Jincai Yin,Wenxin Fan,Zihan Xu,Jinghua Duan,Yanzhi Xia,Zhihong Nie,Kunyan Sui
The intellectualization and complication of existing self-shaping materials are limited by the inseparable monotonic relationship between their deformation rate and deformation degree (i.e., a higher deformation rate is accompanied by a high deformation degree). This causes that they can only deform from 2D to 3D states. Here, a simple yet versatile strategy to decouple the monotonic correlation between the deformation rate and deformation degree of self-shaping hydrogels is presented for achieving complex deformations from 2D to temporary 3D to 3D (2D-to-4D). It is demonstrated that when the gradient hydrogels prepared by photopolymerization possess dense polymer networks, the local regions with a high deformation rate can exhibit a low deformation degree. The resulting hydrogels can thus deform in a novel 2D-to-4D mode under external stimuli. During the deformation, they first transform into the temporary shapes induced by the local deformation rate difference, and then transform into the final shapes determined by the local deformation degree difference. Through controlling the ultraviolet irradiation direction and time to precisely program the local gradients of self-shaping hydrogels, they can be designed to produce various unprecedented yet controllable 2D-to-4D shape evolutions on demand, such as transformable origami, sequential gesture actions in finger-guessing games, mobile octopuses, time switch, etc.
Oxygen release and electrolyte decomposition under high voltage endlessly exacerbate interfacial ramifications and structural degradation of high energy-density Li-rich layered oxide (LLO), leading to voltage and capacity fading. Herein, the dual-strategy of Cr x B complex coating and local gradient doping is simultaneously achieved on LLO surface by a one-step wet chemical reaction at room temperature. Density functional theory (DFT) calculations prove that stable B–O and Cr–O bonds through the local gradient doping can significantly reduce the high-energy O 2 p states of interfacial lattice O, which is also effective for the near-surface lattice O, thus greatly stabilizing the LLO surface. Besides, differential electrochemical mass spectrometry (DEMS) indicates that the Cr x B complex coating can adequately inhibit oxygen release and prevents the migration or dissolution of transition metal ions, including allowing speedy Li + migration. The voltage and capacity fading of the modified cathode (LLO-CrB) are adequately suppressed, which are benefited from the uniformly dense cathode electrolyte interface (CEI) composed of balanced organic/inorganic composition. Therefore, the specific capacity of LLO-CrB after 200 cycles at 1C is 209.3 mA h g −1 (with a retention rate of 95.1%). This dual-strategy through a one-step wet chemical reaction is expected to be applied in the design and development of other anionic redox cathode materials.
The high sensitivity and wide linearity are crucial for flexible tactile sensors in adapting to diverse application scenarios with high accuracy and reliability. However, conventional optimization strategies of constructing microstructures suffer from the mutual restriction between the high sensitivity and wide linearity. Herein, a novel design of localized gradient conductivity (LGC) with partly covered low-conductivity (low- σ ) carbon/Polydimethylsiloxane layer on high-conductivity (high- σ ) silver nanowires film upon the micro-dome structure is proposed. The LGC configuration enables a unique pressure-motivated series-parallel switching to allow the low- σ and high- σ components to separately take dominant effects in different pressure ranges. The ultrawide linearity can thus be realized by customizing the segmented linear current variation via the rationally associated coverage degree and conductivity gradient of the low- σ and high- σ components. Moreover, the ultrahigh sensitivity can be originally endowed by the conductivity difference between the low- σ and high- σ components without compromising linearity. The optimized sensor exhibits an ultrahigh sensitivity of 1546.35 kPa −1 within an ultrabroad linear sensing range of 0–3000 kPa, which is first reported. With such an excellent sensing performance, the potential applications, e.g., reliable healthcare monitoring, convenient smart home control, and ground detection of intelligent vehicles, are successfully demonstrated.
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