A lithium-sulfur battery system with constant voltage output and applications thereof

Abstract

The application discloses a lithium-sulfur battery system with constant voltage output, comprising at least one lithium-sulfur battery pack, each of which is connected with a DC / DC converter for voltage stabilization and then is connected in series and / or parallel to form a lithium-sulfur battery pack, wherein the lithium-sulfur battery pack comprises a box body and at least one lithium-sulfur battery soft package cell monomer arranged in the box body, each of which is connected with a DC / DC converter for voltage stabilization, and the lithium-sulfur battery soft package cell monomers are connected in series and / or parallel to form the lithium-sulfur battery pack. The lithium-sulfur battery system has the advantages of simple assembly method of the lithium-sulfur battery pack, reduced module weight, modular design of the lithium-sulfur battery pack or the lithium-sulfur battery system according to actual use scenes, dynamic adjustment of output voltage of the power supply according to the requirements of a third-party equipment, effectively improved popularization and application of the lithium-sulfur battery product, effectively promoted commercial application of the lithium-sulfur battery, and replacement of traditional lithium ion batteries to a certain extent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium-sulfur batteries, and particularly relates to a lithium-sulfur battery system with constant voltage output and application thereof. BACKGROUND

[0002] Lithium ion battery is a kind of green renewable energy, and is one of the research focuses in the current battery field. However, the theoretical capacity of the positive electrode material of the traditional lithium ion battery is low, and the cost is high, which is difficult to meet the demand for high-performance lithium batteries. Therefore, in recent years, the lithium-sulfur battery system has attracted the attention of scientific researchers. Compared with the traditional lithium ion battery, the lithium-sulfur battery has higher theoretical specific capacity and theoretical energy density, and has the advantages of rich sulfur reserves and low price, and is considered as one of the most potential batteries, which can be widely applied in portable electronic products, electric vehicles and unmanned aerial vehicle applications and other fields.

[0003] Although lithium-sulfur battery has many advantages, it still faces many technical problems in commercial applications, such as low life caused by polysulfide shuttle effect, low utilization of sulfur positive electrode and large volume expansion effect, etc. In order to accelerate the industrialization application of lithium-sulfur battery, it is necessary to carry out appropriate application level research outside the lithium-sulfur battery material layer to overcome these bottlenecks. From the application level, the voltage characteristics and discharge behavior of lithium-sulfur battery are different from those of traditional lithium-ion battery. The open-circuit voltage of lithium-sulfur battery can reach more than 3 V. In the actual use process as a power supply, the voltage window of lithium-sulfur battery is generally 1.7 V~3.0 V, and its voltage-capacity curve has two platforms. In the discharge process, the first discharge platform appears at about 2.3 V, and the corresponding first-stage electrochemical reaction is that sulfur is reduced to long-chain polysulfide by getting electrons. Although the conductivity of elemental sulfur and long-chain polysulfide is very low, Li2S8, Li2S6 and Li2S4 can be dissolved in electrolyte and will not affect the electrochemical reaction after elemental sulfur, so the reaction rate of the first stage is very fast, and the capacity provided by this process can account for one-fourth of the theoretical capacity. The long discharge platform at about 2.1 V corresponds to the second stage of the discharge process. This process converts long-chain polysulfide into Li2S2 and Li2S which are insoluble in electrolyte and deposited on the surface of conductive material. The dynamics performance of this process is poor, mainly because the conductivity of Li2S2 and Li2S is extremely low and attached to the surface of the conductive material, which reduces the electron transport capacity and slows down the reaction kinetics. At the end of the reaction, it also causes very large polarization, and lithium-sulfur battery shows very fast pressure drop, which appears as a relatively flat discharge curve at about 2.1 V on the voltage-capacity curve, and then the voltage drops significantly. The capacity provided by the second-stage reaction accounts for three-fourths of the theoretical capacity and is the main contribution to the capacity of lithium-sulfur battery. It can be seen that compared with the relatively stable voltage output of lithium-ion battery, the voltage fluctuation of lithium-sulfur battery is large and changes quickly, which puts high requirements on the power equipment using lithium-sulfur battery.

