Positive electrode carbon-enhanced and negative electrode fully-carbonized electrode and preparation process of positive electrode carbon-enhanced and negative electrode fully-carbonized electrode

Abstract

The invention discloses a positive electrode carbon-enhanced and negative electrode fully-carbonized electrode and a preparation process thereof, and relates to the technical field of energy storage, the positive electrode preparation process comprises a positive electrode preparation process and a negative electrode preparation process, the positive electrode preparation process comprises the following steps: 1, constructing a CNT conductive skeleton: taking a Pb-Ca-Sn alloy grid plate as a substrate, taking Fe and Al2O3 as a composite catalyst, and preparing the CNT conductive skeleton; cH4 and H2 gas are introduced for CVD growth to form a CNT conductive skeleton; and 2, PbO2 electro-deposition: taking a mixed solution of H2SO4 and Pb (NO3) 2 as an electrolyte for electro-deposition, and taking the CNT conductive skeleton as an anode. According to the positive electrode, PbO2 phase change is inhibited through the TiO2 coating layer, positive electrode PbO2 particle aggregation is reduced, and battery capacity attenuation is relieved; the negative electrode forms a surface functional group through N and S co-doping treatment, additional pseudocapacitance is provided, and the specific capacity of the all-carbon negative electrode is improved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of energy storage, in particular to a positive electrode carbon-enhanced and negative electrode full-carbonized electrode and a preparation process thereof. BACKGROUND

[0002] Lead-acid batteries are still an important pillar in the energy storage field due to their reliability and cost advantage. However, the environmental burden and weight bottleneck of lead have prompted the industry to seek change. Lead-acid batteries are faced with the core bottlenecks of lead pollution and low energy density. Carbon materials have become ideal lead replacement materials due to their high conductivity, theoretical capacity and environmental friendliness.

[0003] Patent CN119208603A discloses a positive electrode lead paste for lead-acid batteries and a preparation method thereof. The positive electrode lead paste formula comprises lead powder, dilute sulfuric acid, water and additives. According to 1000 parts of the mass of the lead powder, the additives comprise 2-6 parts of manganese dioxide / three-dimensional carbon-based composite electrode material, 1-2 parts of antimony trioxide, 1-2 parts of stannous sulfate, 20-50 parts of red lead, and 0.8-1.2 parts of polyester fiber.

[0004] The defects of the existing lead-acid batteries include: heavy environmental burden, 60-70 kg of lead contained in a single 100 Ah battery and pollution risk in recycling; performance bottleneck, low energy density (30-40 Wh / kg), short cycle life (500-800 deep cycles), and poor low-temperature performance (more than 50% capacity attenuation at-20℃). SUMMARY

[0005] The application aims to provide a positive electrode carbon-enhanced and negative electrode full-carbonized electrode and a preparation process thereof to solve the problems in the background art.

[0006] To achieve the above-mentioned purpose, the application provides the following technical solution: a preparation process of an electrode, comprising a positive electrode preparation process and a negative electrode preparation process, the positive electrode preparation process comprising the following steps:

[0007] I. Constructing a CNT conductive framework: taking a Pb-Ca-Sn alloy grid plate as a substrate, taking Fe and Al2O3 as a composite catalyst, and introducing CH4 and H2 gas for CVD growth to form a CNT conductive framework;

[0008] II. PbO2 electrodeposition: taking a mixed solution of H2SO4 and Pb(NO3)2 as an electrolyte for electrodeposition, taking the CNT conductive framework as an anode, and performing electrodeposition under constant current density and voltage conditions to form a PbO2 layer on the surface of the CNT framework;

[0009] Three, TiO2 atomic layer coating: TiCl4 and H2O as precursors, which are alternately pulsed into the reaction chamber, and the PbO2 layer surface occurs layer-by-layer chemical adsorption and reaction, forming a TiO2 atomic layer coating;

[0010] Four, filling mesoporous carbon: TiO2 atomic layer immersed in sucrose solution, followed by annealing in a nitrogen atmosphere, forming mesoporous carbon on the surface of the TiO2 atomic layer;

[0011] The negative electrode preparation process comprises the following steps:

[0012] A, preparation of graphene current collector: graphene oxide is then coated into a film, and the graphene current collector is formed by heat reduction in an argon atmosphere;

[0013] B, preparation of active layer slurry: hard carbon is used as the main lithium storage material, activated carbon is used to increase the double-layer capacity, and PTFE binder is used to increase the mechanical strength, and the active layer slurry is prepared in proportion, and the active layer slurry is coated on the surface of the graphene current collector, and then dried and compacted;

[0014] C, N, S co-doping treatment: NH3 and H2S are mixed in proportion for co-doping treatment.

