Magnesium/chloride co-doping of lithium vanadium phosphate cathodes for enhanced stable lifetime in lithium-ion batteries

Abstract

Combining XRD with 31P NMR, it is demonstrated that the Mg and Cl atoms of the new Mg and Cl co-doped Li3V2(PO4)3/C material occupy V and O sites in its structure, respectively.

Raising the capacity of lithium vanadium phosphate via anion and cation co-substitution

“…3+ or other ions with proper radius have been adopted to enhance the Li + transportation rate because of expanded ion pathway [15,[23][24][25]. Of noteworthy, the Mg 2+ can refine the crystal size [26], which is consistent with the aim of downsizing the particle size to shorten the ion and electron transporting distance. At the same time, the halogen substitution at oxygen sites of phosphate group can lead to a wide lattice spacing [27,26], and give rise to a dramatic augmentation in conductivity, and thus lower the resistance and energy barrier during battery operation [28,29].…”

“…The ratios of V 3+ /V 4+ are 0.33 and 0.41 from V 2p 3/2 deconvolations for LVP and LVMgPCl, respectively. This result means that the anion and cation co-substitution will maintain more vanadium element at low valence state and bring in more charge variation during electrochemical reactions [25], which is also testified by the respectively characteristic peaks of Mg 2+ and Cl − binding energy at 1303.8 and 192.7 eV [26,35,36] (Figure 3(c, d ) is in the same order of magnitude for V 3+ /V 4+ couple but is slightly lower than that of LVMgPCl (Figure S4, S5), indicating a more favorable dynamic after anion and cation cosubstitution and uniform carbon coating. Meanwhile, the GITT measurement fits well to calculate the chemical dif- fusion coefficient for conductors with mixed electrons and ions [40][41][42].…”

“…The thermal analysis indicates that the weight ratio of coated carbon is ca. [26,32], which will be discussed in the following part. The obtained LVMgPCl is also coated by a carbon layer within 6 nm with homogeneous element distribution after calcination (Figure 2(b, c) and Figure S2).…”

Improved Na storage performance of Na3V2(PO4)3 cathode material for sodium-ion batteries by K-Cl co-doping

“…For example, Lim et al [30] replaced the Na sites with K + with a larger ionic radius; this enhanced the stability of the crystal structure and widened the Na + transmission channel, thereby improving the electrochemical performance. Substituting anion Cl − for PO 4 3− in Li 3 V 2 (PO 4 ) 3 materials can cause lattice distortion and can improve electronic conductivity [31]. However, research on anion and cation co-doping modified NVP is still relatively rare.…”

Unraveling the Relationship between Ti4+ Doping and Li+ Mobility Enhancement in Ti4+ Doped Li3V2(PO4)3

“…The traditional design concept of doping is to control the initial raw materials ratio. It is widely believed that low-valence dopants (such as Na + , ) substitute lithium ions and high-valence dopants (such as Co 2+ , Mg 2+ , − Mn 2+ , Ni 2+ , , Fe 3+ , Al 3+ , , Ce 3+ , Cr 3+ , and Ti 4+ ,, ) are doped at the V sites of LVP. Ti 4+ and V 3+ have similar ionic radii, which makes Ti 4+ an ideal candidate for V 3+ substitution.…”