High-tap density electrode materials are greatly desired for Li-ion batteries with high volumetric capacities to fulfill the growing demands of electric vehicles and portable smart devices. TiO2, which is one of the most attractive anode materials, is limited in their application for Li-ion batteries because of its low tap density (usually <1 g cm−3) and volumetric capacity. Herein, we report uniform mesoporous TiO2 submicrospheres with a tap density as high as 1.62 g cm−3 as a promising anode material. Even with a high mass loading of 24 mg cm−2, the TiO2 submicrospheres have impressive volumetric capacities that are more than double those of their counterparts. Moreover, they can be synthesized with ~100% yield and within a reaction time of ~6 h by optimizing the experimental conditions and formation mechanism, exhibiting potential for large-scale production for industrial applications. Other mesoporous anode materials, i.e., high-tap density mesoporous Li4Ti5O12 submicrospheres, are fabricated using the generalizedmethod. We believe that our work provides a significant reference for the industrial production of mesoporous materials for Li-ion batteries with a high volumetric performance.随着人们对电动汽车和可穿戴电子产品需求的增加, 开发具有高体积比容量的锂离子二次电池非常必要, 特别是制备高振实密度的电极材料尤为重要. TiO2是一种具有应用前景的阳极材料, 然而它们的振实密度普遍较低(通常小于<1 g cm−3). 本论文报道了一种均匀的亚微米级TiO2介孔球, 其振实密度高达1.62 g cm−3. 以其作为锂离子二次电池的阳极材料时, 在高达24 mg cm−2的负载量的情况下, TiO2介孔球的体积比容量比其他对比TiO2材料的体积比容量高出2倍之多. 制备该TiO2介孔球仅需6 h的反应时间且产率接近100%, 因此其工业化生产可能性很大. 此外, 该制备方法的普适性非常好,其他高振实密度介孔材料, 如亚微米级Li4Ti5O12介孔球, 也可采用类似方法制备. 因此,本工作可为工业化制备高振实密度介孔材料及其在高体积比容量锂离子二次电池中的应用提供重要借鉴.

Flexible actuators responsive to multiple stimuli are much desired in wearable electronics. However, general designs containing organic materials are usually subject to slow response and limited lifetime, or high triggering threshold. In this study, we develop flexible, all-inorganic actuators based on bimorph structures composed of vanadium dioxide (VO2) and carbon nanotube (CNT) thin films. The drastic, reversible phase transition of VO2 drives the actuators to deliver giant amplitude, fast response up to ∼100 Hz, and long lifetime more than 1 000 000 actuation cycles. The excellent electrical conductivity and light absorption of CNT thin films enable the actuators to be highly responsive to multiple stimuli including light, electric, and heat. The power consumption of the actuators can be much reduced by doping VO2 to lower its phase transition temperature. These flexible bimorph actuators find applications in biomimetic inspect wings, millimeter-scale fingers, and physiological-temperature driven switches.Keywords: actuator; carbon nanotube; doping; phase transition; Vanadium dioxide;

Adaptive camouflage in thermal imaging, a form of cloaking technology capable of blending naturally into the surrounding environment, has been a great challenge in the past decades. Emissivity engineering for thermal camouflage is regarded as a more promising way compared to merely temperature controlling that has to dissipate a large amount of excessive heat. However, practical devices with an active modulation of emissivity have yet to be well explored. In this letter we demonstrate an active cloaking device capable of efficient thermal radiance control, which consists of a vanadium dioxide (VO2) layer, with a negative differential thermal emissivity, coated on a graphene/carbon nanotube (CNT) thin film. A slight joule heating drastically changes the emissivity of the device, achieving rapid switchable thermal camouflage with a low power consumption and excellent reliability. It is believed that this device will find wide applications not only in artificial systems for infrared camouflage or cloaking but also in energy-saving smart windows and thermo-optical modulators.