[0015] Preferably, in step one, the thickness of the Pb-Ca-Sn alloy grid plate is 1.2 mm, the pore size is 2 mm, the ratio of CH4 and H2 gas is 3:1, the flow rate of the gas is 200 sccm, and the CVD growth is carried out at 800℃ for 30 min.

[0016] Preferably, in step two, the density of H2SO4 is 1.25 g / cm 3 , the concentration of Pb(NO3)2 is 0.1 mol / L, the current density is 20 mA / cm 2 , and the voltage of the electrode potential is 1.8 VS.Hg / Hg2SO4.

[0017] Preferably, in step three, the pulse time of TiCl4 is 0.1 s, the inert gas is introduced to purge the reaction chamber for 15 s, the pulse time of H2O is 0.05 s, the inert gas is introduced to purge the reaction chamber for 10 s, and the pulse number is 100 times.

[0018] Preferably, in step four, the concentration of the sucrose solution is 20 wt%, and the sucrose solution is annealed at a temperature of 600℃ for 2 h.

[0019] Preferably, in step A, the thickness of the coated film is 200 μm, and the heat reduction temperature is 300℃.

[0020] Preferably, in step B, the proportion of hard carbon is 70%, the proportion of activated carbon is 25%, the proportion of PTFE binder is 5%, the film thickness of the active layer slurry is 220 μm, the film thickness after drying treatment is 180 μm, and the compaction treatment is carried out under a pressure of 20 MPa.

[0021] Preferably, in step C, the volume ratio of NH3 and H2S is 4:1, the doping treatment temperature is 800℃, and the doping treatment time is 2h.

[0022] The application also discloses a positive electrode carbon-reinforced and negative electrode full-carbonized electrode.

[0023] The gradient carbon-reinforced positive electrode has a CNT conductive network as a bottom layer, a TiO2-coated PbO2 as an intermediate layer, and a mesoporous carbon buffer layer as a surface layer, forming a gradient carbon-reinforced structure.

[0024] The full-carbon negative electrode comprises a graphene current collector and an active layer slurry subjected to N,S co-doping treatment, and forms a hierarchical pore structure composed of active carbon and hard carbon through N,S co-doping treatment.

[0025] An electrolyte;

[0026] The gradient carbon-reinforced positive electrode is inhibited from phase transition by the TiO2 coating layer, thereby reducing the agglomeration of PbO2 particles in the positive electrode and relieving the capacity attenuation of the gradient carbon-reinforced positive electrode battery; and the negative electrode forms surface functional groups through N,S co-doping treatment, thereby providing additional pseudo-capacitance and improving the specific capacity of the full-carbon negative electrode.

[0027] Preferably, the CNT conductive network is a vertically grown three-dimensional carbon nanotube array, and the three-dimensional conductive network replaces the current collector, thereby reducing the internal resistance; the TiO2 coating layer has a thickness in the range of 5-6 nm and forms Ti-O-C bonds with carbon, thereby enhancing the interface stability, inhibiting the destruction of the carbon structure, relieving the capacity attenuation of the gradient carbon-reinforced positive electrode battery, and the mesoporous carbon buffer layer has a specific surface area in the range of 2000-2200 m 2 / g, and an average pore size in the range of 3.5-4.0 nm, and the porous carbon provides non-faradic capacity compensation, and the non-faradic capacity can partially compensate for the total capacity loss, thereby delaying the decline rate of the total capacity of the battery.

[0028] Preferably, the N, S co-doped activated carbon has an N content in the range of 5-6 at%, and an S content in the range of 1-2 at%, the hierarchical pore structure comprises micropores and mesopores, the micropores have a pore size of no more than 2 nm, the micropores enhance the adsorption capacity of ions through intermolecular forces to improve the ion storage capacity, the mesopores have a pore size in the range of 2-50 nm, and the network structure formed by the interconnected mesopores shortens the transmission path of ions from the electrolyte to the inside of the electrode and reduces the diffusion time.