[0004] There are many components in electrical equipment, most of which require a stable voltage from the power supply. The stability of the power supply voltage is also a key factor for the smooth use of the power supply. For example, the flight control system of a drone relies on precise electronic components, including microcontrollers, sensors, and communication modules. These components usually require a stable power supply. If the voltage is unstable, it may cause the system to restart, communication to be interrupted, or even the drone to lose control. In addition, other portable electronic devices such as tablets and wearable devices are also sensitive to voltage fluctuations. Voltage instability can cause devices to malfunction or even damage hardware. At the same time, due to the limited voltage and capacity of lithium-sulfur single batteries, it is necessary to form a series-parallel battery pack for use in many cases. In the application of power battery packs and energy storage systems, it is common to have hundreds of series-connected batteries. Any problem with a single battery in a series of hundreds of batteries can have serious consequences for the battery pack. Since it is difficult to achieve complete consistency in series-connected single batteries, this can cause voltage inconsistencies in single batteries during charging and discharging, leading to large changes in the output voltage of the entire battery pack, and even safety hazards. There is not much research on lithium-sulfur battery systems in the existing technology. Most research still only involves lithium-sulfur battery materials, such as CN104054209A, which discloses a water-based electrolyte lithium-sulfur battery with an anode structure containing an electrically active material, a cathode containing a solid-state electron transfer medium, a water-based electrolyte in contact with the electron transfer medium, and an active sulfur species in contact with the water-based electrolyte. The anode electrically active material is separated from the water-based electrolyte. The combination of water-based electrolyte and inexpensive sulfur as cathode active material can be a key driver for the power and automotive industries, providing a cost-effective and miniaturized solution for load balancing, electric vehicles, and renewable energy storage. CN118100334A discloses a charging equalization control circuit for a lithium-sulfur battery. During initial charging, the charging control chip MCU first outputs a pulse signal, which is converted into a voltage signal by the drive chip and output to the charging equalization circuit. The charging circuit drives the MOSFET tube to conduct based on this voltage signal, and the equalization circuit starts working. The charging management chip MCU collects the battery voltage signal in real time, and when the battery voltage reaches the charging cutoff voltage, the charging control chip MCU changes the output pulse signal to drive the MOSFET tube to close, i.e. the charging current does not pass through this single battery, preventing battery overcharging and solving the problem of inconsistent voltage when charging a lithium-sulfur battery pack in series. This can increase the overall charging capacity of the battery pack and greatly improve the service life of the battery pack.CN108551260A discloses a power management circuit and power management board for small and medium-sized unmanned aerial vehicle development board, the power management circuit includes toggle switch, filter circuit, voltage conversion module, voltage stabilizing circuit and resistance voltage dividing circuit, the toggle switch is arranged between the power input end and the filter circuit, the voltage stabilizing circuit is arranged between the voltage conversion module and the resistance voltage dividing circuit, the voltage conversion module is a power converter chip, and the voltage conversion module has a first to fifth pin, wherein the first pin is grounded, the fourth pin is connected with a first capacitor, the fifth pin is connected with an input voltage end, the third pin is a switch node for providing power to an output, the third pin is connected with the voltage stabilizing circuit and provides power output, and the second pin is connected with the resistance voltage dividing circuit so as to detect the output voltage and adjust the output voltage.

[0005] Although there are many studies on lithium ion battery modules at present, the electrochemical characteristics of lithium-sulfur batteries are different from those of traditional lithium ion batteries, and the voltage platform of lithium-sulfur batteries is special. The charge and discharge cutoff voltage of lithium-sulfur batteries is completely different from that of lithium ion batteries. The system control method applied to traditional lithium ion batteries in the market is difficult to be directly used in lithium-sulfur batteries, which greatly hinders the promotion and large-scale application of lithium-sulfur batteries. Therefore, in order to effectively promote the commercial application of lithium-sulfur batteries and realize the replacement of traditional lithium ion batteries, a lithium-sulfur battery system suitable for various application scenarios and having constant voltage output must be developed. SUMMARY

[0006] The present application aims to overcome the deficiencies in the prior art, and provides a lithium-sulfur battery system with constant voltage output. The lithium-sulfur battery is used as a power supply and combined with a specific circuit integration scheme to maintain stable lithium-sulfur battery voltage output. The present application effectively overcomes the problem that the wide output voltage range of existing lithium-sulfur batteries cannot meet the demand of stable voltage electrical appliances, and effectively promotes the commercial application of lithium-sulfur batteries and realizes the replacement of traditional lithium ion batteries.

