Novel Li3 VO4 Nanostructures Grown in Highly Efficient Microwave Irradiation Strategy and Their In-Situ Lithium Storage Mechanism

In Situ Transmission Electron Microscopy Methods for Lithium-Ion Batteries

In situ Transmission Electron Microscopy (TEM) stands as an invaluable instrument for the real-time examination of the structural changes in materials. It features ultrahigh spatial resolution and powerful analytical capability, making it significantly versatile across diverse fields. Particularly in the realm of Lithium-Ion Batteries (LIBs), in situ TEM is extensively utilized for real-time analysis of phase transitions, degradation mechanisms, and the lithiation process during charging and discharging. This review aims to provide an overview of the latest advancements in in situ TEM applications for LIBs. Additionally, it compares the suitability and effectiveness of two techniques: the open cell technique and the liquid cell technique. The technical aspects of both the open cell and liquid cell techniques are introduced, followed by a comparison of their applications in cathodes, anodes, solid electrolyte interphase (SEI) formation, and lithium dendrite growth in LIBs. Lastly, the review concludes by stimulating discussions on possible future research trajectories that hold potential to expedite the progression of battery technology.

Lithium Polyacrylate as Lithium and Carbon Source in the Synthesis of Li3 VO4 for High-Rate and Long-Life Li-Ion Batteries

Li3 VO4 is a promising anode material for use in lithium-ion batteries, however, the conventional synthesis methods for Li3 VO4 anodes involve the separate use of lithium and carbon sources, resulting in inefficient contact and low crystalline quality. Herein, lithium polyacrylate (LiPAA) was utilized as a dual-functional source and an in-situ polymerization followed by a spray-drying method was employed to synthesize Li3 VO4 . LiPAA serves a dual purpose, acting as both a lithium source to improve the crystal process and a carbon source to confine the particle size within a desired volume during high-temperature treatment. Additionally, the in-situ synthesis of a porous carbon decorating skeleton prevents the growth and agglomeration of Li3 VO4 particles and provides abundant ion/electron diffusion channels and contact areas. Based on the synthesis route and the constructed primary-secondary structure, the Li3 VO4 anodes obtained in this study exhibit an impressive capacity of 596.2 mAh g-1 . Moreover, they demonstrate enhanced rate performance over 600 cycles during 10 periods of rate testing, as well as a remarkably long lifespan of 5000 cycles at high currents. The utilization of LiPAA as a dual-functional source represents a broad approach that holds great potential for future research on high-performance electrodes requiring both lithium and carbon sources.

Heterostructured Li3VO4-Ga2O3-embedded porous carbon nanofibers as advanced anode materials for lithium-ion batteries

The development of lithium-ion batteries (LIBs) is still facing challenges due to the design and optimization of anode materials and their Li-ion storage mechanisms. In this study, we aimed to address this issue by constructing three-dimensional hierarchical heterojunction structures using a double needle electrospinning strategy. The heterostructure was composed of insertion-type Li3VO4 and conversion/alloying-type Ga2O3 embedded porous carbon nanofibers (Li3VO4-Ga2O3@PCNF). The designed heterostructured Ga2O3 and Li3VO4 materials were found to effectively enhance charge transfer dynamics, thereby improving capacity and rate capability. Additionally, the facilitated efficient contact between the electrode and electrolyte, enabling the diffusion of ions and electrons. When applied as an anode material in LIBs, the Li3VO4-Ga2O3@PCNF composite achieved a high capacity of 630.0 mA h g-1 at 0.5 A g-1, and full capacity recovery after 6 periods of rate testing over 480 cycles. When simulating the practical application under a high discharge current of 6.0 A g-1, the Li3VO4-Ga2O3@PCNF could still deliver a high discharge capacity of 322.0 mA h g-1 after 2000 cycles. Furthermore, the composite exhibited a remarkable capacity retention of 77.2% after 2000 cycles at 6.0 A g-1. This research provides valuable guidance for the design of high-performance Li3VO4-based anodes, particularly in addressing the issue of inferior electronic conductivity.

Zero-Strain Insertion Anode Material of Lithium-Ion Batteries

The insertion type materials are the most important anode materials for lithium-ion batteries, but their insufficient capacity is the bottleneck of practical application. Here, LiAl₅ O₈ nanowires with high theoretical capacity and Li-ions diffusion coefficient are prepared and studied as an insertion anode material, which exhibits zero-strain properties upon electrochemical cycling. However, the poor electronic conductivity of LiAl₅ O₈ definitely sacrifices the capacity and limits the rate performance. Therefore, compact LiAl₅ O₈ and carbon composite are further synthesized, in which nanosized LiAl₅ O₈ particles are uniformly embedded in an amorphous carbon matrix. It displays a reversible capacity of 490.9 mAh g^-1 at 1 A g^-1 , and the capacity rises continuously to 996.8 mAh g^-1 after 1000 cycles due to the interfacial storage mechanism, that the excess Li⁺ ions can be accommodated in the grain boundaries and C/LiAl₅ O₈ interfaces.

In/Ce Co-doped Li3VO4 and Nitrogen-modified Carbon Nanofiber Composites as Advanced Anode Materials for Lithium-ion Batteries

Li₃VO₄ (LVO) is considered as a novel alternative anode material for lithium-ion batteries (LIBs) due to its high capacity and good safety. However, the inferior electronic conductivity impedes its further application. Here, nanofibers (nLICVO/NC) with In/Ce co-doped Li₃VO₄ strengthened by nitrogen-modified carbon are prepared. Density functional theory calculations demonstrate that In/Ce co-doping can substantially reduce the LVO band gap and achieve orders of magnitude increase (from 2.79 × 10^-4 to 1.38 × 10^-2 S cm^-1) in the electronic conductivity of LVO. Moreover, the carbon-based nanofibers incorporated with 5LICVO nanoparticles can not only buffer the structural strain but also form a good framework for electron transport. This 5LICVO/NC material delivers high reversible capacities of 386.3 and 277.9 mA h g^-1 at 0.1 and 5 A g^-1, respectively. Furthermore, high discharge capacities of 335 and 259.5 mA h g^-1 can be retained after 1200 and 4000 cycles at 0.5 and 1.6 A g^-1, respectively (with the corresponding capacity retention of 98.4 and 78.7%, respectively). When the 5LICVO/NC anode assembles with commercial LiNi_1/3Co_1/3Mn_1/3O₂ (NCM111) into a full cell, a high discharge capacity of 191.9 mA h g^-1 can be retained after 600 cycles at 1 A g^-1, implying an inspiring potential for practical application in high-efficiency LIBs.

Unraveling the MnMoO4 polymorphism: a comprehensive DFT investigation of α, β, and ω phases

The MnMoO₄ is an environmentally friendly semiconductor material widely employed in technological devices. This material can be obtained on three different polymorphs, and although such phases were reported decades ago, some obscurity over their structure and properties is still perceived. Thus, this work provides a comprehensive DFT investigation of the α, β, and ω phases of MnMoO_4, analyzing their crystalline structure, stability, and electronic and magnetic properties. The results show that all phases of MnMoO₄ are stable at room conditions connected by pressure application or long-time high-temperature treatment. The MnMoO₄ phases are G-type antiferromagnetic with semiconductor bandgap and have enormous potential to develop magnetic, optical, and electronic devices and photocatalytic-based processes. The results also evidence potential antiviral and antibacterial activities of the three MnMoO₄ polymorphs.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10853-022-07277-7.