Enhanced Cyclability and High-Rate Capability of LiNi0.88Co0.095Mn0.025O2 Cathodes by Homogeneous Al3+ Doping.

Abstract

To suppress capacity fading of nickel-rich materials for lithium-ion batteries, a homogeneous Al3+ doping strategy is realized through tailoring the Al3+ diffusion path from the bulk surface to interior. Specifically, the layered LiNi0.88Co0.095Mn0.025O2 cathode with the radial arrangement of primary grains is successfully synthesized through optimization design of precursors. The Al3+ follows the radially oriented primary grains into the bulk by introduction of nano-Al2O3 during the sintering process, realizing the homogeneous Al3+ distribution in the whole material. Particularly, a series of nano-Al2O3-modified LiNi0.88Co0.095Mn0.025O2 are investigated. With the 2% molar weight of Al3+ doping, the capacity retention ratio of the cathode is tremendously improved from 52.26 to 91.57% at 1 C rate after 150 cycles. Even at a heavy current density of 5 (&10) C for the LiNi0.88Co0.095Mn0.025O2-Al2% cathode, a high reversible capacity of 172.3 (&165.7) mA h g-1 can be acquired, which amount to the 84.46 (&81.25) % capacity retention at 0.2 C. Moreover, voltage deterioration is significantly suppressed by homogeneous Al3+ doping from the results of median voltage and dQ/dV curves. Therefore, homogeneous Al3+ doping benefited from the radial arrangement of primary grains provides an effective and practical way to prolong lifespan, as well as improves rate performance and voltage stability of nickel-rich ternary materials.