Potassium‐ion batteries (PIBs), using carbon materials as the anode, are regarded as a promising alternative to lithium‐ion batteries owing to the feasible formation of stage‐1 potassium intercalation compounds (KC8). However, due to the large radius of the potassium ion, graphite‐based electrodes still suffer poor rate capability and insufficient cycling life. In this work, a hierarchically nitrogen‐doped porous carbon (NPC) is reported for the first time. The NPC electrode delivers a high reversible capacity of 384.2 mAh g−1 after 500 cycles at a current density of 0.1 A g−1 and an outstanding rate capability of 185 mAh g−1 at 10.0 A g−1, which surpasses most of the reported carbonaceous electrodes in PIBs. The excellent performance can be ascribed to the surface‐driven behavior dominated K‐storage mechanism, which is verified by quantitative kinetics analysis. Theoretical simulation results further illuminate the enhanced K affinity in N‐doped active sites, which accounts for the superior rate performance of the NPC electrode. In addition, galvanostatic intermittent titration technique measurements further quantify the diffusion coefficient of K ions. Considering the superior electrochemical performance of the electrode and comprehensive investigation of the K storage mechanism, this work can provide fundamental references for the subsequent research of potassium‐ion batteries.

We report the discovery of room temperature in-plane ferroelectricity in van der Waals In2Se3 with β′ phase.

The structure of a single crystal of dehydrated zeolite Na−X selected from a batch grown by Petranovskii in Russia, of composition Na92Si100Al92O384 per unit cell, was determined by X-ray diffraction methods in the cubic space group Fd3̄; a = 25.077(4) Å at 21 °C. R 1 = 0.054 for the 320 reflections for which F o > 4σ(F o); wR 2 based on F 2 and all data is 0.140. Na+ ions are found at four crystallographic sites. Sites I‘ and II are fully occupied with 32 Na+ ions each. The remaining 28 Na+ ions partially occupy two 12-ring (site III‘) positions with 10(4) near an O−Al−O sequence and 18(4) near an O−Si−O sequence. These results differ from those of the two previous investigations of dehydrated Na−X, which, in turn, disagree substantially with each other. The near energy equivalence of two (or more) III‘ sites, the presence of an impurity cation in one determination, and a consideration of the differing qualities of the diffraction data are sufficient to reconcile all results. The substitution of four silicon atoms per unit cell into the aluminum equipoint necessarily has a complicating effect. Considerations involving the ordering of these substituted silicon atoms are not needed.

Rechargeable aqueous Zn‐ion batteries are promising candidates for large‐scale energy storage systems. However, there are many unresolved problems in commercial Zn foils such as dendrite growth and structural collapse. Herein, Cu mesh modified with CuO nanowires is constructed to simultaneously coordinate the ion distribution and electric field during Zn nucleation and growth. Owing to the improved uniformity of Zn plating and the confined Zn growth in the 3D framework, the prepared Zn anodes can be operated steadily in symmetrical cells for 340 h with a low voltage hysteresis (20 mV). This work can provide a new strategy to design the dendrite‐free Zn anodes for practical application.

First principles calculations have been used to investigate the occurrence of site-exchange of Li and M ions and the effect of the site-exchange on Li extraction of silicate cathode materials Li 2 MSiO 4 (M ¼ Mn, Fe, Co and Ni). Total energy calculations suggest that Li (in the 4b site) and M (in the 2a site) ions become siteexchanged upon delithiation. This structural arrangement leads to significant cell expansion as two Li ions are extracted. Elastic property calculations indicate that the ductility of the fully delithiated MSiO 4 is impaired, which is likely to induce structural collapse and rapid capacity attenuation during the chargedischarge cycles. Restraining the site-exchange or improving the ductility may be an effective way of developing high performance Li 2 MSiO 4 for Li-ion batteries.

Sodium-ion batteries (SIBs) have garnered tremendous interests due to their unique advantages of high safety, abundant sodium resources, and low cost. Great research efforts of SIBs have been devoted to...

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