Interface-strain-confined synthesis of amorphous TiO2 mesoporous nanosheets with stable pseudocapacitive lithium storage

Abstract

• A largescale salt-template method is developed to prepare conformable amorphous TiO 2 mesoporous nanosheets. • Interfacial strain between salt and TiO 2 is revealed to assist to suppress the amorphous-to-crystalline transformation. • This amorphous TiO 2 possesses ultrathin structure and rich mesopores that are beneficial for fast lithium-storage. • Remarkable high-rate long-term cycling stability (103 mA h g −1 at 6 A g −1 after 1000 cycles) are demonstrated. Amorphous nanomaterials recently have been demonstrated as a new type of high-power electrodes for many electrochemical energy-storage devices owing to their structural advantages of large surface area, shortened ion-diffused pathway, rich surficial defects and loosely packed structure; However, it is still challenging to prepare amorphous nanomaterials on a large scale via low-cost sol–gel method due to the easy amorphous-to-crystalline transformation upon post calcination process. Herein, we develop a simple and scalable approach to prepare amorphous TiO 2 mesoporous nanosheets by using the potassium chloride (KCl) as the template. The experimental results combined with density functional theory (DFT) calculations have revealed that the interfacial strain between the KCl and TiO 2 suppresses the crystallization of TiO 2 , which maintains amorphous characteristics even at a relative high temperature of 400 °C. Benefiting from short Li + -diffused distance, accessible mesoporous structure, and surface pseudo-capability, the amorphous TiO 2 nanosheet electrode exhibits fast and durable lithium-storage/-release ability, such as delivering a high reversible capacity of 103 mA h g −1 at 6 A g −1 after 1000 cycles. This study may pave a new way for the design of amorphous nanoarchitectures, and highlight the function of the templates, not only leading to the formation of various morphologies, but also affecting the surface microstructure.