[0029] Preferably, the density of sulfuric acid in the electrolyte is in the range of 1.25-1.28 g / cm 3 , and the Na2SO4 concentration is in the range of 0.4-0.6 mol / L.

[0030] Compared with the prior art, the present application has the beneficial effects that, by performing carbon enhancement treatment on the positive electrode and full carbonization and doping treatment on the negative electrode, the electrochemical performance, cycle stability and conductive performance of the electrode are significantly improved, and the specific content is as follows.

[0031] 1. In the present application, the TiO2 coating layer of the positive electrode inhibits PbO2 phase change, reduces positive electrode PbO2 particle agglomeration, and alleviates battery capacity attenuation; the N, S co-doping treatment of the negative electrode forms surface functional groups, provides additional pseudo-capacitance, and improves the specific capacity of the full-carbon negative electrode;

[0032] 2. In the present application, the three-dimensional CNT conductive network replaces the traditional current collector, reduces the internal resistance, and improves the kinetic performance of the electrode reaction;

[0033] 3. In the present application, the TiO2 coating layer forms a Ti-O-C bond with carbon, enhances the interface stability, inhibits carbon structure damage, and further alleviates the positive electrode battery capacity attenuation;

[0034] 4. In the present application, the hierarchical pore structure of the negative electrode comprises micropores and mesopores, the micropores enhance the adsorption capacity of ions through intermolecular forces to improve the ion storage capacity, and the network structure formed by the interconnected mesopores shortens the transmission path of ions from the electrolyte to the inside of the electrode and reduces the diffusion time, thereby optimizing the ion transmission. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 FIG. 1 is a structural schematic diagram of a positive electrode carbon enhancement and negative electrode full carbonization electrode according to the present application;

[0036] Figure 2 FIG. 3 is a positive electrode preparation process flowchart in the preparation process of an electrode according to the present application;

[0037] Figure 3 FIG. 5 is a negative electrode preparation process flowchart in the preparation process of an electrode according to the present application;

[0038] Figure 4A positive electrode process effect diagram for a preparation process of an electrode of the present application;

[0039] Figure 5 A negative electrode process effect diagram for a preparation process of an electrode of the present application. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than 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.

[0041] Embodiment one: refer to Figure 1 As shown: a positive electrode carbon reinforced and negative electrode full carbon electrode, including gradient carbon reinforced positive electrode, full carbon negative electrode and electrolyte, gradient carbon reinforced positive electrode, gradient positive electrode takes CNT conductive network as bottom layer, takes TiO2 coated PbO2 as intermediate layer, and takes mesoporous carbon buffer layer as surface layer to form a gradient carbon reinforced structure; the full carbon negative electrode includes graphene current collector and N, S co-doped active layer slurry, and the N, S co-doping treatment forms a hierarchical pore structure composed of activated carbon and hard carbon.

[0042] The gradient carbon reinforced positive electrode suppresses PbO2 phase transition through the TiO2 coating layer, thereby reducing positive electrode PbO2 particle agglomeration and relieving the capacity attenuation of the gradient carbon reinforced positive electrode battery; the negative electrode forms surface functional groups through N, S co-doping treatment, thereby providing additional pseudo-capacitance and improving the specific capacity of the full carbon negative electrode.

[0043] The CNT conductive network is a three-dimensional carbon nanotube array vertically grown, which replaces the current collector through a three-dimensional conductive network to reduce internal resistance, the TiO2 coating layer has a thickness in the range of 5-6 nm and forms Ti-O-C bonds with carbon, the Ti-O-C bonds enhance interface stability, inhibit carbon structure damage, relieve the capacity attenuation of the gradient carbon reinforced positive electrode battery, the mesoporous carbon buffer layer has a specific surface area in the range of 2000-2200 m 2 / g, and an average pore size in the range of 3.5-4.0 nm, the porous carbon provides non-faradic capacity compensation, the non-faradic capacity can partially compensate for total capacity loss, and delay the decline rate of total battery capacity.

[0044] The N content of the N and S co-doped activated carbon is in the range of 5-6 at%, the S content is in the range of 1-2 at%, the hierarchical pore structure comprises micropores and mesopores, the micropores have a pore size of not more than 2 nm, the micropores enhance the adsorption capacity of ions through intermolecular forces, and the ion storage capacity is improved, the mesopores have a pore size in the range of 2-50 nm, and the network structure formed by the interconnection of the mesopores shortens the transmission path of ions from the electrolyte to the inside of the electrode and reduces the diffusion time.

