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Direct-contact prelithiation (PL) is a facile, practical, and scalable method to overcome the first-cycle loss and large volume expansion issues for silicon anode (with 30 wt % Si loading) material, and a detailed study is absent. Here, an understanding of direct-contact PL as a function of the PL time, and the effects of externally applied pressure (weight), microstructure, and operating temperature have been studied. The impact of PL on the Si–C electrode surfaces has been analyzed by electrochemical techniques and different microstructural analyses. The solid electrolyte interface (SEI) layer thickness increases with the increase in PL time and decreases after 2 min of PL time. The ideal PL time was found to be between 15 (PL-15) and 30 (PL-30) min with 83.5 and 97.3% initial Coulombic efficiency (ICE), respectively, for 20 g of externally applied weight. The PL-15 and PL-30 cells showed better cyclic stability than PL-0 (without prelithiation), with more than 90% capacity retention after 500 cycles at 1 A g–1 current density. The discharge capacities for PL-15 and PL-30 have been observed as highest at 45 °C operating temperature with limited cyclability. We propose here a synchronization strategy in prelithiation time, pressure, and temperature to achieve excellent cell performance.

Among multifunctional double perovskite oxides, La2NiMnO6 has recently drawn significant attention due to its importance both in terms of understanding of fundamental physics and potential for device applications. The relative alteration in Ni:Mn ratio strongly influences the structural and magnetic properties of La2NiMnO6. The cation ratio and degree of cation order significantly affect the magnetic coupling of the two B‐site cations in these compounds. In the present study, La2Ni1−xMn1+xO6 (x = −0.25, 0, 0.25) samples with different Ni:Mn ratio have been prepared using sol–gel method and modifications of the above physical properties from that of a stoichiometric sample of La2NiMnO6 are discussed. The crystalline structures of the samples varied with different ionic ratios. While all samples exhibited ferromagnetic behavior, long‐range Ni/Mn magnetic ordering was detected in selected samples only. The experimental values of saturation magnetization were smaller than the theoretical spin‐only moments, which suggests a less ordered state for all samples. Due to an increased antiferromagnetic interaction caused by antisite disorders, the saturation magnetization decreases while the coercive field increases with decreasing Mn content.

Extreme volume changes and concomitant mechanical instabilities (viz., origin and proliferation of cracking) in Si-based anodes are responsible for premature failure in lithium-ion batteries. Thus, it is a crucial hurdle toward the development of high-performance Si-based batteries, especially in the current scenario of electric vehicles. Accordingly, this research demonstrates a significant improvement in the mechanical stainability of Si-based anode material via in situ incorporation of carbide with a specific design, thereby bestowing outstanding stability in the electrochemical performance. At this juncture, we have established a bridge between nanomechanical and electrochemical properties, investigated via nanoindentation and in-operando stress measurements during electrochemical cycling for Si and in situ reinforced Si–SiC composite. Enhancing the hardness (H) of Si–SiC composite to almost twice as well as enhancing the hardness to effective Young’s modulus (E*) ratio (H 3/E*2) of the same to almost thrice than that of Si, helped resist the occurrence of plastic deformation and cracking in significant terms. In-operando study shows the typical stress flattening (cum, anisotropic behavior) in the case of the unreinforced Si electrode, which is a manifestation of plastic flow/cracking. By contrast, monotonous stress profiles and absence of the signature of plastic flow/cracking are observed for the Si–SiC electrode, which is an advantage for long cycle life, as observed here. Overall, this kind of experimental study could establish the nanomechanical to electrochemical tie-up, leading to 82% capacity retention over 650 cycles in a Li-ion full-cell along with the Si–SiC composite anode. The “power cycle” of the Si–SiC composite anode, with a variation of current density from 0.5 to 6.0 A g–1, also reveals excellent stability up to 2500 cycles.

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