Al Substitution for Mn during Co-Precipitation Boosts the Electrochemical Performance of LiNi_0.8Mn_0.1Co_0.1O₂

Abstract

Nickel-rich layered oxides, such as LiNi0.8Mn0.1Co0.1O2 (NMC 811), are considered as one of the most promising candidates for the next-generation cathode because of their high energy densities and relatively low cost. However, the poor first Coulombic efficiency of NMC 811 leads to around a 15% capacity loss in the first cycle at a cut-off voltage of 4.4 V. Moreover, the structure degradation during cycling results in capacity fading and safety concerns, due to potential oxygen loss after charging. Here, with aluminum substitution for manganese through a developed continuous co-precipitation approach, the electrochemical performance of NMC 811 cathodes has been greatly enhanced. Among different Al% substituted samples, LiNi0.8Mn0.06Co0.1Al0.04O2 cathodes reduced by 50% the first capacity loss of pristine NMC 811(18.0 vs 35.9 mAh g−1) and improved the capacity retention from 81.4 to 96.4% after 60 cycles at 0.5C in the voltage range of 2.8–4.4 V.

Single crystal Ni-rich NMC cathode materials for lithium-ion batteries with ultra-high volumetric energy density

“…Upon cycling at 1C, both SC622 and SC811 samples exhibit remarkable cycling stability and retained ~91% and ~81% of the initial capacity after 300 cycles, respectively, that is significantly higher than the capacity retention of the polycrystalline analogues amounting to ~81% in PC622 and 70% in PC811 (Figure 3e, f). Moreover, the single crystal materials obtained in the present work demonstrate improved or comparable electrochemical performance being benchmarked against the previously reported single crystal Ni-rich NMCs with other octahedral morphology [16,[23][24][25][26] (Table 1). For instance, being cycled at 1C rate, SC811 synthesized within this work shows increased capacity retention (95% after 100 cycles) in comparison with single crystal NMC811 reported in the literature (78% after 300 cycles) [25].…”

“…3e and f). Moreover, the single crystal materials obtained in the present work demonstrate improved or comparable electrochemical performance being benchmarked against the previously reported single crystal Ni-rich NMCs with octahedral morphology 16,[23][24][25][26] (Table 1). For instance, being cycled at 1C rate, SC811 synthesized within this work shows increased capacity retention (95% after 100 cycles) in comparison with single crystal NMC811 reported in the literature (78% after 300 cycles).…”

“…The asymmetry is a typical feature of Ni 3+ , indicating considerable increase in Ni 3+ amount increases on going from 622 to 811 compositions. The tap density, measured using a tapped density analyzer, reaches values of 3.0 g/cm 3 and 2.9 g/cm 3 for the SC622 and SC811 materials, respectively, while polycrystalline PC622 and PC811 show significantly lower values albeit typical for the polycrystalline NMC materials (Table 1) [22,23]. This ultra-high tap density is achieved due to compact packing of the round-shaped single crystal particles which possess no internal porosity, in contrast to spherical secondary agglomerates of the polycrystalline samples.…”

“…The tap density, measured using a tapped density analyzer, reaches 3.0 g cm À3 and 2.9 g cm À3 for the SC622 and SC811 materials, respectively, while polycrystalline PC622 and PC811 show significantly lower values albeit typical for the polycrystalline NMC materials (Table 1). 22,23 This ultra-high tap density is achieved due to compact packing of the round-shaped single crystal particles which possess no internal porosity, in contrast to spherical secondary agglomerates in the polycrystalline samples. Besides, powder compact density of single crystal SC622 and SC811 exceeds that of previously reported octahedral SC NMCs materials 24 (Table 1).…”

Conditioning the Surface and Bulk of High-Nickel Cathodes with a Nb Coating: An In Situ X-ray Study

“…Surface coating using Al 2 O 3 , ZrO 2 , Li 3 PO 4 , Li 2 ZrO 3 , and Li–Nb–O has been shown to be effective in suppressing the dissolution of transition metal ions, alleviating the side reactions between the electrolyte and electrode, and reducing the first cycle loss. Substitution with cations, including Al 3+ , Zr 4+ , Nb 5+ , , Mg 2+ , and W 6+ , is applied to the bulk to improve the conductivity and stability of the lattice, thereby enhancing capacity retention upon extended cycling.…”