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Rechargeable potassium-oxygen (K-O ) batteries promise to provide higher round-trip efficiency and cycle life than other alkali-oxygen batteries with satisfactory gravimetric energy density (935 Wh kg ). Exploiting a strong electron-donating solvent, for example, dimethyl sulfoxide (DMSO) strongly stabilizes the discharge product (KO ), resulting in significant improvement in electrode kinetics and chemical/electrochemical reversibility. The first DMSO-based K-O battery demonstrates a much higher energy efficiency and stability than the glyme-based electrolyte. A universal KO growth model is developed and it is demonstrated that the ideal solvent for K-O batteries should strongly stabilize superoxide (strong donor ability) to obtain high electrode kinetics and reversibility while providing fast oxygen diffusion to achieve high discharge capacity. This work elucidates key electrolyte properties that control the efficiency and reversibility of K-O batteries.

air and organic electrolytes. [1c,e,7] Furthermore, the cost of Mg metal is 30 times lower than that of Li. [8] Therefore, magnesium-sulfur (Mg-S) batteries theoretically offer a higher volumetric energy density, greater safety, and much lower cost than Li-S batteries.The development of Mg-S batteries is still in its infancy and is limited by several challenges, including high cell polarization, low capacity, and rapid capacity fading. One of the most critical challenges is the high cell polarization (>1000 mV overpotential), [8,9] which has been widely attributed to the sluggish kinetics and passivation of Mg anodes. [9a,10] Substantial effort has been made to develop electrolytes that allow fast and reversible electroplating/stripping of divalent magnesium and are compatible with sulfur cathodes. [1e,7] Commonly used chloride-and boron-based electrolytes have successfully reduced the polarization potential of Mg electroplating/stripping to ≈200 mV. However, the overpotential of Mg-S cells is still high (>1000 mV in chloride-based electrolytes [6a,7,11] and ≈600 mV in boron-based electrolytes [12] ), leading to low energy efficiency (≈47% in chloride-based electrolytes and ≈56% in boron-based electrolytes). Other challenges such as low capacity and rapid capacity fading have been attributed to the loss of soluble polysulfide. [7,13] Sulfur reactions in Mg-S batteries are reported to follow similar reaction pathways with that in Li-S batteries. During discharge, the elemental sulfur is reduced to soluble polysulfides, first to long-chain polysulfides followed by short-chain polysulfides via chain-shortening reactions. The short-chain polysulfides subsequently reduce to solid sulfide and precipitates onto the cathode. Meanwhile, part of the polysulfides could diffuse to the anode, resulting in irreversible loss. [6b,13d,14] Consequently, similar to Li-S batteries, addressing the loss of polysulfides is considered the priority in Mg-S batteries. To overcome these challenges, interlayer and host materials [13a,15] have been designed according to the strategies developed for Li-S batteries. [16] These approaches increase the first discharge capacity to ≈1000 mAh g −1 below 0.1 C, which is lower than that of Li-S batteries (1400-1600 mAh g −1 at a C rate of ≥0.1 C). Despite considerable efforts, the performance of Mg-S cells is still far from satisfactory, which raises the question of what truly limits the reversibility of Mg-S batteries.In this work, we reveal that the sluggish sulfur reaction is the main origin of poor Mg-S cell performance. Exploiting Magnesium-sulfur batteries promise a higher theoretical volumetric energy density, improved safety, and lower cost compared to lithium-sulfur batteries. However, Mg-S batteries suffer from poor cycle life and low energy efficiency. Here, it is revealed that Mg-S reactions are dominated by "solid-solid" reactions due to much lower polysulfide solubility in the presence of Mg 2+ compared to that of Li + in 1,2-dimethoxyethane (DME)-based electrolyte, leading ...

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Magnesium batteries suffer from low power density and poor cycle life due to severe Mg passivation. Using nucleophilic electrolytes is effective to stabilize the Mg anode, but it prohibits the use of organic and conversion cathodes due to chemical reactivity. Here, we report an effective non-passivating anion additive, the reduced perylene diimide–ethylene diamine (rPDI), to enable fast and reversible Mg deposition/dissolution in a simple non-nucleophilic electrolyte. The rPDI additive exhibits higher adsorption energy than the TFSI– salt on the Mg surface, preventing TFSI– decomposition and Mg anode passivation. Using 0.2 mM rPDI additives, we demonstrated a Mg–organic full cell achieving a high power density (2.0 mW cm–2) and a stable cycle life (>200 cycles). Our study provides a facile and effective strategy for non-nucleophilic electrolytes, enabling the combination of Mg anode with a wide variety of organic and conversion cathodes beyond intercalation chemistries.

DELLA proteins, negative regulators of the gibberellin (GA) pathway, play important roles in plant growth, development and pathogen resistance by regulating multiple phytohormone signals. Yet, whether and how they regulate plant herbivore resistance remain unknown. We found that the expression of the rice DELLA gene OsSLR1 was down-regulated by an infestation of female adults of the brown planthopper (BPH) Nilaparvata lugens. On one hand, OsSLR1 positively regulated BPH-induced levels of two mitogen-activated protein kinase and four WRKY transcripts, and of jasmonic acid, ethylene and H O . On the other hand, silencing OsSLR1 enhanced constitutive levels of defence-related compounds, phenolic acids, lignin and cellulose, as well as the resistance of rice to BPH in the laboratory and in the field. The increased resistance in rice with silencing of OsSLR1 is probably due to impaired JA and ethylene pathways, and, at least in part, to the increased lignin level and mechanical hardness of rice leaf sheaths. Our findings illustrate that OsSLR1, acting as an early negative regulator, plays an important role in regulating the resistance of rice to BPH by activating appropriate defence-related signalling pathways and compounds. Moreover, our data also provide new insights into relationships between plant growth and defence.

ZnS@MoS2 hollow polyhedrons display outstanding cycling performance and high reversible specific capacity in LIB anodes.

Hybrid redox flow batteries (RFBs) offer a much higher energy density compared to all liquid RFBs. However, negative electrodes of hybrid RFBs normally utilize metal deposition reactions (e.g. zinc metal),...