[0045] The density of sulfuric acid in the electrolyte is in the range of 1.25-1.28 g / cm 3 The Na2SO4 concentration is in the range of 0.4-0.6 mol / L, and the multi-stage constant current-constant voltage control algorithm is realized by adjusting the charging current and voltage in sections, and the electrochemical characteristics of the positive and negative electrode materials are adapted.

[0046] Embodiment two: refer to Figure 2 - Figure 5 The preparation process of an electrode includes a positive electrode preparation process and a negative electrode preparation process;

[0047] The steps of the positive electrode preparation process are as follows:

[0048] 1) Constructing a CNT conductive framework (CNT is a one-dimensional quantum carbon material with a special structure): using a Pb-Ca-Sn alloy grid plate as a substrate (Pb itself is a good conductive metal, and after forming an alloy with Ca and Sn, it can still maintain a high electronic conductivity, which can be used as a "current collecting substrate" of the CNT conductive framework, to ensure that the overall electrode has a low resistance characteristic after the growth of the CNT array, which is beneficial to electron transmission), using Fe and Al2O3 as a composite catalyst, and introducing CH4 and H2 gas to form a CNT conductive framework by CVD growth, and loading Fe and Al2O3 catalysts on the surface of the substrate, wherein Fe is used as an active component to catalyze the decomposition of the carbon source, and Al2O3 carrier can uniformly disperse Fe particles to avoid agglomeration to ensure the catalytic efficiency;

[0049] 2) PbO2 electrodeposition: using a mixture of H2SO4 and Pb(NO3)2 as an electrolyte for electrodeposition, and using the CNT conductive framework as an anode, electrodeposition is carried out under constant current density and voltage conditions, and a PbO2 layer is formed on the surface of the CNT framework. During the electrodeposition process, the CNT conductive framework is oxidized as the anode, the Pb 2+ in the electrolyte migrates to the anode under the action of an electric field and is oxidized to PbO2 on the surface of the anode. The specific reaction is: Pb 2+ + 2H2O - 2e - → PbO2↓ + 4H + This reaction continues under constant current density and voltage conditions, so that the generated PbO2 continuously deposits on the surface of the CNT framework, gradually forming a continuous PbO2 layer.

[0050] 3) TiO2 atomic layer coating: TiCl4 and H2O are used as precursors, which are alternately pulsed into the reaction chamber, and layer-by-layer chemical adsorption and reaction occur on the surface of the PbO2 layer to form a TiO2 atomic layer coating. Based on atomic layer deposition (ALD) technology, the two precursors TiCl4 and H2O are alternately pulsed into the reaction chamber and chemically react with the PbO2 electrodeposition surface to realize the controllable growth of TiO2 thin film layer by layer;

[0051] 4) Filling mesoporous carbon: The TiO2 atomic layer is immersed in a sucrose solution. When the substrate coated with the TiO2 atomic layer is immersed in the sucrose solution, sucrose molecules penetrate into the surface of the TiO2 layer and possible small pores through capillary action and intermolecular forces (such as hydrogen bonds), and are uniformly adsorbed on the surface of TiO2. Sucrose as a carbon source, its molecular chain can combine with active groups such as hydroxyl (-OH) on the surface of TiO2 to form a stable physical-chemical adsorption layer, and then annealed in a nitrogen atmosphere to form mesoporous carbon on the surface of the TiO2 atomic layer;

[0052] When high-temperature annealing is performed, sucrose undergoes three stages of dehydration, decomposition, and carbonization:

[0053] Dehydration: low-temperature stage (about 100-200℃), sucrose loses crystal water, and the molecular structure gradually becomes dense;

[0054] Decomposition: medium-temperature stage (about 200-500℃), the organic functional groups (such as hydroxyl, carbonyl) in the sucrose molecule are broken, releasing small molecule gases such as CO, CO2, and forming a carbon-rich intermediate;

[0055] Carbonization: high-temperature stage (usually above 500℃), the carbon-rich intermediate is further graphitized to form carbon materials with a graphite-like structure.

