Tungsten and phosphate polyanion co-doping of Ni-ultrahigh cathodes greatly enhancing crystal structure and interface stability

Abstract The Ni-ultrahigh cathode material is one of the best choices for further increasing energy–density of lithium-ion batteries (LIBs), but they generally suffer from the poor structure stability and rapid capacity fade. Herein, the tungsten and phosphate polyanion co-doped LiNi0.9Co0.1O2cathode materials are successfully fabricated in terms of Li(Ni0.9Co0.1)1–xWxO2–4y(PO4)y by the precursor modification and subsequent annealing. The higher bonding energy of W O (672 kJ∙mol−1) can extremely stabilize the lattice oxygen of Ni-rich oxides compared with Ni O (391.6 kJ∙mol−1) and Co O (368 kJ∙mol−1). Meanwhile, the stronger bonding of Ni (PO43–) vs. Ni O could fix Ni cations in the transition metal layer, and hence suppressing the Li/Ni disorder during the charge/discharge process. Therefore, the optimized Li(Ni0.9Co0.1)0.99W0.01O1.96(PO4)0.01 delivers a remarkably extended cycling life with 95.1% retention of its initial capacity of 207.4 mA∙h∙g−1 at 0.2 C after 200 cycles. Meantime, the heteroatoms doping does not sacrifice the specific capacity even at different rates.