithium titanate and the electrolyte, and effectively suppress the gas production during use; then a layer of graphene is coated, and its ultra-high conductivity is utilized to improve the conductivity of the lithium titanate negative electrode, thereby providing a lithium titanate composite electrode material with anti-flatulence and high conductivity.

[0081] As shown in Figure 5, the lithium titanate composite electrode material can be bonded together using an organic adhesive to form the lithium titanate composite electrode material disclosed in the present invention. As such an organic adhesive, polyvinylidene fluoride (PVDF) or the like can be used. By using polyvinylidene fluoride or the like as an adhesive to bond the lithium titanate composite particles together, the conductivity of the electrode material can be improved while maintaining the strength of the lithium titanate composite electrode material.

[0082] Hereinafter, the main components constituting the lithium titanate composite electrode material disclosed in the present invention will be described respectively.

[0083] (i) Nano-scale lithium titanate

[0084] Nano-scale lithium titanate is the main material for the negative electrode of lithium-ion batteries, providing binding sites for lithium ion embedding during the charging process.

[0085] (ii) Oxide layer

[0086] The oxide layer, as a surface modification layer of lithium titanate, the main material of the battery's negative electrode, inhibits the gas production behavior of the reaction between lithium titanate and the electrolyte. As the oxide constituting the oxide layer, at least one of aluminum oxide, zinc oxide, and titanium dioxide can be used. For example, aluminum oxide can be selected. The Al2O3 coating layer can greatly reduce the interfacial side reactions between lithium titanate and the electrolyte, inhibit the gas production behavior during the use of the lithium titanate battery, and significantly improve the battery's cycle stability. In addition, the preparation process of the Al2O3 coating layer is simple, easy to scale, and low-cost.

[0087] (iii) Graphene layer

[0088] The graphene layer acts as a conductive agent for the lithium titanate electrode, a highly conductive current collector for the lithium titanate battery, and a channel for transmitting electrons to the external circuit. The graphene layer has ultra-high conductivity, which can improve the conductivity of the lithium titanate electrode, thereby improving the charge and discharge capacity of the battery.

[0089] Next, the method for preparing the lithium titanate composite electrode disclosed in the present invention is described.

[0090] As a method for preparing the lithium titanate composite electrode disclosed herein, the following preparation process can be cited, but the present disclosure is not limited thereto.

[0091] ①Use lithium titanate composite electrode material Li4Ti5O 12 After mixing the Al2O3 / graphene ingredients, the powder electrode is formed into a disc-shaped powder after being pressed by a tablet press. It is used as the negative electrode of the battery and then dried for later use; or

[0092] ②Use lithium titanate composite electrode material Li4Ti5O 12 After mixing the lithium titanate powder electrode with the Al2O3 / graphene ingredients, the powder electrode is formed into a disc-shaped powder electrode by a tablet press. While pressing the tablet, an aluminum mesh grid is pressed onto one side of the lithium titanate powder electrode to form a disc-shaped negative electrode with a current collector, which is then dried for later use; or

[0093] ③ Using lithium titanate composite electrode material Li4Ti5O 12 After the / Al2O3 / graphene ingredients are mixed, a layer of slurry is coated on the aluminum foil by a coating machine and dried to prepare an ultra-thin lithium titanate composite electrode; the ultra-thin lithium titanate composite electrode is formed into an ultra-thin circular battery negative electrode sheet after rolling and cutting, and then dried for use.

[0094] (2) Positive electrode of the battery

[0095] The positive electrode of the battery disclosed herein is used for lithium ion insertion and extraction. As such a positive electrode material, at least one selected from a lithium iron phosphate electrode, a lithium cobalt oxide electrode, and a lithium manganate electrode can be used, wherein a lithium iron phosphate electrode is used as an example. By using a lithium iron phosphate electrode, the characteristics of the stable crystal structure of lithium iron phosphate can be brought into play, and the volume expansion and contraction of the positive electrode material during the charge and discharge process or in an extreme over-discharge state are small, and the damage to the positive electrode material crystal is small. Furthermore, by combining it with a lithium titanate composite electrode as a negative electrode, the over-discharge resistance of the lithium titanate battery can be further improved.

