Sodium metal is a promising anode, but uneven Na deposition with a dendrite growth seriously impedes its application. Herein, a fibrous hydroxylated MXene/carbon nanotubes (h‐Ti3C2/CNTs) composite is designed as a scaffold for dendrite‐free Na metal electrodes. This composite displays fast Na+/electron transport kinetics and good thermal conductivity and mechanical properties. The h‐Ti3C2 contains abundant sodiophilic functional groups, which play a significant role in inducing homogeneous nucleation of Na. Meanwhile, CNTs provide high tensile strength and ease of film‐forming. As a result, h‐Ti3C2/CNTs exhibit a high average Coulombic efficiency of 99.2 % and no dendrite after 1000 cycles. The h‐Ti3C2/CNTs/Na based symmetric cells show a long lifespan over 4000 h at 1.0 mA cm−2 with a capacity of 1.0 mAh cm−2. Furthermore, Na‐O2 batteries with a h‐Ti3C2/CNTs/Na anode exhibit a low potential gap of 0.11 V after an initial 70 cycles.

For lithium (Li) metal batteries, the decrease in operating temperature brings severe safety issues by more disordered Li deposition. Here, we demonstrate that the solvating power of solvent is closely related to the reversibility of the Li deposition/stripping process under low-temperature conditions. The electrolyte with weakly solvating power solvent shows lower desolvation energy, allowing for a uniform Li deposition morphology, as well as a high deposition/stripping efficiency (97.87 % at À 40 °C). Based on a weakly solvating electrolyte, we further built a full cell by coupling the Li metal anode with a sulfurized polyacrylonitrile electrode at a low anode-to-cathode capacity ratio for steady cycling at À 40 °C. Our results clarified the relationship between solvating power of solvent and Li deposition behavior at low temperatures.

Dynamic interphases provide a general method for achieving energy-dense metal batteries based on earth-abundant anode chemistries.

Quasi-solid polymer electrolytes (QPE) composed of Li salts, polymer matrix, and solvent, are beneficial for improving the security and energy density of batteries. However, the ionic conduction mechanism, existential form of solvent molecules, and interactions between different components of QPE remain unclear. Here we develop a multispectral characterization strategy combined with first-principles calculations to unravel aforesaid mysteries. The results indicate that the existential state of solvent in QPE is quite different from that in liquid electrolyte. The Li cations in gel polymer electrolyte are fully solvated by partial solvent molecules to form a local high concentration of Li + , while the other solvent molecules are fastened by polymer matrix in QPE. As a result, the solvation structure and conduction mechanism of Li + are similar to those in high-concentrated liquid electrolyte. This work provides a new insight into the ionic conduction mechanism of QPE and will promote its application for safe and high-energy batteries.

This review provides a detailed analysis and summary of the design principles and strategies for the synthesis of fluorinated electrolyte solvents for Li-based batteries.

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1,8‐Diazabicyclo[5.4.0]undec‐7‐ene (DBU)/imine, DBU/imide DESs were designed and synthesized as CO2 trapping agents. Toward this end, the optimal absorption temperature and the maximum absorption capacity were determined. It was found that ionicity is a key factor to affect the absorption capacity of CO2. Combined with the ionicity calculation, a new CO2 capture mechanism has been proposed. HBD in DES can be divided into two parts. One can undergo proton transfer, obeying anion 2:1 absorption, whereas the other, without proton transfer, is amine 1:1 absorption. The degree of proton transfer in DES determines the ionicity and affects the absorption performance. The DFT calculation results confirmed this mechanism by micro perspective. DBU/2‐Pyrrolidinone and DBU/Oxazolidinone were proved to be good CO2 trapping agents with high absorption capacity, being 1.064 mol CO2/mol DES and 0.827 mol CO2/mol DES, respectively, and excellent recyclability when the mole ratio of HBA:HBD is 2:1.

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