A flower ball-shaped Bi2O3 lithium-sulfur battery positive electrode material and a preparation method thereof

Abstract

The application discloses a kind of flower ball Bi2O3 positive electrode material, its preparation method includes the following steps: first, hollow flower ball Bi2O3 is prepared using solvothermal method: bismuth source is taken into organic solvent, and solution A is obtained;Template agent is taken into organic solvent, and solution B is obtained;A solution is dropped into B solution, and mixed solution C is obtained;Mixed solution C is placed in reaction kettle, and solvothermal reaction is carried out to obtain hollow flower ball Bi2O3.Then, sublimation S is combined with the hollow flower ball Bi2O3 prepared above by melting to obtain positive electrode material S / Bi2O3.The lithium-sulfur battery based on flower ball Bi2O3 positive electrode material provided by the application shows excellent electrochemical performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electrochemistry, and in particular to a flower-spherical Bi2O3 lithium-sulfur battery positive electrode material and a preparation method thereof. BACKGROUND

[0002] Currently, rechargeable batteries, such as lithium ion batteries (LIBs) and lead (Pb)-acid batteries, have ideal characteristics such as high energy density, high efficiency, simple operation and environmental friendliness, and have important applications in large-scale grid energy storage and electrified transportation. However, due to the limitation of intercalation chemistry of electrode materials, LIBs have almost reached the upper limit of energy density 350 Wh kg -1 , and it is difficult to meet the growing demand of the energy industry. Lithium-sulfur batteries (LSBs) with elemental sulfur as a positive electrode active material are considered to be an ideal choice to achieve high energy density batteries. The charging and discharging process of LSBs is different from that of LIBs, involving a multi-electron conversion reaction, so the specific capacity of the sulfur positive electrode can theoretically reach 1672 mAh g -1 ; and the energy density is theoretically 26000 Wh kg -1 , which is 7 times higher than that of LIBs.

[0003] In summary, the research on lithium-sulfur batteries with high specific energy and long cycle life is of great significance to improve energy utilization and meet the energy needs of society. SUMMARY

[0004] In order to find and develop new high-performance lithium-sulfur battery positive electrode materials, the application provides a flower-spherical Bi2O3 lithium-sulfur battery positive electrode material, a preparation method and application thereof.

[0005] The application is achieved by the following technical solutions:

[0006] A preparation method of a flower-spherical Bi2O3 lithium-sulfur battery positive electrode material, comprising the following steps:

[0007] Step 1: hollow flower-spherical Bi2O3 is prepared by a solvothermal method:

[0008] Step 1-1: a bismuth source is taken and added to an organic solvent to obtain solution A;

[0009] Step 1-2: a template agent is taken and added to an organic solvent to obtain solution B;

[0010] Step 1-3: the A solution is added dropwise to the B solution to obtain a mixed solution C;

[0011] Step 1-4: the mixed solution C is placed in a reaction kettle to perform a solvothermal reaction to obtain hollow flower-spherical Bi2O3;

[0012] Step 2: the sublimation S and the hollow flower ball-shaped Bi2O3 prepared in step 1 are fused to prepare the positive electrode material S / Bi2O3.

[0013] In the process of configuring solution A and solution B, in order to ensure that the solution is fully dissolved, solution A and solution B can be heated and kept in a water bath respectively, so that they become colorless, clear and transparent solutions after complete dissolution.

[0014] Further optionally, in steps 1-3, the dropping speed is 0.02 mL / min to 0.09 mL / min.

[0015] Further optionally, in step 1-4, the solvothermal reaction temperature is 150 DEG C to 180 DEG C, and the reaction time is 20 h to 25 h.

[0016] Further optionally,

[0017] The bismuth source includes a bismuth nitrate salt;

[0018] And / or the template agent includes polyvinylpyrrolidone; the template agent (such as polyvinylpyrrolidone (PVP)) is added to facilitate the formation of a petal-shaped structure.

[0019] And / or the organic solvent includes N,N-dimethylformamide.