[0096] (3) Positive electrode current collector

[0097] The positive electrode current collector is the medium that transmits electrons between the battery's positive electrode and the positive electrode casing. It can be constructed as a current collector mesh with a certain degree of elasticity, which, through its extrusion and deformation, enables reliable electrical connection and electron transfer between the positive electrode and the positive electrode casing. Examples of such a current collector mesh include aluminum mesh. Alternatively, the positive electrode current collector can be aluminum foil, which directly contacts the positive electrode casing over a large area for electrical conductivity. This eliminates the need for welding between the current collector and the tab, or welding between the tab and the external conductive electrode column.

[0098] (4) Diaphragm

[0099] As an isolation membrane between the positive / negative electrodes, it has a rich pore structure that can store a certain amount of electrolyte and allow lithium ions to pass freely. At the same time, it is an electrical insulator that hinders the passage of electrons.

[0100] (5) Electrolyte

[0101] As the battery electrolyte, it fills the positive electrode, negative electrode and diaphragm pores inside the battery and is the liquid medium for the movement of lithium ions.

[0102] (6) Positive electrode shell and negative electrode shell

[0103] The positive electrode shell and the negative electrode shell are connected to each other by a sealing rubber ring, thereby isolating the battery from the external environment and serving as a conductive medium between the battery and an external power source or load during charging and discharging.

[0104] (7) Sealing rubber ring

[0105] As an elastic filling medium between the positive electrode shell and the negative electrode shell of the battery, it plays the role of isolating the positive electrode shell and the negative electrode shell of the battery. At the same time, its elastic deformation can ensure that after the battery is sealed, there is an interference fit between the positive electrode shell and the sealing rubber ring, and between the negative electrode shell and the sealing rubber ring, thereby ensuring the effectiveness of the seal.

[0106] After the sealing rubber ring is assembled to the negative electrode shell through the injection molding process and integrated with the negative electrode shell, the positive electrode shell is riveted to the sealing rubber ring through the riveting process, thereby clamping them together. Furthermore, the positive electrode shell, the sealing rubber ring and the negative electrode shell are placed in the packaging mold, and the positive electrode shell, the negative electrode shell and the rubber ring are squeezed and sealed using a one-time or two-time molding sealing process.

[0107] In addition, the lithium titanate button-type secondary battery of the present disclosure may further include:

[0108] (8) Sealing glue

[0109] The sealing glue can be a sealing coating located at the end of the battery seal, which plays the role of completely isolating the battery from the external environment and preventing moisture in the external environment from entering the interior of the battery through the tiny pores of the sealing rubber ring. Regarding the above-mentioned "battery sealing end", as shown in Figures 6 to 13, it refers to the position between the end of the positive electrode shell and the negative electrode shell. By further applying the sealing glue, especially the metal-specific waterproof sealant, at the position between the end of the positive electrode shell and the negative electrode shell after the battery is activated and formed, full sealing can be achieved, which can enhance the effect of completely isolating the battery from the external environment. In the present disclosure, the application of the sealing glue only needs to be completed through a simple heating coating and curing process after the assembly of each battery component. The process is simple, does not require complicated processing steps, and has an excellent sealing effect.

[0110] By further providing a sealing glue, the lithium titanate button-type secondary battery disclosed in the present invention has full sealing, which can reduce the volatilization of the electrolyte and the intrusion of water vapor during use, thereby improving the stability and service life of the lithium titanate battery.

[0111] As such a sealing glue, an epoxy-type low-temperature curing insulating sealant can be used, especially an epoxy-type low-temperature curing insulating sealant with a high water and oxygen barrier rate. By selecting an appropriate curing temperature, the sealing glue can be quickly cured and achieve a high water and oxygen barrier effect. As a specific example of such a sealant, YB-7300B epoxy resin glue can be listed.

[0112] In the lithium titanate button secondary battery of the present disclosure, the exemplary lithium titanate composite electrode is in direct contact with the negative electrode shell to conduct electricity. 12 The graphene layer in / Al2O3 / graphene acts as a current collector and directly contacts the battery negative electrode shell for conductivity. Compared with the traditional secondary battery structure, it reduces the negative electrode current collector and eliminates the traditional secondary battery negative electrode slurry coating process on the negative electrode current collector copper foil. It optimizes the preparation process, reduces the power consumption of the negative electrode preparation, and can also improve the energy density of the lithium titanate battery.

[0113] Furthermore, the lithium titanate composite electrode disclosed herein can also be further connected to the negative electrode shell via a negative electrode shell conductive glue. The negative electrode shell conductive glue serves as a conductive coating on the negative electrode shell of the battery, and plays a role in enhancing the electrical conductivity between the negative electrode and the negative electrode shell. As such a negative electrode shell conductive glue, graphite conductive glue can be listed. Because the conductivity of graphite is better than that of negative electrode shell stainless steel, the conductivity between the negative electrode and the negative electrode shell can be further enhanced, thereby further improving the charge and discharge capacity of the battery.

