High-performance micron-sized porous Si/C anodes from natural graphite tailings for lithium-ion batteries

doi:10.1016/j.metadv.2026.03.002

Abstract

Abstract:

With the growing demand for high-energy-density and long-lifespan lithium-ion batteries (LIBs), silicon/graphite composites have emerged as promising anode materials, as they synergize the ultrahigh capacity of silicon (Si) and the structural stability of carbon. To address the intrinsic volume variation issue of silicon, this work demonstrates a scalable and environmentally benign synthesis of micron-sized porous silicon/graphite composites (NGT-pSi/C) via the integration of FeCl₃-etched spherical porous silicon (pSi) and waste-derived natural graphite tailings (NGT). The as-prepared NGT-pSi/C features a watermelon-like multi-core-shell architecture. The pores in pSi effectively accommodate the large volume expansion during cycling. Meanwhile, the upcycled NGT form a conductive layer to disperse mechanical stress, and the glucose-derived carbon layer constructs a conductive network. This waste-to-wealth approach enables the conversion of industrial byproducts into high-performance LIB anode materials. Comprehensive physicochemical and electrochemical characterizations reveal that abundant pores and continuous conductive networks in NGT-pSi/C synergistically mitigate Si pulverization, suppress interfacial degradation and enhance charge transfer kinetics. The NGT-pSi/C anode delivers exceptional cycling stability (591.2 mAh g⁻¹ after 400 cycles at 0.5 A g⁻¹) and superior rate capability. Furthermore, full cells paired with NCA90 (LiNi_0.9Co_0.05Al_0.05O₂) cathodes maintain 72.6% of their initial capacity after 800 cycles. The corresponding pouch cell exhibits a high discharge capacity of 0.7 Ah and retains 74.43% capacity after 500 cycles. This practical strategy achieves a cost-performance synergy. Overall, by using near-zero-cost graphite waste and adopting a non-acidic etching process, this work establishes a sustainable and economically viable pathway for the scalable production of high-performance Si-based anodes.

Key words: Silicon/graphite anode, Natural graphite tailing, Porous silicon anode, Pouch cell, Lithium-ion batteries

Yuxuan Zhang, Chen Wang, Fang Zhang, Yan Xin, Bijiao He, Shiguo Zhang, Huajun Tian. High-performance micron-sized porous Si/C anodes from natural graphite tailings for lithium-ion batteries[J]. Metals Advances, 2026, 44: 88-98.

Figures/Tables 6

Fig. 1. (a) Schematic illustration of the synthesis procedure for the NGT-pSi/C composite. SEM images of (b) pSi, (c) NGT, and (d) NGT-pSi/C. (e, i) TEM image, and (f-h) corresponding elemental mappings of NGT-pSi/C. (j) HRTEM image, and (k) SAED pattern of NGT-pSi/C.

Fig. 2. (a) XRD patterns, (b) Raman spectra, and (c) XPS surveys of NGT-pSi/C, NGT-mSi/C, SNG-pSi/C, and NGT-pSi. High-resolution XPS spectra of NGT-pSi/C: (d) C 1s, (e) O 1s, (f) Si 2p. (g) TGA curves. (h) N2 adsorption-desorption isotherm, and (i) pore-size distribution of NGT-pSi/C, NGT-mSi/C, SNG-pSi/C and NGT-pSi.

Fig. 3. (a) Initial three CV curves at 0.1 mV s−1, and (b) GCD curves at 0.1 A g−1 of NGT-pSi/C. (c) Rate performance of NGT-pSi/C, NGT-mSi/C, SNG-pSi/C, and NGT-pSi under 0.1-1.0 A g−1. (d) GCD curves of NGT-pSi/C at different current densities. (e) Long-term cycling performance at 0.3 A g−1. (f) Cycling performances of NGT-pSi/C electrodes under high mass loadings. (g) Long-term cycling performance at 0.5 A g−1.

Fig. 4. (a) CV curves of NGT-pSi/C half cells at scanning rates of 0.1-1.0 mV s−1. Correlation between current and square root of scan rate for (b) peak 1, and (c) peak 2. (d) Nyquist plots of NGT-pSi/C, NGT-mSi/C, SNG-pSi/C, and NGT-pSi anodes. (e) Nyquist plots of NGT-pSi/C anodes at the initial state, after 10 and 100 cycles. Li+ diffusion coefficients for (f) lithiation, and (g) delithiation processes. (h) Rct at different temperatures. (i) Arrhenius behavior and activation energies (Ea) of Li+ transport.

Fig. 5. Cross-sectional SEM images of NGT-pSi/C anodes with thickness markings at different cycles: (a) initial, (b) after 10 cycles, and (c) after 100 cycles. Surface morphologies of (d) NGT-pSi/C, (e) NGT-mSi/C, (f) SNG-pSi/C, (g) NGT-pSi anodes after 100 cycles. Typical AFM morphologies of (h) NGT-pSi/C, (i) NGT-mSi/C, (j) SNG-pSi/C, and (k) NGT-pSi anodes.

Fig. 6. (a) Initial GCD curves at 0.1 C. (b) Long-term cycling performance of full cells at 1 C using different electrodes. (c) Charge-discharge curves of NGT-pSi/C//NCA90 full cells under different cycles. (d) Rate capability from 0.1 to 5.0 C. (e) Charge-discharge curves of NGT-pSi/C//NCA90 full cells at different rates. (f) Long-term cycling performance of NGT-pSi/C//NCA90 pouch cell at 0.5 C. (g) Demonstration of the pouch cell powering a mobile phone.

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