Degradation mechanism and performance enhancement strategies of LiNixCoyAl1−x−yO2 (x ≥ 0.8) cathodes for rechargeable lithium-ion batteries: a review

Understanding the Feasibility of Manganese Substitution for Cobalt in the Synthesis of Nickel-Rich and Cobalt-Free Cathode Materials

“…The unfavorable phase-transition process, the layered spinel-rock salt phase, is a natural consequence of cation mixing, which leads to the loss of lattice oxygen. The oxygen intermediates on the cathode surface are rapidly depleted by an electrolyte solvent, making the oxygen precipitation process inside the cathode more kinetically hindered; the degree of phase transformation of the layered spinel-rock salt usually increases with increasing operating voltage and the number of cycles, leading to a decrease in material capacity and working potential . Although the increase in Mn helps to stabilize the material structure and inhibit the precipitation of lattice oxygen inside the material, excessive Mn increases the degree of Ni Li mixing in the material.…”

“…The kinetic properties of the material can be revealed by the lithium diffusion coefficient ( D Li ), which is calculated by the following equation , F and R represent Faraday’s constant (96 485.3383 ± 0.0083 C·mol –1 ) and the ideal gas constant (8.314 J·mol –1 ·K –1 ), respectively, T is the room temperature (300 K), A is the surface area of the electrode (cm 2 ), n is the charge-transfer number, which is equal to 1 for Li + , and C is the lithium concentration in the electrode (mol·cm –3 ), which can be obtained from the following equation The effect of mass transfer is reflected by the Warburg coefficient σ. As shown in Figure b,d, the Warburg coefficient σ can be obtained by measuring the slope of such curves by Randles plotting Z ′ with ω –1/2 (ω = 2π f ) against the Warburg coefficient.…”

“…The oxygen intermediates on the cathode surface are rapidly depleted by an electrolyte solvent, making the oxygen precipitation process inside the cathode more kinetically hindered; the degree of phase transformation of the layered spinel-rock salt usually increases with increasing operating voltage and the number of cycles, leading to a decrease in material capacity and working potential. 35 Although the increase in Mn helps to stabilize the material structure and inhibit the precipitation of lattice oxygen inside the material, excessive Mn increases the degree of Ni Li mixing in the material. The proper degree of Ni Li mixing instead helps to enhance the electrochemical performance, which has been mentioned in previous studies, but excessive Ni Li mixing increases the instability of the material structure, resulting in the electrochemical performance of the material being affected, and the results in Figures 5 and 6 also confirm this conclusion.…”

Carbon-Coatings Improve Performance of Li-Ion Battery

“…Moreover, the fabrication of NCA and the reaction of LiNiO 2 with H 2 O and CO 2 from the air both produce the residual lithium compounds on the surface of NCA cathode, leading to the slurry gelation and battery swelling. Furthermore, the microcracks caused by the anisotropic volume changes form the excessive solid electrolyte interface to prevent the diffusion of Li-ions [ 98 ]. Therefore, surface coating providing a physical protection is an effective strategy to modify the performance of NCA cathodes, preventing the oxygen evolution and reactions between electrode and electrolyte.…”

Micron-Sized Monodisperse Particle LiNi0.6Co0.2Mn0.2O2 Derived by Oxalate Solvothermal Process Combined with Calcination as Cathode Material for Lithium-Ion Batteries

“…Traditional commercial Ni-rich NCMs are spherical secondary particles (micron-sized) composed of many randomly oriented primary particles (nano-sized). However, extensive applications of traditional Ni-rich NCMs are restricted due to their inferior structural stability and poor cycle stability, which, in turn, results from (1) a larger specific surface area caused by the gap between primary particles, which increases the number of side reactions or structural corrosions of the electrolyte and (2) a portion of microcracks is easily generated because of the random orientation of primary particles during the Li + extraction/insertion process, resulting in the pulverization of secondary particles—this is a key reason for capacity loss during the cycle [ 12 , 13 , 14 , 15 ]. Several strategies, including optimizing synthesis parameters [ 16 , 17 , 18 ], coating [ 19 , 20 , 21 ], and element doping [ 22 , 23 , 24 ], have been devoted to address these issues and enhance the properties of NCMs.…”