Tailoring Particle Morphology and Crystal Structure of Ni-Rich Cathodes for Next-Generation Lithium and All-Solid-State Batteries

Ni-rich layered oxides Li[Ni1-x-yCoxMny]O2 with Ni above 80 mol% offer the energy density required for long-range electric vehicles and urban air mobility, but suffer an intrinsic trade-off among capacity, cycle life, and thermal stability. The abrupt H2-to-H3 transition near the end of charge imposes an anisotropic lattice contraction close to 10%, nucleating microcracks along grain boundaries; electrolyte then penetrates and converts the exposed interior into a NiO-like rock-salt phase, electrochemically insulating the particle.

This talk summarizes strategies that engineer particle microstructure and crystal structure together. Controlling the chemical and hydrodynamic conditions of co-precipitation grows precursors from radially assembled nanosheets, inherited by the lithiated oxide as radially aligned rod-shaped primary particles; charge-induced strain is dissipated toward the surface and capacity retention after 1,000 cycles rises from 49% to 83%. Doping with high-valence elements (Nb, Ta, Mo) segregates Li-X-O compounds to grain boundaries and suppresses grain coarsening, preserving this texture over a far wider calcination window. A two-step route that introduces the dopant after preliminary lithiation confines Nb more sharply to grain boundaries and forms a layered/rock-salt/spinel nanocomposite whose transition is reversible; the resulting cathode sustains 1,000 cycles under an eVTOL duty profile with 6 C hover pulses.

These principles extend to sulfide-based all-solid-state batteries, where fading additionally arises from interfacial side reactions, contact loss, and isolation of inner particles. Side reactions dominate at 80 mol% Ni, whereas isolation and detachment govern above 90 mol%. Combining a surface coating with radial morphology modification markedly improves the cycling stability of Ni-rich cathodes in this system, showing that surface chemistry and particle architecture must be designed together.