The Na3V2-xCux(PO4)(3)/C (x = 0, 0.01, 0.03, 0.05 and 0.07) cathodes have been prepared by ballmilling and spray-drying assisted high-temperature solid-state reaction. The effects of Cu doping on Na3V2(PO4)(3)/C are characterized by XRD, SEM, XPS, EPR and electrochemical measurements. The results show that the Na3V1.95Cu0.05(PO4)(3)/C delivers the highest discharge capacity of 90.6 mAh g(-1) at 50 C and superior cyclic retention of 88.2% after 2000 cycles at 20 C, which could be mainly attributed to the high electronic conductivity (7.2 x 10(-2) S cm(-1)) and Na ion diffusion coefficient (1.695 x 10(-12) cm(2) s(-1)). The introduction of Cu2+ into the Na3V2(PO4)(3)/C lattice produces oxygen vacancies with accompanying conduction electrons, which lead to the enhanced electronic conductivity and Na ion diffusion coefficient. Besides, inactive Cu2+ acts as a pillar to reduce the negative effects caused by the volume shrinking/swelling during the Na+ extraction/insertion, resulting in increased cycle stability of the Cu-doped Na3V2(PO4)(3) system. (c) 2017 The Electrochemical Society. All rights reserved.