[0007] To achieve the above-mentioned purposes of the present application, the first aspect of the present application provides a lithium-sulfur battery system with constant voltage output, which comprises at least one lithium-sulfur battery pack, each lithium-sulfur battery pack is connected with a DC / DC converter for voltage stabilization and then connected in series and / or parallel to form a lithium-sulfur battery pack. The lithium-sulfur battery pack comprises a box body and at least one lithium-sulfur battery soft package cell monomer arranged in the box body, each lithium-sulfur battery soft package cell monomer is connected with a DC / DC converter for voltage stabilization, and the lithium-sulfur battery soft package cell monomers are connected in series and / or parallel to form the lithium-sulfur battery pack. The connection mode of the lithium-sulfur battery pack or the lithium-sulfur battery soft package cell monomer can be adjusted according to actual needs, such as being set to series and / or parallel connection. The above-mentioned series or parallel connection mode is completed through the cell tabs on the lithium-sulfur battery soft package cell.

[0008] As a preferred technical solution, the connection mode between the lithium-sulfur battery soft package cell monomers in each lithium-sulfur battery pack is the same, and each lithium-sulfur battery pack has the same output voltage.

[0009] As a preferred solution, the lithium-sulfur battery system includes a lithium-sulfur battery pack 1 connected to the DC / DC converter 1 after voltage stabilization as the input power supply of the power device, the lithium-sulfur battery pack includes a box body and two lithium-sulfur battery soft package cell monomers (11, 12) arranged in the box body, the lithium-sulfur battery soft package cell monomer 11 is connected to the DC / DC converter 11 for voltage stabilization, the lithium-sulfur battery soft package cell monomer 12 is connected to the DC / DC converter 12 for voltage stabilization, and the lithium-sulfur battery soft package cell monomer 11 and the lithium-sulfur battery soft package cell monomer 12 are connected in series to form the lithium-sulfur battery pack 1, and the output voltage of the lithium-sulfur battery system is 5V.

[0010] As a preferred solution, the lithium-sulfur battery system further includes a voltage detection unit and a battery management system, the voltage detection unit detects the voltage of each lithium-sulfur battery soft package cell monomer and stores the set standard voltage of the lithium-sulfur battery soft package cell monomer, and inputs a signal to the DC / DC converter connected to the lithium-sulfur battery soft package cell monomer according to whether the voltage of the lithium-sulfur battery soft package cell monomer is the same as the standard voltage to adjust the voltage of the cell monomer.

[0011] As a preferred solution, the DC / DC converter is selected from one of Buck-Boost converter, Cuk converter, Sepic converter, Zeta converter, Flyback converter, Push-Pull, Forward converter.

[0012] As a preferred solution, the four sides of the lithium-sulfur battery soft package cell monomer are wrapped in the cell frame, the cell frame is alternately provided with protrusions and grooves on the two sides parallel to the two sides of the lithium-sulfur battery soft package cell monomer which are not wrapped, and the adjacent two cell frames are fixedly connected by one-to-one matching of the grooves and protrusions to form the box body. As a further preferred solution, the lithium-sulfur battery pack further includes a cover body arranged on the side of the box body where the cell tabs pass through, the cover body is mechanically connected to the box body, and is used to protect the cell tabs and the DC / DC converters connected to the cell tabs. The cell frame can be made of organic materials or metal alloys with good heat dissipation and high strength, such as magnesium alloy and aluminum alloy, which can improve the mechanical strength of the module and effectively reduce the weight.

[0013] As a preferred solution, a through hole is provided on the cell frame, a penetrating rod is inserted into the through hole, and the two ends of the penetrating rod are fixed by nuts.

[0014] As a preferred embodiment, the groove is one of the following shapes: cross-shaped, triangular, quadrilateral, pentagonal, hexagonal, and elliptical, and the protrusion has a matching shape.

[0015] Another aspect of the present invention provides an application of a lithium-sulfur battery system with constant voltage output. This lithium-sulfur battery system is used in the power supply of a drone to supply power to the electrical equipment on the drone. It enables the drone to fly stably for a long time with the lithium-sulfur battery as the power source, which has relatively low voltage stability, and the electrical equipment on the drone can work normally.

[0016] As a preferred embodiment, the lithium-sulfur battery system has a gravimetric energy density of 400~700Wh / kg and a volumetric energy density of 400~700Wh / L, and the lithium-sulfur battery system is composed of 3~5 lithium-sulfur battery packs connected in parallel.

