Phosphorus‐Based Anodes for Fast Charging Lithium‐Ion Batteries: Challenges and Opportunities

Balancing Potassiophilicity and Catalytic Activity of Artificial Interface Layer for Dendrite-Free Sodium/Potassium Metal Batteries

Potassium metal batteries (PMBs), with high energy density and low cost, are considered a promising option for grid-scale energy storage systems. However, challenges such as the uneven nucleation of K and instability of the solid electrolyte interphase (SEI) layer result in dendrite growth and poor cyclic performance, limiting practical application. To address them, constructing an artificial interface layer with rich defects can enhance the potassium affinity and promote the uniform nucleation of potassium, yet this can also catalyze electrolyte to decompose, leading to unstable SEI formation and poor cycle stability. Herein, a carbon layer with a locally ordered structure (SC-1600) is constructed as the artificial interface to achieve a balance between K affinity and catalytic activity. This optimized design allows for the uniform nucleation of potassium metal and the formation of a dense SEI layer. SC-1600@K symmetric cell can operate for 2000 h at 0.5 mA cm-2 with a capacity of 0.5 mAh cm-2, and the developed full cell shows a high capacity retention of 78% after 1500 cycles at 1 A g-1. Besides, SC-1600@Na effectively extend the life of sodium metal batteries. This work provides a new insight for the construction of efficient K metal artificial interface layer.

Optimization of Porous Structures of Carbon Matrices for Loading Red Phosphorus to Achieve High-Capacity and Long-Life Anodes for All-Solid-State Lithium-Ion Batteries

All-solid-state lithium-ion batteries (ASSLIBs) using sulfide electrolytes and high-capacity alloy-type anodes have attracted sizable interest due to their potential excellent safety and high energy density. Encapsulating insulating red phosphorus (P) inside nanopores of a carbon matrix can adequately activate its electrochemical alloying reaction with lithium. Therefore, the porosity of the carbon matrix plays a crucial role in the electrochemical performance of the resulting red P/carbon composites. Here, we use zeolite-templated carbon (ZTC) with monodisperse micropores and mesoporous carbon (CMK-3) with uniform mesopores as the model hosts of red P. Our results reveal that micropores enable more effective pore utilization for the red P loading, and the P@ZTC material can achieve a record-high content (65.0 wt %) of red P confined within pores. When used as an anode of ASSLIBs, the P@ZTC electrode delivers an ultrahigh capacity of 1823 mA h g-1 and a high initial Coulombic efficiency of 87.44%. After 400 deep discharge-charge cycles (running over 250 days) at 0.2 A g-1, the P@ZTC electrode still holds a reversible capacity of 1260 mA h g-1 (99.92% capacity retention per cycle). Moreover, a P@ZTC||LiNi0.8Co0.1Mn0.1O2 full cell can deliver a reversible areal capacity of over 3 mA h cm-2 at 0.1C after 100 cycles.

Fast-Charging Phosphorus-Based Anodes: Promises, Challenges, and Pathways for Improvement

Fast-charging batteries are highly sought after. However, the current battery industry has used carbon as the preferred anode, which can suffer from dendrite formation problems at high current density, causing failure after prolonged cycling and posing safety hazards. The phosphorus (P) anode is being considered as a promising successor to graphite due to its safe lithiation potential, low ion diffusion energy barrier, and high theoretical storage capacity. Since 2019, fast-charging P-based anodes have realized the goals of extreme fast charging (XFC), which enables a 10 min recharging time to deliver a capacity retention larger than 80%. Rechargeable battery technologies that use P-based anodes, along with high-capacity conversion-type cathodes or high-voltage insertion-type cathodes, have thus garnered substantial attention from both the academic and industry communities. In spite of this activity, there remains a rather sparse range of high-performance and fast-charging P-based cell configurations. Herein, we first systematically examine four challenges for fast-charging P-based anodes, including the volumetric variation during the cycling process, the electrode interfacial instability, the dissolution of polyphosphides, and the long-lasting P/electrolyte side reactions. Next, we summarize a range of strategies with the potential to circumvent these challenges and rationally control electrochemical reaction processes at the P anode. We also consider both binders and electrode structures. We also propose other remaining issues and corresponding strategies for the improvement and understanding of the fast-charging P anode. Finally, we review and discuss the existing full cell configurations based on P anodes and forecast the potential feasibility of recycling spent P-based full cells according to the trajectory of recent developments in batteries. We hope this review affords a fresh perspective on P science and engineering toward fast-charging energy storage devices.

