Asphalt-resin composite carbon negative electrode material and sodium-ion full battery thereof

Abstract

The application aims at giving full play to the structural advantages of resin and pitch, improving the sodium storage capacity of the composite carbon negative electrode material, and provides a pitch-resin composite carbon negative electrode material and a sodium ion full battery thereof.The pitch-resin composite carbon negative electrode material has pitch and resin powder as reaction raw materials, wherein the mass fraction of pitch is greater than 40%, the reaction raw materials are mixed, a precursor is obtained through high-temperature and high-pressure homogenization heat treatment, and then the precursor is carbonized to obtain a carbon negative electrode material; the main body is composed of graphite domains and highly disordered curved carbon layers, most of the disordered carbon layers are surrounded by graphite microcrystals, the interlayer spacing is 0.37+ / -1 nm, and the microcrystal units are randomly oriented.The application improves the dispersity and interfacial bonding force of pitch-resin in the composite material through high-temperature and high-pressure homogenization heat treatment, so that the composite material has rich active sites, good conductivity and excellent stability, and a sodium ion full battery with high capacity and long cycle life is obtained.

Description

Technical Field

[0001] This invention relates to the field of sodium-ion battery technology, specifically to a composite carbon anode material derived from pitch-resin pyrolysis and a sodium-ion full battery thereof. Background Technology

[0002] Sodium-ion batteries (SIBs) have shown great promise for large-scale energy storage and distributed power systems due to their low cost and excellent safety. However, the sodium storage performance of the anode material remains one of the bottlenecks limiting the commercialization of SIBs, especially under high-rate charge and discharge conditions, where the kinetic properties and structural stability of the electrode material urgently need to be improved.

[0003] Resin precursors, as an important source of hard carbon materials, have become a research focus in recent years for sodium-ion battery anode materials due to their high carbon yield, structural design flexibility, and good electrochemical performance. Compared with traditional carbon sources, resin carbon can form larger interlayer spacing, abundant disordered carbon structures, and widely distributed semi-closed pores during carbonization. These microstructures can effectively alleviate the spatial constraints of Na⁺ intercalation, provide more active sites, and improve electrolyte wettability, thus contributing to higher specific capacity and excellent rate performance. However, resin hard carbon materials still suffer from limited sodium storage kinetics, especially under high-rate conditions, where the diffusion process in the intercalation-void filling mechanism is slow, affecting its practical application performance.

[0004] Asphalt, as a carbon source, has advantages such as rich variety, wide availability, and high carbon yield. However, it is prone to graphitization during carbonization, forming an ordered carbon layer structure, which is not conducive to the effective intercalation of Na⁺. Therefore, researchers have attempted to modify asphalt through various strategies to regulate its carbonization structure and mitigate the tendency to graphitize.

[0005] In recent years, some studies have attempted to combine resin and asphalt to achieve higher-performance sodium-ion battery anode materials by combining the advantages of both. For example, Liu et al. (Materials Today Communications, 2024, 40, 109854-109854) used asphalt as a soft carbon coating agent to repair the exposed pore structure caused by resin carbonization and breakage. Thermoplastic resin powder (PR) was first pre-carbonized in nitrogen at 600 °C for 2 hours to obtain PR-600 carbon blocks. Then, PR-600 and asphalt powder finely ground to 2 μm were mixed in a mixer at a 1:1 ratio at 400 rpm for 2 hours, and then pyrolyzed at 1150 °C for 2 hours to obtain the anode material CHC-1150. This material, as a sodium-ion anode material, showed a reversible capacity of 175 mAh / g after 100 cycles at a current density of 0.06 A / g. Yin et al. (Small, 2021, 18(5), e2105568) dispersed resin polymer powder and 20% asphalt in water, mixed with ethanol at a volume ratio of 1:1, stirred at 75 °C until the solvent was completely evaporated, then transferred the dried sample to a high-temperature tube furnace, and finally heated the sample to 1000 °C and held for 4 hours to obtain a carbon material. When matched with Na3V2(PO4)3 in a full cell, the material exhibited a reversible capacity of up to 164 mAh / g after 450 cycles at 1 A / g (based on the mass of the hard carbon anode).

