Dry Pouch Cells with NFPP + Hard Carbon for Sodium-Ion Battery, 1 Ah/pcs/pack, CSIBDPCNFPPHC

Assembling Dry Pouch Cells using Na2FeP2O7 (NFPP, Sodium Iron Pyrophosphate) as the cathode and Hard Carbon (HC) as the anode is an increasingly popular choice for "low-cost, high-safety" Sodium-Ion Battery (SIB) research. Compared to layered oxides (NFM) or Prussian Blue, NFPP is a polyanionic material. Its structure is exceptionally stable due to the strong P-O covalent bonds, making it nearly immune to the "thermal runaway" oxygen release seen in other chemistries. In a "dry" state, these cells are extremely stable and ideal for studying long-term interfacial chemistry.

For NFPP/HC systems, the dry pouch cell serves as a controlled "reaction vessel" for several specific research goals: (1) Minimal Pre-conditioning: Because NFPP is more air-stable than layered oxides, the "Dry" cell fabrication can be done with slightly less stringent ambient controls, though a vacuum-drying step at 100 °C cost-assembly is still recommended to remove moisture from the Hard Carbon. (2) Interfacial Study: Since NFPP doesn't phase-transition significantly during cycling, any capacity fade observed after electrolyte injection is usually due to the Hard Carbon/Electrolyte interface. The dry cell provides a pristine baseline for these surface-science studies. (3) Safety Benchmarking: Dry cells are used as "dummy" samples for mechanical abuse testing (nail penetration, crush) to establish the baseline structural integrity of the pouch before adding flammable electrolytes.

Testing Processes:

(1) Electrolyte Filling with recommended amount in glovebox.
(2) First Time Aging: 45°C, aging time ≥ 15h in an oven.
(3) Formation conditions: 45°C, 5 min rest; 0.02C constant current charging (10% theoretical capacity or 5 h); 0.1C constant current charging (30% theoretical capacity, 3 h); 5 min rest; total capacity is 40% or 8 h;
(4) Second Time Aging: 45°C, aging time ≥ 24h in a oven
(5) Battery Analyzer for charging and discharging.

References:

1. Y. Jin, et al., Low-solvation electrolytes for high-voltage sodium-ion batteries, Nat. Energy, 2022, 7, 718–725. 
2. B. Liu, et al., Super-wetting interface engineering of space-confined micron-sized alloying anodes for high-performance sodium-based dual-ion batteries, Matter, 2025, 8, 102294.