Interface modification of an Al current collector for ultrafast lithium-ion batteries

The ability to provide a reasonable design and a practical modification of the interfacial structure in lithium-ion batteries (LIBs) is a key technology to enhance electrochemical kinetics and to improve ultrafast cycling performances. However, in recent years, despite considerable structural engineering efforts focused on active materials, in practice, ultrafast LIB performances still are characterized by low ultrafast cycling capacity and poor stability at the current density above 6 C. To solve these problems, in the present study, we propose a unique interface modification of the Al foil having crater porous interface using the electrochemical etching process. The cathode fabricated with a crater porous interface of the Al foil exhibits a remarkably enhanced ultrafast storage performance, such as high ultrafast cycling capacity (91.0 mAh g−1 at 10 C) and superb ultrafast cycling stability (76.2 mAh g−1 with the capacity retention of 84.8% at 10 C after 250 cycles) as compared to those of the cathode fabricated with the bare Al foil and commercial-etched Al foil. These improved electrochemical performances can be explained by the combined effects of improved electrical conductivity related to fast charge transport and increased interface contact area between the active material and the current collector related to enhanced interface adhesion during ultrafast cycling performance.