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Li-rich electrode materials of the family xLi₂MnO₃·(1−x)LiNi_aCo_bMn_cO₂ (a + b + c = 1) suffer a voltage fade upon cycling that limits their utilization in commercial batteries despite their extremely high discharge capacity, ≈250 mA h g⁻¹. Li-rich, 0.35Li₂MnO₃·0.65LiNi_0.35Mn_0.45Co_0.20O₂, is exposed to NH₃ at 400 °C, producing materials with improved characteristics: enhanced electrode capacity and a limited average voltage fade during 100 cycles in half cells versus Li. Three main changes caused by NH₃ treatment are established. First, a general bulk reduction of Co and Mn is observed via X-ray photoelectron spectroscopy and X-ray absorption near edge structure. Next, a structural rearrangement lowers the coordination number of CoO and MnO bonds, as well as formation of a surface spinel-like structure. Additionally, Li⁺ removal from the bulk causes the formation of surface LiOH, Li₂CO₃, and Li₂O. These structural and surface changes can enhance the voltage and capacity stability of the Li-rich material electrodes after moderate NH₃ treatment times of 1–2 h.

Li-rich, xLi₂MnO₃·(1−x)LiNi_aCo_bMn_cO₂ (a + b + c = 1), Li-ion battery cathode materials suffer a debilitating voltage fade during cycling that prohibits their commercialization. NH₃ treatment of Li-rich materials is shown herein to limit voltage fading throughout cycling. This is caused by a bulk reduction of the material, subtle surface changes, and extraction of Li-salts.

Na-ion batteries, promising large-scale energy storage and conversion devices, can store wind and solar energy through smart grids efficiently, that provides power supply to thousands of households. In article number 1600275, Chuan Wu and co-workers systematically summarize the characteristics of different kinds of polyanion-type compounds for Na-ion batteries. In addition, constructive strategies to enhance the electrochemical performances of such materials are also proposed.

This study has proposed to use a well-defined oligomer F4TBT4 to replace its analogue polymer as electron acceptor toward tuning the phase separation behavior and enhancing the photovoltaic performance of all-polymer solar cells. It has been disclosed that the oligomer acceptor favors to construct pure and large-scale phase separation in the polymer:oligomer blend film in contrast to the polymer:polymer blend film. This gets benefit from the well-defined structure and short rigid conformation of the oligomer that endows it aggregation capability and avoids possible entanglement with the polymer donor chains. The charge recombination is to some extent suppressed and charge extraction is also improved. Finally, the P3HT:F4TBT4 solar cells not only output a high V_OC above 1.2 V, but also achieve a power conversion efficiency of 4.12%, which is two times higher than the P3HT:PFTBT solar cells and is comparable to the P3HT:PCBM solar cells. The strategy of constructing optimum phase separation with oligomer to replace polymer opens up new prospect for the further improvement of the all-polymer solar cells.

A well-defined oligomer F4TBT4 is proposed to replace its polymer PFTBT as electron acceptor to fabricate fullerene-free polymer solar cells. The oligomer acceptor favors to construct pure and large-scale phase separation in polymer blend film due to decreased chain entanglement. The resulted P3HT:F4TBT4 solar cells not only output a high V_OC above 1.2 V, but also achieve a PCE of 4.12%.

Two-dimensional (2D) materials have recently attracted wide attention and rapidly established themselves in various applications. In particular, 2D materials are regarded as promising building blocks for gas sensors due to their high surface-to-volume ratio, ease in miniaturization, and flexibility in enabling wearable electronics. Compared with other 2D materials, MoS2 is particularly intriguing because it has been widely researched and exhibits semiconducting behavior. Here, we have fabricated MoS2 resistor based O2 sensors with a back gate configuration on a 285 nm SiO2/Si substrate. The effects of applying back gate voltage stress on O2 sensing performance have been systematically investigated. With a positive gate voltage stress, the sensor response improves and the response is improved to 29.2% at O2 partial pressure of 9.9 × 10⁻⁵ millibars with a +40 V back-gate bias compared to 21.2% at O2 partial pressure of 1.4 × 10⁻⁴ millibars without back-gate bias; while under a negative gate voltage stress of −40 V, a fast and full recovery can be achieved at room temperature. In addition, a method in determining O2 partial pressure with a detectability as low as 6.7 × 10⁻⁷ millibars at a constant vacuum pressure is presented and its potential as a vacuum gauge is briefly discussed.