Red Phosphorus Anodes Research Articles

Nacre-Inspired Structure Enables Ultrahigh 'Strong-Tough' Design of Phosphorus Anode.

Red phosphorus anode, attributed to its high specific capacity of 2596 mAh g-1, is expected to improve the energy density of Na-ion batteries. However, the P anode currently is unsatisfactory for practical usage due to the large volume expansion beyond 300 %, which brings out uncontrolled brittle failure. To address this challenge, we here design a nacre-like phosphorus anode by resilient graphene oxide staggered together. The staggered structure simultaneously offers mechanical strength and interwoven toughness. Finite element modeling reveals that the sodiation stress from P nanoparticles will be transferred into interlayer pillars as the elastic medium to release sodiation stress. The prepared anode achieves an ultrahigh areal capacity of 13 mAh cm-2 at a mass loading of 5.8 mg cm-2. Notably, the volume change of the anode is limited to approximately 8.1 % at full sodiation, significantly lower than that of the traditional phosphorus electrodes.

Fluorine Doping Modulating Pore Structure and Adsorption Capability of Carbon Matrix Boosting Potassium Storage Performance of Red Phosphorus Anode

AbstractThe application of alloying‐typed red phosphorus (red P) anode in potassium‐ion batteries (KIBs) with ultra‐high theoretical capacity is hindered by the limited capacity and fast capacity decay due to poor electronic conductivity and huge volume change. Herein, a facile and efficient strategy of fluorine (F) doping is innovatively developed to modulate the pore structure of carbon matrix (F‐CNS) to encapsulate red P with enhanced potassium storage capability. Theoretical calculations reveal that F doping induces additional defects within the carbon layer, which facilitates P4 molecules embedding into the F‐doping‐induced micropores, enhances the adsorption ability toward K atoms and P4 molecules, and improves electrochemical kinetics assisted with more charge transfer obtained from the electron density difference, thus enabling robust potassium storage capability for such unique Red P@F‐CNS anode. Accordingly, the Red P@F‐CNS anode demonstrates outstanding cycling stability (90% capacity retention after 800 cycles at 2A g−1), and the potassium‐ion full cell (Red P@F‐CNS//KFeHCF) exhibits exceptional long‐term cycling performance (129 mAh g−1 after 2500 cycles at 5 A g−1 with only 0.014% decay per cycle). In situ characterizations confirm the superior structural integrity of the carbon‐based matrix. This study offers a rational design principle for engineering high‐performance carbon‐supported alloying‐typed anodes for KIBs.

Homogeneous Adsorption of Multiple Potassiation Products of Red Phosphorus Anode toward Stable Potassium Storage.

Potassium ion batteries (PIBs) are a viable alternative to lithium-ion batteries for energy storage. Red phosphorus (RP) has attracted a great deal of interest as an anode for PIBs owing to its cheapness, ideal electrode potential, and high theoretical specific capacity. However, the direct preparation of phosphorus-carbon composites usually results in exposure of the RP to the exterior of the carbon layer, which can lead to the deactivation of the active material and the production of "dead phosphorus". Here, the advantage of the π-π bond conjugated structure and high catalytic activity of metal phthalocyanine (MPc) is used to prepare MPc@RP/C composites as a highly stable anode for PIBs. It is shown that the introduction of MPc greatly improves the uneven distribution of the carbon layer on RP, and thus improves the initial Coulombic efficiency (ICE) of PIBs (the ICE of FePc@RP/C is 75.5% relative to 62.9% of RP/C). The addition of MPc promotes the growth of solid electrolyte interphase with high mechanical strength, improving the cycle stability of PIBs (the discharge-specific capacity of FePc@RP/C is 411.9 mAh g-1 after 100 cycles at 0.05 A g-1). Besides, density functional theory theoretical calculations show that MPc exhibits homogeneous adsorption energies for multiple potassiation products, thereby improving the electrochemical reactivity of RP. The use of organic molecules with high electrocatalytic activity provides a universal approach for designing superior high-capacity, large-volume expansion anodes for PIBs.

