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Highlights There is a novel “hydrolysis-driven synthesis” approach for the preparation of a dual-surface functionalized micron-sized Si anode with a SiO x /C layer. The functionalized inner pores and dual-functional SiO x /C layer synergistically alleviate volume change of Si lithiation, minimize stress concentration and improve electrochemical reaction kinetics. The optimized micron-Si anode performs impressive lifespan, excellent high rate capacity and outstanding stack cell volumetric energy density. Micro-silicon (Si) anode that features high theoretical capacity and fine tap density is ideal for energy-dense lithium-ion batteries. However, the substantial localized mechanical strain caused by the large volume expansion often results in electrode disintegration and capacity loss. Herein, a microporous Si anode with the SiO x /C layer functionalized all-surface and high tap density (~ 0.65 g cm⁻ 3 ) is developed by the hydrolysis-driven strategy that avoids the common use of corrosive etchants and toxic siloxane reagents. The functionalized inner pore with superior structural stability can effectively alleviate the volume change and enhance the electrolyte contact. Simultaneously, the outer particle surface forms a continuous network that prevents electrolyte parasitic decomposition, disperses the interface stress of Si matrix and facilitates electron/ion transport. As a result, the micron-sized Si anode shows only ~ 9.94 GPa average stress at full lithiation state and delivers an impressive capacity of 901.1 mAh g⁻ 1 after 500 cycles at 1 A g⁻ 1 . It also performs excellent rate performance of 1123.0 mAh g⁻ 1 at 5 A g⁻ 1 and 850.4 at 8 A g⁻ 1 , far exceeding most of reported literatures. Furthermore, when paired with a commercial LiNi 0.8 Co 0.1 Mn 0.1 O 2 , the pouch cell demonstrates high capacity and desirable cyclic performance.

Si anode materials are promising candidates for next-generation Li-ion batteries (LIBs) because of their high capacities. However, expansion and low conductivity result in rapid performance degradation. Herein, we present a facile one-pot method for pyrolyzing polystyrene sulfonate (PSS) polymers at low temperatures (≤400 °C) to form a thin carbonaceous layer on the silicon surface. Specifically, micron silicon (mSi) was transformed into porous mSi (por-mSi) by a metal-assisted chemical etching method, and a phenyl-based thin film derived from the thermolysis of PSS formed a strong Si–C/Si–O–C covalent bonding with the Si surface, which helped maintain stable cycle performance by improving the interfacial properties of mSi. Additionally, PSS-grafted por-mSi (por-mSi@PSS) anode was coated with polyaniline (PANI) for endowing additional electrical conductivity. The por-mSi@PSS/PANI anode demonstrated a high reversible capacity of ~1500 mAh g−1 at 0.1 A g−1 after 100 cycles, outperforming or matching the performance reported in recent studies. A thin double layer composed of phenyl moieties and a conductive PANI coating improved the stability of Si-based anodes and provided an effective pathway for Li+ ion transport to the Si interface, suggesting that polymer-modified Si anodes hold significant promise for advanced LIB applications.

Porous silicon/carbon (Si/C) anode materials for Lithium-ion batteries was synthesized successfully by hydrochloric acid etching and calcination method using micron Si-Al alloy as silicon source and phenolic resin as carbon source. The microstructure and morphology were characterized by XRD, SEM, TEM, XPS and BET. The electrochemical performance were measured by constant current charge-discharge test and EIS. The results show that Si/C is porous structure and its pores are distributed between 1 and 6 nm. The specific discharge specific capacity of Si/C is 1287.0 mAh/g at a current density of 100 mA/g after 50 cycles, corresponding to the capacity retention of 91.0 % (for the second cycle). Si/C delivers a high specific discharge capacity of 605.9 and 359.0 mAh/g at 1 A/g and 2 A/g, respectively. The lithium ion diffusion coefficient of Si/C is 5.98 × 10 − 11 cm 2 s − 1 , which is higher than that of 7.57 × 10 − 12 cm 2 s − 1 for porous Si.