High specific capacity battery electrode materials have attracted great research attention. Phosphorus as a low-cost abundant material has a high theoretical specific capacity of 2596 mAh/g with most of its capacity at the discharge potential range of 0.4-1.2 V, suitable as anodes. Although numerous research progress have shown other high capacity anodes such as Si, Ge, Sn, and SnO2, there are only a few studies on phosphorus anodes despite its high theoretical capacity. Successful applications of phosphorus anodes have been impeded by rapid capacity fading, mainly caused by large volume change (around 300%) upon lithiation and thus loss of electrical contact. Using the conducting allotrope of phosphorus, "black phosphorus" as starting materials, here we fabricated composites of black phosphorus nanoparticle-graphite by mechanochemical reaction in a high energy mechanical milling process. This process produces phosphorus-carbon bonds, which are stable during lithium insertion/extraction, maintaining excellent electrical connection between phosphorus and carbon. We demonstrated high initial discharge capacity of 2786 mAh·g(-1) at 0.2 C and an excellent cycle life of 100 cycles with 80% capacity retention. High specific discharge capacities are maintained at fast C rates (2270, 1750, 1500, and 1240 mAh·g(-1) at C/5, 1, 2, and 4.5 C, respectively).

Potassium−sulfur (K−S) batteries are a promising alternative to lithium ion batteries for large-area energy storage applications, owing to their high capacity and inexpensiveness, but they have been seldom investigated. Here we report room-temperature K−S batteries utilizing a microporous carbon-confined small-molecule sulfur composite cathode. The synergetic effects of the strong confinement of microporous carbon matrix and the small-molecule sulfur structure can effectually eliminate the formation of soluble polysulfides and ensure a reversible capacity of 1198.3 mA h g −1 and retain 72.5% after 150 cycles with a Coulombic efficiency of ∼97%. The potassium-storage mechanism was investigated by X-ray photoelectron spectroscopy analysis and theoretical calculations. The results suggest that K 2 S is the final potassiation product along with the reaction of 2K + S ↔ K 2 S, giving a theoretical capacity of 1675 mA h g −1 . Our findings not only provide an effective strategy to fabricate high-performance room-temperature K−S batteries but also offer a basic comprehension of the potassium storage mechanism of sulfur cathode materials.

Red phosphorus (P) has been recognized as a promising storage material for Li and Na. However, it has not been reported for K storage and the reaction mechanism remains unknown. Herein, a novel nanocomposite anode material is designed and synthesized by anchoring red P nanoparticles on a 3D carbon nanosheet framework for K-ion batteries (KIBs). The red P@CN composite demonstrates a superior electrochemical performance with a high reversible capacity of 655 mA h g at 100 mA g and a good rate capability remaining 323.7 mA h g at 2000 mA g , which outperform reported anode materials for KIBs. The transmission electron microscopy and theoretical calculation results suggest a one-electron reaction mechanism ofP + K + e → KP, corresponding to a theoretical capacity of 843 mA h g ,which is the highest value for anode materials investigated for KIBs. The study not only sheds light on the rational design of high performance red P anodes for KIBs but also offers a fundamental understanding of the potassium storage mechanism of red P.

The development of high-efficiency and durable bifunctional electrocatalysts for both the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is critical for the widespread application of rechargeable zinc–air (Zn–air) batteries. This calls for rational screening of targeted ORR/OER components and precise control of their atomic and electronic structures to produce synergistic effects. Here, we report a Mn-doped RuO2 (Mn-RuO2) bimetallic oxide with atomic-scale dispersion of Mn atoms into the RuO2 lattice, which exhibits remarkable activity and super durability for both the ORR and OER, with a very low potential difference (ΔE) of 0.64 V between the half-wave potential of ORR (E 1/2) and the OER potential at 10 mA cm–2 (E j10) and a negligible decay of E 1/2 and E j10 after 250 000 and 30 000 CV cycles for ORR and OER, respectively. Moreover, Zn–air batteries using the Mn-RuO2 catalysts exhibit a high power density of 181 mW cm–2, low charge/discharge voltage gaps of 0.69/0.96/1.38 V, and ultralong lifespans of 15 000/2800/1800 cycles (corresponding to 2500/467/300 h operation time) at a current density of 10/50/100 mA cm–2, respectively. Theoretical calculations reveal that the excellent performances of Mn-RuO2 is mainly due to the precise optimization of valence state and d-band center for appropriate adsorption energy of the oxygenated intermediates.

Ion selective separators with the capability of conducting lithium ion and blocking polysulfides are critical and highly desired for high-performance lithium−sulfur (Li−S) batteries. Herein, we fabricate an ion selective film of covalent organic framework (denoted as TpPa-SO 3 Li) onto the commercial Celgard separator. The aligned nanochannels and continuous negatively charged sites in the TpPa-SO 3 Li layer can effectively facilitate the lithium ion conduction and meanwhile significantly suppress the diffusion of polysulfides via the electrostatic interaction. Consequently, the TpPa-SO 3 Li layer exhibits excellent ion selectivity with an extremely high lithium ion transference number of 0.88. When using this novel functional layer, the Li−S batteries with a high sulfur loading of 5.4 mg cm −2 can acquire a high initial capacity of 822.9 mA h g −1 and high retention rate of 78% after 100 cycles at 0.2 C. This work provides new insights into developing high-performance Li−S batteries via ion selective separator strategy.