Conductive polymer-coated red phosphorus encapsulated in 3D graphene oxide aerogel for high-performance sodium-ion batteries anode

Relying on the high theoretical capacity for sodium storage, red phosphorus (RP) has attracted tremendous attention. However, its utilization is confronted with numerous limitations, such as substantial volume expansion and inferior conductivity. Herein, a RP anode (P/PPy@rGO) coated by conductive polypyrrole (PPy) was encapsulated in a spatially self-assembled reduced graphene oxide (rGO) aerogel by electrostatic interaction. The coating of PPy can not only enhance the conductivity of RP effectively, but also facilitate the connection between RP and rGO. Moreover, the rGO aerogel can accommodate the volume expansion of RP. Benefited from this unique structure, the P/PPy@rGO electrode can exhibit an enhanced rate performance (619 mAh/g at 5.2A g−1) and excellent cycling stability with a capacity retention of 89.5 % after 100 cycles. This work would contribute to the suitable design of phosphorus-based anode for sodium storage.

Electron-deficient sites on boron-doped graphite enable air-stable and durable red phosphorus anode for lithium-ion batteries

Electron-deficient boron doping into graphite can enhance the chemical affinity to electron-rich RP via strong P–C bonds, which can maintain the structural stability and effective electrical contact between them during long-term cycling processes.

Heteroatomic phosphorus selenides molecules encapsulated in porous carbon as a highly reversible anode for sodium-ion batteries

Red phosphorus has been recognized as a promising anode material for sodium ion batteries (SIBs) because of its large theoretical capacity and suitable sodiation potential. However, low conductivity, large volume change, and incomplete alloy/de-alloy caused by a high formation energy (Ef) of a Na3P sodiation product hinder its practical applications. Herein, we found that element Se can offer a relatively low Ef for a sodiation product and form a robust P–Se bond, which effectively improves the conductivity and Na+ reaction kinetics. In this direction, heteroatomic amorphous phosphorus-rich phosphorus selenides molecules encapsulated into porous carbon nanotubes (a-P9Se@pCNTs) were successfully prepared, showing a highly reversible Na+ storage ability with high initial Coulombic efficiency of 85.9%, a high specific capacity of 2215 mAh/g, and an excellent rate capability even at a high mass loading of ∼70 wt %. The combined density functional theory calculations and comprehensive experimental study authenticate that the lower formation energy of a sodiated product and the fast ion transport ability of P9Se can significantly accelerate reversible alloy/de-alloy reaction, improve pulverization issues, and restrain the undesired decomposition of an electrolyte, resulting in full nearly utilization of an active material and a stable solid electrolyte interphase. The present finding demonstrates an innovative design pathway for a red phosphorus anode and guides substantial progress of energy storage devices.

NaF-rich interphase and high initial coulombic efficiency of red phosphorus anode for sodium-ion batteries by chemical presodiation.

Red phosphorus/carbon (P/C) materials have been extensively studied as promising anodes for sodium-ion batteries (SIBs) owing to their high capacities and moderate working potentials. However, the low initial Coulombic efficiency (ICE) and unstable solid-electrolyte interphase (SEI) of P/C composites limit their widespread applications. In this study, we develop an effective presodiation method to compensate for the irreversible sodium loss of the S-doped P/C (P/C@S) anode and yield a thin, uniform, and NaF-rich SEI layer on the presodiated P/C@S (pNa-P/C@S) anode during cycling. Consequently, the pNa-P/C@S anode exhibits a remarkable ICE of 98.7% as well as superior cycling performance and rate capability in the half cell. When pNa-P/C@S anode is coupled with conventional Na3V2(PO4)2F3, Na3V2(PO4)3, and NaCu0.12Ni0.23Fe0.33Mn0.33 cathodes, all the full cells demonstrate desirable ICEs (>98%), high energy densities, and excellent cycling performance. The proposed method has been extended to another anode (SnO2) to demonstrate its applicability in fabricating anodes with a high ICE and stable NaF-rich SEI layer.