[0017] As a preferred embodiment, a lithium-sulfur battery system with constant voltage output includes m lithium-sulfur battery packs. Lithium-sulfur battery pack 1 is connected to a DC / DC converter 1 for voltage regulation. Lithium-sulfur battery pack 1 includes a housing and n lithium-sulfur battery pouch cells (11, 12, 13...1n) disposed within the housing. Each lithium-sulfur battery pouch cell 1n is connected to a DC / DC converter 1n for voltage regulation. The lithium-sulfur battery pouch cells (11, 12, 13...1n) are connected in parallel to form the lithium-sulfur battery pack 1. Lithium-sulfur battery pack 2 and DC / DC converter 1... C / DC converter 2 is connected to a voltage regulator..., and the lithium-sulfur battery pack m is connected to the DC / DC converter m for voltage regulation. The lithium-sulfur battery pack m includes a housing and n lithium-sulfur battery pouch cells (m1, m2...mn) housed within the housing. Each lithium-sulfur battery pouch cell mn is connected to the DC / DC converter mn for voltage regulation. The lithium-sulfur battery pouch cells (m1, m2...mn) are connected in parallel to form the lithium-sulfur battery pack m. The above m lithium-sulfur battery packs are connected in series, and each lithium-sulfur battery pack has the same output voltage. The lithium-sulfur battery system also includes a voltage detection unit and a battery management system (…). Figure 1 (Not shown in the image), the voltage detection unit detects and acquires the voltage of each lithium-sulfur battery pouch cell, and stores the set standard voltage of the lithium-sulfur battery pouch cell. Based on whether the voltage of the lithium-sulfur battery pouch cell is the same as the standard voltage, it inputs a signal to the DC / DC converter connected to the lithium-sulfur battery pouch cell to perform voltage regulation adjustment of the cell. The DC / DC converter is a Buck-Boost converter. The four sides of the lithium-sulfur battery pouch cell 1 are wrapped in the cell frame 2. The cell frame 2 and the four sides of the wrapped lithium-sulfur battery pouch cell 1 are provided with recesses or locking posts on their opposite surfaces to accommodate or fix the lithium-sulfur battery pouch cell. Figure 1The lithium-sulfur battery system further comprises a cover body arranged on the side of the box body from which the cell tabs pass out, the cover body is mechanically connected with the box body, and is used for protecting the cell tabs and DC / DC converters connected with the cell tabs. The lithium-sulfur battery system is applied to a power supply of an unmanned aerial vehicle, and is used for supplying power to electric equipment on the unmanned aerial vehicle. m and n are each independently an integer greater than or equal to 2, and m and n can be the same or different.

[0018] The application further provides application of the lithium-sulfur battery system with constant voltage output to a charging power supply of a smart phone or an LED lamp.

[0019] Compared with the prior art, the lithium-sulfur battery system has the beneficial effects as follows:

[0020] 1. The assembling method is simple, and the accessory cost is low. The lithium-sulfur battery system adopts the cell frame wrapped around four sides of the lithium-sulfur battery soft package cell monomer, and the cell frame is inserted and fixed by the protrusions and recesses arranged on the surface, so that the strength of the module is ensured, the weight of the module is effectively reduced, the overall specific energy of the power supply is improved, the modular degree is improved, and the manufacturing is more convenient.

[0021] 2. The lithium-sulfur battery system can ensure stable voltage output under different SOC of the lithium-sulfur battery, and can be modularly designed according to actual use scenes, so that the output voltage of the power supply can be dynamically adjusted according to the requirements of a third-party device, the popularization and application of the lithium-sulfur battery product are effectively improved, the commercial application of the lithium-sulfur battery is effectively promoted, and the traditional lithium ion battery can be replaced to a certain extent. Meanwhile, the lithium-sulfur battery system can effectively solve the problem of poor power supply voltage stability caused by voltage fluctuation of the lithium-sulfur battery, so that the lithium-sulfur battery system can adapt to more electronic equipment requirements and provide stable power supply for the electronic equipment. Not only the working efficiency and stability of the equipment are improved, but also the service life of the equipment is prolonged, and damage of electronic components caused by voltage fluctuation is avoided.

[0022] 3. The lithium-sulfur battery system has low requirements for the performance of the lithium-sulfur battery, effectively reduces the cost of the battery system, is independent between the battery groups, has good stability, a simple overall structure, is easy to realize, and has high reliability. DETAILED DESCRIPTION

[0023] Figure 1 is a structural schematic diagram of the lithium-sulfur battery system with constant voltage output.