[0114] In addition, the lithium titanate button secondary battery disclosed herein may further include, for example, an aluminum mesh grid as a negative electrode current collector or aluminum foil as a negative electrode current collector, and press-fitted to the electrode sheet through a sheet pressing process, thereby further reducing the contact impedance between the negative electrode and the negative electrode shell.

[0115] The lithium titanate button-type secondary battery disclosed herein adopts assembly processes such as electrode pressing, extrusion contact, and one-step mold molding and sealing. Compared with existing lithium-ion batteries, the preparation process is simple and does not require welding between the current collector and the electrode tab, or welding between the electrode tab and the external conductive electrode column; instead, the power transmission between the inside and outside of the battery is achieved through extrusion contact.

[0116] In addition, for the lithium titanate button-type secondary battery disclosed in the present invention, the positive / negative electrode shell can directly contact the load end for conductivity, and is easy to install when used on an electronic price tag.

[0117] Furthermore, the entire positive / negative electrode shell is an effective heat dissipation area, while traditional secondary batteries only have external tabs or poles that can effectively dissipate heat, and the heat dissipation area ratio of the battery body is greatly improved.

[0118] The lithium titanate button-type secondary battery disclosed herein has excellent over-discharge resistance and safety performance. After long-term over-discharge, the voltage will not be lower than 0V. It does not have the over-discharge copper precipitation anomaly of lithium iron phosphate batteries and ternary lithium-ion batteries, and no lithium dendrites are generated inside the battery. It can be recharged and used again, providing a maintenance-free energy storage battery device for electronic price tags.

[0119] Hereinafter, the specific structure of the lithium titanate coin-type secondary battery of the present disclosure will be described with examples, but the structure of the lithium titanate coin-type secondary battery of the present disclosure is not limited thereto.

[0120] As shown in FIG6 , the lithium titanate button-type secondary battery disclosed herein may have a structure in which the positive electrode uses a current collector and the negative electrode has no current collector (ie, the lithium titanate composite electrode is in direct contact with the negative electrode housing for electrical conduction).

[0121] As shown in FIG7 , the lithium titanate button-type secondary battery disclosed herein may have a structure in which the positive electrode uses aluminum foil for current collection and the negative electrode has no current collector (ie, the lithium titanate composite electrode is in direct contact with the negative electrode housing for electrical conduction).

[0122] In the case of such a structure, since the outermost layer of the lithium titanate composite electrode material disclosed herein is a graphene layer, the graphene layer has ultra-high conductivity and can be used as a current collector to directly contact the battery negative electrode shell for conductivity. Therefore, there is no need to set up a negative electrode current collector, no need to weld between the current collector and the tab, and no need to weld the tab to the external conductive electrode column.

[0123] As shown in FIG8 , the lithium titanate button-type secondary battery disclosed herein may have a structure in which both the positive electrode and the negative electrode use current collecting nets for current collection.

[0124] As shown in FIG9 , the lithium titanate button-type secondary battery disclosed herein may have a structure in which both the positive electrode and the negative electrode are collected using aluminum foil.

[0125] In the case of such a structure, since the negative electrode current collector can be pressed onto the electrode sheet through a sheet pressing process, in particular, the negative electrode current collector can be directly pressed onto the lithium titanate composite electrode disclosed in the present invention, the contact impedance between the negative electrode and the negative electrode shell can be further reduced.

[0126] 10 to 13 show a structure further including a negative electrode conductive paste.

[0127] FIG10 shows a structure in which the positive electrode uses a current collecting net for current collection and the negative electrode shell is coated with a conductive adhesive (i.e., the lithium titanate composite electrode is in contact with the negative electrode shell through the conductive adhesive for electrical conduction);

[0128] FIG11 shows a structure in which the positive electrode uses aluminum foil for current collection and the negative electrode shell is coated with conductive glue (i.e., the lithium titanate composite electrode is in contact with the negative electrode shell through the conductive glue for electrical conduction);

[0129] FIG12 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which both the positive and negative electrodes use current collecting nets and the negative electrode shell is coated with conductive adhesive;

[0130] FIG13 is a schematic diagram of a stack of lithium titanate button-type secondary batteries in which both the positive and negative electrodes are collected using aluminum foil and the negative electrode shell is coated with conductive adhesive.