[0020] Further optionally, in step 2, the steps used include:

[0021] First, the sublimation S, the conductive carbon material and the hollow flower ball-shaped Bi2O3 prepared in step 1 are mixed by grinding;

[0022] Then the mixture is placed in a reaction kettle and heated to melt to prepare the positive electrode material S / Bi2O3.

[0023] The conductive carbon material is preferably a high-conductive carbon material, such as one or more of ketchen black, mesoporous carbon, microporous carbon and graphene.

[0024] Further optionally, the heating and melting temperature is 150 DEG C to 160 DEG C, and the constant temperature heating and melting time is 10 h to 12 h.

[0025] Further optionally, the mass ratio of the conductive carbon material, Bi2O3 and sublimation S is 1:1:7.5 to 1:1:8.

[0026] Specifically, the conductive carbon material, Bi2O3 and sublimation S are added to a mortar in proportion, and are fully ground into uniform powder; then the powder is poured into a reaction kettle and placed in a constant temperature oven for constant temperature heating and melting at 155 DEG C for 12 h. After natural cooling to room temperature, the positive electrode material S / Bi2O3 is obtained.

[0027] A kind of positive electrode material based on Bi2O3, hollow flower ball-shaped Bi2O3 is carrier and active substance S is loaded, and is named as S / Bi2O3.

[0028] A lithium battery positive electrode comprising the positive electrode material prepared by the preparation method.

[0029] Preferably, the composition of the lithium battery positive electrode comprises S / Bi2O3, conductive carbon black (SP) and polyvinylidene fluoride (PVDF); more preferably, S / Bi2O3, conductive carbon black (SP) and polyvinylidene fluoride (PVDF) are in a mass ratio of 8:1:1.

[0030] A positive electrode preparation method comprising the steps of:

[0031] S / Bi2O3, conductive carbon black (SP) and polyvinylidene fluoride (PVDF) are mixed in a mass ratio and dispersed in N-methylpyrrolidone (NMP) solvent, and placed in a marver for sufficient grinding. The above slurry is scraped onto the surface of a carbon-coated aluminum foil and dried in an oven. After cooling to room temperature, it is cut into circular electrode pieces of corresponding diameter using a slicer.

[0032] The positive electrode material prepared by the preparation method or the positive electrode material or the lithium battery positive electrode is applied in a lithium-sulfur battery.

[0033] The present application has the following advantages and beneficial effects:

[0034] 1. The flower ball-shaped Bi2O3 material provided by the present application is a hollow structure with petals on the surface. The hollow structure can carry more active substance S and withstand the volume expansion of the positive electrode, thereby reducing the damage to the structure caused by the expansion of the positive electrode. The petal-shaped appearance has a larger specific surface area, which can provide more active sites for the chemical adsorption of lithium polysulfide, thereby effectively inhibiting the shuttle effect of lithium polysulfide and prolonging the service life of the battery.

[0035] 2. The positive electrode material S / Bi2O3 provided by the present application can not only improve the electrochemical performance of the battery, but also effectively improve the service life of the battery.

[0036] Compared with KB electrodes, the lithium-sulfur battery positive electrode made of S / Bi2O3 shows more excellent adsorption performance and catalytic activity, can improve the electrochemical reaction kinetics during charging and discharging, and makes the battery have better rate performance and cycle stability; at the same time, the spherical Bi2O3 can physically carry the expansion of the positive electrode, slow down the structural collapse and loss of active substances, and can provide enough active sites in the electrochemical aspect, show extremely high catalytic activity, improve the reaction kinetics, inhibit the shuttle effect, and reduce the corrosion of lithium negative electrode.

[0037] 3. The preparation method of the positive electrode material provided by the application has the advantages that raw materials are cheap and easy to obtain, the flower ball-shaped Bi2O3 is prepared by one-step hot solvent method, and then S and Bi2O3 are combined by heating and melting, and the overall operation method is simple. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the embodiments of the application. In the drawings:

[0039] Figure 1 is a SEM image of Example 1; wherein, Figure 1 (a) represents a SEM image with a scale of 1 μm, Figure 1 (b) represents a SEM image with a scale of 300 nm, Figure 1 (c) represents a SEM image with a scale of 1 μm and reflecting a hollow structure, Figure 1 (d) represents a SEM image with a scale of 500 nm.

