First Authors: Miao Cheng, Shaoqing Pan
Corresponding Author: Bo Liu
Article Title: “Bimetallic Bi–Sn nanoparticles in-situ anchored in carbon nanofiber as flexible self-supporting anode toward advanced magnesium ion batteries”
Impact Factor: 13.4
Article Link: https://doi.org/10.1016/j.cej.2025.159626
01 Instructor Profile
Professor Liu Bo is a Researcher at the School of Materials Science and Engineering at Suzhou University of Science and Technology. He also serves as an Adjunct Researcher at the Shanghai Institute of Microsystem and Information Technology (SIMIT) under the Chinese Academy of Sciences (CAS) and as a Visiting Professor at Qilu University of Technology. His primary research focuses on nanoscale optoelectronic materials and devices. He has led or participated in over 60 research projects, including major national initiatives such as the National Basic Research Program of China (Program 973). To date, he has published 317 journal articles (including 230 SCI-indexed papers) and has been granted 119 Chinese invention patents and 5 U.S. invention patents.
02 Research Background
With the booming development of flexible electronic devices, the exploration and development of high-performance flexible energy storage systems have become increasingly critical. Among these, flexible lithium-ion batteries have achieved significant progress in practical applications involving flexible electronics and wearable devices; however, challenges to their further development and application persist—specifically, the high costs associated with limited lithium resources and the safety risks posed by uncontrolled lithium dendrite formation. Consequently, there is an urgent need to develop alternative battery systems characterized by high natural abundance, low cost, and high safety. Rechargeable magnesium-ion batteries hold great promise as a reliable alternative to lithium-based systems, given that magnesium resources are abundant and inexpensive, possess a high theoretical specific capacity and a suitable reduction potential, do not form dendrites during electrochemical deposition/dissolution processes, and offer high operational safety. Nevertheless, research concerning flexible electrode materials for magnesium-ion batteries remains scarce. In recent years, electrospinning has been widely recognized as one of the most convenient, cost-effective, and industrially viable techniques for fabricating 3D porous membranes; consequently, an increasing number of researchers are focusing on utilizing electrospun nanofiber-based composites as flexible electrodes.
03 Paper Highlights / Abstract
With the unprecedented advancement of flexible electronics technology, the development of compatible flexible power supply systems has become imperative. Magnesium-ion batteries (MIBs), as a promising next-generation battery system, demonstrate immense potential as power sources for flexible electronic devices. However, research into flexible magnesium-ion batteries remains in its nascent stages; thus, the exploration of novel and reliable flexible electrodes is of critical importance. In this work, a binder-free, flexible, and self-supporting electrode was fabricated via electrospinning combined with an in-situ thermal reduction process. This electrode consists of bimetallic Bi-Sn nanoparticles anchored within carbon nanofibers (CNF@Bi-Sn) and is applied to magnesium-ion batteries for the first time. The CNF@Bi-Sn architecture synergistically integrates several advantages: a hierarchical porous carbon nanofiber framework, uniformly dispersed nanoscale Bi-Sn particles, and an increased density of phase/grain boundaries. These characteristics collectively contribute to enhancing the structural stability of the flexible electrode material and facilitating the diffusion kinetics of Mg²⁺ ions. The CNF@Bi-Sn alloy anode exhibits exceptional electrochemical performance, featuring a high initial specific capacity of 738 mAh g⁻¹, outstanding rate capability, and excellent cycling stability; notably, it retains a reversible capacity of 150 mAh g⁻¹ after 100 cycles at a current density of 40 mA g⁻¹. Through quantitative kinetic analysis, as well as ex-situ SEM, TEM, and XRD characterizations, this study elucidates the structural evolution of the flexible electrode material during cycling and reveals the underlying magnesium storage mechanism, which is based on a reversible two-phase alloying/de-alloying conversion reaction. Furthermore, a full-cell device was assembled to demonstrate the potential of this electrode in practical applications. This research offers novel insights into the exploration and development of high-performance flexible, self-supporting alloy anodes.
04 | Illustrated Analysis
I: Bi-Sn Nanoparticles Uniformly Anchored within Carbon Nanofibers as a Flexible, Self-Supporting Anode for Magnesium-Ion Batteries
A flexible film (CNF@Bi-Sn) loaded with bimetallic Bi-Sn nanoparticles was fabricated using a method combining electrospinning and in-situ thermal reduction. This film exhibits excellent flexibility and can withstand various forms of deformation (bending, twisting, folding, etc.). During the battery assembly process, no current collectors, conductive agents, or binders were utilized. SEM and TEM analyses reveal that the Bi-Sn nanoparticles are uniformly distributed throughout the carbon nanofibers.
II: CNF@Bi-Sn Demonstrates High Reversible Capacity, Excellent Rate Performance, and Good Cycling Stability
CNF@Bi-Sn exhibits a high initial specific capacity of 738 mAh g⁻¹. Following cycling at various rates, its discharge specific capacity recovers to 214 mAh g⁻¹, thereby demonstrating the excellent rate performance of the CNF@Bi-Sn electrode. Furthermore, even after 100 cycles at a current density of 40 mA g⁻¹, it maintains a high reversible capacity of 150 mAh g⁻¹.
III: Structural Evolution and Magnesium Storage Mechanisms Revealed via Ex Situ Characterization
The morphological and structural evolution of CNF@Bi-Sn during the magnesiation/demagnesiation process was investigated using ex situ characterization techniques, including SEM, TEM, and XRD. TEM analysis demonstrated that, following full discharge (Mg insertion) and charge (Mg extraction), the Bi-Sn nanoparticles within the CNF@Bi-Sn electrode remained well-encapsulated and uniformly dispersed throughout the carbon nanofibers; this effectively mitigated volume changes during the alloying process and prevented the loss of active material. EDS results indicated that, in the discharged state, the Bi, Sn, and Mg elements were uniformly distributed within the carbon matrix; furthermore, ex situ XRD confirmed that the magnesium storage mechanism of the CNF@Bi-Sn electrode is predicated upon a reversible two-phase alloying/dealloying transformation reaction.
05 Equipment Used in This Study
The miniature assisted tube furnace utilized in the experiments by Professor Liu Bo’s research group was supplied by Kemi Instruments. Anhui Kemi Instruments Co., Ltd. was also specifically acknowledged in the paper; we would like to take this opportunity to express our sincere gratitude to Professor Liu for choosing and endorsing Kemi Instruments.
