Li2MnSiO4 nanorods-embedded carbon nanofibers for lithium-ion battery electrodes

A review on the origin of nanofibers/nanorods structures and applications

In this review work, we highlight the origin of morphological structures such as nanofibers/nanorods in case of various materials in nano as well as bulk form. In addition, a discussion on different cations of different ionic radii and other intrinsic factors is provided. The materials (ceramic titanates, ferrites, hexaferrites, oxides, organic/inorganic composites, etc.,) exhibiting the nanofibers/nanorods like morphological structures are tabulated. Furthermore, the significance of nanofibers/nanorods obtained from distinct materials is elucidated in multiple scientific and technological fields. At the end, the device applications of these morphological species are also described in the current technology. The nucleation and growth mechanism of α-MnO₂ nanorods using natural extracts from Malus domestica and Vitis vinifera [3].

Understanding the Improved Kinetics and Cyclability of a Li2MnSiO4 Cathode with Calcium Substitution

Limited practical capacity and poor cyclability caused by sluggish kinetics and structural instability are essential aspects that constrain the potential application of Li₂MnSiO₄ cathode materials. Herein, Li₂Mn_{1- x}Ca _xSiO₄/C nanoplates are synthesized using a diethylene-glycol-assisted solvothermal method, targeting to circumvent its drawbacks. Compared with the pristine material, the Ca-substituted material exhibits enhanced electrochemical kinetics and improved cycle life performance. In combination with experimental studies and first-principles calculations, we reveal that Ca incorporation enhances electronic conductivity and the Li-ion diffusion coefficient of the Ca-substituted material, and it improves the structural stability by reducing the lattice distortion. It also shrinks the crystal size and alleviates structure collapse to enhance cycling performance. It is demonstrated that Ca can alleviate the two detrimental factors and shed lights on the further searching for suitable dopants.

Crystallographic Habit Tuning of Li2MnSiO4 Nanoplates for High-Capacity Lithium Battery Cathodes

Li₂MnSiO₄ has attracted significant attention as a cathode material for lithium ion batteries because of its high theoretical capacity (330 mA h g^-1 with two Li⁺ ions per formula unit), low cost, and environmentally friendly nature. However, its intrinsically poor Li diffusion, low electronic conductivity, and structural instability preclude its use in practical applications. Herein, elongated hexagonal prism-shaped Li₂MnSiO₄ nanoplates with preferentially exposed {001} and {210} facets have been successfully synthesized via a solvothermal method. Density functional theory calculations and experimental characterization reveal that the formation mechanism involves the decomposition of solid precursors to nanosheets, self-assembly into nanoplates, and Ostwald ripening. Hydroxyl-containing solvents such as ethylene glycol and diethylene glycol play a crucial role as capping agents in tuning the preferential growth. Li₂MnSiO₄@C nanoplates demonstrate a near theoretical discharge capacity of 326.7 mA h g^-1 at 0.05 C (1 C = 160 mA h g^-1), superior rate capability, and good cycling stability. The enhanced electrochemical performance is ascribed to the electrochemically active {001} and {210} exposed facets, which provide short and fast Li⁺ diffusion pathways along the [001] and [100] axes, a conformal carbon nanocoating, and a nanoscaled platelike structure, which offers a large electrode/electrolyte contact interface for Li⁺ extraction/insertion processes.