[0040] Figure 2 is a TEM image of Example 1; wherein, Figure 2 (a) represents a SEM image with a scale of 2 μm, Figure 2 (b) represents a SEM image with a scale of 500 nm, Figure 2 (c) represents a SEM image of materials with different particle sizes with a scale of 500 nm, Figure 2 (d) represents a SEM image with a scale of 100 nm.

[0041] Figure 3 is an element distribution diagram of Example 1; wherein, Figure 3 (a) represents a cross section of Example 1, Figure 3 (b) represents the distribution of Bi element, Figure 3 (c) represents the distribution of O element.

[0042] Figure 4 is a HRTEM image and XRD pattern of Example 1; wherein, Figure 4 (a) represents a HRTEM image of Example 1, Figure 4 (b) represents an image obtained by inverse Fourier transform (IFFT) of the HRTEM, Figure 4 (c) represents a test method of interplanar spacing of the HRTEM, Figure 4 (d) represents an XRD pattern.

[0043] Figure 5 is an XPS spectrum of Example 1; wherein, Figure 5 (a) represents C1s, Figure 5 (b) represents O1s, Figure 5 (c) represents Bi4f.

[0044] Figure 6 Static adsorption tests of LiPSs for different samples; wherein, Figure 6 (a) represents Li2S6 solution soaked with KB, Figure 6 (b) represents Li2S6 solution soaked with Bi2O3.

[0045] Figure 7 are the cyclic voltammetry test results of lithium-sulfur batteries based on different cathode materials at 0.1 mV S -1

[0046] Figure 8 are the multiple cycle CV curves of lithium-sulfur batteries based on different cathode materials at 0.2 mV S -1 Figure 8 (a) represents the CV curve of Comparative Example 1, Figure 8 (b) represents the CV curve of Example 3.

[0047] Figure 9 are the Tafel plots of lithium-sulfur batteries based on different cathode materials corresponding to different redox stages; wherein, Figure 9 (a) and Figure 9 (b) represent the Tafel plots corresponding to the conversion of solid Li2S to liquid chain LiPSs and oxidation to solid S8, Figure 9 (c) and Figure 9 (d) represent the Tafel plots corresponding to the reduction of LiPSs to Li2S.

[0048] Figure 10 are the electrochemical performances of lithium-sulfur batteries based on different cathode materials at 0.2C current density; wherein, Figure 10 (a) represents the first charge-discharge curve of Comparative Example 1, Figure 10 (b) represents the first charge-discharge curve of Example 3, Figure 10 (c) represents the polarization degree and coulombic efficiency plot, Figure 10 (d) represents the electrochemical performance plot at 0.2C, 200 cycles.

[0049] Figure 11 are the rate performances of lithium-sulfur batteries based on different cathode materials.

[0050] Figure 12 are the morphologies of lithium anodes of lithium-sulfur batteries after cycling for different cathode materials; wherein, Figure 12 (a) represents the anode corrosion of Comparative Example 1, Figure 12 (b) represents the anode corrosion of Example 3. DETAILED DESCRIPTION

[0051] ​​In order to make the objects, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with embodiments and drawings, the illustrative embodiments and the description thereof are only used to explain the present application, and do not limit the present application.

[0052] Embodiment 1

[0053] The embodiment provides a Bi2O3-based positive electrode material S / Bi2O3, which is a hollow flower ball structure, and the specific preparation method is as shown below:

[0054] Step 1: hollow flower ball Bi2O3 is prepared by a solvothermal method.

[0055] Step 1-1: 5 mmol of bismuth nitrate is added to an organic solvent N,N-dimethylformamide to obtain 30 mL of solution A.

[0056] Step 1-2: 1.2 g of a template agent polyvinylpyrrolidone is added to an organic solvent N,N-dimethylformamide to obtain 20 mL of solution B.

[0057] mL solution B.

[0058] Step 1-3: solution A and solution B are respectively placed in an ultrasonic water bath kettle at 60 DEG C for 1.5 h, so that solution A and solution B are completely dissolved into colorless, clear and transparent solutions.

