Science China Materials

Lithium (Li) metal is regarded as the holy grail anode material for high-energy-density batteries owing to its ultrahigh theoretical specific capacity. However, its practical application is severely hindered by the high reactivity of metallic Li against the commonly used electrolytes and uncontrolled growth of mossy/dendritic Li. Different from widely-used approaches of optimization of the electrolyte and/ or interfacial engineering, here, we report a strategy of in-situ cerium (Ce) doping of Li metal to promote the preferential plating along the [200] direction and remarkably decreased surface energy of metallic Li. The in-situ Ce-doped Li shows a significantly reduced reactivity towards a standard electrolyte and, uniform and dendrite-free morphology after plating/ stripping, as demonstrated by spectroscopic, morphological and electrochemical characterizations. In symmetric half cells, the in-situ Ce-doped Li shows a low corrosion current density against the electrolyte and drastically improved cycling even at a lean electrolyte condition. Furthermore, we show that the stable Li LiCoO2 full cells with improved coulombic efficiency and cycle life are also achieved using the Ce-doped Li metal anode. This work provides an inspiring approach to bring Li metal towards practical application in high energy-density batteries.

The advancement of technology has had a profound impact on all areas of life, with an ever more intimate integration of the digital and biological spheres, but it may also be accompanied by an environmental crisis caused by the abuse of large quantities of electronics and petrochemicals. Next-generation “green” electronics or iontronics with high biocompatibility, biodegradation, low cost and mechanical compliance promise to mitigate these adverse effects, but are often limited by the finite choices of materials and strategies. Herein, maltose syrup, a traditional water-dissolvable saccharide food called “JiaoJiao” in Chinese, is engineered to replace unsustainable conductive components of current electronic devices. After churning and pulling with two chopsticks, known as aeration, the aerated maltose syrup has optimized viscoelasticity, mechanical adaptation, robustness, remodeling and self-healing capability, yet with transient behavior. Moreover, the structural and viscoelastic evolution during aeration is also analyzed to maximize the contribution from structures. As a proof-of-concept, a type of “green” skinlike iontronics is prepared, which exhibits reliable strain sensing ability and is subsequently applied for intelligent information encryption and transmission based on a novel concept of sending Morse code. This work greatly extends the current material choice and is expected to shed light on the development of a sustainable future.

MIL-101(Cr)是最重要的金属有机框架(MOFs)材料之一, 稳定的框架结构和超高的比表面积使其在众多科学领域得到了广泛研究和应用. 但是MIL-101(Cr)的合成条件比较苛刻, 且稳定性较强, 因此, 有关于其分级结构的研究报道仍比较少. 本文提出了一种简单制备分级纳米孔结构MIL-101(Cr)的方法, 即以乙酸作为调节剂, 采用水热合成的方法, 一步得到具有微孔-介孔-大孔分级结构的MIL-101(Cr)材料. 实验结果表明, 该分级结构的MIL-101(Cr)与无分级结构的MIL-101(Cr)相比, 其大分子染料吸附能力和催化能力均有显著提高. 而且分级结构MIL-101(Cr)负载了磷钨酸催化剂之后, 表现出了与均相催化剂(纯磷钨酸)相当的催化能力. 进一 步研究发现, 使用其他短碳链的一元羧酸作为调节剂, 如丙酸、 丁酸等, 也可获得类似分级纳米结构MIL-101(Cr).

Rational composition design of trimetallic phosphide catalysts is of significant importance for enhanced surface reaction and efficient catalytic performance. Herein, hierarchical CoxNiyFezP with precise control of stoichiometric metallic elements (x:y:z = (1–10):(1–10):1) has been synthesized, and Co1.3Ni0.5Fe0.2P, as the most optimal composition, exhibits remarkable catalytic activity (η = 320 mV at 10 mA cm−2) and long-term stability (ignorable decrease after 10 h continuous test at the current density of 10 mA cm−2) toward oxygen evolution reaction (OER). It is found that the surface P in Co1.3Ni0.5Fe0.2P was replaced by O under the OER process. The density function theory calculations before and after long-term stability tests suggest the clear increasing of the density of states near the Fermi level of Co1.3Ni0.5Fe0.2P/Co1.3Ni0.5Fe0.2O, which could enhance the OH− adsorption of our electrocatalysts and the corresponding OER performance.

水蒸发生电器件(WEG)是近年来发现的一种从自然水蒸发中获 取能量的新方法, 其巨大的应用潜力引起了广泛的研究兴趣. 然而, WEG通常需要提供液态水源, 不利于其便携式应用. 这里, 我们开发了一种基于聚丙烯酰胺水凝胶与网状电极复合的便携式柔性WEG. 当器件的一侧暴露在空气中时, 不对称的水分蒸发会产生持续3天以上0.2 V左右的开路电压输出. 即使在温度低至−5°C情况下, 也可以连续工作. 尽管低温下由于水分蒸发受到抑制, 其输出电压会降低. 水凝胶出色的柔韧性和可拉伸性为构建可拉伸应变高达60%以上的WEG提供了可能. 其输出电压几乎不受所施加应变的影响, 展示了其在便携式电源应用中的巨大潜力.