[0006] Existing conventional grinding and solvent dispersion methods cannot achieve molecular-level mixing of the two polymers. To fully utilize the structural advantages of resin and pitch, this invention proposes a pitch-resin homogeneous heat treatment strategy to effectively control the interfacial active sites and graphite crystallite size, thereby improving the sodium storage capacity of the composite carbon anode material. Summary of the Invention

[0007] The purpose of this invention is to fully utilize the structural advantages of resin and asphalt to improve the sodium storage capacity of the composite carbon anode material, and to provide an asphalt-resin composite carbon anode material and its sodium-ion full battery. Through high-temperature and high-pressure homogenous heat treatment, the dispersibility and interfacial bonding of the asphalt-resin in the composite material are improved, thereby giving the composite material abundant active sites (oxygen doping and vacancy defects), good conductivity, and excellent stability, resulting in a high-capacity, long-cycle-life sodium-ion full battery.

[0008] The formation mechanism of the asphalt-resin composite carbon anode material PPFC is as follows: Under high temperature and pressure, resin and asphalt are homogeneously mixed to form a mutually penetrating composite precursor. During heat treatment, asphalt decomposes and regulates the voids in the resin matrix. During carbonization, resin decomposes and inhibits the graphitization of asphalt, ultimately forming a composite structure in which disordered carbon and graphite microcrystals are uniformly interwoven, thereby improving the sodium storage capacity of the composite carbon anode material.

[0009] The specific contents of this invention are as follows:

[0010] A pitch-resin composite carbon anode material, wherein the reaction raw materials are pitch and resin powder, wherein the mass fraction of pitch is greater than 40%, the reaction raw materials are mixed and subjected to high temperature and high pressure homogenization heat treatment to obtain a precursor, denoted as PPF, and then the PPF is carbonized to obtain a carbon anode material, denoted as PPFC.

[0011] The PPFC matrix consists of graphite domains and highly disordered bent carbon layers. Most of the disordered carbon layers are surrounded by graphite crystallites with an interlayer spacing of 0.37 nm and random orientation of the crystallite units.

[0012] Furthermore, in the aforementioned asphalt-resin composite carbon anode material, the mixing of the reaction raw materials followed by high-temperature and high-pressure homogenization heat treatment can be performed using any of the following methods:

[0013] The first method is high-temperature and high-pressure stirring heat treatment: after mixing asphalt and resin powder, the mixture is placed in a high-pressure reactor and heated at 350~400 ℃ for 180~300 minutes under N2 or argon protection and stirring. The initial pressure inside the reactor is 2~8 MPa. After the reaction is completed, the steam inside the reactor is released, the reactor is opened, and after cooling, a homogeneous precursor, namely PPF, is obtained.

[0014] Second, solvothermal treatment: 1) Mix asphalt powder and solvent quinoline at a mass ratio of 1:1~3 and place them in a solvothermal reactor. Heat in a sealed container at 180~220 ℃ for 18~48 hours, and then cool. 2) Centrifuge the cooled solution to remove insoluble matter, and the resulting solution is denoted as QS. 3) Add resin powder and mix it, then place it in a solvothermal reactor. Heat in a sealed container at 180~220 ℃ for 18~48 hours. 4) After cooling, place it in a tube furnace and heat it to 200~220 ℃ under N2 protection for 1~3 hours. After cooling, a homogeneous precursor, PPF, is obtained.

[0015] Furthermore, the carbonization process for the aforementioned pitch-resin composite carbon anode material is as follows: after drying and grinding the PPF, carbonization is carried out in an N2 or argon atmosphere at a carbonization temperature of 900~1200℃, and the temperature is maintained for 1.5~3 hours. The carbonization product is then cooled and ground to obtain PPFC.

[0016] Furthermore, in the sodium-ion full battery using the aforementioned pitch-resin composite carbon anode material, the pitch used is medium-temperature coal tar pitch with a softening point of 80-90 ℃; and the resin used is thermosetting phenolic resin.

[0017] The present invention also provides a sodium-ion full battery using an asphalt-resin composite carbon anode material, which employs the above-mentioned carbon anode material and is a sodium-ion full battery Na-PPFC / / NFM composed of a Na-PPFC anode, a sodium nickel iron manganese oxide NFM cathode, an electrolyte, and a separator.

[0018] Among them, the Na-PPFC negative electrode is obtained by pre-sodiumizing a PPFC negative electrode made of PPFC as the active material; the NFM positive electrode is made of sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 is made from active materials.