[0059] Step 1-4: solution A is added to solution B at a dropping speed of 0.05 mL / min to obtain a mixed solution C.

[0060] Step 1-5: the mixed solution C is placed in a reaction kettle, and is heated at 160 DEG C for 24 h to perform a solvothermal reaction. The reacted solution is centrifuged and dried to obtain white Bi2O3 powder, which is hollow flower ball Bi2O3. The centrifugal speed is 1000 r / min.

[0061] Step 2: sublimation S and the hollow flower ball Bi2O3 prepared in step 1 are fused and compounded to prepare a positive electrode material S / Bi2O3.

[0062] Step 2-1: sublimation S, Ketjen black and the hollow flower ball Bi2O3 prepared in step 1 are placed in a mortar in a mass ratio of 8:1:1, and are fully ground into a uniform mixed powder.

[0063] Step 2-2: the mixed powder is placed in a reaction kettle, and the reaction kettle is placed in a constant temperature oven for constant temperature heating and melting. After natural cooling to room temperature, the positive electrode material S / Bi2O3 is obtained and taken out for standby. The temperature in the constant temperature oven is 155 DEG C, and the constant temperature heating and melting time is 12 h.

[0064] Embodiment 2

[0065] This embodiment provides a lithium battery positive electrode sheet, and the specific preparation method is shown below:

[0066] The S / Bi₂O₃, conductive carbon black (SP), and polyvinylidene fluoride (PVDF) prepared in Example 1 were dispersed in N-methylpyrrolidone (NMP) solvent at a mass ratio of 8:1:1, and then thoroughly ground in a mortar to obtain a homogeneous slurry. The slurry was then coated onto the surface of carbon-coated aluminum foil and dried in an oven at 50°C for 6 hours. After cooling to room temperature, it was cut into circular electrode sheets with a diameter of 13 mm using a slicing machine.

[0067] Example 3

[0068] This embodiment provides a lithium-sulfur battery, and the specific assembly method is shown below:

[0069] The battery was assembled in an argon-filled glove box (oxygen partial pressure <1ppm). The electrode prepared in Example 2 was used as the positive electrode. 20μL of lithium-sulfur battery electrolyte (the electrolyte is ethylene glycol dimethyl ether / dimethyl oxalate (DME / DMO) containing 1.0M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 0.2M LiNO3 (DME / DMO volume ratio 1:1)) was added to one side of the positive electrode. Then, a separator was stacked, and another 20μL of electrolyte was dropped onto the separator. A gasket and spring sheet were then stacked, with a pressure of 800kg / cm². 2 Pressure-assembled button cells.

[0070] Comparative Example 1

[0071] This case study provides a lithium-sulfur battery based on Ketjenblack (KB) cathode material, and its preparation method is as follows:

[0072] Step 1: Prepare the positive electrode material S / KB.

[0073] KB is the finished product of Shanghai Trial (National Pharmaceutical Group), and the specific preparation method is the same as step 2 of Example 1.

[0074] Step 2: Prepare the positive electrode sheet.

[0075] The specific preparation method is the same as in Example 2.

[0076] Step 3: Assemble the lithium-sulfur battery.

[0077] The specific preparation method is the same as in Example 3.

[0078] I. Characterization Analysis

[0079] 1. SEM characterization analysis.

[0080] Depend on Figure 1It can be observed that the prepared Bi2O3 presents a clear flower ball morphology. The shape is uniform, and the size is similar, and the diameter is about 1 μm. After magnification, it can be seen that there are obvious petal-like wrinkles on the surface. This structure makes it have a larger specific surface area, which can provide more active sites for the chemical adsorption of lithium polysulfide, thereby effectively inhibiting the shuttle effect of lithium polysulfide and prolonging the service life of the battery. Figure 1 (c)It can be seen that its hollow structure can carry more active material sulfur, and when the lithium-sulfur battery positive electrode material expands, it can also withstand the damage of the positive electrode expansion to the structure because of its hollow structure.

[0081] 2, TEM characterization analysis.

