In Situ Formed Weave Cage-Like Nanostructure Wrapped Mesoporous Micron Silicon Anode for Enhanced Stable Lithium-Ion Battery

The Planar Architecture of Silicon Anode Enables Stress Relief in Stable Lithium-Ion Batteries

Silicon is a promising anode for lithium-ion batteries but suffers tremendous volume change during cycling. Scalable and low-cost fabrication of silicon anodes with minimized internal stress, avoiding electrode degradation and capacity decline, remains a significant challenge. Herein, a planar silicon demonstrates internal stress release in the electrode at electrochemical cycling, which indicates a favorable areal capacity of 3.4 mAh cm-2 and a stable specific capacity of 810 mAh g-1 even after 600 cycles at a remarkable current density of 3.6 A g-1. Such good results are mainly ascribed to the planar structure that changes the expansion direction, which enables stress relief in the electrode. In addition, the planar structure provides abundant contact area, which aligns the anode stack and then shortens the ion diffusion. This work demonstrates useful insights on stress release through structure engineering and revolutionizes the traditional design for lithium-ion batteries, ensuring energy storage devices transcend current limitations.

Formicarium-Like Micron Porous Si Synergistically Adjusted by Surface Hard-Soft Nanoencapsulation as Long-Life Lithium-Ion Battery Anode

Micron porous silicon (MPSi) is a promising lithium-ion battery (LIB) anode that can provide enough space to effectively alleviate the volume expansion and large number of transmission channels to rapidly transport the Li-ions. However, a long-term stable MPSi anode at high current density is still a great challenge. Herein, a double-regulated formicarium like-MPSi composite using the surface hard-soft titanium dioxide-few layered MXene nanotemplate (FMPSi@TiO2@FMXene) was designed and synthesized via an in situ assembly strategy as long-life LIB anode. Such hard-soft TiO2-FMXene nanoencapsulation can collaboratively tune the internal/external stress, inhibit the volume expansion, reduce the interfacial reactions, and improve the electrical conductivity of MPSi, resulting in the great enhancement of structural stability and electrochemical performance in cycling even at high current density. Especially, this FMPSi@TiO2@FMXene anode exhibits a high reversible capacity of 1254.9 and 970.4 mAh/g after 500 cycles at 0.5 and 1 A/g, respectively. Moreover, a full cell is assembled with the FMPSi@TiO2@FMXene anode and commercial LiFePO4 (LFP) cathode, exhibiting a high capacity retention rate of 91.6% in 100 cycles. This work provides an effective surface nanoengineering tactic to obtain the structurally stable MPSi anodes by hard-soft nanotemplate for large-scale and long-term LIB application.

Si@Fe3O4/AC composite with interconnected carbon nano-ribbons network for high-performance lithium-ion battery anodes

Si-based anode materials have a relatively high theoretical specific capacity and low operating voltage, greatly enhancing the energy density of rechargeable lithium-ion batteries (LIBs). However, their practical application is seriously hindered by the instability of active particles and anode electrodes caused by the huge swelling during cycling. How to maintain the stability of the charge transfer network and interface structure of Si particles is full of challenges. To address this issue, we have developed a novel Si@Fe3O4/AC/CNR anode by in-situ growing one-dimensional high elastic carbon nano-ribbons to wrap Si nanoparticles. This special structure can construct fast channels of electron transport and lithium ion diffusion, and stabilize the surface structure of Si nanoparticles during cycling. With these promising architectural features, the Si@Fe3O4/AC/CNR composite possesses a high specific capacity of 1279.4 mAh/g at 0.5 A/g, and a superior cycling life with 80 % capacity retention after 700 cycles. Even at a high current density of 20.0 A/g, the composite still delivers a capacity of 621.2 mAh/g. The facile synthetic approach and high performance of Si@Fe3O4/AC/CNR anodes provide practical insight into advanced anode materials with large volume expansion for high-energy-density LIBs.

Si@nitrogen-doped porous carbon derived from covalent organic framework for enhanced Li-storage

Due to ultra-high theoretical capacity (4200 mAh g^-1), silicon (Si) is an excellent candidate for the anode of lithium-ion batteries (LIBs). However, the application of Si is severely limited by its volume expansion of approximately 300% during the charge/discharge process. Herein, nitrogen-doped porous carbon (NC) capped nano-Si particles (Si@NC) composites with a core-shell structure were obtained by calcination of covalent organic frameworks (COFs) encapsulated nano-Si. COFs is a crystalline material with well-ordered structures, adjustable and ordered pores and abundant N atoms. After carbonization, the well-ordered pores and frameworks were kept well. Compared with other Si@NC composites, the well-ordered NC framework shell derived from COFs possesses high elasticity and well-ordered pores, which provides space for the volume expansion of nano-Si, and a channel to transfer Li⁺. The core-shell Si@NC composite exhibited good performances when applied as the anode of LIBs. At a current density of 100 mA g^-1, it exhibited a discharge-specific capacity of 1534.8 mAh g^-1 after 100 cycles with a first-coulomb efficiency of 69.7%. The combination of COFs with nano-Si is a better strategy for the preparation of anode materials of LIBs.