Lithiation of phosphorus at the nanoscale: a computational study of LinPm clusters

Systematic structure prediction of LinPm nanoclusters was performed for a wide range of compositions (0 ≤ n ≤ 10, 0 ≤ m ≤ 20) using the evolutionary global optimization algorithm USPEX coupled with density functional calculations. With increasing Li concentration, the number of P-P bonds in the cluster reduces and the phosphorus backbone undergoes the following transformations: elongated tubular → multi-fragment (with mainly P5 rings and P7 cages) → cyclic topology → branched topology → P-P dumbbells → isolated P ions. By applying several stability criteria, we determined the most favorable LinPm clusters and found that they are located in the compositional area between m ≈ n/3 and m ≈ n/3 + 6. For instance, the Li3P7 cluster has the highest stability and is known to be the structural basis of the corresponding bulk crystal. The obtained results provide valuable insights into the lithiation mechanism of nanoscale phosphorus which is of interest for development of novel phosphorus-based anode materials.

Emerging Multiscale Porous Anodes toward Fast Charging Lithium-Ion Batteries

With the accelerated penetration of the global electric vehicle market, the demand for fast charging lithium-ion batteries (LIBs) that enable improvement of user driving efficiency and user experience is becoming increasingly significant. Robust ion/electron transport paths throughout the electrode have played a pivotal role in the progress of fast charging LIBs. Yet traditional graphite anodes lack fast ion transport channels, which suffer extremely elevated overpotential at ultrafast power outputs, resulting in lithium dendrite growth, capacity decay, and safety issues. In recent years, emergent multiscale porous anodes dedicated to building efficient ion transport channels on multiple scales offer opportunities for fast charging anodes. This review survey covers the recent advances of the emerging multiscale porous anodes for fast charging LIBs. It starts by clarifying how pore parameters such as porosity, tortuosity, and gradient affect the fast charging ability from an electrochemical kinetic perspective. We then present an overview of efforts to implement multiscale porous anodes at both material and electrode levels in diverse types of anode materials. Moreover, we critically evaluate the essential merits and limitations of several quintessential fast charging porous anodes from a practical viewpoint. Finally, we highlight the challenges and future prospects of multiscale porous fast charging anode design associated with materials and electrodes as well as crucial issues faced by the battery and management level.

Oxygen Defect Engineering toward Zero-Strain V2O2.8@Porous Reticular Carbon for Ultrastable Potassium Storage

Potassium-ion batteries (KIBs) are promising candidates for large-scale energy storage devices due to their high energy density and low cost. However, the large potassium-ion radius leads to its sluggish diffusion kinetics during intercalation into the lattice of the electrode material, resulting in electrode pulverization and poor cycle stability. Herein, vanadium trioxide anodes with different oxygen vacancy concentrations (V2O2.9, V2O2.8, and V2O2.7 determined by the neutron diffraction) are developed for KIBs. The V2O2.8 anode is optimal and exhibits excellent potassium storage performance due to the realization of expanded interlayer spacing and efficient ion/electron transport. In situ X-ray diffraction indicates that V2O2.8 is a zero-strain anode with a volumetric strain of 0.28% during the charge/discharge process. Density functional theory calculations show that the impacts of oxygen defects are embodied in reducing the band gap, increasing electron transfer ability, and lowering the diffusion energy barriers for potassium ions. As a result, the electrode of nanosized V2O2.8 embedded in porous reticular carbon (V2O2.8@PRC) delivers high reversible capacity (362 mAh g-1 at 0.05 A g-1), ultralong cycling stability (98.8% capacity retention after 3000 cycles at 2 A g-1), and superior pouch-type full-cell performance (221 mAh g-1 at 0.05 A g-1). This work presents an oxygen defect engineering strategy for ultrastable KIBs.

2D Layered Materials for Fast-Charging Lithium-Ion Battery Anodes

The development of electric vehicles has received worldwide attention in the background of reducing carbon emissions, wherein lithium-ion batteries (LIBs) become the primary energy supply systems. However, commercial graphite-based anodes in LIBs currently confront significant difficulty in enduring ultrahigh power input due to the slow Li+ transport rate and the low intercalation potential. This will, in turn, cause dramatic capacity decay and lithium plating. The 2D layered materials (2DLMs) recently emerge as new fast-charging anodes and hold huge promise for resolving the problems owing to the synergistic effect of a lower Li+ diffusion barrier, a proper Li+ intercalation potential, and a higher theoretical specific capacity with using them. In this review, the background and fundamentals of fast-charging for LIBs are first introduced. Then the research progress recently made for 2DLMs used for fast-charging anodes are elaborated and discussed. Some emerging research directions in this field with a short outlook on future studies are further discussed.