[0056] Due to the space limitation of the TiO2 atomic layer surface and the channels left by the gas escaping during sucrose decomposition, the final carbon layer presents a rich mesoporous structure. Based on the impregnation-carbonization process of sucrose, through the adsorption, solidification and high-temperature carbonization of sucrose on the surface of the TiO2 atomic layer, the formation of mesopores is mainly due to two aspects:

[0057] First, the uniform distribution of sucrose molecules during adsorption on the surface of TiO2, which retains the intermolecular gaps after carbonization;

[0058] Second, the gas bubbles formed in the carbon layer during the carbonization process form bubble channels, which form interconnected mesopores after cooling. This structure not only ensures the high specific surface area of the carbon layer, but also provides channels for ion transport, matching the design requirements of the "gradient carbon reinforced" positive electrode.

[0059] The negative electrode preparation process is:

[0060] 1) Preparation of graphene current collector (the current collector is a key component for collecting and conducting electrons generated by electrode active materials, and supporting electrode structure, the graphene current collector is an electrode current collector taking graphene as core material, which is used to replace traditional metal current collector (such as copper foil) to undertake the functions of collecting and conducting electrons, supporting active materials, and optimizing the overall performance of the battery through the unique performance of graphene): graphene oxide is then coated into a film, and heated in Ar atmosphere to form a graphene current collector, when heated to 300℃ in Ar, unstable oxygen-containing functional groups (such as epoxy group and hydroxyl group) will decompose to release small molecules such as CO, CO2 and H2O, and part of the sp 2 Conjugated structure of graphene is restored, which makes electrons transfer within and between layers, and the conductivity is significantly improved, meeting the core requirement of the current collector for efficient electron conduction;

[0061] 2) Preparation of active layer slurry: hard carbon is used as the main lithium storage material to provide the main capacity of the battery, activated carbon is used to increase the double-layer capacity, auxiliary power storage and improve conductivity, optimize the rate performance, PTFE binder is used to increase the mechanical strength and ensure the structural integrity, the active layer slurry is prepared in proportion, the active layer slurry is coated on the surface of the graphene current collector as the substrate, and then dried and compacted, in the overall structure of the negative electrode, the active layer is usually directly coated on the surface of the current collector to form a double-layer structure of "current collector-active layer";

[0062] 3) N, S co-doping treatment: NH3 and H2S are mixed in proportion for co-doping treatment, the electronegativity of N (3.04) is higher than that of carbon (2.55), and additional lone pair electrons are introduced after doping to increase the conductivity and polarity of the material; the atomic radius of S (102 pm) is larger than that of carbon (77 pm), and defects are easily formed after doping to provide more active sites.

[0063] The thickness of the Pb-Ca-Sn alloy grid plate is 1.2 mm, the pore size is 2 mm, the ratio of CH4 and H2 gas introduced is 3:1, the flow rate of the introduced gas is 200 sccm, the composite catalyst takes Al2O3 as the carrier and loads Fe as the active component, the particle size is 5 nm, and the CVD growth is carried out at 800℃ for 30 min.

[0064] The density of H2SO4 is 1.25 g / cm 3 , the concentration of Pb(NO3)2 is 0.1 mol / L, the current density is 20 mA / cm 2 , the voltage of the electrode potential is 1.8 V, and the deposition amount of PbO2 electrodeposition is calibrated by weighing method as 60±2 mg / cm 2 .

[0065] The pulse time of TiCl4 is 0.1s, the inert gas is blown for 15s, the pulse time of H2O is 0.05s, the inert gas is blown for 10s, and the pulse number is 100.

[0066] The concentration of the sucrose solution is 20wt%, and the sucrose solution is annealed at 600℃ for 2h.

[0067] The thickness of the film formed by coating is 200μm, and the thermal reduction temperature is 300℃.

[0068] The proportion of hard carbon is 70%, the proportion of activated carbon is 25%, the proportion of PTFE binder is 5%, the thickness of the active layer slurry film is 220μm, the film thickness after drying treatment is 180μm, and the compaction treatment is carried out under the pressure of 20MPa.

[0069] The volume ratio of NH3 and H2S is 4:1, the doping treatment temperature is 800℃, and the doping treatment time is 2h.

[0070] (I) Experimental test

[0071] The battery is subjected to material characterization, and the test conditions are as follows:

[0072] Test item Test condition / standard Microtopography Accelerating voltage 200 kV Specific surface area ISO 9277:2010 Surface chemistry Al K a radiation, step 0.1 eV

[0073] The battery is subjected to electrochemical test:

[0074] Test object: The half-cell test is carried out on the positive electrode (carbon reinforced composite electrode) and the negative electrode (full carbon electrode) respectively.