[0082] (1) Figure 2 is a TEM image of the prepared Bi2O3 sample. As can be seen from the figure, the Bi2O3 provided in the embodiment is a hollow petal-shaped material.

[0083] (2) Figure 3 is an element distribution map of the prepared Bi2O3. As can be seen from the figure, Bi and O elements exist and both elements are uniformly dispersed in the Bi2O3 material.

[0084] 3, HRTEM and XRD characterization analysis.

[0085] The prepared Bi2O3 sample was observed by high-resolution transmission electron microscopy (HRTEM).

[0086] The lattice fringes shown by Figure 4 ( Figure 4 (a), Figure 4 (b), Figure 4 (c)) correspond to a crystal face spacing of 0.275 nm, corresponding to the (200) crystal face. By comparing with the data card, the crystal face spacing of the (200) crystal face of the Bi2O3 material is 0.276 nm, therefore, it is proved that the prepared material is indeed Bi2O3.

[0087] From the XRD results of Figure 5 (d), it can be seen that Bi2O3 has four obvious peaks, and the 2θ angles are 27.92, 32.34, 46.39 and 55.02, respectively, corresponding to the crystal face indices of the crystal face of Bi2O3 are (111), (200), (220) and (311), respectively.

[0088] 4, XPS characterization analysis.

[0089] The prepared Bi2O3 sample was characterized by XPS, and the results are shown in Figure 5 .

[0090] The full spectrum was calibrated by chemical shift at 248.8 eV for the C-C bonds of element C. Figure 5 (a)). Figure 5 The strongest peak of O1s (531.5 eV) in (b) corresponds to oxygen in Bi2O3. In the XPS spectrum of Bi4f ( Figure 6 (c)), the characteristic peaks at 164.32 eV and 158.99 eV correspond to Bi 4f, respectively. 5 / 2 and Bi 4f 7 / 2 The XPS spectrum of element O1s shows a characteristic peak at 531.15 eV. The XPS test results confirm the successful preparation of Bi2O3 material.

[0091] 5. Static adsorption test.

[0092] Take equal masses of Bi₂O₃ and KB (5 mg), and add them to equal volumes of Li₂S₆ solution (8 mmol / L). -1 It was placed in the solution and left to stand for 6 hours. The results were as follows: Figure 7 As shown in the figure, the Li2S6 solution soaked in Bi2O3 (Figure b) is lighter in color than the Li2S6 solution soaked in KB (Figure a), indicating that Bi2O3 has a stronger adsorption capacity for LiPSs than KB. Adsorption of polar LiPSs can effectively suppress the LiPSs shuttle effect, resulting in superior electrochemical performance and cycling stability.

[0093] II. Electrochemical Performance Testing

[0094] 1. Cyclic Voltammetry (CV) Test.

[0095] Figure 8 The diagram shows a battery with S / Bi2O3 as the positive electrode material (i.e., the battery provided in Example 3) and a battery with S / KB as the positive electrode material (i.e., the battery provided in Comparative Example 1) operating at 0.1 mV S. -1Figure 6 shows the CV curves of the battery with S / Bi203as the positive material (i.e. the battery provided in Example 3) and the battery with S / KB as the positive material (i.e. the battery provided in Comparative Example 1) at a scan rate of 0.2 mV S-1in the potential range of 1.7-2.8 V. For the battery provided in Example 3, two cathodic reduction peaks can be observed at 2.299 eV (Peak b) and 2.002 eV (Peak c) during the negative scan, corresponding to the heterogeneous reaction from solid S8to soluble liquid long-chain LiPSs and the heterogeneous reaction from LiPSsto solid Li2S2 / Li2S, respectively. In the following positive scan, an anodic shoulder peak appears at 2.330 eV and 2.412 eV (Peak a), corresponding to the process of the conversion of solid Li2S2 / Li2S to liquid long-chain LiPSs and further oxidation to solid S8. The CV curves of Comparative Example 1 also show the same redox peaks, but the reduction peak positions are at 2.251 eV (Peak b) and 1.877 eV (Peak c), which are negatively shifted compared to the reduction peaks of Example 3; the oxidation peak positions are at 2.359 eV and 2.433 eV (Peak a), which are positively shifted compared to the oxidation peaks of Example 3, and the response current is significantly smaller, indicating that the battery provided in Example 3 has less internal polarization, which is beneficial to the fast conversion of LiPSs kinetics during the charge and discharge process.