[0019] Furthermore, in the sodium-ion full battery of the above-mentioned asphalt-resin composite carbon anode material, the preparation method of the Na-PPFC anode is as follows: PPFC is mixed with a conductive agent and a binder, and after being slurried and ground evenly, it is uniformly coated on a current collector, then dried, cut to obtain the PPFC anode, and then pre-sodiumized to obtain the Na-PPFC anode.

[0020] Furthermore, for the sodium-ion full battery of the above-mentioned asphalt-resin pyrolysis composite carbon anode material, the pre-sodiumization treatment method is as follows: after adding electrolyte to the PPFC anode, it is brought into contact with metallic sodium, kept for 20~40 min, and then the metallic sodium is removed to obtain Na-PPFC anode.

[0021] Furthermore, in the sodium-ion full battery of the above-mentioned pitch-resin composite carbon negative electrode material, the preparation method of the NFM positive electrode is as follows: NFM is mixed with a conductive agent and a binder, and after being slurried and ground evenly, it is uniformly coated on the current collector, then dried and cut to obtain the NFM positive electrode.

[0022] Furthermore, in the sodium-ion full battery using the aforementioned pitch-resin composite carbon anode material, the current collector is either aluminum foil or copper foil.

[0023] Furthermore, in the sodium-ion full battery using the aforementioned asphalt-resin composite carbon anode material, the separator is made of glass fiber; the electrolyte is either sodium hexafluorophosphate or sodium perchlorate.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] 1. The key feature of this invention's asphalt-resin homogeneous heat treatment strategy lies in the fact that, under high temperature and pressure, combined with stirring / solvent heat treatment, the resin and asphalt undergo homogeneous melting / fusion to form a composite precursor. During the heat treatment process, asphalt decomposition regulates the voids in the resin matrix, while during carbonization, resin decomposition inhibits asphalt graphitization, ultimately forming a composite structure where disordered carbon and graphite microcrystals are uniformly interwoven, providing ideal space and channels for efficient sodium storage. Using high temperature and pressure combined with stirring heat treatment does not place high demands on the asphalt raw materials; using solvent heat treatment removes insoluble polycyclic aromatic hydrocarbons that affect homogeneous mixing, thus reducing the reaction temperature and pressure. Both methods achieve the same result. In summary, the raw materials used in this anode material are low-cost, and the preparation method is simple.

[0026] 2. The PPFC anode subjected to high temperature and high pressure with stirring heat treatment exhibits a reversible specific capacity of 306.9 mAh / g and an initial coulombic efficiency of 75.8% at a current density of 0.05 A / g. After pre-sodiumization, the PPFC reacts with conventional sodium nickel manganese oxide (NaNi) anode. 1 / 3 Fe 1 / 3 Mn 1 / 3 The O2 cathode material is well-matched. The energy density, calculated based on the mass of both the positive and negative electrodes, is approximately 182 Wh / kg. The full cell of this invention, operating at 2 A / g for 2500 cycles, exhibits a capacity decay from an initial 132.4 mAh / g to 91.4 mAh / g. When evaluated at -15 °C, the full cell at 0.1 A / g has a capacity of 104 mAh / g after 100 cycles, with an average coulombic efficiency of 99.3%. When evaluated at 50 °C, the cell at 2 A / g has a capacity of 105.9 mAh / g after 800 cycles, with an average coulombic efficiency of 99.8%.

[0027] 3. The PPFC anode treated with solvothermal heat and the full cell composed of NFM have a specific capacity of 170 mAh / g after 1000 cycles at a current density of 1 A / g, and a specific capacity of more than 100 mAh / g after 4500 cycles.

[0028] 4. The full battery of the present invention has the characteristics of high rate of operation, long cycle life and wide operating temperature range. Attached Figure Description

[0029] Figure 1 This is a SEM image of the PPFC material prepared in Example 1 of the present invention.

[0030] Figure 2 The image shown is an HRTEM image of the PPFC material prepared in Example 1 of this invention.

[0031] Figure 3 This is a graph showing the 2 A / g charge-discharge cycle data of the sodium-ion full battery in Example 1 of the present invention.

[0032] Figure 4 This is a charge-discharge curve of the sodium-ion full battery in Example 1 of the present invention at 0.05 A / g.

[0033] Figure 5 This is a graph showing the cyclic data of a sodium-ion full cell at 0.1 A / g charge-discharge under conditions of -15 °C to 0 °C in Example 1 of the present invention.

