Advances in performance degradation mechanism and safety assessment of LiFePO4for energy storage.

In the context of 'energy shortage', developing a novel energy-based power system is essential for advancing the current power system towards low-carbon solutions. As the usage duration of lithium-ion batteries for energy storage increases, the nonlinear changes in their aging process pose challenges to accurately assess their performance. This paper focuses on the study LiFeO4(LFP), used for energy storage, and explores their performance degradation mechanisms. Furthermore, it introduces common battery models and data structures and algorithms, which used for predicting the correlation between electrode materials and physical parameters, applying to state of health assessment and thermal warning. This paper also discusses the establishment of digital management system. Compared to conventional battery networks, dynamically reconfigurable battery networks can realize real-time monitoring of lithium-ion batteries, and reduce the probability of fault occurrence to an acceptably low level.

Design of Nb5+-doped high-nickel layered ternary cathode material and its structure stability.

LiNi0.8Co0.1Mn0.1O2(NCM811) is one of the most promising cathode materials for high-energy lithium-ion batteries, but there are still problems such as rapid capacity decay during charge and discharge and poor cycle performance. Elemental doping can significantly improve the electrochemical performance of high nickel ternary cathode materials. In this work, Nb5+-doped NCM811 cathode material was successfully synthesized. The results show that Nb5+doping helps to increase the interlayer spacing of the lithium layer, electron transport, and structural stability, thereby significantly improving the conductivity of Li+. At a high voltage of 4.6 V, the initial discharge specific capacity of 1% Nb5+-doped NCM811 cathode material at 0.1 C is 222.3 mAh·g-1, and the capacity retention rate after 100 cycles at 1 C is 92.03%, which is far more than the capacity retention rate of NCM811 under the same conditions (74.30%). First-principles calculations prove that 1% Nb5+-doped NCM811 cathode material shows the highest electronic conductivity and Nb5+doping will not change the lattice structure, demonstrating the effectiveness of the proposed strategy.

Na and Cl co-doping modified LiNi0.5Co0.2Mn0.3O2as cathode for lithium-ion battery.

In recent years, ternary nickel-rich layered oxides have gradually replaced traditional binary cathode materials in the lithium-ion battery market due to their advantages of high energy density and environmental protection. However, their structural instability of cathode materials has seriously affected the cycle performance of the battery. In order to optimize the internal structure of LiNi0.5Co0.2Mn0.3O2(NCM523), the modified LiNi0.5Co0.2Mn0.3O2was prepared byin situdoping Na and Cl wet grinding solid phase method. After 80 cycles at 1 C, the capacity retention rate was 80.91%, which was higher than that of LiNi0.5Co0.2Mn0.3O2by 70.00%. Scanning electron microscopy showed that the surface corrosion of LiNi0.5Co0.2Mn0.3O2was effectively alleviated by Na and Cl co-doping. In addition, the band structure, state density and volume changes were obtained by simulation. The results show that the impedance, capacity and capacity retention data are very compatible with the simulation results. Therefore, Na and Cl doping can effectively optimize the internal structure of LiNi0.5Co0.2Mn0.3O2and improve its electrochemical performance. The combination of simulation and experiment provides a new approach for the modification of ternary cathode materials.

Ti-substituted O3-type layered oxide cathode material with high-voltage stability for sodium-ion batteries.

O3-type layered transition metal oxides (NaxTMO2) have attracted extensive attention as a promising cathode material for sodium-ion batteries because of their high capacity. However, the irreversible phase transition especially cycled under high voltage remains a concerning challenge for NaxTMO2. Herein, a Ti-substituted NaNi0.5Co0.2Mn0.3O2 cathode with strongly suppressed phase transition and enhanced storage stability is investigated. The Ti substitution effectively inhibits the irreversible phase transition and alleviates the structural change even charged to 4.3 V during the repeated Na+ deintercalation process. After storing in air or water, the original O3 phase structure of the material is integrally maintained without the generation of impurity phase. As a result, the as-prepared material shows excellent long-term cycle stability and rate performance when charged to a high voltage of 4.3 V.

Role of Residual Li and Oxygen Vacancies in Ni-rich Cathode Materials.

