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

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 LiNi 0.9 Co 0.1 O 2 cathode materials are successfully fabricated in terms of Li(Ni 0.9 Co 0.1 ) 1– x W x O 2–4 y (PO 4 ) 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 (PO 4 3– ) 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(Ni 0.9 Co 0.1 ) 0.99 W 0.01 O 1.96 (PO 4 ) 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.