TiNb24O62 is explored as a new anode material for lithium-ion batteries. Microsized TiNb24O62 particles (M-TiNb24O62) are fabricated through a simple solid-state reaction method and porous TiNb24O62 microspheres (P-TiNb24O62) are synthesized through a facile solvothermal method for the first time. TiNb24O62 exhibits a Wadsley–Roth shear structure with a structural unit composed of a 3 × 4 octahedron-block and a 0.5 tetrahedron at the block-corner. P-TiNb24O62 with an average sphere size of ∼2 μm is constructed by nanoparticles with an average size of ∼100 nm, forming inter-particle pores with a size of ∼8 nm and inter-sphere pores with a size of ∼55 nm. Such desirable porous microspheres are an ideal architecture for enhancing the electrochemical performances by shortening the transport distance of electrons/Li+-ions and increasing the reaction area. Consequently, P-TiNb24O62 presents outstanding electrochemical performances in terms of specific capacity, rate capability and cyclic stability. The reversible capacities of P-TiNb24O62 are, respectively, as large as 296, 277, 261, 245, 222, 202 and 181 mA h g−1 at 0.1, 0.5, 1, 2, 5, 10 and 20 C, which are obviously larger than those of M-TiNb24O62 (258, 226, 210, 191, 166, 147 and 121 mA h g−1). At 10 C, the capacity of P-TiNb24O62 still remains at 183 mA h g−1 over 500 cycles with a decay of only 0.02% per cycle, whereas the corresponding values of M-TiNb24O62 are 119 mA h g−1 and 0.04%. These impressive results indicate that P-TiNb24O62 can be a promising anode material for lithium-ion batteries of electric vehicles.
Feixiang Ping,Yu Zhong,Xiaodan Guo,Sensen Jia,Jicang Ma,Huanhuan Liu,Linlin Liu,Guofa Cai
Electrochromic smart windows represent a promising technology for reducing building energy consumption through dynamic photo-thermal regulation. However, scalable fabrication of high-performance electrochromic films remains challenging. Herein, we pioneer slot-die coating technique and aqueous inks for the high-speed production (600 cm 2 /min) of Wadsley-Roth structure TiNb 2 O 7 films. Experimental and theoretical analyses reveal that the open crystallographic shear channels in TiNb 2 O 7 enable efficient ion transport with a low diffusion barrier of 0.22 eV, allowing it to achieve a high diffusion coefficient (6.34 × 10 −10 cm 2 /s), good uniformity, and 82.8% large optical modulation at 600 nm. We constructed a series of large-scale electrochromic devices with a size up to 200 cm 2 that demonstrate significant optical modulation (64.6%), rapid switching (23.4/12.4 s), and uniform coloration. We evaluated the photo-thermal management performance of the device using a xenon lamp as a simulated solar source, achieving a notable temperature regulation of 18.8°C. To further validate its practical applicability, we conducted an outdoor test, demonstrating a temperature modulation of ∼5.0°C. Additionally, energy simulation analyses reveal that the device enables an energy saving of 155 MJ·m −2 . This work provides a scalable manufacturing strategy for high-performance electrochromic devices, advancing the development of intelligent energy-saving window technology.
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