Silver Nanowires@Mn 3 O 4 Core–Shell Nanocables as Advanced Electrode Materials for Aqueous Asymmetric Supercapacitors

High‐electrical‐conductivity silver nanowire (AgNW)@Mn 3 O 4 nanocables are prepared by facile chemical precipitation and subsequent thermal treatment; these treatments are environmentally friendly, low cost, and easy for mass production. The obtained Mn 3 O 4 nanoparticles (20–30 nm) possess many interparticle mesoporous structures. The AgNW‐supported Mn 3 O 4 nanoparticles allow for a large exposed electroactive area, rapid ion and electron transport, and robust structural stability. In addition, it is shown that the AgNWs play a positive role in the electrochemical properties of the Mn 3 O 4 electrode used in a supercapacitor. The AgNW@Mn 3 O 4 electrode delivers ultrahigh specific capacitances of 203 and 111 F g −1 at 0.25 and 2 A g −1 , respectively. When matched with the activated carbon (AC) anode, the AgNW@Mn 3 O 4 //AC asymmetric supercapacitor (ASC) device has a wide voltage window of 1.8 V, a specific capacitance of 105 F g −1 at 1 A g −1 , and 94 % capacitance conservation after 5000 cycles. Moreover, the aqueous ASC device exhibits an energy density of 28 Wh kg −1 (power density of 320 W kg −1 ), and maintains a value of 10 Wh kg −1 as the power density increases to 9500 W kg −1 , demonstrating potential for applications.