I. Abstract of the Paper’s Core Research

This study employs a standard slurry consisting of LFP, a conductive additive, and a binder, and utilizes an aerosol layer-by-layer deposition process to fabricate lithium iron phosphate cathodes. A comprehensive electrochemical and microstructural comparison is conducted against conventionally cast‑coated electrodes. The key findings are as follows:

Aerosol-derived bimodal pore microstructure, fabricated in a single step without the use of porogenic agents.

During the layer-by-layer deposition process, semi-dry droplets stack up, forming large‑size lithium‑ion transport channels on the electrode surface. Near the current collector, a dense, thin layer develops, yielding an intrinsic bimodal pore‑size gradient structure. Even after calendering to 80 μm with a porosity of 40%, the macroscopic pore channels at the surface remain intact.

The active electrochemical surface area has increased by 30%, and the ionic transport resistance has been significantly reduced.

Electrochemical impedance spectroscopy confirms that the AJP electrode exhibits an effective electrochemical reaction area 30% larger than that of a conventionally coated electrode of the same specifications, with lower charge-transfer resistance and significantly enhanced lithium-ion diffusion kinetics.

Full-rate-capacity cast electrode

Under a high areal capacity of 15 mg/cm²: the C/5 capacity is 5% higher, the 1C capacity is 10% higher, and the 2C fast‑charge capacity is improved by 14%; after 100 cycles in long‑cycle testing, the average capacity per cycle is 10 mAh/g higher, with superior cycling stability.

Unique deposition mechanism of semi-dry mist droplets

Aerosol droplets undergo pre-drying during flight; upon deposition on a heated substrate, they remain non-coalescent, with particles stacking into protrusions that naturally form three-dimensional interconnected channels. The porosity gradient can be tuned solely by adjusting the nozzle velocity, substrate temperature, and sheath‑gas parameters.

Thick electrodes can withstand stable calendering without delamination or flaking.

The aerosol‑stacked three‑dimensional framework exhibits exceptional mechanical toughness; even after roll‑pressing to reduce its volume by 55%, the electrode structure remains intact, with no cracking or delamination defects, while simultaneously delivering both high volumetric energy density and fast‑charging capability.

II. Complete Preparation Process for Aerosol L Cathode

1) LFP powder, conductive carbon, and binder are dispersed at a ratio of 96:2:2 to formulate an aerosol‑compatible low‑volatility slurry.

2) Ultrasonic atomization generates an aerosol plume, with a nitrogen sheath gas focusing the jet, and a temperature-controlled substrate (with temperature regulation to accelerate solvent pre-drying).

3) The nozzle reciprocates at a constant speed, depositing layer by layer to naturally form a gradient electrode with a porous surface and a dense bulk.

4) Roll-press to a thickness of 80 μm, with porosity maintained at 40%;

5) The electrode sheets are cut, and lithium half-cells are assembled via electrolyte injection; rate capability, long-cycle performance, electrochemical impedance spectroscopy (EIS), and computed tomography (CT) imaging are then characterized.

III. Five Key Process Advantages (Compared with Conventional Cast Coating)

Native gradient bimodal pores are formed in a single step, eliminating the need for templates or porogens.

Conventional coating requires the additional incorporation of porogen materials and laser etching; in contrast, AJP leverages the natural drying behavior of droplets to spontaneously form hierarchical pores, thereby streamlining electrode fabrication and reducing auxiliary material costs.

Compatible with high‑area‑density, thick electrodes, balancing energy density and fast charging.

After roll pressing, high‑velocity ion transport channels remain at the surface, addressing the concentration‑polarization challenges associated with fast charging in thick electrodes and significantly enhancing the rate performance of high‑loading cells.

Highly tunable structure with precisely controllable pore gradients.

The substrate temperature, number of printing layers, and airflow parameters can be precisely tuned to control the surface pore size and the overall tortuosity of the electrode, thereby accommodating battery requirements at different magnifications.

The electrode exhibits excellent mechanical stability, and no delamination occurs during calendering.

Aerosol particles are stacked in a layered, staggered configuration to form a three-dimensional network; roll‑press compaction reduces the volume by 55% without material loss or delamination, resulting in higher production yields.

Digital maskless direct writing, rapid prototyping of customized electrode sheets.

CAD enables customization of electrode geometry, thickness, and regional porosity distribution, facilitating rapid iteration of irregular‑shaped and miniature battery electrodes—ideal for new‑process R&D.

IV. Five Core Technological Innovations of This Study

Innovation 1: Mechanism of Primary Bimodal Porous Electrode Formation via Aerosol Semi-Dry Deposition

The pore-forming mechanism of aerosol‑pre‑dried droplet stacking is elucidated, enabling the fabrication of a gradient dual‑channel structure in a single processing step and filling the gap in one‑step pore‑creation technology for thick electrodes.

Innovation: Two‑gradient pore channels simultaneously resolve the trade‑off between high energy density and fast charging.

The macroporous surface layer shortens the lithium-ion migration path, while the dense underlying layer ensures high volumetric energy density, thereby resolving the longstanding trade-off in conventional electrodes between “high porosity but low energy density” and “dense structure yet poor fast‑charging performance.”

Innovation: 30% increase in active surface area and optimized rate capability.

The gradient pore structure increases the number of electrolyte–electrode contact sites, boosting the 2C high‑rate capacity by 14% and meeting the demands of fast‑charging energy storage and power lithium‑ion batteries.