[0096] Figure 9 Figure 6 shows the CV curves of the battery with S / Bi203as the positive material (i.e. the battery provided in Example 3) and the battery with S / KB as the positive material (i.e. the battery provided in Comparative Example 1) at a scan rate of 0.2 mV S -1 Figure 6 shows the CV curves of the battery with S / Bi203as the positive material (i.e. the battery provided in Example 3) and the battery with S / KB as the positive material (i.e. the battery provided in Comparative Example 1) at a scan rate of 0.2 mV S

[0097] In the following tests, we can find that Example 3 and Comparative Example 1 exhibit different catalytic activities in the redox reaction process of LiPSs. In Figure 9 (b), the stage of the conversion of solid Li2S to liquid chain LiPSs and further oxidation to solid S8(Peak a), Example 3 exhibits a lower Tafel slope compared to Comparative Example 1; at the same time, Figure 10 (d), the two-phase reaction stage of LiPSsto solid Li2S (Peak c), Example 3 also exhibits a lower Tafel slope compared to Comparative Example 1, which indicates that Example 3 has better catalytic activity in the redox reaction process of LiPSs.

[0098] 2, charge and discharge cycle test.

[0099] Figure 10 (a) and Figure 11 (b) are the galvanostatic charge-discharge curves of the battery with S / Bi2O3 as the cathode material (i.e. the battery provided in Example 3) and the battery with S / KB as the cathode material (i.e. the battery provided in Comparative Example 1), respectively, at a current density of 0.2 C. For Example 3, there are two distinct discharge plateaus in the discharge process, corresponding to the process of the solid S8 converting into LiPSs and further converting into Li2S. And there are two charge plateaus in the charge process, corresponding to the process of Li2S being oxidized into LiPSs and further oxidized into S8, which is consistent with the results of the CV curves. Among the two, the polarization of Example 3 is significantly smaller than that of Comparative Example 1 at a current density of 0.2 C, with a ΔE of 180 mV for Example 3 and a ΔE of 199 mV for Comparative Example 1. Meanwhile, the initial discharge specific capacity of Example 3 is 1160 mAh g -1 , which is higher than that of Comparative Example 1 (1140 mAh g -1 ). The initial coulombic efficiency of Example 3 is 98%, while that of Comparative Example 1 is 93%, which means that Example 3 has a higher sulfur utilization than Comparative Example 1. After 200 cycles of charge-discharge at a current density of 0.2 C, the discharge specific capacity of Example 3 decreases to 809 mAh g -1 , with a capacity retention of 69%, while the discharge specific capacity of Comparative Example 1 after cycling is only 534 mAh g -1 , with a capacity retention of 51%. This indicates that Example 3 has a higher specific capacity and capacity retention, faster electrochemical reaction kinetics, and high sulfur utilization, and that the S / Bi2O3 cathode material can effectively suppress the “shuttle effect” of LiPSs, thereby improving the charge-discharge cycle stability of the material.

[0100] 3. Rate performance test.

[0101] Figure 12 The rate performance of the battery with S / Bi2O3 as the cathode material (i.e. the battery provided in Example 3) and the battery with S / KB as the cathode material (i.e. the battery provided in Comparative Example 1) was tested, with the current density increasing from 0.2 C to 5.0 C and then returning to 0.2 C. At different current densities, the discharge specific capacity of Example 3 is significantly higher than that of Comparative Example 1, thanks to the good electrocatalytic activity of S / Bi2O3. Relative to Comparative Example 1, the rate performance of Example 3 is more excellent at different current densities. As the current density continuously increases, the discharge specific capacity of the lithium-sulfur battery decreases significantly, and the specific capacity of Example 3 at rates of 0.2 C, 0.5 C, 1.0 C, 2.0 C, and 5.0 C is 1182, 858, 654, 539, and 230 mAh g -1The specific capacity of Comparative Example 1 at 0.2C, 0.5C, 1.0C, 2.0C and 5.0C rates were 1025, 691, 559, 329 and 86 mAh g -1 The rate performance of Comparative Example 1 was obviously poor, indicating that the electrode electrochemical reaction kinetics process was slow at different current densities, and LiPSs shuttle during the test caused serious active material loss. When the current density returned to 2.0C, the discharge specific capacity of the Bi2O3 electrode was still 694 mAh g -1 , indicating that the positive electrode material had good stability and current adjustment resistance.

