In-situ synthesis of Bi nanospheres anchored in 3D interconnected cellulose nanocrystal derived carbon aerogel as anode for high-performance Mg-ion batteries

Rechargeable magnesium-ion batteries (MIBs) are considered to be promising electrochemical energy storage systems because of their low-cost and high safety features. However, the absence of suitable anodes severely impeded the development of high-performance MIBs. Herein, a unique Bi nanospheres homogenously anchored in cellulose nanocrystal (CNC) derived carbon aerogel (CNC-CA@Bi-NS) hybrid, was for the first time fabricated as anode for MIBs through ion-induced gelation and in-situ thermal reduction processes. The successfully incorporation of near-monodisperse Bi nanospheres (4–9 nm   diameter) into the interconnected CA matrix could effectively alleviate the volume changes during magnesiation/de-magnesiation alloying reaction, as well as prevent the agglomeration and pulverization of Bi nanospheres. Meanwhile, the N -doped porous matrix not only served as a highly electronic conductive framework but also provided enough space and large surface area for electrolyte storage and penetration, which would facilitate the charge transfer kinetics process. Attractively, the CNC-CA@Bi-NS electrode delivered a remarkable reversible specific capacity of 346 mAh/g at 0.5C (90 % of theoretical capacity) after 100cycles. Furthermore, the CNC-CA@Bi-NS exhibited an excellent rate performance and unprecedented long-term cycling stability with a high coulombic efficiency of ∼ 100 % at 2.0C after 5000cycles. This work provided a new strategy to design and synthesize high-performance Bi-based anode for advanced next-generation MIBs.