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Constructing an artificial solid electrolyte interphase (SEI) on lithium metal electrode is a promising approach to address the rampant growth of dangerous lithium morphologies (dendritic and dead Li0) and low Coulombic efficiency that plague development of lithium metal batteries. But it is not known how the Li+ transfer behavior in the SEI is coupled with mechanical properties. We demonstrate here a facile and scalable solution-processed approach to form a Li3N-rich SEI with a phase-pure crystalline structure that minimizes the diffusion energy barrier of Li+ across the SEI. Compared with a polycrystalline Li3N SEI obtained from conventional practice, our phase-pure/single crystalline Li3N-rich SEI constitutes an interphase of high mechanical strength and low Li+ diffusion barrier. We elucidate the correlation among Li+ transference number, diffusion behavior, concentration gradient, and the stability of the lithium metal electrode by integrating phase field simulations with experiments. We demonstrate extreme reversibility and ultra-stable charge/discharge cycling behaviors for both symmetric cells and full lithium-metal batteries constructed using this Li3N-rich SEI. These studies provide new insight into the designing and engineering an ideal artificial SEI for stable and high-performance lithium metal batteries.

Lead (Pb)–Tin (Sn) mixed perovskites suffer from large open-circuit voltage (Voc) loss due to the rapid crystallization of perovskite films, creating Sn and Pb vacancies. Such vacancies act as defe...

Solid-state lithium batteries are generally considered as the next-generation battery technology that benefits from inherent nonflammable solid electrolytes and safe harnessing of high-capacity lithium metal. Among various solid-electrolyte candidates, cubic garnet-type Li7La3Zr2O12 ceramics hold superiority due to their high ionic conductivity (10–3 to 10–4 S cm−1) and good chemical stability against lithium metal. However, practical deployment of solid-state batteries based on such garnet-type materials has been constrained by poor interfacing between lithium and garnet that displays high impedance and uneven current distribution. Herein, we propose a facile and effective strategy to significantly reduce this interfacial mismatch by modifying the surface of such garnet-type solid electrolyte with a thin layer of silicon nitride (Si3N4). This interfacial layer ensures an intimate contact with lithium due to its lithiophilic nature and formation of an intermediate lithium–metal alloy. The interfacial resistance experiences an exponential drop from 1197 to 84.5 Ω cm2. Lithium symmetrical cells with Si3N4-modified garnet exhibited low overpotential and long-term stable plating/stripping cycles at room temperature compared to bare garnet. Furthermore, a hybrid solid-state battery with Si3N4-modified garnet sandwiched between lithium metal anode and LiFePO4 cathode was demonstrated to operate with high cycling efficiency, excellent rate capability, and good electrochemical stability. This work represents a significant advancement toward use of garnet solid electrolytes in lithium metal batteries for the next-generation energy storage devices.

Sodium-ion batteries (SIBs) are considered as a promising alternative to lithium-ion batteries in large-scale energy storage due to the abundant sodium resources and low cost. However, the practical applications are still hindered by several factors such as limited cycling life and low mass loading of the electrode. Herein, a uniform free-standing Sn-based (Sn@CFC) electrode was synthesized via a facile electrospinning method. The cross-link nitrogen-doped carbon fiber and ultrasmall metallic Sn nanoparticles together provide fast ions and electrons pathway, enabling a dominant pseudocapacitance contribution of 87.1% at a scan rate of 0.5 mV s−1. The Sn@CFC electrode hence exhibits a high reversible area capacity of 1.68 mAh cm−2 at 50 mA g−1 and long cycle life of 1000 cycles at 200 mA g−1 with more than 80% capacity retention. Moreover, the facile manufacturing technique yields the Sn@CFC electrode with an extremely high mass loading of 5.5 mg cm−2 with very little sacrifice of electrochemical performances. This study provides a promising route to scalably fabricate electrodes with high area capacity and high energy density for advanced SIBs.

Activated carbons, carbon nanotubes, and crosslinked graphene have been extensively used as electrode materials in electrochemical double-layer capacitors (EDLC). Metal-organic frameworks (MOFs) whose surface area exceeds that of the activated carbon makes MOF as a potential electrode material. However, MOFs is conventionally thought to have very poor electrical conductivity, preventing its use as an electrode material for the EDLC applications. Here, we present a facile hydrothermal synthesis and carbonization of Cu based metal-organic framework and polymer fibers. The novel hierarchical porous carbon thus formed showed rich ionic storage unit and conductive pathway delivering excellent specific capacitance of 400 Fg-1 at the current density of 0.05 Ag-1. This novel carbon-based material can contribute towards development of low-cost, high energy/power density supercapacitors.

Zinc oxide (ZnO) is a wide band gap (~3.37 eV) semiconductor. Thin film ZnO has many attractive applications in optoelectronics and sensors. Recently, nanostructured ZnO (e.g. ZnO quantum dot) has been demonstrated as a hyperbolic material; its dielectric function has opposite signs along different crystal axes within the mid-infrared, making it an interesting material for metamaterials and nanophotonics. Conventional sputtering deposition usually leads to the formation of polycrystalline ZnO films with randomly oriented grains and rough surface. This work demonstrated a solution-based process to grow ZnO thin films with highly oriented nanocrystals. Low-temperature plasmas were employed to modulate the microstructure and optical properties of the films. Such highly anisotropic nanostructured transparent semiconductor films may lead to interesting material properties in developing new optoelectronic devices.