Hierarchical Ion/Electron Networks Enable Efficient Red Phosphorus Anode with High Mass Loading for Sodium Ion Batteries

AbstractRed phosphorus (RP), with high theoretical specific capacity and low working potential, has been regarded as one of the most promising anodes for high‐performance sodium‐ion batteries (SIBs). However, the unsatisfactory performance of RP anodes especially under high mass loading conditions severely limited the development for practical applications, due to its large volume variations during cycling processes, and the poor electronic and ionic conductivity. Here, a hierarchical WDC/CNTs@RP electrode with high mass loadings of RP (up to 14.1 mg cm−2) and superior conductivity is rationally designed for both ions and electrons. Such unique hierarchical structures enable an unprecedented rate performance (1.63 mAh cm−2 under 106.6 mA cm−2), long cycling life, and a decent gravimetric capacity of 468.88 mA h g−1 based on the whole electrode and inactive components. This work presents an essential step toward practical applications of RP anode materials for SIBs batteries.

A novel red phosphorus/reduced graphene oxide-C3N4 composite with enhanced sodium storage capability

• N -enriched rGO-C 3 N 4 hybrid network is proposed as matrix for phosphorus composites. • Interfacial compatibility between rGO-C 3 N 4 and red phosphorus is realized by P N bond. • Interfacial bonding is revealed by theoretical calculations. • Enhanced kinetics is facilitates by the formation of P N bonds. Red phosphorus (RP) has attracted wide attention as a promising anode candidate for sodium ion batteries due to its admirable specific capacity, safe working potential and low cost. However, its large volumetric expansion during desodiation/sodiation process and poor electronic conductivity hinder the progress of red phosphorus electrodes. Here, the N -enriched reduced graphene oxide-C 3 N 4 (rGO-C 3 N 4 ) network is utilized to facilitate the electronic conductivity and construct a robust architecture through P N bonds. Admirable bonding strength between phosphorus and the C 3 N 4 hybrid framework is revealed by the calculations via the first principles based on density function theory. The red phosphorus/rGO-C 3 N 4 anode for sodium ion batteries obtained via a facile ball-milling method exhibits a discharge capacity of 652.6 mA h g −1 after 100 cycles. This method holds great promise on developing red phosphorus anode on sodium-ion batteries.

Redox‐Mediated Red‐Phosphorous Semi‐Liquid Anode Enabling Metal‐Free Rechargeable Na‐Seawater Batteries with High Energy Density

AbstractSodium‐seawater batteries (Na‐SWB) are considered among the most promising electrochemical devices for large‐scale energy storage and the marine sector. In fact, by employing an open‐structured cathode, they benefit from the unlimited supply of sodium from seawater. This means, that the energy of such systems is intrinsically limited by the capacity of the anode. In order to increase the energy of Na‐SWB, it is therefore necessary to introduce a high‐capacity anode such as, e.g., red phosphorus. However, due to its large volume changes upon charge/discharge processes, obtaining thick electrodes and large areal capacity is extremely challenging. Herein, the areal/absolute capacity of the red phosphorus anode is increased by employing a semi‐liquid electrode, which includes two redox mediators, i.e., sodium‐biphenyl and sodium‐pyrene, as reducing and oxidizing species for the exploitation of the full red phosphorus capacity. As a result, the red phosphorus semi‐liquid anode in Na‐SWB provides a high‐capacity of 15 mAh cm–2 in a static anode, showing great energy storage potential for operation in flow‐mode when storing the semi‐liquid negative electrode in a storage tank.

Stress- and Interface-Compatible Red Phosphorus Anode for High-Energy and Durable Sodium-Ion Batteries

Sodium-ion batteries are promising candidates for energy storage application, but the absence of high-capacity and low-cost anode materials significantly limits their practical specific energy and ...

Surface synergistic protections on red phosphorus anode material by poly(3,4-ethylenedioxythiophene) coating and electrolyte strategy in sodium ion batteries

Red phosphorus has attracted more attention as a promising sodium storage material due to its ultra-high theoretical capacity and suitable sodiation potential. However, the low intrinsic electrical conductivity and large volume change of pristine red phosphorus lead to high polarization and fast capacity fading during cycling. Herein, surface synergistic protections on red phosphorus composite are successfully proposed by conductive poly(3,4-ethylenedioxythiophene) (PEDOT) coating and electrolyte strategy. Nanoscale red phosphorus is confined in porous carbon skeleton and the outside is packaged by PEDOT coating via in-situ polymerization. Porous carbon provides rich pathways for rapid Na+ diffusion and empty spaces accommodate the volume expansion of red phosphorus, PEDOT coating isolates the direct contact between electrolyte and active materials to form a stable solid electrolyte interphase. In addition, the reformulated electrolyte with 3 wt% SbF3 additives can stabilize the electrode surface and thus enhance the electrochemical performance, especially cycling stability and rate capability (433 mA·h·g−1 at high current density of 10 A/g).

