155 / 2022-02-11 14:24:50

Dense carbon: a high-initial-coulombic efficiency and low-discharge-plateau K+ storage anode for 4.0V full cells

Low potassium storage potential, High ICE , Carbon materials, full cells

Mineral Materials and Advanced Energy Materials > 3. Carbon Materials

Dense carbon anode materials with low potassium storage voltage, high initial coulombic efficiency (ICE), and high capacity are critical but challenging for the practice utilization of high-energy potassium-ion batteries (PIBs). Herein, a multi-densification strategy is developed to fabricate dense carbon (DC-2H) with sp²-sp³ hybrid structure through chemical welding with oxidized pitch as the building units, thus boosting the K⁺ storage capacity bellow 1V, ICE, rate capability and cyclic stability simultaneously. The hybrid structure not only provides nanographitic domains for low-voltage potassium storage, but also ensures excellent K⁺ transport kinetics in the defective networks. Thus, high reversible capacity at <1 V (248.8mAh g^-1 at 0.05 A g^-1, 71.4% at < 1V), high ICE of 68.2%, high-rate (209.9mAh g^-1 at 1A g^-1) and excellent cyclic stability (79.7% capacity retention after 6000 cycles) are achieved simultaneously. The practice application is evaluated in potassium-ion full cell delivers with the DC-2H as the anode materials, showing a significant discharge plateau at ca. 3.5V and excellent cyclic stability (92.03% capacity retention after 200 cycles). This work provides fresh mechanism insights for high-reversible potassium storage at low-voltage in carbon anode materials, which will greatly promote the practical application of PIBs.