Jahn-Teller effect in LiMn2O4: influence on charge ordering, magnetoresistance and battery performance

Optimization of Desalination Efficiency and Exploratory Applications of TiO2 Active Site Electrode Enhanced by Activated Carbon and Tween 80 in Capacitive Deionization Technology

Capacitive deionization (CDI) is an emerging desalination technology for seawater desalination. The development of high-desalination and long-life electrode materials is a research focus in the global water treatment field. In this experiment, Tween T80 was used as a surface activator, and a modified electrode was prepared by facilitating the deposition of TiO2 active sites onto the surface of activated carbon through a sol-gel/hydrothermal two-step synthesis strategy. The morphology and specific surface area of the composite material were analyzed through scanning electron microscopy, specific surface area measurements, and contact angle tests. The results indicated that the sol-gel/hydrothermal two-step synthesis strategy played a crucial role in the homogeneous combination and performance enhancement of the composite material. Under constant voltage mode, when the working voltage was 1.2 V, the desalination capacity of this composite material in a NaCl solution with an initial conductivity of 3000 μS·cm-1 reached 23.8 mg·g-1 (26% higher than materials prepared by conventional sol-gel methods). After 150 cycles, the capacity retention rate was 78%, and the retention capacity was significant (87%). Overall, the results demonstrate the potential of the sol-gel/hydrothermal two-step synthesis strategy in preparing high-performance CDI electrode materials. The modified electrode prepared using this method offers enhanced desalination capacity and durability, making it a promising candidate for seawater desalination and other water treatment applications.

Determination of lithium ions by stripping voltammetry using single-crystal LiFePO4

Determination of lithium ions is very important for extraction of lithium from salt lakes. Electrochemical sensor is an ideal choice, but it is not available so far. Here, a voltammetric sensor based on lithium iron phosphate (LiFePO4) was developed. Single-crystal LiFePO4 dominated by the (010) lattice plane was synthesized using hydrothermal method; it had good selectivity for lithium ions. Lithium ions were preferentially intercalated into LiFePO4 even if molar ratio of sodium ions, potassium ions, magnesium ions or calcium ions to lithium ions reached 10:1. The intercalation and deintercalation of interfering ions should be avoided because this reduced the selectivity of LiFePO4 for lithium ions. Lithium ion concentration of synthetic Uyuni Salt Lake solution was determined using the standard addition method. The measurement result was only 0.34 % higher than the theoretical value. The sensor provides a highly selective lithium ion analysis method at an extremely low cost, which was very promising to be widely used.

Review of the Scalable Core-Shell Synthesis Methods: The Improvements of Li-Ion Battery Electrochemistry and Cycling Stability

The demand for lithium-ion batteries has significantly increased due to the increasing adoption of electric vehicles (EVs). However, these batteries have a limited lifespan, which needs to be improved for the long-term use needs of EVs expected to be in service for 20 years or more. In addition, the capacity of lithium-ion batteries is often insufficient for long-range travel, posing challenges for EV drivers. One approach that has gained attention is using core-shell structured cathode and anode materials. That approach can provide several benefits, such as extending the battery lifespan and improving capacity performance. This paper reviews various challenges and solutions by the core-shell strategy adopted for both cathodes and anodes. The highlight is scalable synthesis techniques, including solid phase reactions like the mechanofusion process, ball-milling, and spray-drying process, which are essential for pilot plant production. Due to continuous operation with a high production rate, compatibility with inexpensive precursors, energy and cost savings, and an environmentally friendly approach that can be carried out at atmospheric pressure and ambient temperatures. Future developments in this field may focus on optimizing core-shell materials and synthesis techniques for improved Li-ion battery performance and stability.