Electrochemo-Mechanical Properties of Red Phosphorus Anodes in Lithium, Sodium, and Potassium Ion Batteries

Summary Red phosphorus (RP) is a promising anode material for alkali-ion batteries due to a high theoretical capacity at low potentials when alloying with lithium, sodium, and potassium. Most alloy anode materials display large volume changes during cycling, which can lead to particle fracturing, low Coulombic efficiency, loss of electrical contact, and ultimately poor cycle life. In this paper we outline, through comprehensive electrochemo-mechanical characterization and modeling of the cycling stresses, why RP can be cycled at high current densities without fracture. Application of in situ nanoindentation and powder compression allows for measurement of the elastic, plastic, and fracture properties of RP. In situ transmission electron microscopy observation with extreme conditions (anisotropic ion diffusion and high current density) was used to validate the model, observing no catastrophic failure of RP particles. Electrochemo-mechanical characterization with geometry and stress modeling allows for predictions to be made for application of RP in alkali-ion batteries.

Improved fast-charging performances of phosphorus electrodes using the intrinsically flame-retardant LiFSI based electrolyte

Red phosphorus (RP) has recently gained great attention for high-energy-density fast-charging lithium-ion batteries (LIBs) due to its high theoretical specific capacity (2596 mA h g−1) and safe lithiation voltage (ca. 0.7 V vs. Li+/Li). Here, we adopt a new electrolyte system, the thermally stable lithium bis(fluorosulfonyl)imide (LiFSI) in the mixed solvents of intrinsically flame-retardant triethyl phosphate (TEP) and fluoroethylene carbonate (FEC) as a solid electrolyte interface (SEI)-forming additive, resulting in an enhanced electrochemical performance for the application of P anode. LiFSI avoids the side effect of fluorination that is prone to occur at the surface of P particles in commonly used lithium hexafluorophosphate (LiPF6)-based electrolyte. As a result, combining the ternary synergy of LiFSI, TEP and FEC, a favorable and stable lithium fluoride (LiF) and non-LixPFy based SEI is constructed on the RP anode through the preferential reduction of the Li+ solvation structure, and subsequent reduction deposition of FSI− anion and FEC solvent. This stable SEI plays a critical role in alleviating the huge volumetric expansion of P, decreasing the reactivity of P anode within electrolyte during cycling process and thus enhancing the fast-charging performance of P anode.

Fabrication of red phosphorus anode for fast-charging lithium-ion batteries based on TiN/TiP2-enhanced interfacial kinetics

Red phosphorus (RP) is an ideal anode for fast-charging lithium-ion batteries due to its high capacity (2596 ​mA ​h ​g−1) and suitable lithiation potential (0.7 ​V vs. Li/Li+). We embedded amorphous soft RP nanoparticles in the hard and micro-sized TiN nanosheet as well as CNT via high-energy ball milling, thus, TiP2 layer was fabricated at the interface of RP and TiN. This in-situ formed conductive TiP2 substantive layer enhances Li+ diffusion, improves the interfacial stability of RP, and inhibits the side reaction between P and electrolytes. Thus the RP/TiN/CNT electrode shows excellent fast-charging and long-term cycling performances, such as, a high fast-charging retention of 92.6% from the 5th to 200th cycles with charging current density of 8 ​A ​g‒1 (= 3 ​C rate, about 3 ​min) and discharging current density of 0.15 ​A ​g‒1, and a 96.9% capacity retention from 3rd to 850th cycles at 2.3 ​A ​g‒1.

Improving the structure stabilization of red phosphorus anodes via the shape memory effect of a Ni-Ti alloy for high-performance sodium ion batteries.

