A lithium iron phosphate energy storage battery manufacturing process

Abstract

The application discloses a lithium iron phosphate energy storage battery manufacturing process and belongs to the technical field of battery manufacturing processes. The process is as follows: a positive electrode material is prepared by using a low-cobalt-doped and in-situ coated iron source precursor, sintering is performed under a nitrogen atmosphere to obtain a low-cobalt-doped positive electrode material, the positive electrode material is hot-pressed to prepare a pressed sheet, the pressed sheet is cut by laser cutting to obtain a positive electrode sheet; then, an electrolyte is prepared, the electrolyte comprises a basic electrolyte component and an additive, the additive comprises 1.5 wt% fluoroethylene carbonate and 0.5 wt% butanedinitrile; finally, battery integration is performed. The lithium iron phosphate energy storage battery manufacturing process can improve the thermal runaway triggering temperature and the thermal runaway inhibition time, and reduce the cobalt consumption and the material cost.

Description

Technical Field

[0001] This invention specifically relates to a manufacturing process for lithium iron phosphate energy storage batteries, belonging to the field of battery manufacturing technology. Background Technology

[0002] Lithium iron phosphate (LFP) has gradually become the main cathode material for lithium-ion batteries due to its advantages such as low cost, high safety, and long lifespan. With the development of lithium-ion battery technology, the performance requirements for cathode materials are becoming increasingly stringent. For example, Chinese Patent Publication No. CN120809819A discloses a lithium iron phosphate cathode material and its preparation method. This lithium iron phosphate cathode material features high energy density, with iron phosphide impurities accounting for 0.001-0.008 PPM of the total lithium iron phosphate cathode material mass, and a compaction density of 2.68-2.8 g / cm³ under 3T pressure. 3 The powder resistivity is 8-15 Ω·cm, the 0.1C discharge capacity is 161-163 mAh / g, the 0.1C charge / discharge efficiency is 98.5-100%, and the 1C discharge capacity is 145-148 mAh / g. The preparation process controls the phosphorus-to-iron ratio of the iron phosphate precursor and the ratio of carbon source to iron phosphate precursor in the two batches, and controls the sintering temperature. Combined with secondary sintering, the content of iron phosphate impurities in the final lithium iron phosphate product can be controlled to obtain high-energy-density lithium iron phosphate cathode materials. Currently, the preparation of lithium iron phosphate batteries using lithium iron phosphate cathode materials needs to solve the following problems: First, the manufacturing cost is relatively high, affecting market competitiveness; second, the safety risks under extreme conditions (overcharge / overheating / short circuit) have not been completely resolved; in addition, traditional lithium iron phosphate materials have low ionic conductivity and poor stability of interfacial side reactions. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a manufacturing process for lithium iron phosphate energy storage batteries that can improve the thermal runaway trigger temperature and thermal runaway suppression time, while reducing cobalt usage and material costs.

[0004] The manufacturing process for lithium iron phosphate energy storage batteries of the present invention is as follows:

[0005] S1, a cathode material was prepared by in-situ coating of an iron source precursor with low cobalt doping of 0.5 < Co ≤ 1%. The cathode material was prepared by mixing FePO4·2H2O and Li2CO3 at a molar ratio of 1:1.05, adding 5 wt% coating agent and 0.8 wt% cobalt acetate solution, wherein the coating agent is sucrose. In-situ coating was achieved by spray drying. The cathode material was sintered at 750°C for 8 hours under a nitrogen atmosphere to obtain a low cobalt doped cathode material. The cathode material was hot-pressed to prepare a sheet, and the sheet was cut by laser cutting to obtain a cathode sheet.

[0006] S2, preparing an electrolyte, the electrolyte comprising basic electrolyte components and additives, the additives comprising 1.5 wt% fluoroethylene carbonate and 0.5 wt% succinate;

[0007] S3, Battery Integration, the battery integration is as follows: the negative electrode sheet and the positive electrode sheet prepared in step S1 are used to prepare the battery cell using an asymmetric bipolar stacking process, and the battery cell is assembled into the battery box. The tabs of the battery cell are connected to the aluminum current collector by 20kHz ultrasonic welding. Then the electrolyte prepared in step S2 is injected into the battery box.

