Structural origin of the high-voltage instability of lithium cobalt oxide

Revealing Roles of Co and Ni in Mn‐Rich Layered Cathodes

“…A similar phenomenon was observed in the deep delithiated LiCoO 2 due to the transition to the H1–3 phase. [ 3,4 ] When discharged to 2 V, the two peaks merge to one with broadened shape and a shoulder peak, but never fully returned to the original position. Such serious phase segregation and big lattice mismatch in LMCO at high potentials would accumulate tremendous stress at the phase boundaries and further induce lots of microcracks within primary particles, as directly observed in Figure 4d and in Figure S14a,b (Supporting Information).…”

“…[ 1,2 ] Therefore, developing the cathodes possessing both the high performance and low cost has been one of the frontiers in the LIB field. Although the Co‐containing cathodes like LiCoO 2 (LCO), [ 3,4 ] ternary Li(Ni x Mn y Co z )O 2 (NMC; x + y + z = 1; x > 1/3), [ 5,6 ] and Li(Ni 0.80 Co 0.15 Al 0.05 )O 2 (NCA) [ 7,8 ] are now widely used in the current commercial batteries, the call for low‐Co and Co‐free cathodes is an unstoppable trend due to the high cost, high toxicity, and child labor abuse in mining of Co. [ 9–13,15 ] In contrast, the price of Ni is only one‐third of Co, whereas Mn is even cheaper at a fifth of the price of Ni, while the global Mn reserves are even two orders of magnitude higher than those of Ni and Co (Figure S1, Supporting Information). [ 2,14–16 ] Furthermore, the biological toxicity of Mn is also much less than that of Co and Ni.…”

Tailoring Co3d and O2p Band Centers to Inhibit Oxygen Escape for Stable 4.6 V LiCoO2 Cathodes

“…Additionally, the charge compensation and capacity degradation mechanism of high voltage LiCoO 2 are still not very clear. Pan et al reported that the structural stability was related to the flatness of LiCoO 2 layers [9] . However, there are still some issues that have not been well understood.…”

The structure-activity relationship between precursor fine structure and cathodes performance in Ni-rich layered oxide

“…larger cathode's primary particle size can effectively inhibit CEI film formation, structure decay, the intragranular/intergranular cracks formation owing to the alleviation of localized stress.Ni-rich cathodes have attracted much attention in the field of new energy due to their high capacity and low cost. [1][2][3][4][5] The agglomerated polycrystalline NCM cathodes shorten the diffusion length of primary particles and increases the number of pores, resulting in the accelerated transport of Li + . The traditional LiNi1-x-yCoxMnyO2 (NCM) cathodes with micro secondary particles assembled by nano primary particles were prepared using coprecipitation method.…”

“…It can be seen from Fig.1dthat the following phenomena take place in the reactor: (1) after the feed liquid continues to enter the reactor, because hydroxide precipitation reaction rate is very fast, a large number of Ni0.92Co0.04Mn0.04(OH)2 precipitates increase instantaneously, resulting in a rapid increase of supersaturation, and finally a large number of crystal nuclei are produced rapidly. In the case of strong stirring, the crystal nuclei with high surface energy tend to aggregate to form large irregular agglomerates to release energy rapidly, so the number of microns and nanoparticles increases sharply (zone A); (2) when a certain reaction time is reached, the TM(OH)2 slurry in the reactor starts to flow out from the overflow port, resulting in a slow increase in the number of particles, in addition, small particles grow gradually (zone B); (3) with the increase of reaction time, partial small particles dissolve-aggregate and large particles continue to grow (zone C);(4) with the continuous addition of solution in the reactor, the large particles begin to dissolve-recrystallize-aggregate under a certain stirring strength, and finally the small particles increase and the large particles decrease (zone D); (5) the system reaches steady state after the growth rate and nucleation rate of precursor are stable, and the particle size is relatively stable (zone E), as displayed in Fig.1e(Fig.1eis a partial enlarged drawing of zone E).…”