A Ni-Ti memory alloy was introduced to alleviate the huge volume change in red-P anodes for Na-ion batteries. The Ni-Ti-P delivered a high initial coulombic efficiency of 80%, and retained almost 100% of the initial reversible capacity after 20 cycles. Utilizing the shape memory effect to accommodate a huge volumetric change favors the recovery of the anode structure.

Stable Sodium Storage of Red Phosphorus Anode Enabled by a Dual-Protection Strategy.

Red phosphorus is appealing for anode use in sodium-ion batteries. However, the synthesis of electrochemically stable red P anodes remains challenging due to a notable volume variation upon (de)sodiation, and limited synthetic methods arising from the low ignition and sublimation temperatures. To address the above problems, we herein successfully develop an industrially adaptable process for scalable synthesis of affordable phosphorus/carbon (APC) anode materials with an excellent electrochemical performance at a significantly reduced cost. The key to our success is a delicately designed, self-organized, strongly interactive porous P/C structure filled with sodium alginate binder, which maintains the structural integrity of anode and enhances the electrical contact of red P upon its volume variation via a dual protection from porous structure and strong surface interactions. The APC anodes hence present ultrahigh initial Coulombic efficiency (86.2%), excellent cycling stability, and superior rate capability. The industrially adaptable process and excellent electrochemical performance endow the novel APC nano/microspheres with promising applications in high-performance Na-ion batteries.

Anion Radical Mediated High Capacity Redox Flow Battery

The energy density of conventional redox flow batteries (RFBs) is dictated by their capacity (which is directly related to the solubility of the redox species in the electrolyte) and operating potential. RFBs have low operating potentials ca. 1.5 V, resulting in poor energy densities (25 – 30 Wh/kg for an all vanadium RFB), whereas systems containing organic electrolytes with wider electrochemical windows can potentially have moderately higher energy densities. A new approach to improve the performance of nonaqueous redox flow batteries (RFBs) through electrochemically-mediated reactions is demonstrated. Soluble anion radical species (biphenyl and pyrene) mediate reversible sodium storage in a red phosphorus anode located in an external plug flow reactor in the absence of binders or conductive additives. Because the anion radical species can be recycled several times throughout the cell stack during a single charge/discharge cycle, a mediated RFB effectively decouples the battery’s energy density from the redox species’ solubility in the electrolyte. Furthermore, this technology offers inherently safe operation and is unaffected by the large volume changes of red P (>300%) due to the use of an external plug flow reactor. This presentation will describe the mechanism of a mediated RFB and discuss important design considerations (e.g., selection of appropriate electrolyte, mediators, active materials, etc.). Results showing electrochemically mediated sodiation and desodiation of a phosphorus anode in a redox flow configuration will be presented This work is supported by Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U. S. Department of Energy and The Office of Electricity Delivery and Reliability, U. S. Department of Energy.

Red Phosphorus Nanodots on Reduced Graphene Oxide as a Flexible and Ultra-Fast Anode for Sodium-Ion Batteries.

Sodium-ion batteries offer an attractive option for potential low cost and large scale energy storage due to the earth abundance of sodium. Red phosphorus is considered as a high capacity anode for sodium-ion batteries with a theoretical capacity of 2596 mAh/g. However, similar to silicon in lithium-ion batteries, several limitations, such as large volume expansion upon sodiation/desodiation and low electronic conductance, have severely limited the performance of red phosphorus anodes. In order to address the above challenges, we have developed a method to deposit red phosphorus nanodots densely and uniformly onto reduced graphene oxide sheets (P@RGO) to minimize the sodium ion diffusion length and the sodiation/desodiation stresses, and the RGO network also serves as electron pathway and creates free space to accommodate the volume variation of phosphorus particles. The resulted P@RGO flexible anode achieved 1165.4, 510.6, and 135.3 mAh/g specific charge capacity at 159.4, 31878.9, and 47818.3 mA/g charge/discharge current density in rate capability test, and a 914 mAh/g capacity after 300 deep cycles in cycling stability test at 1593.9 mA/g current density, which marks a significant performance improvement for red phosphorus anodes for sodium-ion chemistry and flexible power sources for wearable electronics.