Dual structure engineering of SiOx-acrylic yarn derived carbon nanofiber based foldable Si anodes for low-cost lithium-ion batteries

Silicon (Si) is attracted much attention due to its outstanding theoretical capacity (4200 mAh/g) as the anode of lithium-ion batteries (LIBs). However, the large volume change and low electron/ion conductivity during the charge and discharge process limit the electrochemical performance of Si-based anodes. Here we demonstrate a foldable acrylic yarn-based composite carbon nanofiber embedded by Si@SiO_x particles (Si@SiO_x-CACNFs) as the anode material. Since the amorphous SiO_x and carbon (C) coating on the outside of the Si particles can provide a double buffer for volume expansion while reducing the contact between the Si core and the electrolyte to form a thin and stable solid electrolyte interface (SEI) film. Simultaneous in-situ electrochemical impedance spectroscopy (in-situ EIS) and galvanostatic intermittent titration technique (GITT) tests show that SiO_x and C have higher ion/electron transport rates, and in addition, using acrylic fiber yarn and Zn(Ac)₂ as raw materials reduces the manufacturing cost and enhanced mechanical properties. Therefore, the half-cell can achieve a high initial Coulombic efficiency (ICE) of 82.3% and a reversible capacity of 1358.2 mAh/g after 180 cycles. It can return to its original shape and remain intact after four consecutive folds, and the soft-pack full battery can also light up LED lights under different bending conditions.

Silicon micron cages derived from a halloysite nanotube precursor and aluminum sacrificial template in molten AlCl3 as an anode for lithium-ion batteries

Porous nanostructures have been proposed a promising strategy to improve the electrochemical performance of Si materials as anodes of lithium-ion batteries (LIBs). However, expensive raw materials and the tedious preparation processes hinder their widespread adoption. In this work, silicon micron cages (SMCs) have been synthesized in molten AlCl₃ through using spherical aluminum particles as a sacrificial template, and the earth-abundant and low-cost natural halloysite clay as a precursor. The aluminum spheres (1–3 μm) not only act as a sacrificial template but also facilitate the formation of silicon branches, which connect together to form SMCs. As anodes for LIBs, the SMC electrode exhibits a high reversible capacity of 1977.5 mA h g⁻¹ after 50 cycles at a current density of 0.2 A g⁻¹, and 1035.1 mA h g⁻¹ after 300 cycles at a current density of 1.0 A g⁻¹. The improved electrochemical performance of SMCs could be ascribed to the micron cage structure, providing abundant buffering space and mesopores for Si expansion. This promising method is expected to offer a pathway towards the scalable application of Si-based anode materials in the next-generation LIB technology.

(1) Silicon micron cages (SMCs) was synthesized using natural halloysite as precursor. (2) The electrochemical performance of SMCs as anode materials of lithium-ion batteries can be improved for the micron cage structure.

Boosting the K+-adsorption capacity in edge-nitrogen doped hierarchically porous carbon spheres for ultrastable potassium ion battery anodes

Although carbon materials have great potential for potassium ion battery (KIB) anodes due to their structural stability and abundant carbon-containing resources, the limited K⁺-intercalated capacity impedes their extensive applications in energy storage devices. Current research studies focus on improving the surface-induced capacitive behavior to boost the potassium storage capacity of carbon materials. Herein, we designed edge-nitrogen (pyridinic-N and pyrrolic-N) doped carbon spheres with a hierarchically porous structure to achieve high potassium storage properties. The electrochemical tests confirmed that the edge-nitrogen induced active sites were conducive for the adsorption of K⁺, and the hierarchical porous structure promoted the generation of stable solid electrolyte interphase (SEI) films, both of which endow the resulting materials with a high reversible capacity of 381.7 mA h g^-1 at 0.1 A g^-1 over 200 cycles and an excellent rate capability of 178.2 mA h g^-1 at 5 A g^-1. Even at 5 A g^-1, the long-term cycling stability of 5000 cycles was achieved with a reversible capacity of 190.1 mA h g^-1. This work contributes to deeply understand the role of the synergistic effect of edge-nitrogen induced active sites and the hierarchical porous structure in the potassium storage performances of carbon materials.