One-step synthesis of carbon-coated Li4Ti4.95Nd0.05O12 by modified citric acid sol–gel method for lithium-ion battery

Challenges of Spinel Li4Ti5O12 for Lithium‐Ion Battery Industrial Applications

“…The common dopants in Li + sites include Na + , [80][81][82] K + , [82,83] Mg 2+ , [84] Ca 2+ , [85] Zn 2+ , [86] Cu 2+[87] and La 3+ , [88] including Fe 3+ , [89] Co 3+ , [90] Ni 3+ , [91] Al 3+ , [92][93][94] Cr 3+ , [91,95] La 3+ , [96] Pr 3+ , [97] Bi 3+ , [98] Sc 3+ , [99] Eu 2+/3+ , [100] Sm 3+ , [101] Gd 3+ , [102] Ti 3+ , [103] Mo 4+ , [104] Mn 4+ , [105] Ce 3+/4+ , [106] Sn 4+ , [107] Zr 4+ , [93,[108][109][110] Si 4+ , [109] V 5+ , [111,112] Ta 5+ , [113,114] Sb 5+ , [115] Nb 5+ [114,116] and W 6+ , [117] etc. The role of doping in Li 4 Ti 5 O 12 is thought to be based on the defect equilibrium that Ti 4+ in the octahedral 16d site of spinel lattice can be reduced to Ti 3+ by the aliovalent dopant, thereby intrinsically increasing the electron concentration of Li 4 Ti 5 O 12 bulk.…”

“…Take Mo 4+ for example: the substitution of Ti 4+ with Mo 4+ tends to improve the electronic conductivity by reducing the bandgap of the electronic structure. [111][112][113][114]116,117] However, high valence-state cation substitutions may also lead to the formation of a Li + vacancy or a Ti 4+ vacancy. [124] Moreover, high valence state dopant ions, such as V 5+ , Ta 5+ , Nb 5+ , W 6+ , etc., entering octahedral 16d Ti 4+ sites may improve the electronic conductivity by increasing the electron concentration through the formation of Ti 3+ .…”

“…The common dopants in Li + sites include Na + , K + , Mg 2+ , Ca 2+ , Zn 2+ , Cu 2+ and La 3+ , etc. ; a lot of dopants have been reported in Ti 4+ sites, including Fe 3+ , Co 3+ , Ni 3+ , Al 3+ , Cr 3+ , La 3+ , Pr 3+ , Bi 3+ , Sc 3+ , Eu 2+/3+ , Sm 3+ , Gd 3+ , Ti 3+ , Mo 4+ , Mn 4+ , Ce 3+/4+ , Sn 4+ , Zr 4+ , Si 4+ , V 5+ , Ta 5+ , Sb 5+ , Nb 5+ and W 6+ , etc. ; the dopants in O sites include F and Br .…”

“…Moreover, high valence state dopant ions, such as V 5+ , Ta 5+ , Nb 5+ , W 6+ , etc., entering octahedral 16d Ti 4+ sites may improve the electronic conductivity by increasing the electron concentration through the formation of Ti 3+ . However, high valence‐state cation substitutions may also lead to the formation of a Li + vacancy or a Ti 4+ vacancy.…”