Dual-Site Doping Strategy for Enhancing the Structural Stability of Lithium-Rich Layered Oxides

Abstract

Lithium-rich layered oxide (LLO) cathode materials are considered to be one of the most promising next-generation candidates of cathode materials for lithium-ion batteries due to their high specific capacity. However, some inherent defects of LLOs hinder their practical application due to the oxygen loss and structure collapse resulting from intrinsic anion and cation redox reactions, such as poor cycle stability, sluggish Li+ kinetics, and voltage decay. Herein, we put forward a facile synergistic strategy to respond to these shortcomings of LLOs via dual-site doping with cerium (Ce) and boron (B) ions. The doped Ce ions occupy the octahedral sites, which not only enlarge the cell volume but also stabilize the layered framework and introduce abundant oxygen vacancies for LLOs, while B ions occupy the tetrahedral sites in the lattice, which block the migration path of transition metal (TM) ions and reduce the oxygen loss using the strong B–O bond. Based on this dual-site doping effect, after 100 cycles at 1 C, the dual-site doped materials exhibit excellent structural stability with a capacity retention of 91.15% (vs 75.12%) and also greatly suppress the voltage decay in LLOs with a voltage retention of 93.60% (vs 87.83%).

Nano and Battery Anode: A Review

“…According to Figure b, because the silicon nanoparticles change volume, after returning to another initial state, the electrical connection between the nanoparticles, the carbon conductive material is lost, the capacity is reduced. To solve the above problem in the method shown in Figure c, amorphous silicon, which also has a stress-modulating role, is used as an adhesive to bond silicon nanoparticles so that the electrical connection is no longer interrupted and the capacity will remain [ 25 , 37 , 38 , 96 , 97 ]. In another method, nanoparticles in the field of polyaniline conductive polymer, which have both a modulating and electron conducting role, have been prepared and observed to have a good cycle life of 1000 while maintaining a capacity of 1600 mAh/g.…”

“…Faster ion transfers and oxidation reactions increase power and even energy, because ion transfer (sometimes in addition to electron transfer) is a potential loss (concentration polarization) of both the anode and cathode electrodes of a lithium battery, this polarization decreases as the penetration distance decreases and the energy density improves [44][45][46]. Finally, because silicon is a semiconductor, it has less electron conductivity than graphite, which is a metalloid [33,38,58].…”

“…Metal oxides (Fe 2 O 3 , Fe 3 O 4 , CoO, Co 3 O 4 , MnxOy, Cu 2 O/CuO, NiO, Cr 2 O3, RuO 2 , MoO 2 /MoO 3 etc.) 500–1200 High capacity High energy Low cost Environmentally compatibility High specific capacity Low operation potential and Low polarization than counter oxides Low coulumbic efficiency Unstable SEI formation Large potential hysteresis Poor cycle life Poor capacity retention Short cycle life High cost of production [ 32 , 33 , 35 – 38 ] Conversion materials b. Metal phoshides/sulfides/nitrides (MXy; M ¼ Fe, Mn, Ni, Cu, Co etc.…”

“…Metal phoshides/sulfides/nitrides (MXy; M ¼ Fe, Mn, Ni, Cu, Co etc. and X ¼ P, S, N) 500–1800 High capacity High energy Low cost Environmentally compatibility High specific capacity Low operation potential and Low polarization than counter oxides Low coulumbic efficiency Unstable SEI formation Large potential hysteresis Poor cycle life Poor capacity retention Short cycle life High cost of production [ 33 , 37 , 38 ] …”

“…This is also an advantage of LTO, as the preparation of TiO 2 nanostructures is very popular. Due to the problem of low volumetric density and agglomeration of nanomaterials, micron secondary particles made from nanoscale primary particles are more useful [ 33 , 38 , 58 , 59 ].…”