Constructing a Protective Pillaring Layer by Incorporating Gradient Mn⁴⁺ to Stabilize the Surface/Interfacial Structure of LiNi_0.815Co_0.15Al_0.035O₂ Cathode

Abstract

Nickel-rich layered oxides are regarded as very promising materials as cathodes for lithium-ion batteries because of their environmental benignancy, low cost, and high energy density. However, insufficient cycle performance and poor thermotic characteristics induced by structural degradation at high potentials and elevated temperatures pose challenging hurdles for nickel-rich cathodes. Here, a protective pillaring layer, in which partial Ni ions occupy Li slabs induced by gradient Mn, is integrated into the primary particle of LiNiCoAlO to stabilize the surface/interfacial structure. With the stable outer surface provided by the enriched Mn gradient concentration and the pillar effect of the NiO-like phase, Mn-incorporated quaternary cathodes show enhanced structural stability and improved Li diffusion as well as lithium-storage properties. Compared with the severe capacity fade of a pure layered structure, the cathode with gradient Mn exhibits more stable cycling behavior with a capacity retention of 80.0% after 500 cycles at 5.0 C.

New Insight into the Role of Mn Doping on the Bulk Structure Stability and Interfacial Stability of Ni‐Rich Layered Oxide

“…A high ratio value of I(003)/I(104) (> 1.2) indicates a well-ordered crystal structure for all three samples after calcination, [3] while the value decreases when increasing Mn dopant, which means more Ni 2 + ions migrate to lithium layer and aggravate the cation mixing. [18,26,27] Therefore, it is inferred that Mn ions are successfully doped in the pristine NCA, and further verifications will be performed in the following discussion.…”

“…reported a novel surface pillaring layer for the first time, and the treated material exhibited excellent structural stability at high temperature and charging states during cycling. Xu et al . synthesized surface Mn 4+ ‐enriched Li(Ni 0.815 Co 0.15 Al 0.035 ) 1−x Mn x O 2 cathode materials by coating Mn(Ac) 2 ⋅ 4H 2 O on precursor, the material displayed excellent electrochemical performance and enhanced structural stability.…”

“…Cho et al [26] reported a novel surface pillaring layer for the first time, and the treated material exhibited excellent structural stability at high temperature and charging states during cycling. Xu et al [27] synthesized surface Mn 4 + -enriched Li(Ni 0.815 Co 0.15 Al 0.035 ) 1À x Mn x O 2 cathode materials by coating Mn(Ac) 2 · 4H 2 O on precursor, the material displayed excellent electrochemical performance and enhanced structural stability. However, most of the modifying works above have been mainly focused on the opinion that the improved electrochemical performance is the generation of the protective surface pillaring layer.…”

Structure and electrochemical performance modulation of a LiNi0.8Co0.1Mn0.1O2 cathode material by anion and cation co-doping for lithium ion batteries

“…3d) with a spacing about 0.2704 nm, matching to (101) plane of the layered structure. [32][33][34] The result of Fast Fourier Transform analysis is shown in Fig. 3e, which shows that the material of NCM/CB is wellpreserved as the R 3m phase.…”

“…The last H2 + H3 phase transition at around 4.2 V is account for the irreversible phase transition related to capacity fade. 9,33 Obviously, the peak intensity corresponding to H2 + H3 phase transition for the NCM/CB is lower than that for NCM and NCM/C at initial cycle. As Fig.…”