Effects of sulphate modification of stoichiometric and lithium-rich LiNiO2 cathode materials
Lithium nickel oxide (LiNiO2) has attracted considerable interest as a high energy cathode for next generation lithium-ion batteries. The established process, however, has some shortcomings which hinder its practical application, such as significant cycling capacity decay and low stability in ambient atmosphere. Consequently, most work has focused on the more stable Mn and Co doped analogues Li (Ni, Mn, Co)O2.
In this paper* published in Journal of Materials Chemistry A, the authors from this department, University of Birmingham, The Faraday Institution, The Henry Royce Institute, Oak Ridge National Laboratory, University of Bath and Leiden Institute of Chemistry report an investigation of an alternative strategy, sulfate modification, into the LiNiO2 system.
The authors show that improved performance can be achieved, attributed to the dual effect of a low level of bulk doping and the presence of a self-passivation Li2SO4 layer formed beyond the solid solution limit. Ab initio simulations suggest that the behaviour is similar to that of other high valent dopants such as W and Mo.
These dual effects contribute to the improved air stability and enhanced electrochemical performance for the sulfate modified lithium-rich LiNiO2, leading to high initial capacities (~245 MA h g -1 at 25 mA g-1, and ~205 mA h g-1 at 100 mA g-1) and better capacity retention.
Overall, the results show that polyanion modification represents an excellent alternative low-cost strategy to improve the performance of lithium nickel oxide cathode materials.
*'Effects of sulfate modification of stoichiometric and lithium-rich LiNiO2 cathode materials'.
