Ternary Na 3 V 2 (PO 4 ) 3 /Na 3 V 2 (PO 4 ) 2 F 3 /NaV(P 2 O 7 ) Heterogeneous Structure with Interactive Built‐in Electric Field Enables Advanced Sodium Storage Performance

Abstract Traditional polyanion cathode suffers from the poor electronic and ionic transportation. Low capacity and energy seriously hinders its further development. Herein, konjac glucomannan (KGM) acts as inducer to synthesize ternary Na 3 V 2 (PO 4 ) 3 /Na 3 V 2 (PO 4 ) 2 F 3 /NaV(P 2 O 7 ) heterogeneous cathode (NVP@KGM/F‐10%). The detailed formation mechanism is clearly revealed by ex‐situ high‐temperature XRD. The multispatial Na sites in NVP@KGM/F‐10% is investigated by NMR, further demonstrating the co‐existence of ternary cathodes. XAFS ensures the elongated V‐O bond, which constructs a lager framework for accelerated Na + migration. Moreover, NVP@KGM/F‐10% possesses a unique columnar porous morphology with a high specific surface area of 84.53 m 2 g −1 , facilitating the electrolyte immersion. Ex‐situ XRD/XPS reveal the charge compensation mechanism of NVP@KGM/F‐10% and elaborate the stability effects of C‐F bond. Significantly, due to the difference of work function and band gap among Na 3 V 2 (PO 4 ) 3 /Na 3 V 2 (PO 4 ) 2 F 3 /NaV(P 2 O 7 ), three interactive built‐in electric fields are constructed at the heterogeneous interfaces, directly promoting the kinetics inside the NVP@KGM/F‐10% electrode, which has been verified by DFT calculations and experimental characterizations. Notably, the DOS of Na 3 V 2 (PO 4 ) 3 /Na 3 V 2 (PO 4 ) 2 F 3 /NaV(P 2 O 7 ) heterostructures and energy barriers between the heterogeneous interface are also evaluated by DFT, further demonstrating the great superiority of ternary heterogeneous structure. This work provides guidance for designing multiple phases heterogeneous cathodes with advanced properties.