[0008] In the composite electrolyte additives: fluoroethylene carbonate is preferentially reduced at the negative electrode to construct a LiF-rich inorganic SEI film with a high Young's modulus (>50 GPa), effectively inhibiting dendrite growth and improving thermal stability by 30°C compared to conventional SEI films; succinic acid possesses both a high dielectric constant and HOMO / LUMO energy levels, preferentially adsorbing on the positive electrode surface to oxidize and form a stable CEI film, effectively inhibiting electrolyte decomposition and transition metal dissolution under high voltage (>3.65 V). The synergistic effect of fluoroethylene carbonate and succinic acid, along with the interweaving of LiF generated from FEC decomposition and polycyano compounds generated from SN decomposition, forms a gradient interface film structure.

[0009] Furthermore, the basic electrolyte composition consists of the following components: 1M LiPF6 in EC: EMC: DEC, wherein the volume ratio of 1M LiPF6 in EC: EMC: DEC is 3:5:2.

[0010] Furthermore, the asymmetric bipolar tab stacking process is as follows: the tabs of the positive and negative electrodes are staggered, and the tabs of each layer of positive and negative electrodes are alternately drawn out on both sides through winding or stacking processes to form 2n tabs, where n is the number of winding turns.

[0011] Furthermore, the cathode material also includes 0.8 wt% perfluorohexylethylene and 0.3 wt% BPO. When mixing the dry powder of the cathode material, a small amount of perfluorohexylethylene (polymerizable monomer) and BPO (initiator) are added to initiate polymerization during subsequent hot pressing. The resulting polymer network serves as a solid solvent and binder phase, which can further improve the mechanical strength and interfacial stability of the electrode. Through the polymerization reaction induced by the initiator, a three-dimensional cross-linked structure is formed inside the electrode, which significantly improves the mechanical strength and ion transport efficiency; it can also improve the electrochemical stability and interfacial stability of the electrolyte.

[0012] Furthermore, in the preparation of the cathode material, FePO4·2H2O and Li2CO3 are first ball-milled and mixed for 4 hours, and then sucrose and cobalt acetate solution are added for spray granulation.

[0013] Furthermore, the battery also integrates a BMS unit and an active liquid cooling module. The BMS unit monitors voltage, temperature and current in real time, and the overcharge / short circuit response time is <100ms.

[0014] Furthermore, the hot pressing temperature of the hot pressing molding is 175-185℃, and the hot pressing pressure is 4.8-5.2 MPa.

[0015] Furthermore, the cathode material also includes Mg and V; FePO4·2H2O, Li2CO3, Mg and V are mixed in a molar ratio of 1:1.05:0.42:0.3; based on low cobalt doping, Mg (magnesium) and V (vanadium) are introduced for core-shell doping, with Mg doping predominating on the surface to broaden lithium-ion migration channels; and V doping predominating in the bulk phase to stabilize the crystal framework; compared with low cobalt doping, it can further reduce the cobalt content while increasing the intrinsic electronic conductivity of the material by an order of magnitude through the synergy of Mg and V, thereby improving the lithium-ion diffusion coefficient.

[0016] Furthermore, the additive also includes 0.8 wt of an imidazole ionic liquid; the specific component of the imidazole ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt; the fluoroethylene carbonate, succinate, and imidazole ionic liquid in the additive form a ternary composite electrolyte system by introducing the imidazole ionic liquid on the basis of the fluorosulfonate and nitrile composite system; the imidazole ionic liquid can significantly improve the thermal stability and electrochemical window of the electrolyte, and synergistically with the fluorosulfonate and succinate to construct a denser, more stable, and highly ionicly conductive film at the positive and negative electrode interfaces.

[0017] Furthermore, the additive also includes 0.2 wt% lithium bis(oxalato)borate. By introducing a very small amount of borate into the electrolyte, the boron-containing component can preferentially participate in film formation at a lower potential and may act as a bridge to promote the crosslinking of FEC and SN decomposition products, further improving the compactness and ionic conductivity (>1×10⁻⁶) of the I film. -3 The S / cm and the bonding force with the electrode effectively reduce the initial coulombic loss and improve long-term cycling stability.

