Ultra-Uniform and Functionalized Nano-Ion Divider for Regulating Ion Distribution toward Dendrite-Free Lithium-Metal Batteries.

Ionic dividers with uniform pores and functionalized surfaces display significant potential for solving Li-dendrite issues in Li-metal batteries. In this study, single metal and nitrogen co-doped carbon-sandwiched MXene (M-NC@MXene) nanosheets are designed and fabricated, which possess highly ordered nanochannels with a diameter of ≈10 nm. The experiments and computational calculations verified that the M-NC@MXene nanosheets eliminate Li dendrites in several ways: (1) redistributing the Li-ion flux via the highly ordered ion channels, (2) selectively conducting Li ions and anchoring anions by heteroatom doping to extend the nucleation time for Li dendrites, and (3) tightly staggering on a routine polypropylene (PP) separator to obstruct the growth path of Li dendrites. With a Zn-NC@MXene-coated PP divider, the assembled Li||Li symmetric battery shows an ultralow overpotential of ≈25 mV and a cycle life of 1500 h at a high current density of 3 mA cm-2 and high capacity of 3 mAh cm-2 . Remarkably, the life of a Li||Ni83 pouch cell with an energy density of 305 Wh kg-1 is improved by fivefold. Moreover, the remarkable performance of Li||Li, Li||LiFePO4 , and Li||sulfur batteries reveal the significant potential of the well-designed multifunctional ion divider for further practical applications.

Tristate ferroelectric memory effect attained by tailoring the ferroelectric behavior in Bi1/2(Na0.8K0.2)1/2TiO3 with Eu doping.

The ferroelectric behavior of Bi1/2(Na0.8K0.2)1/2TiO3 has been tailored by Eu3+ doping and the intermediate relaxor state is utilized for tristate ferroelectric memory effect. As Eu3+ content increases, the local structural disorder tends to get enhanced and the stability of ferroelectric order gets weakened. The disruption effect of Eu3+ is manifested structurally in XRD and PL spectra, and electrically in the ferroelectric, dielectric and piezoelectric properties. We found that the BNKT:3.0%Eu which owns a relaxor state under electrical cycle would be suitable for tristate ferroelectric memory, where two ferroelectric states and the relaxor state are respectively served as the "±1" and "0" memory states. We designed the verification experiments, and the results show good feasibility and stability. Moreover, it is innovative using PL spectra of Eu3+ to understand the structural changes related to different memory states, owning to its sensitivity to local structural symmetry. It also implies the possibility for non-destructive optical readout.

Comprehensive H2 O Molecules Regulation via Deep Eutectic Solvents for Ultra-Stable Zinc Metal Anode.

The corrosion, parasitic reactions, and aggravated dendrite growth severely restrict development of aqueous Zn metal batteries. Here, we report a novel strategy to break the hydrogen bond network between water molecules and construct the Zn(TFSI)2 -sulfolane-H2 O deep eutectic solvents. This strategy cuts off the transfer of protons/hydroxides and inhibits the activity of H2 O, as reflected in a much lower freezing point (<-80 °C), a significantly larger electrochemical stable window (>3 V), and suppressed evaporative water from electrolytes. Stable Zn plating/stripping for over 9600 h was obtained. Based on experimental characterizations and theoretical simulations, it has been proved that sulfolane can effectively regulate solvation shell and simultaneously build the multifunctional Zn-electrolyte interface. Moreover, the multi-layer homemade modular cell and 1.32 Ah pouch cell further confirm its prospect for practical application.

Large-Scale Integration of a Zinc Metasilicate Interface Layer Guiding Well-Regulated Zn Deposition.

Uneven distribution of electric fields at the electrolyte-anode interface and associated Zn dendrite growth is one of the most critical barriers that limit the life span of aqueous zinc-ion batteries. Herein, new-type Zn-A-O (A = Si, Ti) interface layers with thin and uniform thickness, porosity, and hydrophilicity properties are developed to realize homogeneous and smooth Zn plating. For ZnSiO3 nanosheet arrays on Zn foil (Zn@ZSO), their formation follows an "etching-nucleation-growth" mechanism that is confirmed by a well-designed Zn-island-based identical-location microscopy method, the geometric area of which is up to 1000 cm2 in one-pot synthesis based on a low-temperature wet-chemical method. Guided by the structural advantages of the ZSO layer, the Zn2+ flux gets equalized. Besides ultralow polarization, the life spans of symmetric cells and full cells coupled with a high-mass-loading K0.27 MnO2 ·0.54H2 O (8 mg cm-2 ) cathode, are increased by 3-7 times with the Zn@ZSO anode. Moreover, the large-scale preparation of Zn@ZSO foil contributes to a 0.5 Ah multilayer pouch cell with high performance, further confirming its prospects for practical application.