Homogeneous alloying reaction via self-assembly strategy for high-areal-density dual-ion batteries

Dual-ion battery (DIB) has sparked growing interest in recent years due to its high working voltage, low cost, and eco-benignity. However, the reported low areal density of cathode (<2.5 mg cm^-2) leads to low energy density, far from commercial application. Besides, alloying-type anodes such as aluminum (Al) with high theoretical capacity suffer from uneven alloying reaction and remarkable volume change during cycling, especially when matched with high areal-density cathode. Herein, we introduce a facile interface engineering strategy, namely self-assembly of graphite oxide (GO) on an Al foil anode with further pre-lithiation to redistribute Li⁺ ions and render a uniform alloying reaction. This strategy can effectively decrease the transfer barrier of Li⁺ ions and inhomogeneous "hot spots " on the surface of the Al anode. Consequently, when paired with an expanded graphite cathode with high-areal-density (10.2 mg cm^-2), the modified Al anode exhibits much improved structural stability. The assembled DIB exhibits good cycling stability with high capacity retention of 95.5% over 200 cycles. Moreover, the DIB with high areal density achieves high energy density of up to ∼ 176 Wh kg^-1 based on the total mass of electrode materials and electrolyte, which is among the best values of reported DIBs to date.