[0018] Compared with the prior art, the lithium iron phosphate energy storage battery manufacturing process of the present invention has the following advantages:

[0019] 1. When performing electronic structure modulation with low cobalt doping, additional valence electrons are introduced to form shallow donor states in the Fe3d band, thereby improving the intrinsic electronic conductivity of the material; Crystal field stabilization: Co atoms with slightly different radii are introduced. 2+ Ions, producing local lattice distortion to optimize Li +The diffusion channel significantly improves the lithium-ion diffusion coefficient; the in-situ coating enhances the effect: sucrose and cobalt solution are added during the co-precipitation of FePO4. In the subsequent sintering process at 750℃, the amorphous carbon coating layer formed by sucrose carbonization works synergistically with the Co doping modification. The thickness of the carbon coating layer is controlled at 2-5nm, and it is more tightly bound to the particles, which reduces the charge transfer impedance at the electrode interface.

[0020] 2. Low-cobalt-doped (Co≤1%) lithium iron phosphate cathode materials are synthesized using in-situ iron source precursor coating technology. Combined with fluorosulfonate and nitrile composite electrolyte additives, the amount of cobalt used can be reduced by 60%. While significantly reducing the amount of precious metal cobalt, the intrinsic electronic conductivity, structural stability, and compatibility with the electrolyte of the material are simultaneously improved, thereby achieving a synergistic effect of high specific capacity and high thermal stability (initial decomposition temperature ≥180℃) from the source. The thermal runaway trigger temperature and thermal runaway suppression time are improved, and the unit energy consumption is reduced. The asymmetric bipolar and full-tab stacked structure is adopted, and the current distribution is optimized through finite element analysis, reducing the interface impedance. The battery also integrates a BMS unit and an active liquid cooling module to achieve a single-cell temperature difference ≤1.5℃. The module-level thermal runaway suppression time is improved. Detailed Implementation

[0021] Example 1:

[0022] The manufacturing process for lithium iron phosphate energy storage batteries of the present invention is as follows:

[0023] S1, a cathode material was prepared by low cobalt doping and in-situ coating with an iron source precursor. The specific preparation method was as follows: FePO4·2H2O and Li2CO3 were mixed at a molar ratio of 1:1.05, and 5 wt% coating agent and 0.8 wt% cobalt acetate solution were added. The coating agent was sucrose. In-situ coating was achieved by spray drying. The cathode material was sintered at 750°C for 8 hours under a nitrogen atmosphere to obtain a low cobalt-doped cathode material. The cathode material was then hot-pressed to prepare a sheet, and then... Laser cutting is used to cut the compressed sheet to obtain the positive electrode sheet; when preparing the positive electrode material into a compressed sheet, the low cobalt-doped positive electrode material prepared above and acrylic acid-grafted PVDF are used as binders and mixed as dry powder at a mass ratio of 92:8; this achieves rheological control and facilitates the formation of a fiber network; during hot pressing, fine hot pressing can be performed, and segmented variable temperature hot pressing is used: 160℃ in the inlet zone, 180℃ in the middle zone, and 150℃ in the outlet zone; this reduces the contact resistance between the electrode active material, conductive agent, and current collector;

[0024] S2, preparing an electrolyte, the electrolyte comprising basic electrolyte components and additives, the additives comprising 1.5 wt% fluoroethylene carbonate and 0.5 wt% succinate;

[0025] S3, Battery Integration, the battery integration is as follows: the negative electrode sheet and the positive electrode sheet prepared in step S1 are used to prepare the battery cell using an asymmetric bipolar stacking process, and the battery cell is assembled into the battery box. The tabs of the battery cell are connected to the aluminum current collector by 20kHz ultrasonic welding. Then the electrolyte prepared in step S2 is injected into the battery box.

[0026] The basic electrolyte composition consists of the following components: 1M LiPF6 in EC:EMC:DEC, wherein the volume ratio of 1M LiPF6 in EC:EMC:DEC is 3:5:2.

[0027] The asymmetric bipolar tab stacking process is as follows: the tabs of the positive and negative electrodes are staggered, and the tabs of each layer of positive and negative electrodes are alternately drawn out on both sides through winding or stacking processes to form 2n tabs, where n is the number of winding turns.

