Enhancement of electrochemical performance in lithium-ion battery via tantalum oxide coated nickel-rich cathode materials

Nickel-rich cathode materials are increasingly being applied in commercial lithium-ion batteries to realize higher specific capacity as well as improved energy density.However,low structural stability and rapid capacity decay at high voltage and temperature hinder their rapid large-scale application.Herein,a wet chemical method followed by a post-annealing process is utilized to realize the surface coating of tantalum oxide on LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),and the electrochemical performance is improved.The modified Li Ni_(0.88)Mn_(0.03)Co_(0.09)O_(2)displays an initial discharge capacity of~233 m Ah/g at0.1 C and 174 m Ah/g at 1 C after 150 cycles in the voltage range of 3.0 V–4.4 V at 45℃,and it also exhibits an enhanced rate capability with 118 m Ah/g at 5 C.The excellent performance is due to the introduction of tantalum oxide as a stable and functional layer to protect the surface of LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),and the surface side reactions and cation mixing are suppressed at the same time without hampering the charge transfer kinetics.

Probing the improved stability for high nickel cathode via dual-element modification in lithium-ion

One of the major hurdles of nickel-rich cathode materials for lithium-ion batteries is the low cycling stability,especially at high temperature and high voltage,originating from severe structural degradation,which makes this class of cathode less practical.Herein,we compared the effect of single and dual ions on electrochemical performance of high nickel(LiNi_(0.88)Mn_(0.03)Co_(0.09)O_(2),NMC)cathode material in different temperatures and voltage ranges.The addition of a few amounts of tantalum(0.2 wt%)and boron(0.05 wt%)lead to improved electrochemical performance.The co-modified Li Ni_(0.88)Mn_(0.03)Co_(0.09)O_(2)displays an initial discharge capacity of 234.9 m Ah/g at 0.1 C and retained 208 m Ah/g at 1 C after 100 cycles at 45℃,which corresponds to a capacity retention of 88.5%,compared to the initial discharge capacity of234.1 m Ah/g and retained capacity of 200.5 m Ah/g(85.6%).The enhanced capacity retention is attributed to the synergetic effect of foreign elements by acting as a surface structural stabilizer without sacrificing specific capacity.