An Ultrahigh‐Mass‐Loading Integrated Free‐Standing Functional All‐Carbon Positive Electrode Prepared using an Architecture Tailoring Strategy for High‐Energy‐Density Dual‐Ion Batteries

Dual-ion batteries (DIBs) have been attracting great attention for the storage of stationary energy due to their low cost, environmental friendliness, and high working voltage. However, most reports on DIBs involve low-mass-loading electrodes (<2.5 mg), while the use of high mass-loading electrodes (>10 mg cm-2 ), which are critical for practical application, is overlooked. Herein, an integrated free-standing functional carbon positive electrode (named MSCG) with a "point-line-plane" hierarchical architecture at the practical level of ultrahigh mass-loading (>50 mg cm-2 ) is developed for high-energy-density DIBs. The rationally designed microstructure and the advanced assembly method that is adopted produce a well-interconnected ion/electron transport channel in the MSCG electrode, which confers rapid ion/electron kinetic properties while maintaining good mechanical properties. Consequently, the DIBs with ultrahigh-mass-loading MSCG electrodes exhibits a high discharge capacity of 100.5 mAh g-1 at 0.5 C (loading mass of 50 mg cm-2 ) and a long-term cycling performance with a capacity retention of 87.7% at 1 C after 500 cycles (loading mass of 23 mg cm-2 ). Moreover, the DIB with the ultrahigh-mass-loading positive electrode achieves a high energy density of 379 Wh kg-1 based on the mass of electrode materials, the highest value recorded to date for any DIBs.