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a) GITT potential curves and chemical diffusion coefficient [log(DLi⁺)] of LFP, and LF0.5M0.5P cathodes at the first cycle. b) GITT potential curves and chemical diffusion coefficient [log(DNa⁺)] of NFP, and NF0.7M0.3P cathodes at the first cycle. c) In situ XRD patterns of LFP and LF0.5M0.5P. The diffraction peaks of (002), (131), and (112) marked by blue or red dashed lines are attributed to LiFePO4 (LFP) and FePO4 (FP), respectively. d) Ex situ XRD patterns of NFP and NF0.7M0.3P in different voltages. The diffraction peaks marked by blue dashed lines (220), (121), and (131) are attributed to the NaFePO4.
Source publication
Both LiFePO4 (LFP) and NaFePO4 (NFP) are phosphate polyanion‐type cathode materials, which have received much attention due to their low cost and high theoretical capacity. Substitution of manganese (Mn) elements for LFP/NFP materials can improve the electrochemical properties, but the connection between local structural changes and electrochemical...
Citations
... All of the microstructure, phase components, particle shape, particle size, and specific surface of NaFePO 4 /C cathode materials were resources constrains their application in energy storage systems. Sodium (Na) and lithium (Li) are in the same main group of the periodic table and share similar chemical properties, which suggests that NaFePO 4 can theoretically offer performance comparable to LiFePO 4 [7][8][9][10][11][12][13]. However, sodium resources are more abundant, NaFePO 4 cathode material attracts much attention. ...
Among the various types of cathode materials for sodium-ion batteries, NaFePO4 has attracted much attention due to its high theoretical capacity (155 mAh g⁻¹), low cost, and high structural stability. However, the thermodynamically stable maricite form of NaFePO4 is regarded as electrochemically inactive because of its closed framework, which lacks pathways for Na⁺ diffusion. While numerous modification techniques exist, many require substantial energy input. In this study, the NaFePO4/C cathode materials with amorphous and maricite phases were in situ constructed through an extremely simple sol–gel method at different calcination temperatures without incorporating other complicated technology. All of the microstructure, phase components, particle size, and specific surface of NaFePO4/C cathode materials were well controlled by this one-step method. Among them, the NaFePO4/C with amorphous and maricite phases calcined at 450 °C had an excellent electrochemical performance, the discharge specific capacity maintained at 123.6 mAh g⁻¹ after 10 cycles and becomes stable, and the capacity decay rate was only 4.00% after 100 cycles at 0.1 C at room temperature, Na⁺ diffusion coefficient of 1.026 × 10–17 cm² s⁻¹, and charge transfer resistance of 998.6 Ω.
... Polyanionic-type materials such as LiFePO 4 and LiMnPO 4 exhibit remarkable safety and long-term cycling performance. However, their energy densities, although designed to approach theoretical values, still fall short of meeting the urgent requirements of long-life electrical devices [10][11][12][13]. Conversely, another category of spinel material, characterized by a stable crystal structure, derives advantages from its ideal crystal framework, wherein O 2ions occupy 32e sites, thereby forming a resilient cubic close-packed (ccp) structure [14]. ...
Sodium-ion batteries (SIBs) have garnered significant interest due to their potential as viable alternatives to conventional lithium-ion batteries (LIBs), particularly in environments where low-temperature (LT) performance is crucial. This paper provides a comprehensive review of current research on LT SIBs, focusing on electrode materials, electrolytes, and operational challenges specific to sub-zero conditions. Recent advancements in electrode materials, such as carbon-based materials and titanium-based materials, are discussed for their ability to enhance ion diffusion kinetics and overall battery performance at colder temperatures. The critical role of electrolyte formulation in maintaining battery efficiency and stability under extreme cold is highlighted, alongside strategies to mitigate capacity loss and cycle degradation. Future research directions underscore the need for further improvements in energy density and durability and scalable manufacturing processes to facilitate commercial adoption. Overall, LT SIBs represent a promising frontier in energy storage technology, with ongoing efforts aimed at overcoming technical barriers to enable widespread deployment in cold-climate applications and beyond.
The high‐voltage induced undesirable surface passivation bilayer (cathode/electrolyte interface and cation‐densified surface phase) of LiCoO2 inevitably leads to battery degradation. Herein, a continual/uniform enamel‐like olivine layer on LiCoO2 surface is fabricated by employing a high‐speed mechanical fusion method . The enamel‐like layer suppresses interfacial side reactions by tuning EC dehydrogenation, contributing to an ultrathin and stable cathode/electrolyte interface. The strong bonding affinity between LiCoO2 and enamel‐like layer restrains both lattice oxygen loss and associated layered‐to‐spinel structural distortion. Moreover, the thermal stability of highly delithiated LiCoO2 is improved, as both the onset temperatures of layered‐to‐spinel transition and O2 evolution are simultaneously postponed. Stable operation of LiCoO2 at 4.6 V high‐voltage and 55 °C elevated temperature (both >85% capacity retention after 200 cycles) is achieved. This facile and scalable high‐speed solid‐phase coating strategy establishes a technical paradigm to enhance surface/interface stability of high‐energy‐density cathode candidates by constructing an ideal enamel‐like surface layer.