[0075] Electrolyte: 1.28g / cm 3 of H2SO4+0.5M Na2SO4 mixed solution is used.

[0076] Test equipment: Bio-Logic VMP3 electrochemical workstation is used.

[0077] Test content: including cyclic voltammetry (0.1-1.8V, scan rate 0.1-10mV / s) and constant current charge and discharge (0.2C-10C rate, cut-off voltage 1.8V / 1.0V), etc., which are used to analyze the key indicators such as capacity, reaction kinetics and rate performance of the electrode.

[0078] After the test is completed, the full battery is assembled, and the parameters are as follows:

[0079] Design item Positive electrode surface capacity Positive electrode surface capacity Separator Electrolyte Design parameter 32 Ah / cm2 2 ]] 38 Ah / cm 2 ]] AGM glass fiber 15 mL / Ah

[0080] (II) Analysis of test results

[0081] The improvement of the positive electrode conductivity is as follows:

[0082]

[0083]

[0084] Conclusion analysis:

[0085] Due to the effect of CNT three-dimensional conductive network, the internal resistance is reduced by 68%; the Tafel slope is reduced by 38%, and the reaction kinetics is significantly improved.

[0086] Traditional positive electrode:

[0087] - capacity decay to 92% after 100 cycles

[0088] - sharply decreased to 68% after 500 times

[0089] Carbon reinforced positive electrode:

[0090] - maintain 91% capacity after 1000 cycles

[0091] - still maintain 82.5% after 3000 times

[0092] The improvement of the positive electrode conductive performance is as follows:

[0093] Material 0.2 C capacity (Ah / kg) 10 C capacity retention rate -30 °C capacity retention rate Conventional lead negative electrode 120 45％ 58％ N, S-doped carbon negative electrode 42.1 91％ 83.7％

[0094] Conclusion analysis:

[0095] 1. Surface functional groups (C=O, -SO x ) provide additional pseudo-capacitance;

[0096] 2. Hierarchical pore structure (microporous + mesoporous) optimizes ion transport.

[0097] The working principle and method of using the device: The gradient carbon reinforced positive electrode takes the vertically grown three-dimensional CNT conductive network as the bottom layer, replacing the traditional current collector to reduce the internal resistance, the middle layer is coated with PbO2 through TiO2, which inhibits the phase transition and particle agglomeration of PbO2, and the Ti-O-C bond formed enhances the interface stability, the surface mesoporous carbon buffer layer provides non-faradic capacity compensation to delay the total capacity decline with high specific surface area and specific pore size; The all-carbon negative electrode takes graphene current collector as the base, and the N, S co-doped active layer (containing hard carbon, activated carbon and PTFE binder) provides additional pseudo-capacitance through surface functional groups, hierarchical pore structure (microporous enhances ion adsorption, mesoporous shortens transmission path) optimizes ion transport, and improves specific capacity; Cooperate with a specific concentration of sulfuric acid and Na2SO4 electrolyte, the positive and negative electrodes synergistically realize efficient electron and ion conduction, inhibit capacity decay, and improve cycle stability and electrochemical performance.

[0098] Although the present application has been described in detail with reference to the foregoing embodiments, the technical solutions recorded in the foregoing embodiments can be modified, or some of the technical features can be replaced by equivalent features, by those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for preparing an electrode, characterized in that: This includes positive electrode preparation processes and negative electrode preparation processes. The positive electrode preparation process includes the following steps: S1. Constructing the CNT conductive framework: Using a Pb-Ca-Sn alloy grid as the substrate and Fe and Al2O3 as the composite catalyst, CVD growth is carried out by introducing CH4 and H2 gases to form the CNT conductive framework. S2, PbO2 electrodeposition: Using a mixture of H2SO4 and Pb(NO3)2 as the electrolyte for electrodeposition, and CNT conductive framework as the anode, electrodeposition is carried out under constant current density and voltage conditions to form a PbO2 layer on the surface of CNT framework. S3. Coating TiO2 atomic layer: Using TiCl4 and H2O as precursors, they are alternately pulsed into the reaction chamber, and layer-by-layer chemical adsorption and reaction occur on the surface of PbO2 layer to form TiO2 atomic layer coating; S4. Filling mesoporous carbon: Immerse the TiO2 atomic layer in a sucrose solution, and then anneal in a nitrogen atmosphere to form mesoporous carbon on the surface of the TiO2 atomic layer. The anode fabrication process includes the following steps: A. Preparation of graphene current collector: Graphene oxide is coated into a film and then thermally reduced in an Ar atmosphere to form a graphene current collector; B. Preparation of active layer slurry: Hard carbon is used as the main lithium storage material. The capacity of the double layer is increased by activated carbon and the mechanical strength is increased by PTFE binder. The active layer slurry is prepared in proportion. The active layer slurry is coated on the surface with graphene current collector as substrate and then dried and compacted. C, N, S co-doping treatment: NH3 and H2S are mixed and co-doped in a certain proportion.

