Li3V2(PO4)3 encapsulated flexible free-standing nanofabric cathodes for fast charging and long life-cycle lithium-ion batteries

Investigation of Lithium-Ion Battery Performance Utilizing Magnetic Controllable Superionic Conductor Li3(V1-x Fe x )2(PO4)3/C (x = 0.05 and 0.10)

Lithium-ion batteries with Li3V2(PO4)3/C as the cathode have been a popular research topic in recent years; however, studies of the effects of external magnetic fields on them are less common. This study investigates the effects of an external magnetic field applied parallel to the direction of the anode and cathode on the ion transport through iron-doped Li3(V1-x Fe x )2(PO4)3, the outer carbon coating, the film/electrolyte/separator, and up to the lithium metal electrode on a microscopic level. The results reveal that for the x = 0.05 sample with lower doping, the magnetostriction expansion of Li3(V1-x Fe x )2(PO4)3 and the magnetostrictive contraction effect of the outer ordered carbon layer cancel each other out, resulting in no significant enhancement of the battery's energy and power density due to the external magnetic field. In contrast, the x = 0.1 sample, lacking magnetostrictive contraction in the outer ordered carbon layer, shows that its energy and power density can be influenced by the magnetic field. Under zero magnetic field, the cyclic performance exhibits superior average capacity performance in the x = 0.05 sample, while the x = 0.1 sample shows a lower decay rate. Both samples are affected by the magnetic field; however, the x = 0.1 sample performs better under magnetic conditions. In particular, in the C-rate tests under a magnetic field, the sample with x = 0.1 showed a significant relative reduction in capacity decay rate by 20.18% compared to the sample with x = 0.05.

An interlayer spacing design approach for efficient sodium ion storage in N-doped MoS2

MoS₂ in a graphene-like structure that possesses a large interlayer spacing is a promising anode material for sodium ion batteries (SIBs). However, its poor cycling stability and bad rate performance limit its wide application. In this work, we synthesized an N-doped rGO/MoS₂ (ISE, interlayer spacing enlarged) composite based on an innovative strategy to serve as an anode material for SIBs. By inserting NH₄⁺ into the interlayer of MoS₂, the interlayer spacing of MoS₂ was successfully expanded to 0.98 nm. Further use of N plasma treatment achieved the doping of N element. The results show that N-rGO/MoS₂(ISE) exhibits a high specific capacity of 542 mA h g^-1 after 300 cycles at 200 mA g^-1. It is worth mentioning that the capacity retention rate reaches an ultra-large percentage of 97.13%, and the average decline percentage per cycle is close to 0.01%. Moreover, it also presents an excellent rate performance (477, 432, 377, 334 mA h g^-1 at 200, 500, 1000, 2000 m A g^-1 respectively). This work reveals a unique approach to fabricating promising anode materials and the electrochemical reaction mechanism for SIBs.

Boosting the cycling stability of Ni-rich layered oxide cathode by dry coating of ultrastable Li3V2(PO4)3 nanoparticles

Nickel (Ni)-rich layered oxides such as LiNi_0.6Co_0.2Mn_0.2O₂ (NCM622) represent one of the most promising candidates for next-generation high-energy lithium-ion batteries (LIBs). However, the pristine Ni-rich cathode materials usually suffer from poor structural stability during cycling. In this work, we demonstrate a simple but effective approach to improve the cycling stability of the NCM622 cathode by dry coating of ultrastable Li₃V₂(PO₄)₃-carbon (LVP-C) nanoparticles, which leads to a robust composite cathode (NCM622/LVP-C) without sacrificing the specific energy density compared with pristine NCM622. The optimal NCM622/LVP-C composite presents a high specific capacity of 162 mA h g^-1 at 0.5 C and excellent cycling performance with 85.0% capacity retention after 200 cycles at 2 C, higher than that of the pristine NCM622 (67.6%). Systematic characterization confirms that the LVP-C protective layer can effectively reduce the side reactions, restrict the cation mixing of NCM622 and improve its structural stability. Moreover, the NCM622/LVP-C||graphite full cells also show a commercial-level capacity of 3.2 mA h cm^-2 and much improved cycling stability compared with NCM622/LVP-C||graphite full cells, indicating the great promise for low-cost, high-capacity and long-life LIBs.

Stabilized covalent interfacial coupling design of Li3V2(PO4)3 with carbon framework for boosting lithium storage kinetics

LVP@C with stabilized electronic conductive layer is prepared by a facile organic–inorganic hybrid hydrogel-enabled methodology, in which LVP is chemically interacting with carbon framework via P–C and P–O–C bonds.

A mini-review: emerging all-solid-state energy storage electrode materials for flexible devices

New technologies for future electronics such as personal healthcare devices and foldable smartphones require emerging developments in flexible energy storage devices as power sources. Besides the energy and power densities of energy devices, more attention should be paid to safety, reliability, and compatibility within highly integrated systems because they are almost in 24-hour real-time operation close to the human body. Thereupon, all-solid-state energy devices become the most promising candidates to meet these requirements. In this mini-review, the most recent research progress in all-solid-state flexible supercapacitors and batteries will be covered. The main focus of this mini-review is to summarize new materials development for all-solid-state flexible energy devices. The potential issues and perspectives regarding all-solid-state flexible energy device technologies will be highlighted.

