High-temperature treatment induced carbon anode with ultrahigh Na storage capacity at low-voltage plateau

Sodium-ion batteries (NIBs) show great prospect on the energy storage applications benefiting from their low cost and the abundant Na resources despite the expected lower energy density compared with lithium-ion batteries (LIBs). To further enhance the competitive advantage, especially in energy density, developing the high-capacity carbon anode materials can be one of the effective approaches to realize this goal. Herein, we report a novel carbon anode made from charcoal with a high capacity of similar to 400 m Ah g(-1), wherein about 85% (>330 mAh g(-1)) of its total capacity is derived from the long plateau region below similar to 0.1 V, which differs from those of typical hard carbon materials (similar to 300 mAh g(-1)) in NIBs but is similar to the graphite anode in LIBs. When coupled with air-stable Na0.9Cu0.22Fe0.30Mn0.48O2 oxide cathode, a high-energy density of similar to 240 Wh kg(-1) is achieved with good rate capability and cycling stability. The discovery of this promising carbon anode is expected to further improve the energy density of NIBs towards large-scale electrical energy storage. (C) 2018 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.