[0131] By adopting such a structure, in addition to the excellent effects described above, the graphite conductive paste is further provided as the negative electrode conductive paste, which can further enhance the conductivity between the negative electrode and the negative electrode shell, thereby further improving the charge and discharge capacity of the battery.

[0132] The present disclosure also provides an electronic price tag, particularly a rechargeable electronic price tag, using the above lithium titanate button secondary battery as an energy storage device.

[0133] Rechargeable electronic price tags have two strong requirements for secondary batteries: first, good over-discharge resistance. This means that after a long period of deep over-discharge, the battery can be activated by charging with a low current in the uA range, with little capacity degradation and little self-discharge current after over-discharge. Second, the battery voltage range must be compatible with the electronic price tag circuit, minimizing the power adapter circuit at the battery output.

[0134] According to the verification of the inventors of the present application, the lithium titanate button-type secondary battery disclosed in the present invention is a secondary battery with both of the above characteristics. Under the optimal capacity and load conditions, the optimal operating voltage range of the lithium titanate button-type secondary battery disclosed in the present invention is 2.3-2.7V. The electronic price tags currently using EPD and low-power MCU require the operating voltage range of the power supply to be generally 2.3-3.6V to keep all circuits working normally. The operating voltage range of the lithium titanate button-type secondary battery disclosed in the present invention is fully adapted to the low-power electronic price tags using EPD. When the lithium titanate button-type secondary battery disclosed in the present invention is used in the electronic price tag, the voltage conversion circuits such as the step-up and step-down circuits required for general secondary batteries can be omitted, thereby achieving the simplification of the process and the thinning and miniaturization of the structure of the electronic price tag, which can be said to have revolutionary innovative significance for the use of electronic price tags.

[0135] In addition, the applicant should clarify that commonly used secondary batteries, such as lithium cobalt oxide batteries, lithium manganese oxide batteries, ternary lithium batteries, and lithium iron phosphate batteries, all have poor over-discharge resistance. Even with over-discharge protection circuits, over-discharge cannot be completely avoided. Furthermore, the operating voltage ranges of lithium cobalt oxide batteries, lithium manganese oxide batteries, and ternary lithium batteries are not fully compatible with electronic price tags that use EPDs and low-power MCUs. Voltage conversion circuits must be added to the battery output. Such voltage conversion circuits complicate and enlarge the structure, making these commonly used secondary batteries unsuitable for compact devices like electronic price tags.

[0136] In view of the characteristics of low power consumption ESL (i.e., electronic price tag) that require low charging current value (usually <10mA) and low battery capacity, the ESL of the lithium titanate button secondary battery disclosed in the present invention is exemplified. As shown in FIG14 , the electronic price tag disclosed in the present invention can include an electronic price tag main circuit and an electronic price tag charging management module. As mentioned above, the voltage conversion circuit can be omitted between the electronic price tag charging management module and the battery output terminal and the electronic price tag main circuit. Instead, it can be composed of a constant voltage current limiting circuit such as DCDC / LDO, a battery protection circuit, an electrical isolation circuit for multiple types of charging power supplies, and a battery direct output control switch (1). In addition, when the lithium titanate button secondary battery disclosed in the present invention is used for the electronic price tag, the above-mentioned battery protection circuit can also be omitted, thereby further achieving thinning and miniaturization of the device.

[0137] Hereinafter, each component of the electronic price tag of the present disclosure will be described in detail.

[0138] ①Constant voltage current limiting circuit

[0139] For ESL's lithium titanate battery application, a constant voltage and current limiting device or circuit such as DCDC / LDO (such as 2.7V LDO) is used to charge the lithium titanate battery through this circuit. When the charging power supply voltage is basically equal to the voltage of the energy storage device, charging is naturally cut off.

[0140] ②Battery directly controls the switch

[0141] When this switch is in the closed state, the lithium titanate battery is directly output to the back-end ESL load circuit without the need for voltage conversion.

[0142] ③Electrical isolation circuit

[0143] The electrical isolation circuit is used to electrically isolate the power supply from the power consumption circuit, and can be an electrical isolation circuit for multiple types of charging power supplies.

[0144] Hereinafter, description will be given of components that are essential elements in a general electronic price tag but can be omitted when the lithium titanate coin-type secondary battery of the present disclosure is used.

[0145] ④Voltage conversion circuit

[0146] The voltage conversion circuit is used to convert the battery voltage output to match the voltage range of the back-end ESL main circuit.