[0028] In the preparation of the cathode material, FePO4·2H2O and Li2CO3 are first ball-milled and mixed for 4 hours, and then sucrose and cobalt acetate solution are added for spray granulation.

[0029] The battery also integrates a BMS unit and an active liquid cooling module. The BMS unit monitors voltage, temperature and current in real time, and the overcharge / short circuit response time is <100ms.

[0030] The hot pressing temperature for hot pressing is 175-185℃, and the hot pressing pressure is 4.8-5.2 MPa.

[0031] The specific process and parameters of this embodiment are as follows:

[0032] Cathode material preparation:

[0033] Raw material proportioning and pretreatment:

[0034] Active ingredient: FePO4·2H2O (purity ≥99.5%, D50=2-4μm);

[0035] Lithium source: Li2CO3 (purity ≥99.2%, moisture ≤0.1%);

[0036] Coating agent: Food-grade sucrose (purity ≥99%, added at 5% of total mass);

[0037] Dopant: Cobalt acetate solution (1 wt% Co concentration, deionized water as solvent);

[0038] Process medium: High-purity nitrogen (purity ≥ 99.999%);

[0039] The above components were first proportioned to FePO4·2H2O and Li2CO3. Then, the above proportioned components were used as the total amount to complete the proportioning of the coating agent and dopant.

[0040] Ball milling and mixing: A planetary ball mill was used with a zircon ball to material ratio of 5:1 and a rotation speed of 350 rpm. Specifically, FePO4·2H2O and Li2CO3 were ball milled and mixed for 4 hours, and then sucrose and cobalt solution were added for spray granulation.

[0041] Spray granulation: Inlet temperature: 180℃; Outlet temperature: 85℃; Atomization pressure: 0.3Mpa; Sintering curve: Heating stage: from room temperature to 750℃ at 5℃ / min; Holding stage: 750℃ constant temperature for 8 hours; Cooling stage: natural cooling to room temperature with the furnace;

[0042] The low-cobalt-doped cathode material was obtained according to the above process, and the treatment quality was tested: Particle size distribution: D50=5.2μm, span (D90-D10) / D50=0.85;

[0043] Next, the positive electrode is prepared:

[0044] Mixing equipment: 500L high-speed dry powder mixer, maximum speed 2000rpm;

[0045] Hot pressing system: Double roller hot press, roller width 600mm, maximum pressure 10Mpa;

[0046] Cutting accuracy: Ultraviolet laser cutting system, positioning accuracy ±0.05mm;

[0047] Process control points: Pre-sintering mixing, mixing time: 30 minutes, to ensure PVDF fiberization; Hot pressing parameters: Pressure: 5MPa (adjustable range 3-8MPa); Temperature: 180℃±2℃; Speed: 2m / min (adjustable range 1-5m / min); Hot pressing speed: 2m / min, electrode thickness 120μm; Online areal density monitoring: sampling and feedback adjustment every 10cm, areal density deviation: ±1.2%; Coating thickness consistency: 96%; Yield: 98.5%;

[0048] Battery fabrication:

[0049] Cell structure: 52mm×30mm×8mm laminated structure, with asymmetrical bipolar tab distribution;

[0050] Liquid cooling system: The flow channel was optimized using a 3D CFD model, with a coolant flow rate of 0.8 m / s;

[0051] BMS unit: Fault prediction model based on edge computing, response time <80ms;

[0052] Cell characteristics were tested: Thermal runaway characteristics: The actual trigger temperature was 175℃ (far exceeding the national standard requirement of ≥170℃); Cycle life: Capacity retention rate was 81.2% after 6050 cycles; System efficiency: DC internal resistance was 0.48mΩ, and energy efficiency was 92.8%.

[0053] Example 2:

[0054] The lithium iron phosphate energy storage battery manufacturing process of this embodiment, based on Example 1, further includes the addition of 0.8 wt% perfluorohexylethylene and 0.3 wt% BPO to the cathode material. During the mixing of the dry powder of the cathode material, a small amount of perfluorohexylethylene (polymerizable monomer) and BPO (initiator) are added to initiate polymerization during subsequent hot pressing. The resulting polymer network serves as a solid solvent and binder phase, further enhancing the mechanical strength and interfacial stability of the electrode. Through the initiator-induced polymerization reaction, a three-dimensional cross-linked structure is formed inside the electrode, significantly improving mechanical strength and ion transport efficiency; it also enhances the electrochemical stability and interfacial stability of the electrolyte.

