Porous Mo3 P/Mo Nanorods as Efficient Mott-Schottky Cathode Catalysts for Low Polarization Li-CO2 Battery.

Li-CO2 battery with high energy density has aroused great interest recently, large-scale applications are hindered by the limited cathode catalysis performance and execrably cycle performance. Herein, Mo3 P/Mo Mott-Schottky heterojunction nanorod electrocatalyst with abundant porous structure is fabricated and served as cathodes for Li-CO2 batteries. The Mo3 P/Mo cathodes exhibit ultra-high discharge specific capacity of 10 577 mAh g-1 , low polarization voltage of 0.15 V, and high energy efficiency of up to 94.7%. Mott-Schottky heterojunction formed by Mo and Mo3 P drives electron transfer and optimizes the surface electronic structure, which is beneficial to accelerate the interface reaction kinetics. Distinctively, during the discharge process, the C2 O4 2- intermediates combine with Mo atoms to form a stable Mo-O coupling bridge on the catalyst surface, which effectively facilitate the formation and stabilization of Li2 C2 O4 products. In addition, the construction of the Mo-O coupling bridge between the Mott-Schottky heterojunction and Li2 C2 O4 promotes the reversible formation and decomposition of discharge products and optimizes the polarization performance of the Li-CO2 battery. This work provides another pathway for the development of heterostructure engineering electrocatalysts for high-performance Li-CO2 batteries.

Flexible Li-CO2 Batteries with Boosted Reaction Kinetics and Cyclelife Enabled by Heterostructured Mo3 N2 @TiN Cathode and Interface-protected Li Anode.

With theoretically endowing with high energy densities and environmentally friendly carbon neutralization ability, flexible fiber-shaped Li-CO2 battery emerges as a multipurpose platform for next-generation wearable electronics. Nevertheless, the ineluctable issues faced by cathode catalysts and Li anodes have brought enormous obstacles to the development of flexible fiber-shaped Li-CO2 batteries. Herein, a flexible fiber-shaped Li-CO2 battery based on Mo3 N2 cathode coating with atomic layer deposited TiN and Li3 N protected Li anode is constructed. Owing to the regulation surface electrons of Mo3 N2 by TiN, heterostructured cathode has more delocalized electrons which enable cathodes to stabilize 2-electron intermediate products Li2 C2 O4 by electron bridge bonds and avoid disproportionation into Li2 CO3 . Li3 N layers not only accelerate Li+ transportation but also avoid contact between Li and CO2 to form Li2 CO3 . Thus, the constructed Li-CO2 battery demonstrates a low charge potential of 3.22 V, low overpotential of 0.56 V, outstanding rate capabilities up to 1 A g-1 , and excellent long-term cycling (≈2000 h) with an energy efficiency of ≈80%. The fabricated flexible fiber-shaped Li-CO2 battery shows an ultrahigh energy density of 14 772.5 Wh kg-1 based on cathodes (340.8 Wh kg-1 based on device mass), and outstanding deformations adaptability, giving it great potential for wearable electronics.

Ultrastretchable, Multihealable, and Highly Sensitive Strain Sensor Based on a Double Cross-Linked MXene Hydrogel.

The ability of a flexible strain sensor to directly adapt the complicated human biological motion or combined gestures and remotely control the artificial intelligence robotics could benefit the wearable electronics such as intelligent robotics and patient healthcare. However, it is a challenge for the flexible strain sensor to simultaneously achieve high sensing performances and stretchability and long sustainability under various deformation stress or damage. Herein, a dual-cross-linked poly(acrylic acid-stearyl methacrylate)/MXene [P(AA-SMA)M] hydrogel with enhanced mechanical stretchability and self-healability is fabricated by importing reversible coordination and hydrophobic interaction into polymer networks. As a result, the hydrogel film not only exhibits high tensile strength (525 kPa) and stretchability (∼2600%) but also achieves repetitive healable property with 843% elongation even after the 20th broken/self-healing cycle. More importantly, the resultant strain sensor delivers a low detection limit, wide sensing range, fast response time, and repeatability of 1000 cycles even after repeated self-healing. So, the sensor can monitor subtle human motions and recognize different handwriting and gestures, which reveals potential applications toward health-care devices, flexible electronics, and human-machine interfacing.