Rendering Redox Reactions of Cathodes in Li-Ion Capacitors Enabled by Lanthanides

Capacitors allow extremely fast charge and discharge operations, which is a challenge faced by recent metal-ion batteries despite having highly improved energy densities. Thus, combined type electric energy storage devices that can integrate high energy density and high power density with high potentials, can overcome the shortcomings of the current metal-ion batteries and capacitors. However, the limited capacities of cathode materials owing to the barren redox reactions are regarded as an obstacle for the development of future high-performance hybrid metal-ion capacitors. In this study, we demonstrate the redox-reaction-rendering effect of the much overlooked lanthanide elements when used as the cathode of lithium-ion capacitors using the mesoporous carbon (MC) as a matrix material. Consequently, these lanthanide elements can effectively enrich the redox reaction, thus improving the capacity of the matrix materials by more than two times. Typically, the Gd-elemental decoration of MC surprisingly enhances the capacity by almost two times as compared with the underacted MC. Furthermore, the La nanoparticles (NPs) decoration depicts the same behavior. Evident redox peaks were formed on the original rectangular cyclic voltammetry (CV) curves. This study provides the first example of embedding lanthanide elements on matrix materials to enrich the desired redox reactions for improving the electrochemical performances.

3D Electronic Channels Wrapped Large-Sized Na3 V2 (PO4 )3 as Flexible Electrode for Sodium-Ion Batteries

The development of portable and wearable electronics has aroused the increasing demand for flexible energy-storage devices, especially for the characteristics of high energy density, excellent mechanical properties, simple synthesis process, and low cost. However, the development of flexible electrodes for sodium-ion batteries (SIBs) is still limited due to the intricate production methods and the relatively high-cost of current collectors such as graphene/graphene oxide and carbon nanotubes. Here, the hierarchical 3D electronic channels wrapped large-sized Na₃ V₂ (PO₄ )₃ is designed and fabricated by a simple electrospinning technique. As flexible electrode material, it exhibits outstanding electrolyte wettability, together with ultrafast electronic conductivity and high Na-ion diffusion coefficients for SIBs, leading to superior electrochemical performances. A high reversible specific capacity of 116 mA h g^-1 (nearly 99% of the theoretical specific capacities) can be obtained at the current density of 0.1 C. Even after a 300-fold current density increased (30 C), the discharge specific capacity of the flexible electrode still remains 63 mA h g^-1 . Such an effective concept of fabricating 3D electronic channels for large-sized particles is expected to accelerate the practical applications of flexible batteries at various systems.

Nanostructured Li3 V2 (PO4 )3 Cathodes

To further increase the energy and power densities of lithium-ion batteries (LIBs), monoclinic Li₃ V₂ (PO₄ )₃ attracts much attention. However, the intrinsic low electrical conductivity (2.4 × 10^-7 S cm^-1 ) and sluggish kinetics become major drawbacks that keep Li₃ V₂ (PO₄ )₃ away from meeting its full potential in high rate performance. Recently, significant breakthroughs in electrochemical performance (e.g., rate capability and cycling stability) have been achieved by utilizing advanced nanotechnologies. The nanostructured Li₃ V₂ (PO₄ )₃ hybrid cathodes not only improve the electrical conductivity, but also provide high electrode/electrolyte contact interfaces, favorable electron and Li⁺ transport properties, and good accommodation of strain upon Li⁺ insertion/extraction. In this Review, light is shed on recent developments in the application of 0D (nanoparticles), 1D (nanowires and nanobelts), 2D (nanoplates and nanosheets), and 3D (nanospheres) Li₃ V₂ (PO₄ )₃ for high-performance LIBs, especially highlighting their synthetic strategies and promising electrochemical properties. Finally, the future prospects of nanostructured Li₃ V₂ (PO₄ )₃ cathodes are discussed.

Anthracite-Derived Dual-Phase Carbon-Coated Li3V2(PO4)3 as High-Performance Cathode Material for Lithium Ion Batteries

In this study, low cost anthracite-derived dual-phase carbon-coated Li₃V₂(PO₄)₃ composites have been successfully prepared via a traditional solid-phase method. XRD results show that the as-prepared samples have high crystallinity and anthracite introduction has no influence on the LVP crystal structure. The LVP/C particles are uniformly covered with a dual-phase carbon layer composed of amorphous carbon and graphitic carbon. The effect of the amount of anthracite on the battery performance of LVP as a cathode material has also been studied. The LVP/C composite obtained with 10 wt % anthracite (LVP/C-10) delivers the highest initial charge/discharge capacities of 186.1/168.2 mAh g^-1 at 1 C and still retains the highest discharge capacity of 134.0 mAh g^-1 even after 100 cycles. LVP/C-10 also displays an outstanding average capacity of 140.8 mAh g^-1 at 5 C. The superior rate capability and cycling stability of LVP/C-10 is ascribed to the reduced particle size, decreased charge-transfer resistance, and improved lithium ion diffusion coefficient. Our results demonstrate that using anthracite as a carbon source opens up a new strategy for larger-scale synthesis of LVP and other electrode materials with poor electronic conductivity for lithium ion batteries.

