Confined Amorphous Red Phosphorus in MOF‐Derived N‐Doped Microporous Carbon as a Superior Anode for Sodium‐Ion Battery

Abstract

Red phosphorus (P) has attracted intense attention as promising anode material for high-energy density sodium-ion batteries (NIBs), owing to its high sodium storage theoretical capacity (2595 mAh g ). Nevertheless, natural insulating property and large volume variation of red P during cycling result in extremely low electrochemical activity, leading to poor electrochemical performance. Herein, the authors demonstrate a rational strategy to improve sodium storage performance of red P by confining nanosized amorphous red P into zeolitic imidazolate framework-8 (ZIF-8) -derived nitrogen-doped microporous carbon matrix (denoted as P@N-MPC). When used as anode for NIBs, the P@N-MPC composite displays a high reversible specific capacity of ≈600 mAh g at 0.15 A g and improved rate capacity (≈450 mAh g at 1 A g after 1000 cycles with an extremely low capacity fading rate of 0.02% per cycle). The superior sodium storage performance of the P@N-MPC is mainly attributed to the novel structure. The N-doped porous carbon with sub-1 nm micropore facilitates the rapid diffusion of organic electrolyte ions and improves the conductivity of the encapsulated red P. Furthermore, the porous carbon matrix can buffer the volume change of red P during repeat sodiation/desodiation process, keeping the structure intact after long cycle life.

Nano-structured red phosphorus/porous carbon as a superior anode for lithium and sodium-ion batteries

“…White P is toxic and flammable, not suitable for battery applications. Red P has received more attention as an anode material for batteries than black P, as the former is abundant and environmentally benign [25][26][27][28]. However, the practical application of red P in batteries is severely hindered by its low electronic conductivity (~10-14 S cm −1 ) and significant volume change during charging/ discharging process (~300% and~400% in LIB and NIB applications, respectively) [26,[29][30][31][32].…”

“…It has been demonstrated that the combination of red P and carbonaceous (P/C) materials is an effective strategy to enhance the electrochemical properties of the red P [27][28][29][30]. There are generally two methods for fabricating P/C composites: ball milling and sublimation-condensation-conversion.…”

“…There are generally two methods for fabricating P/C composites: ball milling and sublimation-condensation-conversion. The facile ball milling method will generate various types of carbonaceous materials (i.e., carbon black [27,28], carbon nanotubes (CNTs) [30], graphite [35] and graphene [29]), which is effective to increase the conductivity and reduce volume change of the composite. Such P/C composites show both high specific capacity and initial Coulombic efficiency (ICE); however, the rate performance and cycle life are insufficient for practical applications.…”

“…Such P/C composites show both high specific capacity and initial Coulombic efficiency (ICE); however, the rate performance and cycle life are insufficient for practical applications. Through the sublimation-condensationconversion method, red P is confined to the surface or the pores of the carbon structures (e.g., single CNTs [26], graphene [32], activated carbon (AC) [31], ordered mesoporous carbon [9], micro-porous carbon [27], and others [34]). The resulting composites show both good rate performance and long cycle life in batteries.…”

“…To address these challenges, some groups have designed and constructed novel structures to improve the electrochemical performance of red P [26,27,29,33,34], including the introduction of conductive additives to increase the red P's electron conductivity and accommodate its volume change during cycling. It has been demonstrated that the combination of red P and carbonaceous (P/C) materials is an effective strategy to enhance the electrochemical properties of the red P [27][28][29][30].…”