[0147] The voltage range of the lithium titanate button secondary battery disclosed in the present invention can match the operating voltage range of most low-power ESL MCUs, EPDs and other devices, so there is no need for voltage conversion devices that were previously required.

[0148] In detail, the operating voltage range of the lithium titanate button secondary battery disclosed in the present invention is 1.8V-2.7V, and the main discharge voltage platform is 2.3-2.7V, which is fully adapted to the operating voltage range of low-power ESL product devices (such as EPD>2.3; MCU 1.8-3.6V; Flash 1.8-3.6V, etc.). No voltage conversion device is required between the battery and the ESL main circuit (the applicant needs to explain that current conventional polymer lithium batteries and other voltages above 4.2V basically require voltage conversion devices).

[0149] ⑤Battery protection circuit

[0150] In the disclosed embodiment, there is no dedicated battery protection circuit, and only the load output or backflow control of the battery is retained. That is, the output of the constant voltage and current limiting circuit is directly connected to the lithium titanate battery, the output of the lithium titanate battery is connected to a voltage comparator, and the output of the voltage comparator is connected to a power switch or voltage conversion circuit to control the output or backflow of the battery.

[0151] When the battery voltage is lower than the preset over-discharge voltage, the voltage comparator outputs a switch enable shutdown signal, and the battery has no output or no backflow, that is, the battery does not discharge, but the external power supply can charge the battery normally;

[0152] When the battery voltage is higher than the preset over-discharge voltage, the voltage comparator outputs a switch enable signal, and the battery can output or return normally, that is, the battery can discharge normally.

[0153] By using the lithium titanate button-type secondary battery disclosed in the present invention as the energy storage device of the rechargeable electronic price tag, in conjunction with a simplified voltage-limited and current-limited charging circuit and a battery output control switch, it is possible to implement charge and discharge management and battery protection of the ESL device without the need for a dedicated battery over-discharge protection circuit, thereby achieving the goal of maintenance-free rechargeable batteries under various conditions during the life cycle of the electronic price tag. Therefore, in the rechargeable electronic price tag using the lithium titanate button-type secondary battery disclosed in the present invention, the battery protection circuit can be omitted.

[0154] In addition, for rechargeable electronic price tags using the lithium titanate button-type secondary battery disclosed herein, the battery can be maintenance-free during the life cycle of the electronic price tag, reducing the maintenance cost of the electronic price tag and expanding the applicable scenarios of the rechargeable electronic price tag.

[0155] Lithium titanate batteries used in ESL and other devices can also utilize conventional charge and discharge management chips and battery protection circuits. These small lithium titanate batteries suitable for ESL and other devices come in a variety of configurations, including ultra-thin soft-pack, cylindrical, and button-type.

[0156] In addition, regarding the rechargeable electronic price tag using the lithium titanate button secondary battery disclosed in the present invention, it is necessary to further explain that:

[0157] (1) In the ESL, based on the lithium titanate button secondary battery disclosed in the present invention, only a small number of devices such as voltage converters and MOS tubes with voltage and current limiting are used as charging circuit controllers and battery output control switches. There is no dedicated battery over-discharge protection circuit, which realizes the design of charge and discharge management and battery protection circuit of the ESL equipment;

[0158] (2) Battery output switch, which controls the output of electrons at the positive electrode through a MOS tube or controls the return of electrons at the negative electrode through a MOS tube, thereby achieving a discharge control circuit design for controlling battery discharge in the ESL;

[0159] (3) In an ESL, based on the lithium titanate button secondary battery disclosed in the present invention, a conventional battery protection circuit is arranged on the PCB circuit board of the ESL;

[0160] (4) Rechargeable ESLs include but are not limited to electronic price tags that are charged by various types of micro-energy such as light energy, electronic price tags with various physical charging interfaces, and electronic price tags that are charged by various types of near-field coupling or radio waves.

[0161] Example

[0162] Furthermore, the inventors of the present application actually prepared a lithium titanate button-type secondary battery.

[0163] First, prepare the lithium titanate composite electrode material disclosed in the present invention, as follows:

[0164] 1) High-purity nano-titanium dioxide (titanium dioxide) and lithium carbonate were mixed in a molar ratio of 1:1, added to an appropriate amount of polyethylene glycol solution, and the slurry was mixed for 24 hours;

[0165] 2) The mixed slurry is further stirred at the nano-scale dispersion stage for 5 hours and then cooled. The slurry is then filtered through a mesh sieve and filtered out.

