Red Phosphorus–Single-Walled Carbon Nanotube Composite as a Superior Anode for Sodium Ion Batteries

Abstract

Sodium ion batteries (SIBs) have been considered as a top alternative to lithium ion batteries due to the earth abundance and low cost of sodium compared with lithium. Among all proposed anode materials for SIBs, red phosphorus (P) is a very promising candidate because it has the highest theoretical capacity (∼2600 mAh/g). In this study, a red P-single-walled carbon nanotube (denoted as red P-SWCNT) composite, in which red P is uniformly distributed between tangled SWCNTs bundles, is fabricated by a modified vaporization-condensation method. Benefiting from the nondestructive preparation process, the highly conductive and mechanically strong SWCNT network is preserved, which enhances the conductivity of the composite and stabilizes the solid electrolyte interphase. As a result, the red P-SWCNT composite presents a high overall sodium storage capacity (∼700 mAh/gcomposite at 50 mA/gcomposite), fast rate capability (∼300 mAh/gcomposite at 2000 mA/gcomposite), and stable long-term cycling performance with 80% capacity retention after 2000 sodiation-desodiation cycles. The red P-SWCNT composite fabricated by the vaporization-condensation method significantly extends the cycling stability of P/carbon composite from current ∼100 cycles to ∼2000 cycles.

Alkali metal ion storage properties of sulphur and phosphorous molecules encapsulated in nanometer size carbon cylindrical pores

“…However, phosphorus electrode still suffers from instability problems, despite the numerous attempts that have been made with different phosphorus polymorphs and/or different kinds of electrode support materials. [31][32][33] In the present study, we use the unique environment provided by the hollow core inside SWCNTs to encapsulate both sulfur and phosphorous molecules, in order to address some of the unanswered questions and performance issues of both LIS and SIB. First, we compare the physical stability of sulfur molecules inserted in MPC and in SWCNTs having different tube diameters, then we report the LIS battery electrode properties of sulfur encapsulated SWCNTs (S@SWCNTs).…”

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

“…These values were much higher than those of other P/C composites prepared by the vaporization-condensationconversion method as reported in the literature [6,9,26,27,31,32,34]. This might be attributed to the structure of the P@AC@CNT-3 composites, on the surface of which the openings were well sealed and the low S BET dramatically decreased the irreversible insertion of Li or Na into AC@CNT (Fig.…”

“…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]. These limitations cause the fracture of the electrode material during cycling, rapid capacity decay, and poor electrochemical performance at high charging/discharging rate [9].…”

“…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].…”

“…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.…”