Improving the cycling performance of LiNi0.8Co0.15Al0.05O2 cathode materials via zirconium and fluorine co-substitution

Stabilizing Ni‐Rich LiNi0.92Co0.06Al0.02O2 Cathodes by Boracic Polyanion and Tungsten Cation Co‐Doping for High‐Energy Lithium‐Ion Batteries

“…[15] A is the electrode area (cm 2 ), D is the diffusion coefficient of lithium, C is the initial concentration of Li-ion (one Li + occupies in the average unit cell, mol cm À 3 ). [7] The Li-ion diffusion coefficient (D Li + ) can be estimated from the slope of the Randles-Sevcik plots of i p versus v 1/2 (Figure 4d-f). The value of lithium-ion diffusion D ox (Li-extraction, oxidation current) and D re (Li-insertion, reduction current) were calculated for all Figure 4.…”

“…Increasing the Ni fraction is the current strategy for further increasing the energy density of batteries, resulting in the development of LiNi 0.88 Co 0.03 Al 0.09 O 2 , LiNi 0.92 Co 0.06 Al 0.02 O 2 and LiNi 0.95 Co 0.04 Mn 0.01 O 2 . [7] However, it is believed that the increase in Ni concentration would accelerate structural degradation and side reaction, leading to rapid capacity decay during cycling. A fundamental problem is that an abundance of reactive Ni 4 + generated in highly delithiated state can be easily reduced to Ni 2 + by a liquid electrolyte, leading to the formation of an electrochemical inactive NiO-like phase on particle surfaces accompanied by the release of oxygen.…”

NCA, NCM811, and the Route to Ni-Richer Lithium-Ion Batteries

“…The fluorine was also associated to Zr. The capacity retention of Zr and F codoped NCA was raised to 90.5% after 200 cycles at 1 C [86] (see Figures 3 and 4). MgF 2 -coated NCA delivers a capacity that is smaller than that of pristine NCA at low C-rate, but the rate capability is better [87].…”

Designing positive electrodes with high energy density for lithium-ion batteries

“…Indeed, various cations and anions (such as B, F, Mg, and Al) have been investigated as dopants for positive-electrode materials with high energy density, all of which improved capacity retention during charge/discharge cycling. [71][72][73][74][75][76][77]92,93,102,103,[106][107][108][109][169][170][171][172][173] For example, doping B into a nickel-rich layered oxide was reported to increase capacity retention aer 100 cycles from 83% to 92% by suppressing crack formation. 92…”