Spinel Li 4 Ti 5 O 12 known as a “zero-strain” anode material for Li-ion battery has attracted much attention because of its superior safety and stability. Herein, we report a novel H 2 O 2 -assisted one-step hydrothermal method to synthesize different ratio Li 4 Ti 5 O 12 /TiO 2 composites with the same amount of raw materials. For the first time, Li 4 Ti 5 O 12 was prepared directly from commercial titania with the presence of H 2 O 2 , and different proportion Li 4 Ti 5 O 12 /TiO 2 composites were fabricated only by adjusting the amount of H 2 O 2 . The reaction mechanism of the novel H 2 O 2 -assisted method was clearly investigated, and H 2 O 2 plays a crucial role in the formation of intermediate Li 1.81 H 0.19 Ti 2 O 5 ·2H 2 O. Further, the electrochemical performance of different ratio Li 4 Ti 5 O 12 /TiO 2 composites have been investigated. This facile method is also applicable for the preparation of Na 2 Ti 6 O 13 /TiO 2 material, and provides us the new way to fabricate composite materials.
Datian Li,Weiqing Liu,Wenhao Chen,Baoshuo Han,Xiaobo Xu,Qingqing Chang,Zhuoyu Yang,Yixiao Wang
The aqueous battery employing multivalent metal ions as charge carriers is theoretically a high energy density electrochemical energy storage device due to the fact that it carries more charges. However, the storage mechanism of multivalent metal ions, especially Al 3+ ions, in TiO 2 materials has not been established. A new model associated with the contribution of multivalent metal ions, water molecules and protons in the charging/discharging process of the electrode is established in this work. The storage mechanism of aqueous Al 3+ ion batteries is revealed from a new perspective by studying the relationship between the charge inside the TiO 2 film and the mass at the interface. More importantly, a highlighted work is to reveal the changes in the amount of interfacial free water molecules and the hydration number of Al 3+ ions due to the adsorption/desorption of hydrated ions during the charging/discharging process. The present work is of great significance for revealing the mechanism of multivalent cations on metal oxide surfaces in aqueous batteries, and meanwhile, the model established can also be extended to other fields such as supercapacitors , photovoltaics, and photocatalysis . The results obtained in this work may have an impact on the performance of energy storage batteries, especially the influence of the rearrangement of interface hydration ions and water molecules on the energy storage mechanism.
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