Double‐Coated Fe 2 N @ TiO 2 @C Yolk‐Shell Submicrocubes as an Advanced Anode for Potassium‐Ion Batteries †

A calculation method for optical properties of yolk shell based on deep learning

The yolk shell is widely used in optoelectronic devices due to its excellent optical properties. Compared to single metal nanostructures, yolk shells have more controllable degrees of freedom, which may make experiments and simulations more complex. Using neural networks can efficiently simplify the computational process of yolk shell. In our work, the relationship between the size and the absorption efficiency of the yolk-shell structure is established using a backpropagation neural network (BPNN), significantly simplifying the calculation process while ensuring accuracy equivalent to discrete dipole scattering (DDSCAT). The absorption efficiency of the yolk shell was comprehensively described through the forward and reverse prediction processes. In forward prediction, the absorption spectrum of yolk shell is obtained through its size parameter. In reverse prediction, the size parameters of yolk shells are predicted through absorption spectra. A comparison with the traditional DDSCAT demonstrated the high precision prediction capability and fast computation of this method, with minimal memory consumption.

Modulating the Graphitic Domains of Hard Carbons Derived from Mixed Pitch and Resin to Achieve High Rate and Stable Sodium Storage

Resin derived hard carbons (HCs) generally demonstrate remarkable electrochemical performance for both sodium ion batteries (SIBs) and potassium-ion batteries (KIBs), but their practical applications are hindered by their high price and high temperature pyrolysis (≈1500 °C). Herein, low-cost pitch is coated on the resin surface to compromise the cost, and meanwhile manipulate the microstructure at a relatively low pyrolysis temperature (1000 °C). HC-0.2P-1000 has a large number of short graphitic layer structures and a relatively large interlayer spacing of 0.3743 nm, as well as ≈1 nm sized nanopores suitable for sodium storage. Consequently, the as produced material demonstrates a superior reversible capacity (349.9 mAh g^-1 for SIBs and 321.9 mAh g^-1 for KIBs) and excellent rate performance (145.1 mAh g^-1 at 20 A g^-1 for SIBs, 48.5 mAh g^-1 at 20 A g^-1 for KIBs). Furthermore, when coupled with Na₃ V₂ (PO₄ )₃ as cathode, the full cell exhibits a high energy density of 251.1 Wh kg^-1 and excellent stability with a capacity retention of 73.3% after 450 cycles at 1 A g^-1 .

Mechanistic Insight and Local Structure Evolution of NiPS3 upon Electrochemical Lithiation

Transition metal phosphorus trisulfide materials have received considerable research interest since the 1980-1990s as they exhibit promising energy conversion and storage properties. However, the mechanistic insights into Li-ion storage in these materials are poorly understood to date. Here, we explore the lithiation of NiPS₃ material by employing in situ pair-distribution function analysis, Monte Carlo molecular dynamics calculations, and a series of ex situ characterizations. Our findings elucidate complex ion insertion and storage dynamics around a layered polyanionic compound, which undergoes intercalation and conversion reactions in a sequential manner. This study of NiPS₃ material exemplifies the Li-ion storage mechanism in transition metal phosphorus sulfide materials and provides insights into the challenges associated with achieving reliable, high-energy phosphorus trisulfide systems.