Red phosphorus (P) have been considered as one of the most promising anode material for both lithium-ion batteries (LIBs) and (NIBs), because of its high theoretical capacity. However, natural insulating property and the large volume expansion of red P during cycling lead to poor cyclability and low rate performance, which prevents its practical application. Here, we significantly improves both lithium storage and sodium storage performance of red P by confining nanosized amorphous red P into the mesoporous carbon matrix (P@CMK-3) using a vaporization-condensation-conversion process. The P@CMK-3 shows a high reversible specific capacity of ∼ 2250 mA h g(-1) based on the mass of red P at 0.25 C (∼ 971 mA h g(-1) based on the composite), excellent rate performance of 1598 and 624 mA h g(-1) based on the mass of red P at 6.1 and 12 C, respectively (562 and 228 mA h g(-1) based on the mass of the composite at 6.1 and 12 C, respectively) and significantly enhanced cycle life of 1150 mA h g(-1) based on the mass of red P at 5 C (500 mA h g(-1) based on the mass of the composite) after 1000 cycles for LIBs. For Na ions, it also displays a reversible capacity of 1020 mA h g(-1) based on the mass of red P (370 mA h g(-1) based on the mass of the composite) after 210 cycles at 5C. The significantly improved electrochemical performance could be attributed to the unique structure that combines a variety of advantages: easy access of electrolyte to the open channel structure, short transport path of ions through carbon toward the red P, and high ionic and electronic conductivity.

Na 3 V 2 (PO 4 ) 3 (denoted as NVP) has been considered as a promising cathode material for room temperature sodium ion batteries. Nevertheless, NVP suffers from poor rate capability resulting from the low electronic conductivity. Here, the feasibility to approach high rate capability by designing carbon-coated NVP nanoparticles confi ned into highly ordered mesoporous carbon CMK-3 matrix (NVP@C@CMK-3) is reported. The NVP@C@CMK-3 is prepared by a simple nanocasting technique. The electrode exhibits superior rate capability and ultralong cyclability (78 mA h g −1 at 5 C after 2000 cycles) compared to carbon-coated NVP and pure NVP cathode. The improved electrochemical performance is attributed to double carbon coating design that combines a variety of advantages: very short diffusion length of Na + /e − in NVP, easy access of electrolyte, and short transport path of Na + through carbon toward the NVP nanoparticle, high conductivity transport of electrons through the 3D interconnected channels of carbon host. The optimum design of the core-shell nanostructures with double carbon coating permits fast kinetics for both transported Na + ions and electrons, enabling high-power performance.

Carbon‐based materials have been considered as the most promising anode materials for both sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs), owing to their good chemical stability, high electrical conductivity, and environmental benignity. However, due to the large sizes of sodium and potassium ions, it is a great challenge to realize a carbon anode with high reversible capacity, long cycle life, and high rate capability. Herein, by rational design, N‐doped 3D mesoporous carbon nanosheets (N‐CNS) are successfully synthesized, which can realize unprecedented electrochemical performance for both SIBs and PIBs. The N‐CNS possess an ultrathin nanosheet structure with hierarchical pores, ultrahigh level of pyridinic N/pyrrolic N, and an expanded interlayer distance. The beneficial features that can enhance the Na‐/K‐ion intercalation/deintercalation kinetic process, shorten the diffusion length for both ions and electrons, and accommodate the volume change are demonstrated. Hence, the N‐CNS‐based electrode delivers a high capacity of 239 mAh g−1 at 5 A g−1 after 10 000 cycles for SIBs and 321 mAh g−1 at 5 A g−1 after 5000 cycles for PIBs. First‐principles calculation shows that the ultrahigh doping level of pyridinic N/pyrrolic N contributes to the enhanced sodium and potassium storage performance by modulating the charge density distribution on the carbon surface.