Constructing Hierarchical Si/PPy/PANI Anodes with Dual Carbon Layers for Enhanced Cycling Stability and Rate Capability

Abstract

Silicon (Si) is considered one of the most promising anode materials for next-generation lithium-ion batteries (LIBs) due to its exceptionally high theoretical capacity. However, the severe volume expansion during charge/discharge cycles leads to particle pulverization and poor cycling stability. To address these challenges, a novel dual carbon source strategy is proposed in this study. A hierarchical Si/PPy/PANI composite is constructed by sequentially coating silicon nanoparticles with polypyrrole (PPy) and polyaniline (PANI) via in-situ polymerization, followed by high-temperature carbonization under an Ar/H₂ atmosphere. The resulting material features a double-layer N-doped carbon shell, where the inner PPy-derived carbon exhibits a high degree of graphitization, forming a dense and conductive network that enhances electronic conductivity and structural robustness. The outer PANI-derived carbon layer contains abundant nitrogen doping and porous structures, which not only offer extra lithium storage sites but also buffer volume expansion and promote fast lithium-ion diffusion. Nitrogen doping further modulates the electronic structure of the carbon matrix, increasing local charge density and facilitating Li⁺ adsorption. Benefiting from this synergistic dual-shell design, the Si/PPy/PANI anode demonstrates outstanding electrochemical performance. At a current density of 1000 mA g⁻¹, it delivers a reversible capacity of 790.1 mAh g⁻¹ after 400 cycles with a high coulombic efficiency of 99.66%. Even at a high rate of 5000 mA g⁻¹, the capacity remains at 882.4 mAh g⁻¹, showing excellent rate capability. These results confirm the effectiveness of the dual carbon shell in enhancing both the cycling stability and rate performance of silicon-based anodes. This work provides a simple and scalable approach to design high-performance Si/C composite anodes with robust structural stability and efficient charge transport. The dual carbon encapsulation strategy offers new insights into advanced electrode engineering for high-energy lithium-ion batteries.

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Article information

Article type
Paper
Submitted
14 May 2025
Accepted
17 Jun 2025
First published
19 Jun 2025

New J. Chem., 2025, Accepted Manuscript

Constructing Hierarchical Si/PPy/PANI Anodes with Dual Carbon Layers for Enhanced Cycling Stability and Rate Capability

J. He, Y. Cui, G. Xun, X. He and K. Zhang, New J. Chem., 2025, Accepted Manuscript , DOI: 10.1039/D5NJ02034D

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