Revealing the Grain-Boundary-Cracking Induced Capacity Decay of a High-Voltage LiCoO₂ at 4.6 V

Alleviating Structure Collapse of Polycrystalline LiNixCoyMn1–x–yO2 via Surface Co Enrichment

“…For P-NCM, such as in the second cycle, the leftmost and rightmost peaks of (003) planes are located at 2θ of 18.383 and 18.810°, and for C-NCM, they are located at 2θ of 18.350 and 18.876°, respectively, which further confirm the higher lattice parameter variations of the C-NCM cathode. Generally, the performance of a polycrystalline NCM cathode can be influenced by multiple factors, including surface regulation, bulk structure stability, the bonding strength of GBs, etc . For the bulk structure stability, the higher the lattice parameter variation, the poorer the cycle stability. , In this work, compared with P-NCM, despite the higher lattice variations, the C-NCM achieves superior cycle stability, which is indeed an abnormal phenomenon, and the surface Co enrichment is regarded as the origin for this abnormal result.…”

Tuning Surface Rock‐Salt Layer as Effective O Capture for Enhanced Structure Durability of LiCoO2 at 4.65 V

“…[ 1a ] For the bulk structure, once charged to beyond 4.55 V, the O3/H1‐3 phase transition occurs with the shrinkage of the lattice volume, triggering the internal stress, which gradually accumulates into the microcracks, and eventually leads to the bulk failure. [ 18 ] Thus, suppressing the irreversible O3/H1‐3 phase transition is vital for enhancing the cycle stability of LCO. The in situ XRD patterns are utilized to reveal the phase evolution of P‐LCO and RS‐LCO in a potential range of 3–4.6 V, and at current of 0.3 C ( Figure 3 a,c).…”

Enhancing the Structural Stability of LiCoO2 at Elevated Voltage via High-Valence Sb Doping

“…The average discharge capacities of PLCO at 0.1, 0.2, 0.4, 0.6, 0. Cyclic voltammetry (CV) was applied to assess the reversibility of phase transitions during cycling, 28 as depicted in Figure 2d,e. The oxidation peak above 4.5 V is associated with the O3 to H1−3 phase transition, and the emergence of the H1−3 phase introduces lattice stress, resulting in the degradation of the LiCoO 2 structure.…”