An in-depth understanding of Al doping homogeneity affecting the performance of LiCoO2 at cut-off voltage over 4.6 V

Interfacial Degradation Analysis via the Combined In Situ Method of Gas Monitoring and Electrochemical Impedance Spectroscopy upon Fast-Aging Cycling at 45 °C

“…33,34 Nonetheless, the LIBs assembled with U-Al/B-NMC, which features a homogeneous mixture of aluminum and boron, facilitate a more efficient transfer of aluminum from the coating layer on the positive electrode to the SEI on the negative electrode, leading to a higher aluminum content than that observed in the LIBs assembled with G-Al/B-NMC. The aluminum and boron also prevent the negative electrode from being attacked by HF, 35,36 and suppress CO 2 , CO, and CH 4 evolution, thus augmenting the stability of the battery. The reactions between aluminum and HF are depicted in eqs 2 and 3 37,38 Al + +…”

“…The corresponding peaks in the Al 2p spectrum, as illustrated in Figure S3c,d, are consistent with those of Al 2 O 3 , indicating that there are no significant compositional differences in the aluminum on the CEI of the two batteries. , Nonetheless, the LIBs assembled with U-Al/B-NMC, which features a homogeneous mixture of aluminum and boron, facilitate a more efficient transfer of aluminum from the coating layer on the positive electrode to the SEI on the negative electrode, leading to a higher aluminum content than that observed in the LIBs assembled with G-Al/B-NMC. The aluminum and boron also prevent the negative electrode from being attacked by HF, , and suppress CO 2 , CO, and CH 4 evolution, thus augmenting the stability of the battery. The reactions between aluminum and HF are depicted in eqs and , .25ex2ex Al 2 normalO 3 + 2 HF → Al 2 O 2 F 2 + H 2 normalO .25ex2ex Al 2 normalO 3 + x PF 6 − → 2 Al 2 normalO 3 − x normalF 2 x + x PO 2 normalF 2 − The different coating formulations on the positive electrode result in different electrode–electrolyte interfaces, which is related to battery degradation.…”