AUTHOR=Pian Chunyuan , Peng Weichao , Ren Haoyu , Ma Chao , Su Yun , Ti Ruixia , Chen Xiuyu , Zhu Lixia , Liu Jingjing , Sun Xinzhi , Wang Bin , Niu Bingxuan , Wu Dapeng TITLE=Robust α-Fe2O3@TiO2 Core–Shell Structures With Tunable Buffer Chambers for High-Performance Lithium Storage JOURNAL=Frontiers in Chemistry VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2022.866369 DOI=10.3389/fchem.2022.866369 ISSN=2296-2646 ABSTRACT=

α-Fe₂O₃ has high potential energy storage capacity and can serve as a green and low-cost anode material for lithium-ion batteries. However, α-Fe₂O₃ suffers large volume expansion and pulverization. Based on DFT calculations, TiO₂ can effectively maintain the integrity of the crystal structure during the discharge/charge process. Well-defined cubic α-Fe₂O₃ is coated with a TiO₂ layer using the hydrothermal method with the assistance of oxalic acid surface treatment, and then α-Fe₂O₃@TiO₂ with tunable buffer chambers is obtained by altering the hydrochloric acid etching time. With the joint efforts of the buffer chamber and the robust structure of the TiO₂ layer, α-Fe₂O₃@TiO₂ alleviates the expansion of α-Fe₂O₃ during the discharge/charge process. The optimized sample (FT-1h) achieves good cycling performance. The reversible specific capacity remains at 893.7 mA h g^-1, and the Coulombic efficiency still reaches up to 98.47% after 150 cycles at a current density of 100 mA g⁻¹. Furthermore, the reversible specific capacity can return to 555.5 mA h g⁻¹ at 100 mA g⁻¹ after cycling at a high current density. Hence, the buffer chamber and the robust TiO₂ layer can effectively improve the cycling stability and rate performance of α-Fe₂O₃.