Enhancing lithium storage performance with silicon-based anodes: a theoretical study on transition metal-integrated SiOx/M@C (M = Fe, Co, Ni) heterostructures.

In lithium-ion batteries, infusible metals with lithium, such as Mg, Fe, Co, Ni, and Cu are often utilized. However, current research predominantly focuses on the experimental aspects of the (de)lithiation process, with limited exploration from a theoretical calculation perspective. The extensive use of experimental methods to study the many electrochemically inert metals is time-consuming and costly. In this study, we successfully constructed and optimized SiOx/M@C (M = Fe, Co, Ni) heterostructures, integrating transition metal nanoparticles to address the electrochemical inertness and slow diffusion kinetics of pristine SiOx. A comprehensive density functional theory (DFT) study was conducted to examine the effects of different metal heterostructures on the structural, migration potential energy, and adsorption properties during lithium-ion intercalation. The results demonstrate that the SiOx/Fe@C heterostructure exhibits the lowest migration energy barrier, significantly enhancing lithium-ion transport compared to SiOx/Co@C and SiOx/Ni@C. Consequently, the SiOx/Fe@C electrode shows superior high-rate discharge capability and excellent cycling performance through electrochemical measurements. Additionally, the study delves into the intrinsic mechanisms through charge density differences and Fermi level calculations, providing valuable insights into the importance of hybrid strategies for incorporating inert metals into anode materials for lithium-ion batteries.

Tailoring and understanding the lithium storage performance of triple-doped cobalt phosphide composites.

Cobalt phosphide (CoP) with high theoretical capacity as well as ceramic-like and metal-like properties is considered as a promising anode for lithium-ion batteries (LIBs). However, the large volume change and sluggish kinetic response limit its practical application. The optimization of composition, structural control and performance regulation of CoP electrodes can be achieved by the bottom-up assembly technique of metal-organic frameworks (MOFs). Due to the effective electronic regulation and lithiophilicity brought by the multiple heteroatoms doping and the synergistic effect of the unique structure derived from MOFs, the N, O, P triple-doped carbon and CoP composites (ZCP@NOP) exhibited excellent rate capability (554.61 mAh g-1 at 2 A g-1) and cycling stability (806.7 mAh g-1 after 500 cycles at 0.5 A g-1). The essence and evolution of lithium storage mechanism in CoP electrodes are also confirmed by the ex-situ techniques. The synergistic benefits of heteroatom co-doping carbon and cobalt phosphide, such as the decrease of the diffusion energy barrier of Li-ions and the optimization of electronic structures, are highlighted in theoretical calculations. In conclusion, new thoughts and ideas for the creation of future battery anode are provided by the combination of the N, O, P co-doping and the adaptable structural adjustment technique.

A Metal-Organic Framework-Derived Strategy for Constructing Synergistic N-Doped Carbon-Encapsulated NiCoP@N-C-Based Anodes toward High-Efficient Lithium Storage.

Transition metal phosphides (TMPs) have been regarded as the prospective anodes for lithium-ion batteries (LIBs). However, their poor intrinsic conductivity and inevitable large volume variation result in sluggish redox kinetics and the collapse of electrode structure during cycling, which substantially hinders their practical use. Herein, an effective composite electrodes design strategy of "assembly and phosphorization" is proposed to construct synergistic N-doped carbon-encapsulated NiCoP@N-C-based composites, employing a metal-organic frameworks (MOFs) as sacrificial hosts. Serving as the anodes for LIBs, one representative P-NCP-NC-600 electrode exhibits high reversible capacity (858.5 mAh g-1, 120 cycles at 0.1 A g-1) and superior long-cycle stability (608.7 mAh g-1, 500 cycles at 1 A g-1). The impressive performances are credited to the synergistic effect between its unique composite structure, electronic properties and ideal composition, which achieve plentiful lithium storage sites and reinforce the structural architecture. By accompanying experimental investigations with theoretical calculations, a deep understanding in the lithium storage mechanism is achieved. Furthermore, it is revealed that a more ideal synergistic effect between NiCoP components and N-doped carbon frameworks is fundamentally responsible for the realization of superb lithium storage properties. This strategy proposes certain instructive significance toward designable high-performance TMP-based anodes for high-energy density LIBs.

Metal-organic-framework derived Zn-V-based oxide with charge storage mechanism as high-performance anode material to enhance lithium and sodium storage.

Transition metal oxides have been extensively studied due to their large theoretical capacities, but their practical application has been hampered by low electrical conductivity and dramatic volume fluctuation during cycling. In this work, we synthesized Zn3V2O8 material using Zn-V-MOF (metal-organic framework) as a sacrificial template to improve the electrochemical characteristics of lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Unique dodecahedral structure, larger specific surface area and higher ability to mitigate volume changes, improve the electrochemical reaction active site while accelerating ion transport. Zn3V2O8 with 2-methylimidazole as a ligand demonstrated a discharge capacity of 1225.9 mAh/g in LIBs and 761.6 mAh/g in SIBs after 300 cycles at 0.2 C. Density functional theory (DFT) calculation illustrates the smaller diffusion barrier energy and higher specific capacity in LIBs that is ascribed to the fact that Li has a smaller size and hence its diffusion is easier. This study may lead to a path for the manufacturing of high-performance LIBs and SIBs.

Metal-organic frameworks-derived MCo2O4 (M = Zn, Ni, Cu) two-dimensional nanosheets as anodes materials to boost lithium storage.

Transition metal oxides (TMOs) have received significant consideration. Because of their enormous theoretical capacity, cheap, and less toxicity. Notably, cobalt-based materials hold promises as negative electrode materials for batteries, but they suffer from less electrical conductivity and significant volume changes during operation. In order to address these challenges, sacrificial templating techniques at the nanoscale offer a potential solution for improving the electrochemical stability and rate performance of these materials. More specifically, these tactics have proven popular for designing Li-ion storages. To ascertain the impact of multiple metal ions on the electrochemical capacity, metal organic frameworks (MOFs) derived MCo2O4-MOF (M = Zn, Ni, Cu) were developed. Among these, ZnCo2O4 showed the best electrochemical performance (927.2 mAh g-1 at 0.1 A g-1 after 250 cycles). Furthermore, calculations based on density functional theory (DFT) revealed that ZnCo2O4 had the lowest Li+ adsorption energy, with a minimum value of -1.61 eV. Moreover, this research aims to design controllable nanostructures in order to enhance the design of transition bimetallic oxide composites for energy storage applications.