[0166] 3) drying the filtrate to obtain dry powder;

[0167] 4) The dried powder was placed in a high-temperature furnace lined with a porcelain crucible, heated to 550°C at a rate of 5°C / min, held at that temperature for 12 hours, and then cooled in the furnace;

[0168] 5) The cooled material is ball-milled and sieved to obtain the primary product lithium metatitanate Li2TiO3;

[0169] 6) The product lithium metatitanate and nano-sized titanium dioxide were prepared in a molar ratio of 2:3, added to an appropriate amount of polyethylene glycol solution, and the slurry was mixed for 24 hours;

[0170] 7) Repeat steps 2) and 3);

[0171] 8) The dried powder was placed in a high-temperature furnace lined with a porcelain crucible, heated to 750°C at a rate of 5°C / min, held at that temperature for 10 hours, and then cooled in the furnace;

[0172] 9) The cooled material is ball-milled and sieved to obtain the product lithium titanate Li4Ti5O 12 ;

[0173] 10) The lithium titanate product was dispersed in 5 mmol / L aluminum isopropoxide isopropanol solution, stirred and dispersed at 40°C for 20 min, then dried, ball-milled and sieved again to obtain lithium titanate material Li4Ti5O with Al2O3 surface modification layer. 12 / Al2O3;

[0174] 11) The lithium titanate electrode material with a surface modification layer obtained in the above step is dispersed into an appropriate amount of polyethylene glycol solution, and a high-quality thin-layer graphene aqueous dispersion slurry (GRF-HCGW-LFP-01) is added in an amount of 0.2 wt% of the lithium titanate mass ratio, and then an appropriate amount of ordinary carbon black conductive agent is added and dispersed evenly. The mixture is then filtered, dried, and sintered. After ball milling and sieving, the final product, lithium titanate composite electrode material Li4Ti5O 12 / Al2O3 / graphene.

[0175] The lithium titanate composite electrode material obtained above is further used to prepare the lithium titanate button secondary battery disclosed herein, as detailed below:

[0176] 1) Using lithium titanate composite electrode material Li4Ti5O 12 After the / Al2O3 / graphene ingredients are mixed, they are formed into a disc-shaped powder electrode after being pressed by a tablet press. It is used as the negative electrode of the battery and is dried for later use.

[0177] 2) After lithium iron phosphate is used as the main material, it is formed into a disc-shaped powder electrode after being pressed by a tablet press. While pressing the tablet, an aluminum mesh grid is pressed on one side of the lithium iron phosphate powder electrode to form a disc-shaped positive electrode with a current collecting network, which is then dried for later use;

[0178] 3) Prepare the positive electrode shell and the negative electrode shell by stamping stainless steel (typical grades such as 430 and 304) and clean them;

[0179] 4) On the inner and outer sides of the negative electrode shell, rubber rings are embedded by hot extrusion injection molding to assemble the negative electrode shell cover;

[0180] 5) preparing a graphite conductive adhesive and evenly coating a layer of the conductive adhesive on the inner surface of the negative electrode shell;

[0181] 6) Drying the prepared positive electrode shell and negative electrode shell cover for later use;

[0182] 7) In a dry environment of a glove box, cut a PP separator or a multilayer separator such as PP / PE / PP into a disc having a diameter at least 2 mm larger than the disc-shaped lithium titanate composite electrode;

[0183] 8) In a dry environment of a glove box, a circular lithium titanate composite negative electrode, a circular separator, and a circular positive electrode are sequentially placed in the negative electrode shell cover with their centers aligned, and then an electrolyte for a lithium titanate battery is injected;

[0184] 9) Place the positive electrode shell on the assembly completed in the above steps and seal it with a mold to form the battery;

[0185] 10) Activating the battery;

[0186] 11) Apply a layer of metal-specific waterproof sealant to the gap between the rubber ring of the activated battery positive electrode shell and the negative electrode shell, thereby obtaining a lithium titanate button-type secondary battery HT2016.