[0034] Figure 6 This is a graph showing the 2 A / g charge-discharge cycle data of a sodium-ion full cell at 50 °C in Example 1 of the present invention.

[0035] Figure 7 This is a charge-discharge curve of the sodium-ion full battery in Example 6 of the present invention at 0.05 A / g.

[0036] Figure 8 This is a graph showing the 1 A / g charge-discharge cycle data of the sodium-ion full battery in Example 6 of the present invention. Detailed Implementation

[0037] The following embodiments are assembled into CR2032 button cells according to the battery structure described in the invention and their electrical performance is described.

[0038] Example 1

[0039] A pitch-resin composite carbon anode material is disclosed. The reaction raw materials are medium-temperature coal tar pitch and phenolic resin powder. The medium-temperature coal tar pitch powder and phenolic resin are mixed at a mass ratio of 2:1. The reaction raw materials are then subjected to high-temperature and high-pressure homogenization heat treatment to obtain a precursor, denoted as PPF. The PPF is then carbonized to obtain the carbon anode material PPFC.

[0040] Its preparation method includes the following steps:

[0041] (1) High temperature and high pressure stirring heat treatment: The asphalt raw material used is medium temperature coal tar pitch with a softening point of 80-90 °C. After crushing, grinding, sieving and drying, medium temperature coal tar pitch powder is obtained. The medium temperature coal tar pitch powder and phenolic resin are mixed evenly at a mass ratio of 2:1 and then placed in a high pressure reactor. Under the protection of N2 or argon, it is heated at 380 °C for 240 minutes. The initial pressure inside the reactor is 6 MPa. After the reaction is completed, the steam inside the reactor is discharged, the reactor is opened, and after cooling, a homogeneous precursor, namely PPF, is obtained.

[0042] (2) Carbonization: The obtained PPF is dried and pulverized, and then carbonized in an N2 or argon atmosphere. The carbonization temperature is 1100 °C and the carbonization time is 2 hours. The carbonized product is cooled and ground to obtain the negative electrode active material PPFC.

[0043] Figure 1SEM showed that PPFC was a homogeneous block with a relatively smooth surface. Figure 2 HRTEM showed that the PPFC was mainly composed of graphite domains and highly disordered bent carbon layers. The disordered carbon layers were basically surrounded by graphite crystallites with an interlayer spacing of about 0.373 nm and random orientation of the crystallite units.

[0044] Electrochemical performance testing of PPFC:

[0045] (1) Preparation of PPFC negative electrode: PPFC material, conductive agent acetylene black, and binder polyvinylidene fluoride PVDF are mixed in a mass ratio of 70:15:15. The mixture is prepared with N-methylpyrrolidone NMP solvent, ground evenly, and coated on aluminum foil with a coater. After drying the coated negative electrode sheet under vacuum at 120 °C for 12 hours, it is cut into PPFC negative electrodes with a diameter of 12 mm.

[0046] (2) Assembly of PPFC half-cell: In an argon-filled glove box, a sodium metal block was stamped into a sodium sheet with a diameter of 14 mm and a thickness of about 0.5 mm. This sheet was then used to form a half-cell with the PPFC negative electrode. The separator was a glass fiber separator, and the electrolyte was a 1 M NaClO4 electrolyte formed by dissolving NaClO4 in a mixture with a volume ratio of EC:DMC = 1:1. EC is ethylene carbonate, and DMC is dimethyl carbonate. The assembly sequence of the half-cell was as follows: negative electrode shell, sodium sheet, separator, electrolyte, PPFC negative electrode, gasket, spring, positive electrode shell. After the PPFC half-cell was left to stand for 12 hours, its electrochemical performance was tested. The negative electrode had a reversible specific capacity of 308.7 mAh / g and an initial coulombic efficiency of 75.8% at a current density of 0.05 A / g.

[0047] A sodium-ion full battery utilizes the aforementioned pitch-resin composite carbon anode material, comprising a Na-PPFC anode, a sodium nickel iron manganese oxide (NFM) cathode, an electrolyte, and a separator to form a full battery Na-PPFC / / NFM.

[0048] The diaphragm is a glass fiber diaphragm, and the electrolyte is a 1 M NaClO4 electrolyte formed by dissolving NaClO4 in a mixture with a volume ratio of EC:DMC=1:1.