[0055] Example 3:

[0056] The lithium iron phosphate energy storage battery manufacturing process of this embodiment, based on Embodiment 1, further includes Mg and V as the cathode material; FePO4·2H2O, Li2CO3, Mg and V are mixed in a molar ratio of 1:1.05:0.42:0.3; on the basis of low cobalt doping, Mg (magnesium) and V (vanadium) are introduced for core-shell doping, with Mg doping as the main component on the surface to broaden the lithium ion migration channels; and V doping as the main component in the bulk phase to stabilize the crystal framework; compared with low cobalt doping alone, it can further reduce the cobalt content, and through the synergy of Mg and V, the intrinsic electronic conductivity of the material is increased by an order of magnitude, which can improve the lithium ion diffusion coefficient.

[0057] Example 4:

[0058] The lithium iron phosphate energy storage battery manufacturing process of this embodiment, based on Example 1, further includes 0.8 wt of imidazole ionic liquid as an additive; the specific component of the imidazole ionic liquid is 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt; the fluoroethylene carbonate, succinate, and imidazole ionic liquid in the additive form a ternary composite electrolyte system by introducing the imidazole ionic liquid into the fluorosulfonate and nitrile composite system; the imidazole ionic liquid can significantly improve the thermal stability and electrochemical window of the electrolyte, and synergistically with the fluorosulfonate and succinate to construct a denser, more stable, and highly ionicly conductive film at the positive and negative electrode interfaces; it can raise the battery thermal runaway trigger temperature to 180°C and maintain more than 80% of the discharge capacity at a low temperature of -30°C.

[0059] Example 5:

[0060] The lithium iron phosphate energy storage battery manufacturing process in this embodiment, based on Example 1, further includes 0.2 wt% lithium bis(oxalato)borate as an additive. By introducing a very small amount of borate into the electrolyte using lithium bis(oxalato)borate, the boron-containing component can preferentially participate in film formation at a lower potential and may act as a bridge to promote the crosslinking of FEC and SN decomposition products, further improving the compactness and ionic conductivity (>1×10⁻⁶) of the I film. -3 The S / cm and the bonding force with the electrode effectively reduce the initial coulombic loss and improve long-term cycling stability.

[0061] In this case, a lithium iron phosphate energy storage battery was prepared according to Example 1, and safety tests were conducted under the following conditions:

[0062] Standard: GB / T 36276-2018; Equipment: Adiabatic accelerated calorimeter, needle penetration tester.

[0063] The test results of Example 1 all meet the following requirements: 0.2C discharge specific capacity reaches 178mAh / g; positive electrode areal density deviation ±1.2%; electrode compaction density 2.42g / cm³; overcharge test (1.5 times voltage): no fire or explosion; thermal abuse test (130℃ / 30min): passed; cycle life: 6050 cycles (capacity retention rate 81.2%); system energy efficiency: 92.8%; thermal runaway suppression time: 68 minutes; DC internal resistance: 0.48mΩ; cost reduction: material cost reduced by 15%, manufacturing energy consumption reduced by 40%, and overall cost reduced by ≥20% compared to traditional processes; safety improvement: thermal runaway trigger temperature ≥180℃, module-level suppression time >60 minutes; performance optimization: cycle life ≥6000 cycles, system energy efficiency ≥92%, low-temperature discharge capacity retention rate ≥82.5%; environmentally friendly process: zero VOCs emissions.

[0064] The test data of the batteries prepared in Examples 1 to 5 are shown in Table 1:

[0065] Table 1: Comparison of Actual Measurements of Lithium Iron Phosphate Energy Storage Batteries

[0066]

[0067] As can be seen from the above, the lithium iron phosphate energy storage battery prepared in Example 1 has the following advantages compared with existing lithium iron phosphate energy storage batteries:

[0068] Ultra-long cycle life: The cycle life has been increased from the industry standard of 5,000 cycles to 6,050 cycles, which means that the total cyclic energy output of the battery system has increased by more than 20%, significantly reducing the initial investment cost per charge and discharge and extending the investment payback period.

