No abstract

A sulfonated diamine monomer, 4,4‘-diaminodiphenyl ether-2,2‘-disulfonic acid (ODADS), was successfully synthesized by direct sulfonation of a commercially available diamine, 4,4‘-diaminodiphenyl ether (ODA), using fuming sulfuric acid as the sulfonating reagent. A series of sulfonated polyimides were prepared from 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), ODADS, and common nonsulfonated diamines. The resulting sulfonated polyimides displayed much better stability toward water than those derived from the widely used sulfonated diamine 2,2‘-benzidinedisulfonic acid (BDSA). This is because ODADS-based polyimide membranes have a more flexible structure than the corresponding BDSA-based ones. Fenton's reagent test revealed that ODADS-based polyimide membranes also had fair good stability to oxidation. Polyimide membranes with good water stability as well as high proton conductivity were developed. NTDA−ODADS/BAPB(1/1) copolyimide membrane (BAPB refers to 4,4‘-bis(4-aminophenoxy)biphenyl)), for example, did not lose mechanical properties after being soaked in water at 80 °C for 200 h, while its proton conductivity was still at a high level (comparable to that of Nafion 117).

Potassium metal batteries are considered as attractive alternatives beyond lithium-ion batteries. However, the uncontrollable dendrite growth on the potassium metal anode has restrained their practical applications. Herein, we report a high-performance potassium anode achieved by confining potassium metal into a titanium-deficient nitrogen-containing MXene/carbon nanotube free-standing scaffold. The high electronic transport and fast potassium diffusion in this scaffold enable reduced local current density and homogeneous ionic flux during plating/stripping process. Furthermore, as verified by theoretical calculations and experimental investigations, such "potassium-philic" MXene sheets can induce the nucleation of potassium, and guide potassium to uniformly distribute in the scaffold upon cycling. Consequently, the as-developed potassium metal anodes exhibit a dendrite-free morphology with high Coulombic efficiency and long cycle life during plating/stripping process. Such anodes also deliver significantly improved electrochemical performances in potassium-sulfur batteries compared with bare potassium metal anodes. This work can provide a new avenue for developing potassium metal-based batteries. Received: ((will be filled in by the editorial staff)) Revised: ((will be filled in by the editorial staff))

Zinc anode-based batteries have been widely studied due to their low cost, high capacity and high energy density. However, the formation of dendrites on the zinc anode during cycling severely affects the stability and safety of this type of battery. In this work, a series of electrolyte additives with potential to counter this problem were studied. We found that lithium chloride (LiCl) additive can suppress the growth of dendrites and stabilize the Zn metal anode, on which the cations (Li + ) preferentially form Li2O/Li2CO3 upon the Zn surface and provide a shielding effect to suppress dendritic deposition, while a moderate amount of anions (Cl -) decrease the Zn polarization and facilitate ion transport.Asymmetric cells with LiCl additives in the electrolyte showed notably higher stability during the long cycling process.

HIGHLIGHTSNovel synthesis of aerogel-like porous MXene architectures Porous MXene architectures can effectively prevent the restack of MXene nanosheets Porous MXene demonstrated a high electroadsorption capacity MXene electrodes achieved a high capacitive deionization capacity