Oral Presentation Royal Australian Chemical Institute National Congress 2026

An entropy-stabilised surface dopant zone enabling durable 4.5 V cycling of Ni-rich NCM811 (137098)

Leqi Zhao 1 2 , Zezhou Lin 3 , Yijun Zhong 1 , Hanwen Liu 1 , Xiao Sun 2 , Yu-Cheng Huang 1 , William Rickard 2 , Tony Tang 4 , Zongping Shao 1
  1. Curtin Centre for Advanced Energy Materials and Technologies, WA School of Mines: Minerals, Energy and Chemical Engineering (WASM-MECE), Curtin University, Perth, WA, Australia
  2. John De Laeter Centre, Curtin University, Perth, WA, Australia
  3. Department of Applied Physics, The Hong Kong Polytechnic University, Hong Kong, CHINA
  4. WA School of Mines: Minerals, Energy and Chemical Engineering (WASM-MECE), Curtin University, Perth, WA, Australia

Ni-rich layered LiNi0.8Mn0.1Co0.1O2 (NCM811) can deliver high energy density, but operation to high cut-off voltages accelerates degradation driven by oxygen loss, surface reconstruction, impedance growth, and particle fracture. Here we use a correlative microscopy–spectroscopy framework to link dopant spatial distribution to structural evolution and high-voltage electrochemical behaviour. Two multi-element designs incorporating Ce/La/Zr/Al are compared: a bulk-distributed high-entropy analogue (BHE-NCM) and a surface-zoned architecture (SHE-NCM) formed through stepwise, temperature-mediated processing that concentrates dopants near the particle exterior.

Diffraction and electron microscopy show that dopant architecture strongly influences phase stability. While both materials retain the layered framework, BHE-NCM exhibits additional diffraction features consistent with secondary perovskite-type phases, indicating segregation associated with broad bulk incorporation. High-resolution TEM further reveals strain signatures in BHE-NCM (notably elongated (003) lattice fringes). In contrast, SHE-NCM suppresses impurity reflections and shows improved layered-ordering indicators, including an increased I(003)/I(104) ratio (2.21), consistent with reduced Li/Ni cation mixing. HAADF-STEM/EDS mapping and depth-resolved XPS confirm that Ce/La/Zr/Al are enriched at the surface and progressively diminish with etching, whereas the Ni/Li-rich core remains comparatively unchanged. Complementary Ni K-edge XANES/EXAFS indicates that the bulk Ni environment in SHE-NCM remains close to that of pristine NCM, supporting a surface-confined modification that avoids disrupting the interior lattice.

Thermal and electrochemical measurements connect these nanoscale observations to high-voltage durability. For delithiated electrodes, SHE-NCM delays layered-to-spinel conversion (258.7 °C) and shifts oxygen evolution to higher temperature (302.4 °C) with a reduced peak release rate (79.3 μmol·min-1·g-1). Staircase potentiostatic impedance spectroscopy shows lower interphase and charge-transfer resistances across 3.9–4.5 V. In Li∥cathode half-cells cycled to 4.5 V, SHE-NCM achieves 211.8 mAh·g-1 initial discharge capacity with 86.5% initial coulombic efficiency and retains 182.9 mAh·g-1 after 50 cycles (86.4%). Post-cycling SEM reveals substantially reduced micro-/macro-cracking, while ToF-SIMS depth profiling indicates a thinner, more uniform cathode–electrolyte interphase with fewer decomposition signatures. Overall, correlative microscopy demonstrates that an entropy-stabilised surface dopant zone suppresses oxygen-loss-driven reconstruction and fracture, enabling durable high-voltage cycling of Ni-rich cathodes1.

  1. 1. Zhao, L., et al., Engineering of entropy-driven surface doping towards stabilized high-voltage NCM cathodes: Li (Ni, Co, Mn, Ce, La, Zr, Al) Ox. Materials Reports: Energy, 2025/11/01. 5(4).