[0024] Figure 2 is a structural schematic diagram of a lithium-sulfur battery pack of the present application;

[0025] Legend: 1, lithium-sulfur battery soft pack cell monomer; 2, cell frame; 3, cell tab; 4, protrusion; 5, groove. DETAILED DESCRIPTION

[0026] In order to make the technical problems solved by the present application, the technical solutions adopted and the technical effects achieved more clear, the technical solutions of the embodiments of the present application will be further described in detail below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0027] It should be noted that the reference to "embodiments" in this text means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase at various places in the specification does not necessarily mean that it refers to the same embodiment, nor is it independent or alternative to other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0028] The experimental methods in the following examples are all conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial channels unless otherwise specified.

[0029] Example 1

[0030] The lithium-sulfur battery system with constant voltage output comprises three lithium-sulfur battery groups, a lithium-sulfur battery group 1 is connected to a DC / DC converter 1 for voltage stabilization, the lithium-sulfur battery group 1 comprises a box body and at least two lithium-sulfur battery soft package cell monomers (11, 12) arranged in the box body, the lithium-sulfur battery soft package cell monomer 11 is connected to a DC / DC converter 11 for voltage stabilization, the lithium-sulfur battery soft package cell monomer 12 is connected to a DC / DC converter 12 for voltage stabilization, the lithium-sulfur battery soft package cell monomers 11 and 12 are connected in series to form the lithium-sulfur battery group 1; a lithium-sulfur battery group 2 is connected to a DC / DC converter 2 for voltage stabilization, the lithium-sulfur battery group 2 comprises a box body and two lithium-sulfur battery soft package cell monomers (21, 22) arranged in the box body, the lithium-sulfur battery soft package cell monomer 21 is connected to a DC / DC converter 21 for voltage stabilization, the lithium-sulfur battery soft package cell monomer 22 is connected to a DC / DC converter 22 for voltage stabilization, the lithium-sulfur battery soft package cell monomers 21 and 22 are connected in series to form the lithium-sulfur battery group 2; a lithium-sulfur battery group 3 is connected to a DC / DC converter 3 for voltage stabilization, the lithium-sulfur battery group 3 comprises a box body and two lithium-sulfur battery soft package cell monomers (31, 32) arranged in the box body, the lithium-sulfur battery soft package cell monomer 31 is connected to a DC / DC converter 31 for voltage stabilization, the lithium-sulfur battery soft package cell monomer 32 is connected to a DC / DC converter 32 for voltage stabilization, the lithium-sulfur battery soft package cell monomers 31 and 32 are connected in series to form the lithium-sulfur battery group 3; the lithium-sulfur battery system further comprises a voltage detection unit and a battery management system, the voltage detection unit detects and obtains the voltage of each lithium-sulfur battery soft package cell monomer, stores the set standard voltage of the lithium-sulfur battery soft package cell monomer, inputs a signal to the DC / DC converter connected to the lithium-sulfur battery soft package cell monomer according to whether the voltage of the lithium-sulfur battery soft package cell monomer is the same as the standard voltage, and adjusts the voltage of the cell monomer. The DC / DC converter is a Buck-Boost converter. Four sides of the lithium-sulfur battery soft package cell monomer 1 are wrapped in a cell frame 2, the cell frame 2 is alternately provided with a triangular protrusion 4 and a triangular groove 5 on the two sides parallel to the two sides of the lithium-sulfur battery soft package cell not wrapped, and the adjacent two cell frames are fixedly connected by one-to-one matching of the grooves and protrusions to form the box body, a through hole is arranged on the cell frame, a penetrating rod is inserted into the through hole, and the penetrating rod is fixed by nuts at both ends. The lithium-sulfur battery system is applied to the power supply of a UAV, supplies power to the electric equipment on the UAV, and the weight energy density of the lithium-sulfur battery group in the lithium-sulfur battery system is 500 Wh / kg, and the volume energy density is 600 Wh / L.