[0049] Preparation of PPFC anode: The method is the same as that used for the electrochemical performance test of PPFC (1) Preparation of PPFC anode.

[0050] Preparation of Na-PPFC negative electrode: In an argon-filled glove box, a block of metallic sodium was pressed into a sodium sheet with a diameter of 14 mm and a thickness of approximately 0.5 mm. The metallic sodium was then bonded to the active material of the PPFC negative electrode. After immersing in the electrolyte for 30 min, the PPFC negative electrode was removed to obtain the Na-PPFC negative electrode. The electrolyte used was a 1 M NaClO4 electrolyte formed by dissolving NaClO4 in a mixture with a volume ratio of EC:DMC = 1:1, where EC is ethylene carbonate and DMC is dimethyl carbonate.

[0051] Preparation of NFM cathode: NFM, acetylene black and PVDF are mixed in a mass ratio of 80:10:10, ground evenly with a slurry, and then coated on aluminum foil using a coater. After drying the coated cathode sheet in a vacuum at 120 °C for 12 hours, it is cut into NFM cathodes with a diameter of 12 mm.

[0052] Assemble a full-cell Na-PPFC / / NFM battery: The battery assembly sequence is as follows: negative electrode shell, Na-PPFC negative electrode, separator, electrolyte, NFM positive electrode sheet, gasket, spring sheet, positive electrode shell. Assemble the CR2032 coin cell in an argon-protected glove box. After the battery is assembled, let it stand for 12 hours before electrochemical performance testing.

[0053] The cycle performance of sodium-ion full cells is shown in [reference needed]. Figure 3 At 2 A / g, after 2500 cycles, the capacity of the full battery decreased from the initial 132.4 mAh / g to 91.4 mAh / g. The charge / discharge curves at 0.05 A / g are shown below. Figure 4 The energy density is 182 Wh / kg (based on the total mass of active materials in the negative and positive electrodes). When evaluated at -15 °C, the battery exhibits a capacity of 104 mAh / g over 100 cycles at 0.1 A / g, with an average coulombic efficiency of 99.3%. See the graph for the -15 °C charge / discharge capacity data of the sodium-ion full cell. Figure 5 When evaluated at 50 °C, the battery exhibited a capacity of 105.9 mAh / g over 800 cycles at 2 A / g, with an average coulombic efficiency of 99.8%. See the graph for the 50 °C charge / discharge capacity data of the sodium-ion full cell. Figure 6 .

[0054] Example 2

[0055] A pitch-resin composite carbon anode material and its sodium-ion full cell are disclosed. When preparing the PPFC carbon anode material, the temperature inside the autoclave is 350 °C and the initial pressure is 2 MPa. Other processes are the same as in Example 1.

[0056] The electrochemical performance test results of the full cell in this embodiment:

[0057] It exhibits a high initial discharge capacity of 203 mAh / g at 0.1 A / g, which decays to 144 mAh / g after 100 cycles, while maintaining an average coulombic efficiency of 98.4%.

[0058] Example 3

[0059] A pitch-resin composite carbon anode material and its sodium-ion full battery are disclosed. When preparing the PPFC carbon anode material, after heating in the high-pressure reactor is completed, the reactor is opened after natural cooling. Other processes are the same as in Example 1.

[0060] The electrochemical performance test results of the full cell in this embodiment:

[0061] The full cell exhibits a high initial discharge capacity of 202 mAh / g at 0.1 A / g, which decays to 176.3 mAh / g after 100 cycles, while maintaining an average coulombic efficiency of 98.8%.

[0062] Example 4

[0063] A pitch-resin composite carbon anode material and its sodium-ion full battery are disclosed. The medium-temperature coal pitch powder and phenolic resin are mixed in a mass ratio of 3:1 and then heat-treated. Other processes are the same as in Example 1.

[0064] The electrochemical performance test results of the full cell in this embodiment:

[0065] The full cell exhibits a high initial discharge capacity of 174.2 mAh / g at 0.1 A / g, which decays to 142.1 mAh / g after 100 cycles, while maintaining an average coulombic efficiency of 99.8%.

[0066] Example 5

[0067] A pitch-resin composite carbon anode material and its sodium-ion full battery are disclosed. The medium-temperature coal pitch powder and phenolic resin are mixed in a mass ratio of 3:2 and then heat-treated. Other processes are the same as in Example 1.