Residual Li and oxygen vacancies in Ni-rich cathode materials have a great influence on electrochemical performance, yet their role is still poorly understood. Herein, by simply adjusting the oxygen flow during the high-temperature sintering process, some Li2O can be carried into the exhaust gas and the contents of residual Li and oxygen vacancies in LiNi0.825Co0.115Mn0.06O2 cathodes can be accurately controlled. Residual Li reduces the surficial Li+ diffusion coefficient, thereby limiting the rate property of the cathode. Oxygen vacancies affect the oxygen release energy in the crystal, and the lowest oxygen release energy is found at an oxygen vacancy concentration of 8.35%, resulting in an unstable structure and thereby poor cycle performance. The Ni-rich cathode with low residual Li and oxygen vacancy contents exhibits superior capacity retention (89.55 and 77.66%) at 2C after 300 cycles between 2.7-4.3 and 2.7-4.5 V. These findings clarify the role of residual Li and oxygen vacancies in Ni-rich cathode materials and provide a simple way to obtain high-performance Ni-rich cathodes for high-energy-density Li-ion batteries.

Research Progress on the Surface of High-Nickel Nickel-Cobalt-Manganese Ternary Cathode Materials: A Mini Review.

To address increasingly prominent energy problems, lithium-ion batteries have been widely developed. The high-nickel type nickel-cobalt-manganese (NCM) ternary cathode material has attracted attention because of its high energy density, but it has problems such as cation mixing. To address these issues, it is necessary to start from the surface and interface of the cathode material, explore the mechanism underlying the material's structural change and the occurrence of side reactions, and propose corresponding optimization schemes. This article reviews the defects caused by cation mixing and energy bands in high-nickel NCM ternary cathode materials. This review discusses the reasons why the core-shell structure has become an optimized high-nickel ternary cathode material in recent years and the research progress of core-shell materials. The synthesis method of high-nickel NCM ternary cathode material is summarized. A good theoretical basis for future experimental exploration is provided.

Sn-Doping and Li2SnO3 Nano-Coating Layer Co-Modified LiNi0.5Co0.2Mn0.3O2 with Improved Cycle Stability at 4.6 V Cut-off Voltage.

Nickel-rich layered LiNi1-x-yCoxMnyO2 (LiMO2) is widely investigated as a promising cathode material for advanced lithium-ion batteries used in electric vehicles, and a much higher energy density in higher cut-off voltage is emergent for long driving range. However, during extensive cycling when charged to higher voltage, the battery exhibits severe capacity fading and obvious structural collapse, which leads to poor cycle stability. Herein, Sn-doping and in situ formed Li2SnO3 nano-coating layer co-modified spherical-like LiNi0.5Co0.2Mn0.3O2 samples were successfully prepared using a facile molten salt method and demonstrated excellent cyclic properties and high-rate capabilities. The transition metal site was expected to be substituted by Sn in this study. The original crystal structures of the layered materials were influenced by Sn-doping. Sn not only entered into the crystal lattice of LiNi0.5Co0.2Mn0.3O2, but also formed Li+-conductive Li2SnO3 on the surface. Sn-doping and Li2SnO3 coating layer co-modification are helpful to optimize the ratio of Ni2+ and Ni3+, and to improve the conductivity of the cathode. The reversible capacity and rate capability of the cathode are improved by Sn-modification. The 3 mol% Sn-modified LiNi0.5Co0.2Mn0.3O2 sample maintained the reversible capacity of 146.8 mAh g-1 at 5C, corresponding to 75.8% of its low-rate capacity (0.1C, 193.7mAh g-1) and kept the reversible capacity of 157.3 mAh g-1 with 88.4% capacity retention after 100 charge and discharge cycles at 1C rate between 2.7 and 4.6 V, showing the improved electrochemical property.

Energy Storage and Thermostability of Li3VO4-Coated LiNi0.8Co0.1Mn0.1O2 as Cathode Materials for Lithium Ion Batteries.

