High temperature sodium batteries with inorganic electrolytes are attracting increasing attention due to their high thermal stability, reliability, long-cycle life and safety. Despite the intensive investigation of Na-NiCl2 batteries during last decades, designing a stable conducting network in the cathode is still challenging but desirable. In this work, a new cathode structure composed of Ni nanowires with an effective electron conducting network is proposed for planar sodium–nickel chloride batteries. During the first stage of charge, Ni nanowires reacted with Cl ion to form NiCl2 on the surface and the excessive Ni nanowires inside can serve as conducting framework to facilitate the fast electron transport. As expected, the metal nanowires show a high specific capacity of 130 mA h g−1 (∼14 mAh cm−2) at 0.05 C after 100 cycles. Meanwhile, the batteries show stable cycling performance at 0.05 C with a high cut-off energy density of 360 W h kg−1, much higher than the traditional tubular sodium-nickel chloride batteries (∼100 Wh kg−1). Scanning electron microscope (SEM) images of the cathode after long cycling reveal the ultra-slow growth of Ni particles, confirming the excellent stability of the prepared nanowires cathode.