[0187] In an exemplary embodiment, the present disclosure provides a rechargeable electronic price tag using a lithium titanate button-type secondary battery as an energy storage device. The lithium titanate button-type secondary battery is a button-type battery formed by stacking and connecting a group of the following components in sequence along the thickness direction of the button-type secondary battery: a negative electrode housing; a lithium titanate composite electrode, which serves as the battery's negative electrode; a separator, which is disposed between the positive and negative electrodes; an electrolyte, which fills the positive and negative electrodes and / or the separator pores within the battery; the battery's positive electrode; a positive electrode current collector, which is disposed between the battery's positive electrode and the positive electrode housing; a sealing rubber ring, which is an elastic filling medium, which fills the positive and negative electrode housings; and the positive electrode housing. The lithium titanate composite electrode is formed by a lithium titanate composite electrode material through a sheeting process, and the lithium titanate composite electrode material is composed of lithium titanate composite particles. The lithium titanate composite particles include: nano-scale lithium titanate as a core structure; an oxide layer covering the nano-scale lithium titanate as a first shell; and a graphene layer covering the oxide layer as a second shell.

[0188] In an exemplary embodiment of the present disclosure, the electronic price tag further includes an electronic price tag main circuit and an electronic price tag charging management module. No voltage conversion circuit is used between the electronic price tag charging management module and the battery output terminal and the electronic price tag main circuit. Among them, the lithium titanate composite electrode material is composed of a core-shell structure, which includes nano-scale lithium titanate as a shell structure, and a layer of oxide and a layer of graphene are sequentially coated on the surface of the nano-scale lithium titanate. This structure not only improves the conductivity of the lithium titanate material, but also improves the stability of the material through the oxide layer coated on the surface, reduces the side reactions when in contact with the electrolyte, and extends the battery life. Furthermore, because the outermost layer of graphene has ultra-high conductivity, the lithium titanate composite electrode with a graphene shell can be in direct contact with the negative electrode shell for electrical conductivity, forming a primary battery-like structure. This reduces the current collector and welding processes required in traditional battery designs, making the battery structure simpler. At the same time, the space occupied by the current collector and welding reduced by the internal design of the battery in the present disclosure can be used to fill the positive and negative electrode active materials. Compared with the process of traditional secondary batteries, this can greatly increase the internal space utilization and energy density of lithium titanate batteries of the same volume, especially small sizes, and can flexibly design the thickness of the battery, making micro button-type lithium titanate batteries practically applicable. In this embodiment, lithium titanate button batteries are creatively applied to electronic price tags. In this embodiment, the lithium titanate button secondary battery has a relatively stable output voltage and the output voltage range is very close to the voltage required by the electronic price tag. Therefore, the electronic price tag charging management module and the battery output terminal can be directly connected to the electronic price tag main circuit without the need for an additional voltage conversion circuit.

[0189] Furthermore, the lithium titanate composite electrode is in direct contact with the negative electrode shell for conductivity. The lithium titanate composite electrode material is prepared as follows: lithium titanate is dispersed in an isopropanol solution containing metal ions in the oxide and dried. The lithium titanate electrode material with a surface modification layer obtained is dispersed in a polyethylene glycol solution, and a graphene aqueous dispersion slurry is added thereto. After uniform dispersion, the material is dried and sintered to obtain the lithium titanate composite electrode material.

[0190] Furthermore, the inventors of the present disclosure conducted performance tests using the lithium titanate button-type secondary battery HT2016.

[0191] (1) HT2016 key performance specification requirements

[0192] (2) HT2016 lithium titanate button secondary battery charge and discharge test model

[0193] At 25±2°C, HT2016 battery samples were left unused for 10 minutes, discharged at a constant current of 5mA to 2.3V, left unused for 30 minutes, then charged at a constant current of 5mA to 2.7V, left unused for 10 minutes, and then recharged at a constant voltage of 2.7V with a cutoff current of 0.5mA.

[0194] (3) HT2016 capacity test:

[0195] Figure 15 shows the charge-discharge data curve of the HT2016 lithium titanate button secondary battery after three cycles. The key capacity parameters are basically around 21.2mAh, which meets the capacity design specifications (three charge-discharge cycles are performed according to the above model).

[0196] (4) Circulation performance and flatulence performance test:

[0197] According to the above “(2) HT2016 lithium titanate button secondary battery charge and discharge test model”, the cycle life test and flatulence performance evaluation of HT2016 lithium titanate button secondary battery were carried out.

[0198] a) Capacity decay: After 10,000 cycles of charge and discharge testing, the capacity decay of HT2016 is less than 5%;

[0199] b) Flatulence: After 10,000 charge-discharge cycles, the HT2016 showed no dimensional change in diameter and less than 0.1 mm in thickness, representing an expansion rate of less than 6%. (The average expansion rate of a primary lithium-manganese button cell at the end of its life is approximately 5%).

