Granadilla-Inspired Structure Design for Conversion/Alloy-Reaction Electrode with Integrated Lithium Storage Behaviors

Facile Green Synthesis of Pseudocapacitance-Contributed Ultrahigh Capacity Fe2(MoO4)3 as an Anode for Lithium-Ion Batteries

The investigation into the use of earth-abundant elements as electrode materials for lithium-ion batteries (LIBs) is becoming more urgent because of the high demand for electric vehicles and portable devices. Herein, a new green synthesis strategy, based on a facile solid-state reaction with the assistance of water droplets' vapor, was conducted to prepare Fe₂(MoO₄)₃ nanosheets as anode materials for LIBs. The obtained sample possesses a two-dimensional stacked nanosheet construction with open gaps providing a much higher surface area compared to the bulk sample conventionally synthesized. The nanosheet sample delivers an ultrahigh reversible capacity (1983.6 mA h g^-1) at a current density of 100 mA g^-1 after 400 cycles, which could be related to the contribution of pseudocapacitance. The enhancement in cyclability and rated performance with an interesting increased capacity could be caused by the effect of electrochemical milling and the in situ formation of metallic particles in its lithium-ion storage mechanism.

The rational design of carbon coated Fe2(MoO4)3 nanosheets for lithium-ion storage with high initial coulombic efficiency and long cycle life

Binary metal oxides are potential anode materials for lithium-ion storage due to their high theoretical specific capacities. However, the practical applications of metal oxides are limited due to their large volume changes and sluggish reaction kinetics. Herein, carbon coated Fe₂(MoO₄)₃ nanosheets are prepared via a simple method, adopting urea as the template and carbon source. The carbon coating on the surface helps to elevate the conductivity of the active material and maintain structural integrity during the lithium storage process. Combining this with a catalytic effect from the generated Fe, leading to the reversible formation of a solid electrolyte interface layer, a high initial coulombic efficiency (>87%) can be obtained. Based on this, the carbon coated Fe₂(MoO₄)₃ nanosheets show excellent rate capability (a reversible discharge capacity of 983 mA h g^-1 at 5 A g^-1) and stable cycling performance (1376 mA h g^-1 after 250 cycles at 0.5 A g^-1 and 864 mA h g^-1 after 500 cycles at 2 A g^-1). This simple in situ carbonization and template method using urea provides a facile way to optimize electrode materials for next-generation energy storage devices.

Facile Synthesis of Sn/Nitrogen-Doped Reduced Graphene Oxide Nanocomposites with Superb Lithium Storage Properties

Sn/Nitrogen-doped reduced graphene oxide (Sn@N-G) composites have been successfully synthesized via a facile method for lithium-ion batteries. Compared with the Sn or Sn/graphene anodes, the Sn@N-G anode exhibits a superb rate capability of 535 mAh g⁻¹ at 2C and cycling stability up to 300 cycles at 0.5C. The improved lithium-storage performance of Sn@N-G anode could be ascribed to the effective graphene wrapping, which accommodates the large volume change of Sn during the charge–discharge process, while the nitrogen doping increases the electronic conductivity of graphene, as well as provides a large number of active sites as reservoirs for Li⁺ storage.

Fe2 VO4 Hierarchical Porous Microparticles Prepared via a Facile Surface Solvation Treatment for High-Performance Lithium and Sodium Storage

Preventing the aggregation of nanosized electrode materials is a key point to fully utilize the advantage of the high capacity. In this work, a facile and low-cost surface solvation treatment is developed to synthesize Fe₂ VO₄ hierarchical porous microparticles, which efficiently prevents the aggregation of the Fe₂ VO₄ primary nanoparticles. The reaction between alcohol molecules and surface hydroxy groups is confirmed by density functional theory calculations and Fourier transform infrared spectroscopy. The electrochemical mechanism of Fe₂ VO₄ as lithium-ion battery anode is characterized by in situ X-ray diffraction for the first time. This electrode material is capable of delivering a high reversible discharge capacity of 799 mA h g^-1 at 0.5 A g^-1 with a high initial coulombic efficiency of 79%, and the capacity retention is 78% after 500 cycles. Moreover, a remarkable reversible discharge capacity of 679 mA h g^-1 is achieved at 5 A g^-1 . Furthermore, when tested as sodium-ion battery anode, a high reversible capacity of 382 mA h g^-1 can be delivered at the current density of 1 A g^-1 , which still retains at 229 mA h g^-1 after 1000 cycles. The superior electrochemical performance makes it a potential anode material for high-rate and long-life lithium/sodium-ion batteries.

Highly reversible and fast sodium storage boosted by improved interfacial and surface charge transfer derived from the synergistic effect of heterostructures and pseudocapacitance in SnO2-based anodes

Sodium-ion batteries have attracted worldwide attention as potential alternatives for large scale stationary energy storage due to the rich reserves and low cost of sodium resources. However, the practical application of sodium-ion batteries is restricted by unsatisfying capacity and poor rate capability. Herein, a novel mechanism of improving both interfacial and surface charge transfer is proposed by fabricating a graphene oxide/SnO₂/Co₃O₄ nanocomposite through a simple hydrothermal method. The formation of heterostructures between ultrafine SnO₂ and Co₃O₄ could enhance the charge transfer of interfaces owing to the internal electric field. The pseudocapacitive effect, which is led by the high specific area and the existence of ultrafine nanoparticles, takes on a feature of fast faradaic surface charge-transfer. Benefiting from the synergistic advantages of the heterostructures and the pseudocapacitive effect, the as-prepared graphene oxide/SnO₂/Co₃O₄ anode achieved a high reversible capacity of 461 mA h g^-1 after 80 cycles at a current density of 0.1 A g^-1. Additionally, at a high current density of 1 A g^-1, a high reversible capacity of 241 mA h g^-1 after 500 cycles is obtained. A full cell coupled by the as-prepared graphene oxide/SnO₂/Co₃O₄ anode and the Na₃V₂(PO₄)₃ cathode was also constructed, which exhibited a reversible capacity of 310.3 mA h g^-1 after 100 cycles at a current density of 1 A g^-1. This method of improving both interfacial and surface charge transfer may pave the way for the development of high performance sodium-ion batteries.

Metallic Sn-Based Anode Materials: Application in High-Performance Lithium-Ion and Sodium-Ion Batteries

With the fast-growing demand for green and safe energy sources, rechargeable ion batteries have gradually occupied the major current market of energy storage devices due to their advantages of high capacities, long cycling life, superior rate ability, and so on. Metallic Sn-based anodes are perceived as one of the most promising alternatives to the conventional graphite anode and have attracted great attention due to the high theoretical capacities of Sn in both lithium-ion batteries (LIBs) (994 mA h g-1) and sodium-ion batteries (847 mA h g-1). Though Sony has used Sn-Co-C nanocomposites as its commercial LIB anodes, to develop even better batteries using metallic Sn-based anodes there are still two main obstacles that must be overcome: poor cycling stability and low coulombic efficiency. In this review, the latest and most outstanding developments in metallic Sn-based anodes for LIBs and SIBs are summarized. And it covers the modification strategies including size control, alloying, and structure design to effectually improve the electrochemical properties. The superiorities and limitations are analyzed and discussed, aiming to provide an in-depth understanding of the theoretical works and practical developments of metallic Sn-based anode materials.