Microsized silicon particles are desirable Si anodes because of their low price and abundant sources. However, it is challenging to achieve stable electrochemical performances using a traditional microsized silicon anode due to the poor electrical conductivity, serious volume expansion, and unstable solid electrolyte interface. Herein, a composite microsized Si anode is designed and synthesized by constructing a unique polymer, poly(hexaazatrinaphthalene) (PHATN), at a Si/C surface (PCSi). The Li+ transport mechanism of the PCSi is elucidated by using in situ characterization and theoretical simulation. During the lithiation of the PCSi anode, CN groups with high electron density in the PHATN first coordinate Li+ to form CNLi bonds on both sides of the PHATN molecule plane. Consequently, the original benzene rings in the PHATN become active centers to accept lithium and form stable Li‐rich PHATN coatings. PHATN molecules expand due to the change of molecular configuration during the consecutive lithiation process, which provides controllable space for the volume expansion of the Si particles. The PCSi composite anode exhibits a specific capacity of 1129.6 mAh g−1 after 500 cycles at 1 A g−1, and exhibits compelling rate performance, maintaining 417.9 mAh g−1 at 16.5 A g−1.

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It is a challenge to synthesize highly efficient nonprecious metal electrocatalysts with a well-defined nanostructure and rich active species. Herein, through electron engineering and structure manipulation simultaneously, we constructed Fe-embedded pyridinic-N-dominated carbon nanotubes (CNTs) on ordered mesoporous carbon, showing excellent oxygen reduction reaction activity (half-wave potential, 0.85 V) and an overpotential of 420 mV to achieve 10 mA cm–2 for oxygen evolution reaction in alkaline media (potential difference, 0.80 V). Density functional theory calculation indicates those Fe@N4 clusters improve charge transfer and further promote the electrocatalytic reactivity of the functionalized region in CNTs. Rechargeable Zn–air batteries were assembled, displaying robust charging–discharging cycling performance (over 90 h) with voltage gap of only 0.08 V, much lower than that of the Pt/C + Ir/C electrode (0.29 V). This work presents a highly active nonprecious metal-based bifunctional catalyst toward air electrode for energy conversion.

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