[0068] The electrochemical performance test results of the full cell in this embodiment:

[0069] The full cell exhibits a high initial discharge capacity of 128.5 mAh / g at 0.5 A / g, which decays to 98.1 mAh / g after 100 cycles, while maintaining an average coulombic efficiency of 99.1%.

[0070] Example 6

[0071] A pitch-resin composite carbon anode material and its sodium-ion full cell:

[0072] Removal of quinoline-insoluble matter from pitch: Medium-temperature pitch with a softening point of 80-90 ℃ and a quinoline solution are placed in a polytetrafluoroethylene (PTFE) liner at a mass ratio of 1:2. After ultrasonic mixing, the hydrothermal reactor is sealed and heated at 180 ℃ for 24 hours. After the reactor cools, the material inside is removed and centrifuged at 2000 r / min. The supernatant is collected, and the resulting solution is denoted as QS.

[0073] Dissolve and heat-treat asphalt and resin: Mix QS and thermosetting phenolic resin at a mass ratio of 3:1 and place them in a polytetrafluoroethylene reactor. Seal and heat at 180 ℃ for 24 hours. After cooling, place them in a tube furnace and heat to 220 ℃ at a rate of 3 ℃ / min under N2 protection and hold for 2 hours. The material obtained after cooling is named PPF.

[0074] Carbonization: PPF is ground into powder and heated to 1200 ℃ at a heating rate of 4 ℃ / min under N2 protection. After holding at 1200 ℃ for 2 hours, the carbonized product is obtained. After cooling and grinding, PPFC is obtained.

[0075] The other processes are the same as in Example 1.

[0076] Assembled full-cell Na-PPFC / / NFM: At a current density of 1 A / g, the specific capacity of the full cell is 170 mAh / g after 1000 cycles and exceeds 100 mAh / g after 4500 cycles. Charge-discharge curve data are shown below. Figure 7 See cycle performance Figure 8 .

[0077] Comparative Example 1

[0078] A carbon anode material and its sodium-ion full battery are disclosed. In preparing the carbon anode material, no phenolic resin is added. The asphalt powder is directly carbonized in a N2 atmosphere. The carbonization temperature is 1100 °C and the carbonization time is 2 hours. Other processes are the same as in Example 1.

[0079] The electrochemical performance test results of the full cell in this embodiment:

[0080] The full battery has an initial discharge capacity of 151 mAh / g at 0.1 A / g, which decays to 61 mAh / g after 100 cycles.

[0081] Comparative Example 2

[0082] A carbon anode material and its sodium-ion full battery are disclosed. In preparing the carbon anode material, no asphalt powder is added. The phenolic resin is directly carbonized in a N2 atmosphere. The carbonization temperature is 1100 °C and the carbonization time is 2 hours. Other processes are the same as in Example 1.

[0083] The electrochemical performance test results of the full cell in this embodiment:

[0084] The full battery has an initial discharge capacity of 143 mAh / g at 0.5 A / g, which decays to 112 mAh / g after 100 cycles.

[0085] Comparative Example 3

[0086] A carbon anode material and its sodium-ion full battery are disclosed. In preparing the carbon anode material, no phenolic resin is added, only asphalt powder is used, and the other processes are the same as in Example 1.

[0087] The electrochemical performance test results of the full cell in this embodiment:

[0088] The full battery has an initial discharge capacity of 182 mAh / g at 0.1 A / g, which decays to 77 mAh / g after 100 cycles.

[0089] Comparative Example 4

[0090] A carbon anode material and its sodium-ion full battery are disclosed. When preparing the carbon anode material, no asphalt powder is added, only phenolic resin is used, and the other processes are the same as in Example 1.

[0091] The electrochemical performance test results of the full cell in this embodiment:

[0092] The full battery has an initial discharge capacity of 130 mAh / g at 0.5 A / g, which decays to 103 mAh / g after 100 cycles.

[0093] Comparative Example 5

[0094] A carbon anode material and its sodium-ion full battery are disclosed. When preparing the carbon anode material, the asphalt used has a softening point of 180-200 °C, and the other processes are the same as in Example 1.

[0095] The electrochemical performance test results of the full cell in this embodiment:

[0096] The full battery has an initial discharge capacity of 121 mAh / g at 0.1 A / g, which decays to 82 mAh / g after 100 cycles.

