Ultrafine TiO₂ Nanoparticles Confined in N‐Doped Porous Carbon Networks as Anodes of High‐Performance Sodium‐Ion Batteries

Abstract

TiO2-based nanocomposites w ith rationally designed size, structure and composition are highly desirable for Na-ion storage. In this w ork, various TiO2/N-doped porous carbon nanocomposites (TiO2/NC) have been fabricated by directly carbonizing NH2-MIL-125(Ti) at different temperatures. These TiO2/NC nanocomposites exhibit unique structure features, such as ultrafine TiO2 nanoparticl es, micro-mesoporous structure, and N-doped carbon coating, whi ch can shorten the Na ions diffusion distance, enhance the electroni c conductivity, and prevent nanosized-TiO2 from aggregation. When applied as sodium ion battery anodes, TiO2/NC-600 exhibits the best sodium storage properties among the TiO2/NC nanocomposites produced at different carbonization temperatures. The correlations betw een electrochemical properties and size/structure/compositi on of the TiO2/NC nanocomposites are disclosed. TiO2/NC-600 delivers a high reversible capacity of 190 mA h g -1 up to 500 cycles at 1 C (1 C = 335 mA g -1 ), an ultrahigh capacity of 76 mA h g -1 at a high rate of 20 C, and an excellent long-term cycling stability w ith a capacity of 159 mA h g -1 retained after 2500 cycles at 5 C. The outstanding sodium storage performances of TiO2/NC-600 are attributed to the appropriate crystalline structure, particle size and high nitrogendoping content.

Amorphous TiO2/C Frameworks as Intercalation Pseudocapacitance Anodes for Fast and Durable Sodium Storage

“…In addition, the increase in specific capacity with cycles is generally deemed to an electrochemical activation process. In this process, the fast and efficient Na + intercalation needs to be achieved by repetitive cycles to activate the inner materials, which has been frequently reported in previous studies. − …”

Tunable Pseudocapacitive Behavior in Metal–Organic Framework-Derived TiO2@Porous Carbon Enabling High-Performance Membrane Capacitive Deionization

“…The hysteresis loops and gradual uptakes at a relative pressure from 0.4 to 1.0 are generated from the capillary condensation of nitrogen in the mesopores. The obvious hysteresis loop indicates that the TiO 2 @PC samples possess a hierarchical micro/mesoporous structure. , The micro/mesopores are beneficial for efficient ion adsorption and smooth diffusion of salt ions . It is believed that the high surface area is inherited from MIL-125 precursor (1226.57 m 2 g –1 ), as shown in Figure S7 .…”

“…The obvious hysteresis loop indicates that the TiO 2 @PC samples possess a hierarchical micro/mesoporous structure. 60,61 The micro/mesopores are beneficial for efficient ion adsorption and smooth diffusion of salt ions. 62 It is believed that the high surface area is inherited from MIL-125 precursor (1226.57 m 2 g −1 ), as shown in Figure S7.…”

Porous NaTi2(PO4)3 Nanocubes Anchored on Porous Carbon Nanosheets for High Performance Sodium-Ion Batteries

“…Different nanostructures such as hollow nanocubes, nanoparticles, and hierarchical microspheres have been demonstrated (Wu et al, 2015; Fang et al, 2016; Ye et al, 2017). Among them, porous structures have gained great attention owing to the afforded large surface areas and improved kinetics (Dirican et al, 2015; Zhang et al, 2017; Zhao et al, 2017; Zhou et al, 2017). Moreover, the electronic conductivity of anodes can be largely enhanced by hybridizing them with conductive materials.…”