Hollow double-layer carbon nanocage confined Si nanoparticles for high performance lithium-ion batteries

Yolk shell structured YS-Si@N-doped carbon derived from covalent organic frameworks for enhanced lithium storage

Silicon (Si) has ultra-high theoretical capacity (4200 mAh g-1) and accordingly is widely studied as anode materials for lithium-ion batteries (LIBs). However, its huge volume expansion during charging/discharging is a fatal challenge. The preparation of Si-based composite materials with yolk shell structure is the key to solving the Si volume expansion. Here, N-doped carbon-coated Si nanoparticles (SiNPs) nanocomposites (YS-Si@NC-60) with yolk shell structure derived from covalent organic frameworks (COFs) was prepared. N-doped carbon shells derived from COFs not only maintain the well-ordered nanosized pores of COFs, which facilitates the transport of Li+ to contact with internal SiNPs, but also provide more extra active sites for Li+ storage. Most importantly, the internal void can effectively alleviate the damage effect of SiNPs volume expansion. The obtained YS-Si@NC-60 as a LIBs anode show high cyclic stability and Li+ storage performances. At 0.1 A g-1, the capacity is 1446 mAh g-1 after 110 cycles, and initial coulomb efficiency is as high as 82.2 %. The excellent performance can be attributed to the unique yolk shell structure. This simple and template-free strategy provides a new idea for preparing Si-C nanocomposites with yolk shell structure.

Recent Progress of Hollow Carbon Nanocages: General Design Fundamentals and Diversified Electrochemical Applications

Hollow carbon nanocages (HCNCs) consisting of sp2  carbon shells featured by a hollow interior cavity with defective microchannels (or customized mesopores) across the carbon shells, high specific surface area, and tunable electronic structure, are quilt different from the other nanocarbons such as carbon nanotubes and graphene. These structural and morphological characteristics make HCNCs a new platform for advanced electrochemical energy storage and conversion. This review focuses on the controllable preparation, structural regulation, and modification of HCNCs, as well as their electrochemical functions and applications as energy storage materials and electrocatalytic conversion materials. The metal single atoms-functionalized structures and electrochemical properties of HCNCs are summarized systematically and deeply. The research challenges and trends are also envisaged for deepening and extending the study and application of this hollow carbon material. The development of multifunctional carbon-based composite nanocages provides a new idea and method for improving the energy density, power density, and volume performance of electrochemical energy storage and conversion devices.

Hollow Porous N and Co Dual-Doped Silicon@Carbon Nanocube Derived by ZnCo-Bimetallic Metal-Organic Framework toward Advanced Lithium-Ion Battery Anodes

Silicon (Si) has been recognized as a promising alternative to graphite anode materials for advanced lithium-ion batteries (LIBs) owing to its superior theoretical capacity and low discharge voltage. However, Si-based anodes undergo structural pulverization during cycling due to the large volume expansion (ca. 300-400%) and continuous formation of an unstable solid electrolyte interphase (SEI), resulting in fast capacity fading. To address this challenge, a series of different amounts of silicon nanoparticles (Si NPs)-encapsulated hollow porous N-doped/Co-incorporated carbon nanocubes (denoted as p-CoNC@SiX, where X = 50, 80, and 100) as anode materials for LIBs are reported in this paper. These hollow nanocubic materials were derived by facile annealing of different contents of Si NPs-encapsulated Zn/Co-bimetallic zeolitic imidazolate frameworks (ZIF@Si) as self-sacrificial templates. Owing to the advantages of well-defined hollow framework clusters and highly conductive hollow carbon frameworks, the hollow porous p-CoNC@SiX significantly improved the electronic conductivity and Li⁺ diffusion coefficient by an order of magnitude higher than that of Si NPs. The as-prepared p-CoNC@Si80 with 80 wt % Si NPs delivered a continuously increasing specific capacity of 1008 mAh g^-1 at 500 mA g^-1 over 500 cycles, excellent reversible capacity (∼1361 mAh g^-1 at 0.1 A g^-1), and superior rate capability (∼603 mAh g^-1 at 3 A g^-1) along with an unprecedented long-life cyclic stability of ∼1218 mAh g^-1 at 1 A g^-1 over 1000 cycles caused by low volume expansion (9.92%) and suppressed SEI side reactions. These findings provide new insights into the development of highly reversible Si-based anode materials for advanced LIBs.

Sustainable Materials from Fish Industry Waste for Electrochemical Energy Systems

Fish industry waste is attracting growing interest for the production of environmentally friendly materials for several different applications, due to the potential for reduced environmental impact and increased socioeconomic benefits. Recently, the application of fish industry waste for the synthesis of value-added materials and energy storage systems represents a feasible route to strengthen the overall sustainability of energy storage product lines. This review focused on an in-depth outlook on the advances in fish byproduct-derived materials for energy storage devices, including lithium-ion batteries (LIBs), sodium-ion (NIBs) batteries, lithium-sulfur batteries (LSBs), supercapacitors and protein batteries. For each of these, the latest applications were presented together with approaches to improve the electrochemical performance of the obtained materials. By analyzing the recent literature on this topic, this review aimed to contribute to further advances in the sustainability of energy storage devices.

A Novel Tin-Bonded Silicon Anode for Lithium-Ion Batteries

Poor cyclic stability and low rate performance due to dramatic volume change and low intrinsic electronic conductivity are the two key issues needing to be urgently solved in silicon (Si)-based anodes for lithium-ion batteries. Herein, a novel tin (Sn)-bonded Si anode is proposed for the first time. Sn, which has a high electronic conductivity, is used to bond the Si-anode material and copper (Cu) current collector together using a hot-pressed method with a temperature slightly above the melting point of Sn. The cycling performance of the electrode is studied using a galvanostatic method. Nanoindentation and peeling tests are conducted to measure the mechanical strength of the electrodes. Direct current polarization and galvanostatic intermittent titration techniques are applied to assess the conductivity of the composites. Electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy are conducted to evaluate the effect of the coating layer on the cycling ability of the composites. The Sn-bonded Si anodes show superior cycling stability and high rate performance with an improved initial Coulombic efficiency. Analyses reveal that the low-melting-point Sn helps to markedly improve the electronic conductivity of the electrodes and serves as a metallic binder as well to enhance the adhesive strength of the electrode. It is hopeful that this novel Sn-bonded Si anode provides a new insight for the development of advanced Si-based anodes for LIBs.