[0031] Example 2

[0032] A lithium-sulfur battery system with constant voltage output comprises a lithium-sulfur battery pack 1. The lithium-sulfur battery pack 1 is connected to a DC / DC converter 1 for voltage regulation. The lithium-sulfur battery pack 1 includes a housing and three lithium-sulfur battery pouch cells (11, 12, and 13) disposed within the housing. Lithium-sulfur battery pouch cell 11 is connected to the DC / DC converter 11 for voltage regulation, lithium-sulfur battery pouch cell 12 is connected to the DC / DC converter 12 for voltage regulation, and lithium-sulfur battery pouch cell 13 is connected to the DC / DC converter 13 for voltage regulation. The lithium-sulfur battery pack 1 is formed by connecting battery pouch cells 11 and 12 in series with lithium-sulfur battery pouch cell 13 in parallel. The lithium-sulfur battery system also includes a voltage detection unit and a battery management system. The voltage detection unit detects and acquires the voltage of each lithium-sulfur battery pouch cell and stores a set standard voltage for each cell. Based on whether the cell voltage matches the standard voltage, it inputs a signal to a DC / DC converter connected to the cell for voltage regulation. The DC / DC converter is a Buck-Boost converter. The four sides of the lithium-sulfur battery pouch cell 1 are enclosed in a cell frame 2. Triangular protrusions 4 and triangular grooves 5 are alternately arranged on the two parallel sides of the cell frame 2, which are parallel to the two uncovered sides of the cell. Adjacent cell frames are fixedly connected by corresponding grooves and protrusions to form the housing. This lithium-sulfur battery system is used in LED light power supplies.

[0033] The foregoing has provided a detailed description of a lithium-sulfur battery system with constant voltage output and its applications. The above description, in conjunction with specific preferred embodiments, further illustrates the invention and should not be construed as limiting the scope of the invention to these descriptions. For those skilled in the art, the architecture of this invention can be flexibly varied without departing from its conceptual framework, leading to the development of a series of products. Any simple deductions or substitutions should be considered within the scope of patent protection defined by the submitted claims.

Claims

1. A lithium-sulfur battery system with constant voltage output, comprising at least one lithium-sulfur battery pack, each lithium-sulfur battery pack being connected to a DC / DC converter for voltage regulation before being connected in series and / or in parallel, characterized in that, The lithium-sulfur battery pack includes a housing and at least one lithium-sulfur battery pouch cell disposed within the housing. Each lithium-sulfur battery pouch cell is connected to a DC / DC converter for voltage regulation. The lithium-sulfur battery pouch cells are connected in series and / or in parallel to form the lithium-sulfur battery pack.

2. The lithium-sulfur battery system with constant voltage output according to claim 1, characterized in that, The lithium-sulfur battery cells in each lithium-sulfur battery pack are connected in the same way, and each lithium-sulfur battery pack has the same output voltage.

3. The lithium-sulfur battery system with constant voltage output according to claim 1, characterized in that, The lithium-sulfur battery system also includes a voltage detection unit and a battery management system. The voltage detection unit detects and acquires the voltage of each lithium-sulfur battery pouch cell and stores the set standard voltage of the lithium-sulfur battery pouch cell. Based on whether the voltage of the lithium-sulfur battery pouch cell is the same as the standard voltage, it inputs a signal to the DC / DC converter connected to the lithium-sulfur battery pouch cell to perform voltage regulation adjustment of the cell.

4. The lithium-sulfur battery system with constant voltage output according to claim 1, characterized in that, The DC / DC converter is selected from one of the following: Buck-Boost converter, Cuk converter, Sepic converter, Zeta converter, Flyback converter, Push-Pull converter, and Forward converter.

5. The lithium-sulfur battery system with constant voltage output according to claim 1, characterized in that, The four sides of the lithium-sulfur battery pouch cell are wrapped in the cell frame. The cell frame and the two sides parallel to the two unwrapped sides of the lithium-sulfur battery pouch cell are alternately provided with protrusions and grooves. Two adjacent cell frames are fixedly connected by corresponding grooves and protrusions to form the box.

6. The lithium-sulfur battery system with constant voltage output according to claim 5, characterized in that, A through hole is provided on the battery cell frame, and a through rod is inserted into the through hole and the two ends of the through rod are tightened and fixed by nuts.

7. The lithium-sulfur battery system with constant voltage output according to claim 5, characterized in that, The groove is one of the following shapes: cross-shaped, triangular, quadrilateral, pentagonal, hexagonal, or elliptical, and the protrusion has a matching shape.

8. An application of the lithium-sulfur battery system with constant voltage output according to any one of claims 1 to 7, characterized in that, This lithium-sulfur battery system is used in drone power supplies to power the equipment on the drone.

9. The application according to claim 8, characterized in that, The lithium-sulfur battery system has a gravimetric energy density of 400~700Wh / kg and a volumetric energy density of 400~700Wh / L. The lithium-sulfur battery system consists of 3~5 lithium-sulfur battery packs connected in parallel.

10. An application of the lithium-sulfur battery system with constant voltage output according to any one of claims 1 to 7, characterized in that, This lithium-sulfur battery system is used in smartphones or LED light charging power supplies.

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