Heteroatomic interface engineering in MOF-derived carbon heterostructures with built-in electric-field effects for high performance Al-ion batteries
Confronted with challenges in promoting fast AlxCly− anion diffusion and intercalation for aluminum ion batteries (AIBs), it is of vital importance to rationally design gradient hetero-interfaces with an ideal built-in interfacial electric potential to enhance charge diffusion and transfer kinetics. Herein, we demonstrate an effective strategy to realize accurate tuning gradient heteroatom N and P doping in MOF-derived porous carbon in C@N-C@N,P-C graded heterostructures. Importantly, gradient N and P doping could modify the electronic structure of MOF-derived carbon as certified by DFT calculations, and lead to charge redistribution to induce graded energy levels and a built-in electric field in the C@N-C@N,P-C graded heteroatomic interface, thus boosting interfacial charge transfer and accelerating reaction kinetics. Furthermore, the large surface area and high porosity of C@N-C@N,P-C graded heterostructures could efficiently absorb electrolyte and enhance anion transport kinetics. As expected, the designed gradiently N,P-doped C@N-C@N,P-C heterostructure with a built-in interfacial electric field could facilitate electron and AlCl4− anion transfer spontaneously between N,P-C, N-C and C gradient components, exhibiting a superior capacity of 98 mA h g−1 at a high current density of 5 A g−1 after 2500 cycles. This strategy reveals new insights about the gradient energy band for designing high-performance electrochemical energy storage devices.