Carbon quantum dot-laminated stepped porous Al current collector for stable and ultrafast lithium-ion batteries

Designing an interfacial architecture between the current collector and electrode plays a serious role in developing the specific capacity with cycling stability of lithium-ion batteries (LIBs). Consequently, an original approach to enhance the structure of the interface between the current collector and electrode is necessary. Thus, we developed a novel interface architecture based on carbon quantum dots (CQDs)-laminated on a stepped porous Al (SP-Al) current collector to attain stable and ultrafast-discharge LIBs and CQD-SP-Al for application as LIB cathodes. To this end, the electrochemical etching and ultrasonic spray coating methods were employed. The cathode assembled with CQD-SP-Al displayed the adhesion enhancing, an increased redox reaction kinetics, and the magnificent interfacial stability of the current collector//electrode interface because of the increased surface roughness, stepped pores with N-doped CQD, and uniform CQD lamination layer. The resultant cathode with CQD-SP-Al showed an enhanced specific capacity of 78.2 mAh/g and capacity retention of 92.6% at a high C-rate of 10C after 500 cycles. This great cycling stability is due to an expanded interfacial contact area of current collector//electrode with improved adhesion, as well as to the CQD lamination layer, while the excellent ultrafast discharge capacity is ascribed to the risen number of charge supplying/collecting sites, the stepped porous structure, and the highly conductive N-doped CQD lamination layer.