Enhanced As-COF nanochannels as a high-capacity anode for K and Ca-ion batteries.

Covalent organic frameworks can be used for next-generation rechargeable metal-ion batteries due to their controllable spatial and chemical architectures and plentiful elemental reserves. In this study, the arsenic-based covalent organic framework (As-COF) is designed by employing the geometrical symmetry of a semiconducting phosphazene-based covalent organic framework that uses p-phenylenediamine as a linker and hexachorocyclotriphosphazene as an As-containing monomer in a C3-like spatial configuration. The As-COF with engineered nanochannels demonstrates exceptional anodic behavior for potassium (K) and calcium (Ca) ion batteries. It exhibits a high storage capacity of about 914(2039) mA h g-1, low diffusion barriers of 0.12(0.26) eV, low open circuit voltage of 0.23(0.18) V, and a minimal volume expansion of 2.41(2.32)% for K (Ca) ions. These attributes collectively suggest that As-COF could significantly advance high-capacity rechargeable batteries.

Bi-C monolayer as a promising 2D anode material for Li, Na, and K-ion batteries.

Electrode materials with high electrochemical efficiency are required for battery technology that can be used to store renewable energy. Bismuth (Bi) has shown great potential as an electrode material for metal ion batteries due to its large volumetric capacity and reasonable operating potential. However, the cycling performance deteriorates due to the drastic volume changes that occur during alloying and dealloying. Herein, we design a 2D Bi-C metal sheet using density functional theory and investigate the feasibility of this nanosheet for alkali metal ion batteries. The predicted metallic Bi-C monolayer (ML) are highly stable and show sound electrode performance. Moreover, alkali metal atoms exhibit high diffusivities on both sides (Bi and C sides) with low energy barriers of 0.252/0.201, 0.217/0.169, and 0.179/0.136 eV for Li, Na, and K ions, respectively. Furthermore, the Bi-C ML shows high theoretical storage capacities of (485 mA h g-1) for Li and Na and (364 mA h g-1) for K and low open-circuit voltage of 0.12, 0.24, and 0.32 V for Li, Na, and K ions, respectively. These exciting findings show that the predicted Bi-C ML can be used as an anode material for Li-, Na- and K-ion batteries.

Porous Carbon with Alumina Coating Nanolayer Derived from Biomass and the Enhanced Electrochemical Performance as Stable Anode Materials.

With the ever-increasing world population, the energy produced from green, environmentally friendly approaches is in high demand. In this work, we proposed a green and cost-effective strategy for synthesizing a porous carbon electrode decorated with alumina oxide (Al2O3) from cherry blossom leaves using the pyrolysis method followed by a sol-gel method. An Al2O3-coating nano-layer (4-6 nm) is formed on the porous carbon during the composition fabrication, which further adversely affects battery performance. The development of a simple rich-shell-structured C@Al2O3 nanocomposite anode is expected to achieve stable electrochemical performances as lithium storage. A significant contributing factor to enhanced performance is the structure of the rich-shell material, which greatly enhances conductivity and stabilizes the solid-electrolyte interface (SEI) film. In the battery test assembled with composite C@Al2O3 electrode, the specific capacity is 516.1 mAh g-1 at a current density of 0.1 A g-1 after 200 cycles. The average discharge capacity of carbon is 290 mAh g-1 at a current density of 1.0 A g-1. The present study proposes bioinspired porous carbon electrode materials for improving the performance of next-generation lithium-ion batteries.