2. The electrode fabrication process according to claim 1, characterized in that, In step S1, the thickness of the Pb-Ca-Sn alloy grid is 1.2 mm, the aperture is 2 mm, the ratio of CH4 to H2 gas is 3:1, the gas flow rate is 200 sccm, and CVD growth is carried out at 800℃ for 30 min.

3. The electrode fabrication process according to claim 1, characterized in that, In step S2, the density of H2SO4 is 1.25 g / cm³. 3 The concentration of Pb(NO3)2 was 0.1 mol / L, and the current density was 20 mA / cm². 2 The voltage of the electrode potential is 1.8Vs·Hg / Hg2SO4.

4. The electrode fabrication process according to claim 1, characterized in that, In step S3, the pulse duration of TiCl4 is 0.1s, and the reaction chamber is purged with inert gas for 15s. The pulse duration of H2O is 0.05s, and the reaction chamber is purged with inert gas for 10s. The number of pulses is 100.

5. The electrode fabrication process according to claim 1, characterized in that, In step A, the thickness of the coated film is 200 μm, and the thermal reduction temperature is 300 °C.

6. The electrode fabrication process according to claim 1, characterized in that, In step B, the proportion of hard carbon is 70%, the proportion of activated carbon is 25%, the proportion of PTFE binder is 5%, the film thickness of the active layer slurry is 220μm, the film thickness after drying is 180μm, and it is compacted under a pressure of 20MPa.

7. The electrode fabrication process according to claim 1, characterized in that, In step C, the volume ratio of NH3 to H2S is 4:1, the doping temperature is 800℃, and the doping time is 2h.

8. A positive electrode with carbon enhancement and a negative electrode with full carbonization, characterized in that, The electrode is prepared using the electrode preparation process described in any one of claims 1-7, comprising: A gradient carbon-reinforced positive electrode is formed by using a CNT conductive network as the bottom layer, a TiO2-coated PbO2 as the intermediate layer, and a mesoporous carbon buffer layer as the surface layer to form a gradient carbon-reinforced structure. The all-carbon negative electrode includes a graphene current collector and an active layer slurry treated with N and S co-doping. The N and S co-doping process forms a hierarchical porous structure composed of activated carbon and hard carbon. Electrolyte; Among them, the gradient carbon-enhanced positive electrode suppresses the PbO2 phase transition through the TiO2 coating layer, reducing the agglomeration of PbO2 particles in the positive electrode; the negative electrode forms surface functional groups through N,S co-doping treatment, thereby providing additional pseudocapacitance and improving the specific capacity of the all-carbon negative electrode.

9. The positive electrode with carbon enhancement and the negative electrode with full carbonization according to claim 8, characterized in that: The CNT conductive network is a vertically grown three-dimensional carbon nanotube array, replacing the current collector; the TiO2 coating layer has a thickness in the range of 5-6 nm and forms Ti-OC bonds with carbon, which enhances the interfacial stability; the specific surface area of ​​the mesoporous carbon buffer layer is 2000-2200 m² / g. 2 Within the range of / g, the average pore size is in the range of 3.5-4.0nm, providing non-Radida capacity compensation through porous carbon.

10. The positive electrode with carbon enhancement and the negative electrode with full carbonization according to claim 8, characterized in that: The N,S co-doped activated carbon has an N content in the range of 5-6 at% and an S content in the range of 1-2 at%. The hierarchical pore structure includes micropores and mesopores. The pore size of the micropores does not exceed 2 nm. The micropores adsorb ions through intermolecular forces. The pore size of the mesopores is in the range of 2-50 nm. The network structure formed by the interconnected mesopores promotes the transport of ions from the electrolyte to the inside of the electrode.

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