Structure engineering and heteroatom doping-enabled high-energy and fast-charging dual-ion batteries

Abstract

Sodium dual-ion batteries (SDIBs) have attracted extensive attention due to the high working voltage and low cost. Nevertheless, lack of robust anode materials that can achieve highly efficient insertion/extraction of sodium ions still remains a huge challenge to develop the high-performance SDIBs. Herein, we exhibited excellent long-cycling performance (capacity retention of 85 % over 2000 cycles) with large reversible capacity (1788 mA h g−1 under 0.2 A/g) as well as superior rate capability (721 mA h g−1 under 10 A/g) for sodium-ion storage by encapsulating red phosphorus within nitrogen-doped mesoporous graphene particles. And the structural stability of composite during sodiation was directly demonstrated using in-situ transmission electron microscopy. The results of density functional theory reveal that nitrogen doping and formation of PC chemical bonds within graphene matrix may improve the adsorption energy of P atoms and promote the sturdy contact. The adsorption energies of nitrogen-doped graphene for Na+ and PF6− are −2.12 and −3.62 eV, respectively, which shows that the doping of N element is beneficial to the adsorption of Na+ and PF6−. Upon pairing with nitrogen-doped mesoporous graphene particles as cathode, an innovative SDIBs with high energy-power-density of 324 W h kg−1 at 331 W kg−1 and 187 W h kg−1 at 2665 W kg−1 were manufactured. This study opens up an effective strategy towards high-performance SDIBs for electric vehicles and other applications.