Electrospinning Machine| Desolvated ion screening composite fiber interlayer enables dendrite-free anode for aqueous zinc-ion batteries

With the rapid development of energy storage technology, aqueous zinc-ion batteries (AZIBs) have attracted widespread attention as a promising alternative to lithium-ion batteries due to their low cost, high safety, and environmental friendliness. However, in practical applications, zinc anodes are prone to hydrogen evolution and dendrite growth during plating/stripping, leading to side reactions, electrode surface passivation, and safety hazards. To address these issues, researchers have proposed various strategies from thermodynamic and kinetic perspectives to suppress dendrites and enhance zinc electrode stability. For example, high-concentration electrolytes can reduce water activity and inhibit dendrite growth, while artificial solid electrolyte interphase (SEI) films help improve ion transport kinetics. Additionally, the crystallographic orientation of zinc deposition significantly affects dendrite suppression, and introducing ion-regulating interlayers is considered an ideal strategy.

Recently, the team of Lina Ma from Qingdao University and Hao Luo from Xiamen University of Technology published their latest research titled "Desolvated ion screening composite fiber interlayer enables dendrite-free anode for aqueous zinc-ion batteries" in Materials Today Energy. The researchers prepared a freestanding, lightweight, and flexible boron nitride (BN)/polyacrylonitrile (PAN) composite nanofiber interlayer via electrospinning and hybridization strategies. Benefiting from the incorporation of BN nanoparticles, the resulting BN@PAN fiber membrane carries a negative surface charge, efficiently adsorbing Zn2+ ions, homogenizing ion flux, and suppressing the "tip effect," while improving Zn2+ diffusion and deposition morphology to effectively inhibit zinc dendrite growth. Moreover, the hydrophobic nature of BN reduces direct contact between active water molecules in the electrolyte and the zinc anode, significantly suppressing hydrogen evolution side reactions. The BN@PAN interlayer exhibits excellent ionic conductivity and mechanical strength, enabling stable cycling performance for over 2,600 hours in symmetric cells and significantly improving Coulombic efficiency and cycling stability in full cells. This polymer/inorganic hybrid nanofiber interlayer demonstrates broad application prospects in high-performance aqueous zinc-ion batteries.

Fig. 1: Morphology and EDS elemental mapping of BN@PAN composite nanofiber membranes with varying BN concentrations.

The BN@PAN composite nanofiber membrane was prepared via electrospinning and post-treatment. SEM images show that pure PAN fiber membranes exhibit a uniform, smooth, and interwoven 3D network structure (Fig. 1a-g). After introducing an appropriate amount of BN nanoparticles, the diameter of the resulting BN@PAN fibers slightly decreases, with BN particles uniformly distributed on and within the fibers (Fig. 1b, 1c). EDS elemental mapping further confirms the homogeneous distribution of B and N elements in the fibers, indicating successful doping of BN nanoparticles into the PAN matrix. This uniform distribution and tightly bonded structure not only enhances the mechanical strength of the fiber membrane but also provides continuous and efficient migration channels for Zn2+ ions, facilitating uniform deposition and suppressing zinc dendrite growth, showcasing potential applications in high-performance aqueous zinc-ion batteries.

Fig. 2: Comparison of rate performance and long-term cycling stability of symmetric cells with different BN@PAN composite nanofiber membranes.

As shown in Fig. 2a and 2b, the optimally proportioned BN20@PAN demonstrates better hydrogen evolution suppression and zinc affinity, while symmetric cells maintain stable rate performance (Fig. 2c). Additionally, cycling stability is closely related to the interlayer's ability to regulate zinc ion migration. Thus, cells with the BN20@PAN interlayer exhibit exceptional cycling lifespans, achieving stable operation for over 2,600 hours at 1 mA cm−2 (Fig. 2d-2g), far outperforming unmodified control cells (failure at ~147 hours). In summary, the BN20@PAN interlayer not only suppresses dendrite growth but also effectively reduces hydrogen evolution side reactions, achieving an average Coulombic efficiency of up to 99.73%. This indicates that the BN@PAN composite interlayer significantly enhances zinc anode reversibility and long-term cycling performance by improving ion channel uniformity and interfacial stability.

Fig. 3: Rate performance and long-term cycling stability of full cells with different BN@PAN composite nanofiber membranes.

Compared to unmodified PAN membranes, the BN20@PAN interlayer exhibits superior dendrite suppression and electrochemical stability. In electrochemical tests, the BN20@PAN interlayer shows a larger current response area, higher ionic conductivity, and higher specific capacity (Fig. 4a-c). In full-cell tests, Zn//rGO-VO2 batteries with the BN20@PAN interlayer demonstrate outstanding electrochemical performance. Benefiting from uniform ion channels and efficient dendrite suppression, the battery maintains high specific capacity at high rates, with a capacity retention of 58% after 1,000 cycles at 3 A g−1 (Fig. 2d, 2e), significantly outperforming unmodified control cells. This confirms that the BN@PAN interlayer not only enables stable zinc deposition/stripping in symmetric cells but also improves cycling lifespan and rate performance in full cells, exhibiting superior performance compared to recent studies (Fig. 2f) and demonstrating practical potential for high-performance aqueous zinc-ion batteries.

Fig. 4: Mechanism of BN@PAN composite nanofiber membranes in suppressing hydrogen evolution side reactions and guiding ion deposition.

Furthermore, the excellent performance of the BN@PAN composite interlayer is attributed to its synergistic regulation mechanism. On one hand, the negatively charged BN nanoparticle surface efficiently adsorbs Zn2+ ions, homogenizing interfacial electric field distribution, reducing the "tip effect," and guiding zinc ions to preferentially deposit along the (002) crystal plane, thereby suppressing dendrite formation. On the other hand, the 3D porous nanofiber network of the PAN matrix provides continuous, low-resistance ion channels for Zn2+ migration, enhancing ion diffusion kinetics. Simultaneously, the hydrophobic nature of BN blocks active water molecules in the electrolyte, reducing hydrogen evolution side reactions. Collectively, the BN@PAN interlayer synergistically achieves uniform zinc deposition, dendrite suppression, and interfacial stability through a triple mechanism of "ion regulation–physical isolation–mechanical reinforcement."

Paper link: https://doi.org/10.1016/j.mtener.2025.101973.