Electrospun Nanofiber Electrodes for Lithium-Ion Batteries

Electrospun nanofiber materials have the advantages of good continuity, large specific surface areas, and high structural tunability, which provide many desirable characteristics for lithium-ion battery electrodes. Here, the principles and advantages of electrospinning technology are first elaborated, then the previous studies on high-performance nanofibrous electrode materials prepared by electrospinning technology are comprehensively summarized, and the correlation between 1D nanostructured materials and electrode performances is discussed. Finally, the remaining challenges of nanofibrous electrodes are proposed and some future study directions of this particular area are pointed out. This review provides new enlightenment for the design of nanofibrous electrodes toward high-performance lithium-ion batteries.

Boosting the Electrochemical Performance of a Spinel Cathode with the In Situ Transformed Allogenic Li-Rich Layered Phase

High-voltage spinel materials have attracted widespread attention because of their advantages such as good rate performance, low cost, abundant source, and easy preparation. However, the Mn dissolution and Jahn-Teller effect of spinel materials during cycling limit their practical application. In this paper, the allogenic composites (1 - x)Li(Ni_0.2Co_0.1Mn_0.7)₂ O₄·xLi_1.2(Ni_0.2Co_0.1Mn_0.7)_0.8O₂ (x = 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5) are developed by the carbonate co-precipitation method combined with the high-temperature sintering method, which are certified by the X-ray diffraction (XRD) spectrum and transmission electron microscopy (TEM) image. The results show that the lithium-rich phase of the allogenic composites can effectively improve the initial discharge capacity, alleviate the side reaction between the spinel material and the electrolyte, and improve the cycle stability. This work reveals the relationship between the structure and electrochemical performance of the in situ transformed spinel@Li-rich allogenic composites and provide a new clue to design a high-performance spinel cathode for advanced Li-ion batteries.

Inorganic Colloidal Electrolyte for Highly Robust Zinc-Ion Batteries

Zinc-ion batteries (ZIBs) is a promising electrical energy storage candidate due to its eco-friendliness, low cost, and intrinsic safety, but on the cathode the element dissolution and the formation of irreversible products, and on the anode the growth of dendrite as well as irreversible products hinder its practical application. Herein, we propose a new type of the inorganic highly concentrated colloidal electrolytes (HCCE) for ZIBs promoting simultaneous robust protection of both cathode/anode leading to an effective suppression of element dissolution, dendrite, and irreversible products growth. The new HCCE has high Zn²⁺ ion transference number (0.64) endowed by the limitation of SO₄^2-, the competitive ion conductivity (1.1 × 10^-2 S cm^-1) and Zn²⁺ ion diffusion enabled by the uniform pore distribution (3.6 nm) and the limited free water. The Zn/HCCE/α-MnO₂ cells exhibit high durability under both high and low current densities, which is almost 100% capacity retention at 200 mA g^-1 after 400 cycles (290 mAh g^-1) and 89% capacity retention under 500 mA g^-1 after 1000 cycles (212 mAh g^-1). Considering material sustainability and batteries' high performances, the colloidal electrolyte may provide a feasible substitute beyond the liquid and all-solid-state electrolyte of ZIBs.

Extraction of Lithium from Single-Crystalline Lithium Manganese Oxide Nanotubes Using Ammonium Peroxodisulfate

In this work, a spinel single-crystalline Li_1.1Mn_1.9O₄ has been successfully synthesized using β-MnO₂ nanotubes as the self-sacrifice template. The tubular morphology was retained through solid-state reactions, attributed to a minimal structural reorganization from tetragonal β-MnO₂ to spinel Li_1.1Mn_1.9O₄. The materials were investigated as sorbents for lithium recovery from LiCl solutions, recycled using H₂SO₄ and (NH₄)₂S₂O₈. Li_1.1Mn_1.9O₄ nanotubes exhibited favorable lithium extraction behavior due to tubular nanostructure, single-crystalline nature, and high crystallinity. (NH₄)₂S₂O₈ eluent ensures the structural stability of Li_1.1Mn_1.9O₄ nanotube, registering a Li⁺ adsorption capacity of 39.21 mg g⁻¹ (∼89.73% of the theoretical capacity) with only 0.08% manganese dissolution after eight adsorption/desorption cycles, compared to that of 1.21% for H₂SO₄. It reveals the degradation of sorbent involves with the volume change, Mn reduction, and Li/Mn ratio depletion. New strategies, based on nanotube adsorbent and (NH₄)₂S₂O₈ eluent, can extract lithium ions at satisfactorily high degrees while effectively minimizing manganese dissolution.