[0069] Ultra-high system efficiency: The system energy efficiency reaches 92.8%, which is nearly 3 percentage points higher than the industry standard of 90%. Therefore, under the same charge and discharge capacity, energy loss is reduced by nearly 30%, and the annual power loss cost savings for large-scale energy storage power stations are extremely considerable.

[0070] Excellent environmental adaptability: The superior high and low temperature performance (high temperature cycle retention rate of 96.3% and low temperature discharge retention rate of 82.5%) expands the application range of the product, reduces performance degradation and additional auxiliary energy consumption caused by climate, and improves the economic efficiency of projects in harsh environments.

[0071] Cost reduction and efficiency improvement: Eliminating solvent, coating, drying and solvent recovery processes directly reduces production energy consumption by more than 30%, while saving expensive solvent procurement and VOCs treatment costs.

[0072] Improved yield and consistency: The electrode surface density deviation is controlled within ±1.2%. The extremely high product consistency reduces the loss in the subsequent sorting and grouping process, improves the module integration yield (stable at over 98.5%), and reduces quality costs.

[0073] Compared to Example 1, the lithium iron phosphate energy storage battery in Example 2 has a DC internal resistance (25°C) that can be further reduced by 0.06 mΩ, and the system energy efficiency can be improved by 0.04%. The fluctuations of other indicators are basically the same and can be ignored.

[0074] Compared to Example 1, the lithium iron phosphate energy storage battery in Example 3 has a DC internal resistance (25°C) that can be further reduced by 0.02 mΩ and a system energy efficiency that can be improved by 0.02%.

[0075] The above embodiments are merely preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention are included within the scope of the present invention.

Claims

1. A manufacturing process for lithium iron phosphate energy storage batteries, characterized in that, The specific process is as follows: S1, a cathode material was prepared by low cobalt doping and in-situ coating with an iron source precursor. The cathode material preparation specifically involved mixing FePO4·2H2O, Li2CO3, Mg, and V in a molar ratio of 1:1.05:0.42:0.3; adding 5 wt% coating agent and 0.8 wt% cobalt acetate solution, wherein the coating agent was sucrose; achieving in-situ coating through spray drying; and sintering at 750°C for 8 hours under a nitrogen atmosphere to obtain a low cobalt-doped cathode material. The cathode material also included 0.8 wt% perfluorohexylethylene and 0.3 wt% BPO; hot-pressing the cathode material to obtain a sheet, and then cutting the sheet using laser cutting to obtain the cathode plate. S2, preparing an electrolyte, the electrolyte comprising basic electrolyte components and additives, the additives comprising 1.5 wt% fluoroethylene carbonate and 0.5 wt% succinate; S3, Battery Integration, the battery integration is as follows: the negative electrode sheet and the positive electrode sheet prepared in step S1 are used to prepare the battery cell using an asymmetric bipolar stacking process, and the battery cell is assembled into the battery box. The tabs of the battery cell are connected to the aluminum current collector by 20kHz ultrasonic welding. Then the electrolyte prepared in step S2 is injected into the battery box.

2. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: The basic electrolyte composition consists of 1 molar concentration of LiPF6 dissolved in EC, EMC, and DEC, with the volume ratio of EC:EMC:DEC being 3:5:

2.

3. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: The asymmetric bipolar tab stacking process is as follows: the tabs of the positive and negative electrodes are staggered, and the tabs of each layer of positive and negative electrodes are alternately drawn out on both sides through winding or stacking processes to form 2n tabs, where n is the number of winding turns.

4. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: During the preparation of the positive electrode material, FePO4·2H2O and Li2CO are first mixed. 3、 Mg and V were ball-milled and mixed for 4 hours, and then sucrose and cobalt acetate solution were added for spray granulation.

5. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: The battery also integrates a BMS unit and an active liquid cooling module.

6. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: The hot pressing temperature for hot pressing is 175-185℃, and the hot pressing pressure is 4.8 MPa-5.2 MPa.

7. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: The additive also includes 0.8 wt% imidazole ionic liquid.

8. The manufacturing process for lithium iron phosphate energy storage batteries according to claim 1, characterized in that: The additive also includes 0.2 wt% lithium bis(oxalato)borate.

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