[0102] III. Morphology characterization of lithium anode

[0103] In an Ar atmosphere glove box, the battery after the test was disassembled, and the corrosion of the lithium anode of the battery was analyzed.

[0104] The results are shown in ​ It can be seen that after charge and discharge cycles, the lithium anodes of lithium-sulfur batteries with two different positive electrodes (the positive electrode material of the battery of Example 3 (i.e. the battery provided in Example 3) and the positive electrode material of the battery of Comparative Example 1 (i.e. the battery provided in Comparative Example 1)) were corroded to different degrees, but the surface of the anode of Example 3 was smoother than that of Comparative Example 1, which indicated that it was less corroded. The corrosion of the lithium anode was derived from the shuttle effect of LiPSs during the charge and discharge cycles, which would cause redox reactions between LiPSs and the lithium anode, increase the electrode polarization, and seriously reduce the discharge specific capacity of the battery. Benefiting from the faster electrochemical reaction kinetics of Example 3, it catalyzed the rapid conversion between LiPSs, effectively inhibited the shuttle effect of the lithium-sulfur battery, and the lithium anode of the lithium-sulfur battery of S / Bi2O3 electrode was slowed down corrosion, thereby prolonging the service life of the battery.

[0105] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a flower-like Bi2O3 lithium-sulfur battery cathode material, characterized in that, The method comprises the steps of: Step 1: preparing hollow flower-like Bi2O3 by using a solvothermal method; Step 1-1: taking a bismuth source and adding it to an organic solvent to obtain solution A; Step 1-2: taking a template agent and adding it to the organic solvent to obtain solution B; Step 1-3: separately heating and keeping solution A and solution B in a water bath, so that solution A and solution B are completely dissolved and become colorless, clear and transparent solutions; Step 1-4: adding solution A dropwise to solution B to obtain a mixed solution C; Step 1-5: placing the mixed solution C in a reaction kettle to prepare hollow flower-like Bi2O3 by solvothermal reaction; Step 2: preparing a positive electrode material S / Bi2O3 by melting and compounding sublimation S and the hollow flower-like Bi2O3 prepared in step 1; In step 1-4, the dropwise adding speed is 0.02 mL / min to 0.09 mL / min; In step 1-5, the solvothermal reaction temperature is 150 DEG C to 180 DEG C, and the reaction time is 20 h to 25 h; The bismuth source is a bismuth nitrate salt; The template agent is polyvinylpyrrolidone; The organic solvent in step 1-1 and step 1-2 is N,N-dimethylformamide; In step 2, the steps used include: First, grinding and mixing sublimation S, a conductive carbon material and the hollow flower-like Bi2O3 prepared in step 1; Then, placing the mixture in a reaction kettle and heating and melting to prepare the positive electrode material S / Bi2O3; The heating and melting temperature is 150 DEG C to 160 DEG C, and the constant temperature heating and melting time is 10 h to 12 h; The mass ratio of the conductive carbon material, Bi2O3 and sublimation S is 1:1:7.5 to 1:1:

8.

2. A flower-like Bi203 lithium-sulfur battery cathode material, characterized in that, The method of claim 1 is used to prepare hollow flower-like Bi2O3 as a carrier to load active substance S, which is named S / Bi2O3.

3. A lithium battery cathode, characterized by, The positive electrode material prepared by the preparation method of claim 1.

4. The application of the positive electrode material prepared by the preparation method of claim 1 or the lithium battery positive electrode of claim 3 in a lithium-sulfur battery.

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