Innovative 4-layer, ultra-high-strength roller-compaction structural design

An interwoven, stacked conductive network within the aerosol enhances the electrode’s mechanical strength significantly, is compatible with industrial roll‑pressing processes, and can be directly integrated into existing battery production lines.

Innovation 5: An additional green electrode fabrication route without extra modifications

It does not require the use of sacrificial templates or foaming agents for pore formation; the slurry formulation is fully compatible with conventional lithium‑ion battery processes, resulting in extremely low process‑modification costs.

V. Current Industry Challenges and Corresponding Solutions

Challenge 1: Conventional cast‑on‑film thick electrodes have a single type of pore structure, leading to severe concentration polarization during fast charging.

✅ The aerosol’s natural surface features a hierarchical macroporous structure, which shortens the lithium-ion diffusion path and significantly reduces high‑rate polarization losses.

Challenge 2: The manual pore‑creation process is complex, and the use of formwork and foaming agents increases costs and introduces impurities.

✅ Relying on physical shaping through droplet pre-drying, it requires no functional additives, streamlining the production process and reducing the risk of impurities.

Challenge 3: High-porosity electrodes have low volumetric energy density, making it difficult to simultaneously achieve long endurance.

✅ The dense, compacted structure at the material’s base maintains a balanced compaction density; even after roller pressing, fast‑charging channels remain intact, with no significant loss in energy density.

Challenge 4: Thick electrodes are prone to cracking and active-material delamination during roller pressing, resulting in low mass-production yield.

✅ The three-dimensional conductive skeleton is stacked in a staggered, layer-by-layer configuration; after calendering, the structure remains intact and is compatible with existing electrode‑calendering processes.

Challenge 5: The electrode pore structure is difficult to precisely control, resulting in high R&D trial-and-error costs.

✅ Precisely tune the pore-size gradient by adjusting printing parameters such as substrate temperature and sheath gas flow rate, enabling rapid iteration to optimize the electrode structure.

VI. Future Diversified Industrial Application Scenarios

1 Fast-charging lithium iron phosphate energy storage battery

Commercial and industrial energy storage, as well as residential battery systems, utilize high‑capacity cells to enhance high‑current charge‑and‑discharge performance and reduce charging times.

2 Two-Wheeled Vehicles / Passenger Vehicle Power Lithium Batteries

High‑energy‑density LFP power batteries that deliver both long range and fast charging, suitable for new‑energy scooters and passenger vehicles.

3 Micro Flexible Lithium Batteries

Wearable devices, miniature sensors, and conformal aerosol‑printed electrodes—ultrathin and featuring rapid charge–discharge capabilities.

4 Aviation-specific compact energy storage power supply

Lightweight, high‑rate batteries that meet the instantaneous high‑power discharge requirements of airborne equipment.

5 New Process R&D Platform for Lithium-Ion Battery Companies

An aerosol-based device enables the rapid fabrication of gradient-porosity electrode sheets, facilitating the development of next-generation thick-electrode materials for fast charging.

Image and Text Guide

Figure 1. SEM surface images of AJP-printed LFP cathodes compared with those prepared by blade coating.

Figure 1: Three rows showing magnification (200/40/20 μm scale bars) × four columns of samples: AJ 220 (unpressed), AJ 100 (pressed to 100 μm), AJ 80 (pressed to 80 μm, 40% porosity), and TC 80 (scratched‑coating control, pressed to 80 μm). The surface of the unpressed AJ electrode exhibits numerous protruding features and deep Li⁺‑conducting channels; after roller pressing to 80 μm, these open channels remain partially preserved, whereas the TC electrode surface is dense and devoid of such channels.

Figure 2. FIB-SEM tomographic slices and tortuosity schematic of the AJP electrode and the TC electrode after roll pressing.

Figure 2, left: After calendering, the AJ electrode (top) exhibits large open pores on its surface that gradually narrow toward the bulk phase; in contrast, the TC electrode (bottom) features a densely packed pore structure extending from the surface to the current collector. Right: The schematic illustrates that the AJ electrode has low tortuosity and a high degree of surface lithiation, whereas the TC electrode exhibits high tortuosity and a lower degree of bulk-phase lithiation.

Figure 3. Droplet deposition mechanism of AJP‑fabricated structured electrodes

Figure 3 illustrates: the printer head deposits an aerosol jet onto the heated substrate in the raster direction; the inset zooms in to show that, as the fast-drying droplets approach the substrate, some of the solvent evaporates before deposition, preventing them from spreading into a continuous wet film. Instead, each new droplet adheres to the surface of the previously dried droplet, leading to layer-by-layer stacking that yields a rough electrode structure with open channels.

Figure 4. Electrochemical performance of the full AJ vs TC LFP battery

Figure 4(a) Cycling at a C/2 rate for 100 cycles: The specific capacity of the AJ cell consistently exceeds that of the TC cell by approximately 10 mAh g⁻¹, with coulombic efficiencies all above 99%; (b) Rate capability (C/20 → C/5 → 1C → 2C → C/5): At C/5, 1C, and 2C, the AJ cell delivers discharge capacities 5%, 10%, and 14% higher than those of the TC cell, respectively; (c) Charge–discharge curves for the 1st, 50th, and 100th cycles; (d) Warburg coefficients: AJ = 2.0, TC = 2.6, indicating that the electrochemically active surface area of the AJ electrode is about 30% larger than that of the TC electrode.