Rational Design and Facial Synthesis of Li₃V₂(PO₄)₃@C Nanocomposites Using Carbon with Different Dimensions for Ultrahigh-Rate Lithium-Ion Batteries

Abstract

Li3V2(PO4)3 (LVP) particles dispersed in different inorganic carbons (LVP@C) have been successfully synthesized via an in situ synthesis method. The inorganic carbon materials with different dimensions including zero-dimensional Super P (SP) nanospheres, one-dimensional carbon nanotubes (CNTs), two-dimensional graphene nanosheets, and three-dimensional graphite particles. The effects of carbon dimensions on the structure, morphology, and electrochemical performance of LVP@C composites have been systematically investigated. The carbon materials can maintain their original morphology even after oxidation (by NH4VO3) and high-temperature sintering (850 °C). LVP@CNT exhibits the best electrochemical performances among all of the samples. At an ultrahigh discharge rate of 100C, it presents a discharge capacity of 91.94 mAh g(-1) (69.13% of its theoretical capacity) and maintains 79.82% of its original capacity even after 382 cycles. Its excellent electrochemical performance makes LVP@CNT a promising cathode candidate for lithium-ion batteries.

Gadolinium/chloride co-doping of lithium vanadium phosphate cathodes for lithium-ion batteries

“…2(a) shows the XRD patterns of the Li 3 V 1.98 Gd 0.02 (PO 4 ) 3 -x / 3 Cl x (x = 0.02, 0.05, 0.08) samples and undoped LVP. All diffraction peaks are consistent with the monoclinic LVP phase (standard map PDF#78-1106), signifying no impurity phase was generated in the co-doped samples [15,34]. This reveals that co-doping with small amounts of Gd 3+ and Cl − does not change the overall crystal structure of LVP.…”

“…LVP has three-dimensional pathways for Li + insertion/extraction, which facilitates fast migration of Li + inside it. However, LVP suffers from intrinsically low electronic conductivity because of its arrangement with two separated [VO 6 ] octahedra, which limits its rate performance [15].…”

Lithium Vanadium Phosphate/Carbon Nanofiber Films as Selfstanding, Binderfree, and Flexible Cathodes for Lithium‐Ion Batteries

“…According to previous reports, the Li 3 V 2 (PO 4 ) 3 /C structure is very stable and can be charged to 4.8 V with little influence on the structural integrity of the Li 3 V 2 (PO 4 ) 3 /C cathode in spite of the two‐phase reaction mechanism and the large volume changes. However, in this work and other previous reports, we noted that the discharge capacities are all decreased to different degrees, especially at high charge/discharge current and undergoing long‐term cycling to cut‐off potential of 4.8 V. The capacity fading of Li 3 V 2 (PO 4 ) 3 /C cathode may be related to the kinetic problems or the high resistance to the extraction of the final lithium ion in [Li 3− x V 2 (PO 4 ) 3 , ( x ≥2)]. Precisely, the fully delithiated phase of V 2 (PO 4 ) 3 with some disordering would undergo a Li‐site/electron ordering or a disorder‐to‐order transition during the first lithium insertion that ultimately increases the unit cell size of LiV 2 (PO 4 ) 3 , which could affect the kinetics of the electrochemical reaction and have a deleterious effect on the cycle performance of the Li 3 V 2 (PO 4 ) 3 /C cathode when cycled to 4.8 V …”

Nanostructured Li3V2(PO4)3 Cathodes

“…Besides, Mao et al systematically investigated the effects of carbon dimensions (i.e., 0D super P (SP) nanospheres, 1D CNTs, 2D graphene nanosheets, and 3D graphite particles) on the structure, morphology, and electrochemical performance of the Li 3 V 2 (PO 4 ) 3 @C composites. The electronic conductivity and electrochemical performance results indicated that the carbon dimensions had significant effect on the performance of the Li 3 V 2 (PO 4 ) 3 @C composites, and owing to the strongest connection between the Li 3 V 2 (PO 4 ) 3 NPs and CNTs, the Li 3 V 2 (PO 4 ) 3 @CNT nanocomposite showed the best electrochemical performance among all the samples.…”