Regulation of MIL-88B(Fe) to design FeS2 core-shelled hollow sphere as high-rate anode for a full sodium-ion battery

• The MIL-88B(Fe) with different nanostructure was adjusted for the first time; • CHS-FeS 2 was synthesized originated from MIL-88B(Fe)-0.05; • The Na + diffusion kinetic was improved and volume expansion was released; • CHS-FeS 2 //NVP@C cell achieved high capacity, excellent rate and cycling capability. Rich reserves, lower price, and high theoretical capacity of FeS 2 as a promising anode for SIBs can’t cover up its low Na + diffusion kinetic and severe volume expansion. Herein, the core-shelled hollow sphere FeS 2 (CHS-FeS 2 ) was synthesized using modified MIL-88B(Fe) as templates to promote Na + diffusion kinetic and release volume expansion. In the preparation process of MIL-88B(Fe), the citric acid participated in coordination with Fe 3+ to adjust the concentration of Fe 3+ and regulate MIL-88B(Fe) curvature, thus constructing MIL-88B(Fe) with different nanostructures. After calcination, the Fe 2 O 3 with different nanostructures was achieved due to the different combustion rates of MIL-88B(Fe) catalyzed by Fe 3+ and different diffusion amounts of Fe 3+ to the surface of MIL-88B(Fe). The FeS 2 with different nanostructures were formed after sulfuration. Especially, the uniform sphere-like MIL-88B(Fe) with suited Fe 3+ concentration was achieved when the citric acid was 0.05g, leading to the formation of CHS-FeS 2 after calcination and sulfuration. Additionally, as the electrode for SIBs in a half-cell system, the CHS-FeS 2 exhibited a high specific capacity of 617.5 mAh g -1 at 0.5 A g -1 , maintained 546.5 mAh g -1 after 100 cycles, and still 224 mAh g -1 was retained at a current density of 20 A g -1 . Furthermore, the full cell of CHS-FeS 2 //NVP@C achieved a high specific capacity of 279.3 mAh g -1 at 0.05 A g -1 , a specific capacity of 156.7 mAh g -1 at 1.0 A g -1 , and 87.8 % of initial capacity after 100 cycles at 0.1 A g -1 , reflecting the excellent cycling stability and rate capability. We believe this paper provides an inspiration for constructing hollow structural materials with rich reserves, lower prices, excellent cycling stability, and rate performance.