[0200] In addition, the applicant also conducted comparative tests on cycle life tests using existing lithium iron phosphate batteries, ternary lithium, lithium cobalt oxide, and lithium manganese oxide batteries. The results are as follows:

[0201] 1). After 2000-3000 charge and discharge cycles, the capacity of lithium iron phosphate battery decreases by about 20%;

[0202] 2). The capacity of ternary lithium, lithium cobalt oxide, and lithium manganese oxide batteries decays by about 20% after 500-1000 charge and discharge cycles.

[0203] Furthermore, the applicant also used the existing lithium titanate battery with a non-lithium titanate particle coating structure to measure the flatulence performance, and the results are as follows:

[0204] 3). The titanium ions on the surface of the lithium titanate material catalyze the decomposition of the electrolyte to produce gas, which causes the lithium titanate battery to bloat, with a bloating rate of about 25%.

[0205] The above results show that when the lithium titanate button-type secondary battery of the present disclosure is used, an excellent effect of combining anti-flatulence performance and high electrical conductivity is achieved.

Claims

1. A lithium titanate button secondary battery, characterized in that: The secondary battery is a button-type battery formed by stacking and connecting the following components: The components include: A lithium titanate composite electrode, which is used as a negative electrode of a battery; The positive electrode of the battery; a separator disposed between the positive electrode and the negative electrode; An electrolyte, which fills the positive electrode, negative electrode and / or separator pores inside the battery; Negative electrode housing; Positive electrode housing; a positive electrode current collector disposed between the positive electrode and the positive electrode casing of the battery; and The sealing rubber ring is an elastic filling medium filled between the positive and negative electrode shells of the battery. The lithium titanate composite electrode is formed by a lithium titanate composite electrode material through a tabletting process. The lithium titanate composite electrode material is composed of lithium titanate composite particles, and the lithium titanate composite particles include: nano-scale lithium titanate; an oxide layer covering the nano-scale lithium titanate; and a graphene layer covering the oxide layer.

2. The lithium titanate button-type secondary battery according to claim 1, wherein: The oxide constituting the oxide layer is at least one selected from aluminum oxide, zinc oxide, and titanium dioxide.

3. The lithium titanate button-type secondary battery according to claim 2, wherein: The oxide constituting the oxide layer is aluminum oxide.

4. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein The positive electrode of the battery is a lithium iron phosphate electrode.

5. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein The lithium titanate button-type secondary battery further comprises a sealing glue, which is a sealing coating located at the sealing end of the battery.

6. The lithium titanate button-type secondary battery according to claim 5, wherein: The sealing glue is an epoxy-based low-temperature curing insulating sealant.

7. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein The positive electrode current collector is a current collecting net.

8. The lithium titanate button-type secondary battery according to claim 7, wherein: The current collecting net is an aluminum mesh grid.

9. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein The positive electrode current collector is aluminum foil.

10. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein The lithium titanate composite electrode is in direct contact with the negative electrode shell for electrical conduction.

11. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein A negative electrode shell conductive glue is further provided between the negative electrode and the negative electrode shell of the battery.

12. The lithium titanate button-type secondary battery according to claim 11, wherein: The negative electrode shell conductive glue is graphite conductive glue.

13. The lithium titanate button-type secondary battery according to any one of claims 1 to 3, wherein A negative electrode current collector is further provided between the negative electrode and the negative electrode case of the battery.

14. The lithium titanate button-type secondary battery according to claim 13, wherein: The negative electrode current collector is a current collecting net.

15. The lithium titanate button-type secondary battery according to claim 14, wherein: The current collecting net is an aluminum mesh grid.

16. The lithium titanate button-type secondary battery according to claim 13, wherein: The negative electrode current collector is aluminum foil.

17. An electronic price tag, which is a rechargeable electronic price tag, characterized in that: The lithium titanate button secondary battery according to any one of claims 1 to 16 is used as an energy storage device.

18. The electronic price tag according to claim 17, wherein: The electronic price tag comprises an electronic price tag main circuit and an electronic price tag charging management module, and no voltage conversion circuit is used between the electronic price tag charging management module and a battery output terminal and the electronic price tag main circuit.

19. The electronic price tag according to claim 18, wherein: The electronic price tag charging management module includes a constant voltage current limiting circuit, an electrical isolation circuit and a power switch, wherein a battery protection circuit is not used.

20. The electronic price tag according to claim 17 or 18, wherein: The lithium titanate secondary battery body or battery module used in the electronic price tag does not include a battery over-discharge protection circuit.

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