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Single-crystalline Li_1.1Mn_1.9O₄ nanotubes were developed for lithium extraction

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The sorbent showed Li/Mn ratio depletion over adsorption/desorption processes

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Acid-free extraction minimized the structural change and Mn reduction

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Acid-free extraction improved the chemical stability and reusability of the sorbent

Eggshell-Membrane-Derived Carbon Coated on Li2FeSiO4 Cathode Material for Li-Ion Batteries

Lithium iron orthosilicate (LFS) cathode can be prepared via the polyol-assisted ball milling method with the incorporation of carbon derived from eggshell membrane (ESM) for improving inherent poor electronic conduction. The powder X-ray diffraction (XRD) pattern confirmed the diffraction peaks without any presence of further impure phase. Overall, 9 wt.% of carbon was loaded on the LFS, which was identified using thermogravimetric analysis. The nature of carbon was described using parameters such as monolayer, and average surface area was 53.5 and 24 m2 g−1 with the aid of Langmuir and Brunauer–Emmett–Teller (BET) surface area respectively. The binding energy was observed at 285.66 eV for C–N owing to the nitrogen content in eggshell membrane, which provides more charge carriers for conduction. Transmission electron microscopy (TEM) images clearly show the carbon coating on the LFS, the porous nature of carbon, and the atom arrangements. From the cyclic voltammetry (CV) curve, the ratio of the anodic to the cathodic peak current was calculated as 1.03, which reveals that the materials possess good reversibility. Due to the reversibility of the redox mechanism, the material exhibits discharge specific capacity of 194 mAh g−1 for the first cycle, with capacity retention and an average coulombic efficiency of 94.7% and 98.5% up to 50 cycles.

One-time sintering process to synthesize ZrO2-coated LiMn2O4 materials for lithium-ion batteries

Herein, different amounts of ZrO₂-coated LiMn₂O₄ materials are successfully prepared by one-time sintering ZrO₂-coated Mn₃O₄ and Li₂CO₃. Scanning and transmission electron microscopy results confirm that the ZrO₂ coating layer on the surface of Mn₃O₄ can still be maintained on the surface of the final LiMn₂O₄ particles even after long-term high-temperature heat-treatment. Three key factors to realize ZrO₂-coated LiMn₂O₄ materials via the one-time sintering process are as follows: (i) the Mn₃O₄ precursor is coated by ZrO₂ in advance; (ii) the ionic radius of Zr⁴⁺ is much larger than those of Mn³⁺ and Mn⁴⁺; (iii) the pre-calcination temperature is set in the reaction temperature range between Li₂CO₃ and Mn₃O₄ and lower than that between Li₂CO₃ and ZrO₂. The 3 wt% ZrO₂-coated LiMn₂O₄ material exhibits excellent electrochemical properties with an initial specific discharge capacity of 118.8 mA h g⁻¹ and the capacity retention of 90.1% after 400 cycles at 25 °C and 88.9% after 150 cycles at 55 °C. Compared with the conventional coating method, the one-time sintering process to synthesize ZrO₂-coated LiMn₂O₄ materials is very simple, low-cost, environmentally friendly, and easy to scale up for large-scale industrial production, which also provides a valuable reference for preparing other coating-type cathode materials for lithium-ion batteries.

A facile one-time sintering process was used to synthesize ZrO₂-coated LiMn₂O₄ to greatly enhance its cycling performance.