Vanadium fluorophosphates: advanced cathode materials for next-generation secondary batteries

Next-generation secondary batteries including sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are considered the most promising candidates for application to large-scale energy storage systems due to their abundant, evenly distributed and cost-effective sodium/potassium raw materials. The electrochemical performance of SIBs (PIBs) significantly depends on the inherent characteristics of the cathode material. Among the wide variety of cathode materials, sodium/potassium vanadium fluorophosphate (denoted as MVPF, M = Na and K) composites are widely investigated due to their fast ion transportation and robust structure. However, their poor electron conductivity leads to low specific capacity and poor rate capacity, limiting the further application of MVPF cathodes in large-scale energy storage. Accordingly, several modification strategies have been proposed to improve the performance of MVPF such as conductive coating, morphological regulation, and heteroatomic doping, which boost the electronic conductivity of these cathodes and enhance Na (K) ion transportation. Furthermore, the development and application of MVPF cathodes in SIBs at low temperatures are also outlined. Finally, we present a brief summary of the remaining challenges and corresponding strategies for the future development of MVPF cathodes.

Advances in Electrospun Materials and Methods for Li-Ion Batteries

Electronic devices commonly use rechargeable Li-ion batteries due to their potency, manufacturing effectiveness, and affordability. Electrospinning technology offers nanofibers with improved mechanical strength, quick ion transport, and ease of production, which makes it an attractive alternative to traditional methods. This review covers recent morphology-varied nanofibers and examines emerging nanofiber manufacturing methods and materials for battery tech advancement. The electrospinning technique can be used to generate nanofibers for battery separators, the electrodes with the advent of flame-resistant core-shell nanofibers. This review also identifies potential applications for recycled waste and biomass materials to increase the sustainability of the electrospinning process. Overall, this review provides insights into current developments in electrospinning for batteries and highlights the commercialization potential of the field.

Two-Dimensional Black Phosphorus: Preparation, Passivation and Lithium-Ion Battery Applications

As a new type of single element direct-bandgap semiconductor, black phosphorus (BP) shows many excellent characteristics due to its unique two-dimensional (2D) structure, which has great potential in the fields of optoelectronics, biology, sensing, information, and so on. In recent years, a series of physical and chemical methods have been developed to modify the surface of 2D BP to inhibit its contact with water and oxygen and improve the stability and physical properties of 2D BP. By doping and coating other materials, the stability of BP applied in the anode of a lithium-ion battery was improved. In this work, the preparation, passivation, and lithium-ion battery applications of two-dimensional black phosphorus are summarized and reviewed. Firstly, a variety of BP preparation methods are summarized. Secondly, starting from the environmental instability of BP, different passivation technologies are compared. Thirdly, the applications of BP in energy storage are introduced, especially the application of BP-based materials in lithium-ion batteries. Finally, based on preparation, surface functionalization, and lithium-ion battery of 2D BP, the current research status and possible future development direction are put forward.

Multi-component surface engineering of Na3V2(PO4)2O2F for low-temperature (-40 °C) sodium-ion batteries

A functional Na₃V₂(PO₄)₂O₂F (NVPOF) cathode with a multi-component (Na₃V(PO₄)₂, V₂O₃, and reduced graphene oxide) surface coating is developed via a facile hydrothermal reaction followed by calcination, and exhibits high reversible capability, and long-term cycling stability even at a low temperature of -40 °C. It is demonstrated that the multi-component-coating layer can significantly accelerate the e^-/Na⁺ transport and reduce the interfacial resistance at low temperature. This work provides a novel strategy to boost the kinetics and stability of electrode materials for low-temperature sodium ion batteries.

Vanadium Tetrasulfide for Next-Generation Rechargeable Batteries: Advances and Challenges

Alkali metal-ion batteries (SIBs and PIBs) and multivalent metal-ion batteries (ZIBs, MIBs, and AIBs), among the next-generation rechargeable batteries, are deemed appealing alternatives to lithium-ion batteries (LIBs) because of their cost competitiveness. Improving the electrochemical properties of electrode materials can greatly accelerate the pace of development in battery systems to cover the increasing demands of realistic applications. Vanadium tetrasulfide (VS₄ ) is known as a prospective electrode material due to its unique one-dimensional atomic chain structure with a large chain spacing, weak interactions between adjacent chains, and high sulfur content. This review summarizes the synthetic strategies and recent advances of VS₄ as cathodes/anodes for rechargeable batteries. Meanwhile, we describe the structural characteristics and electrochemical properties of VS₄ . And we describe in detail its specific applications in batteries such as SIBs, PIBs, ZIBs, MIBs, and AIBs as well as modification strategies. Finally, the opportunities and challenges of VS₄ in the domain of energy research are described.