Claims

1. A pitch-resin composite carbon anode material, characterized in that, The reaction raw materials are asphalt and resin powder, wherein the mass fraction of asphalt is greater than 40%. The reaction raw materials are mixed and subjected to high temperature and high pressure homogenization heat treatment to obtain a precursor, denoted as PPF. Then, the PPF is carbonized to obtain a carbon anode material, denoted as PPFC. The PPFC matrix consists of graphite domains and highly disordered bent carbon layers. Most of the disordered carbon layers are surrounded by graphite crystallites with an interlayer spacing of 0.37 nm and random orientation of the crystallite units.

2. The asphalt-resin composite carbon anode material according to claim 1, characterized in that, The mixing of the reaction raw materials, followed by high-temperature and high-pressure homogenization heat treatment, can be carried out using any of the following methods: The first method is high-temperature and high-pressure stirring heat treatment: after mixing asphalt and resin powder, the mixture is placed in a high-pressure reactor and heated at 350~400 ℃ for 180~300 minutes under N2 or argon protection and stirring. The initial pressure inside the reactor is 2~8 MPa. After the reaction is completed, the steam inside the reactor is released, the reactor is opened, and after cooling, a homogeneous precursor, namely PPF, is obtained. Second, solvothermal treatment: 1) Mix asphalt powder and solvent quinoline at a mass ratio of 1:1~3 and place them in a solvothermal reactor. Heat in a sealed container at 180~220 ℃ for 18~48 hours, and then cool. 2) Centrifuge the cooled solution to remove insoluble matter, and the resulting solution is denoted as QS. 3) Add resin powder and mix it, then place it in a solvothermal reactor. Heat in a sealed container at 180~220 ℃ for 18~48 hours. 4) After cooling, place it in a tube furnace and heat it to 200~220 ℃ under N2 protection for 1~3 hours. After cooling, a homogeneous precursor, namely PPF, is obtained.

3. The asphalt-resin composite carbon anode material according to claim 1, characterized in that, The carbonization process is as follows: PPF is dried and ground, then carbonized in an N2 or argon atmosphere at a carbonization temperature of 900~1200℃ for 1.5~3 hours. The carbonized product is then cooled and ground to obtain PPFC.

4. A sodium-ion full battery using an asphalt-resin composite carbon anode material according to claim 1, characterized in that, The asphalt used is medium-temperature coal tar pitch with a softening point of 80-90 ℃; the resin used is thermosetting phenolic resin.

5. A sodium-ion full battery using an asphalt-resin composite carbon anode material, comprising the carbon anode material as described in claim 1, characterized in that... The sodium-ion full cell is composed of Na-PPFC negative electrode, sodium nickel iron manganese oxide NFM positive electrode, electrolyte and separator. Among them, the Na-PPFC negative electrode is obtained by pre-sodiumizing a PPFC negative electrode made of PPFC as the active material; the NFM positive electrode is made of sodium nickel iron manganese oxide (NaNi). 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 is made from active materials.

6. A sodium-ion full battery using an asphalt-resin composite carbon anode material according to claim 5, characterized in that, The preparation method of the Na-PPFC negative electrode is as follows: PPFC is mixed with conductive agent and binder, and after being slurryed and ground evenly, it is uniformly coated on current collector, then dried, cut to obtain PPFC negative electrode, and then pre-sodium treated to obtain Na-PPFC negative electrode.

7. The sodium-ion full battery of the composite carbon anode material of pitch-resin pyrolysis according to claim 5, characterized in that, The pre-sodium treatment method is as follows: after adding electrolyte to the PPFC negative electrode, it is brought into contact with metallic sodium. After maintaining this contact for 20-40 minutes, the metallic sodium is removed to obtain the Na-PPFC negative electrode.

8. A sodium-ion full battery using an asphalt-resin composite carbon anode material according to claim 5, characterized in that, The preparation method of NFM positive electrode is as follows: NFM is mixed with conductive agent and binder, and after being slurryed and ground evenly, it is uniformly coated on current collector, then dried and cut to obtain NFM positive electrode.

9. A sodium-ion full battery using an asphalt-resin composite carbon anode material according to claim 5, characterized in that, The current collector can be either aluminum foil or copper foil.

10. A sodium-ion full battery using an asphalt-resin composite carbon anode material according to claim 5, characterized in that, The diaphragm is made of glass fiber; the electrolyte is either sodium hexafluorophosphate or sodium perchlorate.

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