Iron-Based Phosphate Cathode Core-Coating for Higher Compacted Density

The patent creates a composite material system consisting of Na4Fe3(PO4)2P2O7 active material combined with conductive carbon materials and binder materials. This composite structure allows the active material to maintain its high theoretical capacity while the carbon matrix and binder provide structural integrity and improved packing density. The composite approach resolves the contradiction by combining materials with complementary properties rather than relying on a single material.

The patent optimizes multiple parameters including the mass ratio of active material to carbon material (85:15 to 95:5), particle size distribution (D50 between 3-10 μm), and sintering temperature (400-600°C). By systematically adjusting these parameters, the patent achieves both high theoretical capacity utilization and improved compacted density, resolving the technical contradiction through parameter optimization.

The patent performs preliminary actions during the slurry preparation and drying stages to pre-establish the desired particle distribution and density characteristics. The slurry is carefully formulated with specific component ratios and undergoes controlled drying to achieve uniform particle packing before sintering. This preliminary structuring simplifies subsequent manufacturing steps while achieving high compacted density and energy density.

The patent replaces complex mechanical compaction processes with a chemical-bonding approach during sintering. Instead of relying on high-pressure mechanical compression to achieve density, the slurry is sintered at 400-600°C to form a bonded structure that achieves high density through thermal processing. This substitution simplifies the manufacturing process by replacing complex mechanical systems with more controllable thermal processing.