Carbon Nanofibers Heavy Laden with Li3V2(PO4)3 Particles Featuring Superb Kinetics for High-Power Lithium Ion Battery

Fast lithium ion and electron transport inside electrode materials are essential to realize its superb electrochemical performances for lithium rechargeable batteries. Herein, a distinctive structure of cathode material is proposed, which can simultaneously satisfy these requirements. Nanosized Li3V2(PO4)3 (LVP) particles can be successfully grown up on the carbon nanofiber via electrospinning method followed by a controlled heat-treatment. Herein, LVP particles are anchored onto the surface of carbon nanofiber, and with this growing process, the size of LVP particles as well as the thickness of carbon nanofiber can be regulated together. The morphological features of this composite structure enable not only direct contact between electrolytes and LVP particles that can enhance lithium ion diffusivity, but also fast electron transport through 1D carbon network along nanofibers simultaneously. Finally, it is demonstrated that this unique structure is an ideal one to realize high electron transport and ion diffusivity together, which are essential for enhancing the electrochemical performances of electrode materials.

3D porous Li3V2(PO4)3/hard carbon composites for improving the rate performance of lithium ion batteries

A 3D porous Li₃V₂(PO₄)₃/hard carbon composite delivers a capacity of 98 mA h g⁻¹ after 1000 cycles at 10C.

Roles of coating carbon, conductive additive and binders in lithium vanadium phosphate/reduced graphene oxide composite cathodes

Supreme high rate cycling performance can be achieved by optimizing the composition of LVP electrode.

Carbon wrapped hierarchical Li3V2(PO4)3 microspheres for high performance lithium ion batteries

Nanomaterials are extensively studied in electrochemical energy storage and conversion systems because of their structural advantages. However, their volumetric energy density still needs improvement due to the high surface area, especially the carbon based nanocomposites. Constructing hierarchical micro-scaled materials from closely stacked subunits is proposed as an effective way to solve the problem. In this work, Li₃V₂(PO₄)₃@carbon hierarchical microspheres are prepared by a solvothermal reaction and subsequent annealing. Hierarchical Li₃V₂(PO₄)₃ structures with different subunits are obtained with the aid of polyvinyl pyrrolidone (PVP). Moreover, excessive PVP interconnect and form PVP-based hydrogels, which later convert into conductive carbon layer on the surface of Li₃V₂(PO₄)₃ microspheres during the annealing process. As a cathode material for lithium ion batteries, the 3D carbon wrapped Li₃V₂(PO₄)₃ hierarchical microspheres exhibit high rate capability and excellent cycling stability. The electrode has the capacity retention of 80% after 5000 cycles even at 50C.

Flexible hierarchical membranes of WS2 nanosheets grown on graphene-wrapped electrospun carbon nanofibers as advanced anodes for highly reversible lithium storage

It is still very challenging to achieve effective combination of carbon nanofibers and graphene sheets. In this study, a novel and facile method is developed to prepare flexible graphene/carbon nanofiber (GCNF) membranes with every carbon nanofiber wrapped by conductive graphene sheets, resulting in a remarkable improvement of their electrical conductivity. This method only entails a moderate process of soaking the pre-oxidized electrospun polyacrylonitrile (oPAN) nanofiber membranes in graphene oxide (GO) aqueous dispersion, and subsequent carbonization of the GO/oPAN hybrid membranes. By using the highly conductive GCNF membrane as a template, hierarchical WS₂/GCNF hybrid membranes with few-layer WS₂ nanosheets uniformly grown on GCNF nanofibers were fabricated as high-performance anodes for lithium ion batteries. Benefiting from the synergistic effects of GCNF nanofibers and WS₂ nanosheets, the resulting WS₂/GCNF hybrid membranes possessed a porous structure, large specific surface area, high electrical conductivity and good structural integrity, which are favorable for the rapid diffusion of lithium ions, fast transfer of electrons and overall electrochemical stability. As a result, the optimized WS₂/GCNF hybrid membrane exhibited a high initial charge capacity of 1128.2 mA h g^-1 at a current density of 0.1 A g^-1 and outstanding cycling stability with 95% capacity retention after 100 cycles.

β-Cyclodextrin coated lithium vanadium phosphate as novel cathode material for lithium ion batteries

As a new carbon source, β-cyclodextrin was used to synthesize a Li₃V₂(PO₄)₃/C cathode material for LIB via a rheological phase method. The sample showed high capacity, good rate performance and cycle stability, and low resistance.