Bottom growth strategy for high areal capacity rechargeable aluminum batteries

Among all practical methods to build the high specific energy battery, increasing the areal loading of active materials is a promising choice. However, increasing the areal loading of the active material will inevitably increase the areal deposition amount of aluminum. If aluminum undergoes uneven deposition, dendrite growth is an inevitable problem with the increase of aluminum deposits. In this paper, an anode structure with bottom growth mode (2P-Al₂O₃/Al) are proposed through anodic oxidation and laser etching technology, which can provide an inverted electric field strength (E_bottom>E_top) to induce the directional deposition of Al. We have grown a dense alumina layer on the surface and pores of the 2P-Al₂O₃/Al electrode, which can form a stable electrode/electrolyte interface as an SEI layer. The in-situ deposition image of the electrode indicates that aluminum preferentially grows at the bottom of the electrode, and the deposition process of aluminum is very uniform. In addition, the electrode exhibits excellent cycling stability in both half and full batteries. Even under the large areal special capacity of 20 mAh·cm⁻² without presenting significant interfacial degradation and early short circuit, it can operate cycle over 900 h, which is more than 3 times that of planer aluminum anode. This technology opens a new platform for designing highly safe and stable long-term energy storage system.