The electrochemical performances and thermostability of LiNi0.8Co0.1Mn0.1O2 is affected by temperature. High ambient temperature or irregular heat distribution accelerates the decline of LiNi0.8Co0.1Mn0.1O2 performance, shortens cathode material life. In this work, the energy storage and thermostability of the Li3VO4-coated LiNi0.8Co0.1Mn0.1O2 cathode material were studied for the first time by electrochemical calorimetry methode at different temperatures and rates. Results show that Li3VO4-coated LiNi0.8Co0.1Mn0.1O2 cathode material has excellent rate and cycle performance. The thermal electrochemical experiments further show that the thermal stability of Li3VO4-coated LiNi0.8Co0.1Mn0.1O2 cathode material in charge-discharge energy storage and conversion system is better than LiNi0.8Co0.1Mn0.1O2 at 30, 40, and 50°C. The enhanced performance can be attributed to the fact that Li3VO4 coating promotes the transmission of lithium ions and protects the active material from electrolyte corrosion at different temperature, as well as reduces side reaction, electrode polarization and heat generation of cathode materials. The Li3VO4-coated LiNi0.8Co0.1Mn0.1O2 cathode material has excellent energy storage properties and thermostability, which are beneficial to the development of electronic equipment.

Simple and rapid mercury ion selective electrode based on 1-undecanethiol assembled Au substrate and its recognition mechanism.

A simple and rapid mercury ion selective electrode based on 1-undecanethiol (1-UDT) assembled Au substrate (Au/1-UDT) has been well constructed. 1-UDT was for the purpose of generating self-assembled monolayer on gold surface to recognize Hg2+ in aqueous solution, which had a working concentration range of 1.0×10-8-1.0×10-4molL-1, with a Nernst response slope of 28.83±0.4mV/-pC, a detection limit of 4.5×10-9molL-1, and a good selectivity over the other tested cations. Also, the Au/1-UDT possessed good reproducibility, stability, and short response time. The recovery obtained for the determination of mercury ion in practical tremella samples was in the range of 99.8-103.4%. Combined electrochemical analysis and X-ray photoelectron spectroscopy (XPS) with quantum chemical computation, the probable recognition mechanism of the electrode for selective recognition of Hg2+ has been investigated. The covalent bond formed between mercury and sulfur is stronger than the one between gold and sulfur and thus prevents the adsorption of 1-UDT molecules on the gold surface. The quantum chemical computation with density functional theory further demonstrates that the strong interaction between the mercury atom and the sulfur atom on the gold surface leads to the gold sulfur bond ruptured and the gold mercury metallophilic interaction.

Alleviating Surface Degradation of Nickel-Rich Layered Oxide Cathode Material by Encapsulating with Nanoscale Li-Ions/Electrons Superionic Conductors Hybrid Membrane for Advanced Li-Ion Batteries.

Nickel-rich layered oxide cathode materials for advanced lithium-ion batteries have received much attention recently because of their high specific capacities and significant reduction of cost. However, these cathodes are facing a fundamental challenge of loss in performance as a result of surface lithium residue, side reactions with the electrolyte and structure rearrangement upon long-term cycling. Herein, by capturing the lithium residue on the surface of LiNi0.8Co0.1Mn0.1O2 (NCM) cathode material as Li source, we propose a hybrid coating strategy incorporating lithium ions conductor LixAlO2 with superconductor LixTi2O4 to overcome those obstinate issues. By taking full advantage of this unique hybrid nanomembrane coating architecture, both the lithium ion diffusion ability and electronic conductivity of LiNi0.8Co0.1Mn0.1O2 cathode material are improved, resulting in remarkably enhanced electrochemical performances during high voltage operation, including good cycle performance, high reversible capacity, and excellent rate capability. A high initial discharge capacity of 227 mAh g-1 at 4.4 V cutoff voltage with Coulombic efficiency of 87.3%, and reversible capacity of 200 mAh g-1 with 98% capacity retention after 100 cycles at a current density of 0.5 C can be attained. The improved electrochemical performance can be attributed to the synergetic contribution from the removal of lithium residues and the unique hybrid nanomembrane coating architecture. Most importantly, this surface modification technique could save some cost, simplify the technical procedure, and show great potential to optimize battery performance, apply in a large scale and extend to all nickel-rich cathode material.