Graphene cladded cobalt phosphide nanoparticles with a sandwich structure by plasma for lithium and sodium storage

Controllable preparation of carbon coating Ge nanospheres with a cubic hollow structure for high-performance lithium ion batteries

Germanium based nanomaterials are very promising as the anodes for the lithium ion batteries since their large specific capacity, excellent lithium diffusivity and high conductivity. However, their controllable preparation is still very difficult to achieve. Herein, we facilely prepare a unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) via a hydrothermal synthesis and subsequent pyrolysis using low-cost GeO2 as precursors. The hollow Ge@C nanostructure not only provides abundant interior space to alleviate the huge volumetric expansion of Ge upon lithiation, but also facilitates the transmission of lithium ions and electrons. Moreover, experiment analyses and density functional theory (DFT) calculations unveil the excellent lithium adsorption ability, high exchange current density, low activation energy for lithium diffusion of the hollow Ge@C electrode, thus exhibiting significant lithium storage advantages with a large charge capacity (1483 mAh/g under 200 mA g-1), distinguished rate ability (710 mAh/g under 8000 mA g-1) as well as long-term cycling stability (1130 mAh/g after 900 cycles under 1000 mA g-1). Therefore, this work offers new paths for controllable synthesis and fabrication of high-performance Ge based lithium storage nanomaterials.

The Facile and Controllable Synthesis of Ultrafine Sn Nanocrystals Loaded on Carbon Black for High-Performance Lithium Storage

Sn and C nanocomposites are ideal anode materials for high-energy and high-power density lithium ion batteries. However, their facile and controllable synthesis for practical applications is still a critical challenge. In this work, a facile one-step method is developed to controllably synthesize ultrafine Sn nanocrystals (< 5 nm) loaded on carbon black (Sn@C) through Na reducing SnCl4 by mechanical milling. Different from traditional up-down mechanical milling method, this method utilizes mechanical milling to trigger bottom-up reduction reaction of SnCl4. The in-situ formed Sn nanocrystals directly grow on carbon black, which results in the homogeneous composite and the size control of Sn nanocrystals. The obtained Sn@C electrode is revealed to possesses large lithium diffusion coefficient, low lithiation energy barrier and stable electrochemical property during cycle, thus showing excellent lithium storage performance with a high reversible capacity (942 mAh g-1 at a current density of 100 mA g-1), distinguished rate ability (480 mAh g-1 at 8000 mA g-1) and superb cycling performance (730 mAh g-1 at 1000 mA g-1 even after 1000 cycles).

A Universal In-Situ Interfacial Growth Strategy for Various MXene-Based van der Waals Heterostructures with Uniform Heterointerfaces: The Efficient Conversion from 3D Composite to 2D Heterostructures

Two-dimensional (2D) van der Waals heterostructures endow individual 2D material with the novel functional structures, intriguing compositions, and fantastic interfaces, which efficiently provide a feasible route to overcome the intrinsic limitations of single 2D components and embrace the distinct features of different materials. However, the construction of 2D heterostructures with uniform heterointerfaces still poses significant challenges. Herein, a universal in-situ interfacial growth strategy is designed to controllably prepare a series of MXene-based tin selenides/sulfides with 2D van der Waals homogeneous heterostructures. Molten salt etching by-products that are usually recognized as undesirable impurities, are reasonably utilized by us to efficiently transform into different 2D nanostructures via in-situ interfacial growth. The obtained MXene-based 2D heterostructures present sandwiched structures and lamellar interlacing networks with uniform heterointerfaces, which demonstrate the efficient conversion from 3D composite to 2D heterostructures. Such 2D heterostructures significantly enhance charge transfer efficiency, chemical reversibility, and overall structural stability in the electrochemical process. Taking 2D-SnSe2/MXene anode as a representative, it delivers outstanding lithium storage performance with large reversible capacities and ultrahigh capacity retention of over 97% after numerous cycles at 0.2, 1.0, and 10.0 A g-1 current density, which suggests its tremendous application potential in lithium-ion batteries.

Manganese-facilitated dynamic active-site generation on Ni2P with self-termination of surface reconstruction for urea oxidation at high current density

Electrochemical urea oxidation reaction (UOR) suffers from sluggish reaction kinetics due to its complex 6-electron transfer processes combined with conversion of complicated intermediates, severely retarding the overall energy conversion efficiency. Herein, manganese-doped nickel phosphide nanosheets (Mn-Ni2P) are constructed and employed for driving UOR. Comprehensive analysis deciphers that Mn doping could efficiently accelerate the surface reconstruction of Mn-Ni2P electrode, generating highly reactive NiOOH-MnOOH heterostructure with local nucleophilic and electrophilic regions. Such unique structure could accelerate the targeted adsorption and activation of C and N atoms, promoting fracture of CN bond in urea. In addition, moderate Mn doping could efficiently enhance the adsorption capacities of urea molecules and some key intermediates, and minish the energy barrier for *CO2 desorption, accelerating refreshing of the catalyst. Consequently, the Mn-Ni2P electrode exhibits excellent UOR catalytic activity, achieving an industrial-level current density of 1000 mA cm-2 at 1.46 V (vs. RHE).

Research progress on direct borohydride fuel cells

The rapid development of industry has accelerated the utilization and consumption of fossil energy, resulting in an increasing shortage of energy resources and environmental pollution. Therefore, it is crucial to explore new energy storage devices using renewable and environment-friendly energy as fuel. Direct borohydride fuel cells (DBFCs) are expected to be a feasible and efficient energy storage device by virtue of the read availability of raw materials, non-toxicity of products, and excellent operational stability. Moreover, while utilizing H2O2 as an oxidant, a significant theoretical energy density of 17 kW h kg-1 can be achieved, indicating the broad application prospect of DBFCs in long-range operation and oxygen-free environment. This review summarizes the research progress on DBFCs in term of reaction kinetics, electrode materials, membrane materials, architecture, and electrolytes. In addition, we predict the future research challenges and feasible research directions, considering both performance and cost. We hope this review will help guide future studies on DBFCs.

FeNbO4 nanochains with a five-electron transfer reaction toward high capacity and fast Li storage

High capacity and outstanding rate performance of the FeNbO4 nanochain anode with both intercalation and conversion reactions for lithium-ion batteries are demonstrated. The unique one-dimensional structure and intercalation pseudocapacitive behavior of FeNbO4 accelerate the reaction kinetics. In situ X-ray diffractometer measurement confirms a five-electron transfer mechanism for Li storage.