Lithium-ion batteries continue to be a critical part
of the search
for enhanced energy storage solutions. Understanding the stability
of interfaces (surfaces and grain boundaries) is one of the most crucial
aspects of cathode design to improve the capacity and cyclability
of batteries. Interfacial engineering through chemical modification
offers the opportunity to create metastable states in the cathodes
to inhibit common degradation mechanisms. Here, we demonstrate how
atomistic simulations can effectively evaluate dopant interfacial
segregation trends and be an effective predictive tool for cathode
design despite the intrinsic approximations. We computationally studied
two surfaces, {001} and {104}, and grain boundaries, Σ3 and
Σ5, of LiCoO
2
to investigate the segregation potential
and stabilization effect of dopants. Isovalent and aliovalent dopants
(Mg
2+
, Ca
2+
, Sr
2+
, Sc
3+
, Y
3+
, Gd
3+
, La
3+
, Al
3+
, Ti
4+
, Sn
4+
, Zr
4+
, V
5+
) were studied by replacing the Co
3+
sites in all four
of the constructed interfaces. The segregation energies of the dopants
increased with the ionic radius of the dopant. They exhibited a linear
dependence on the ionic size for divalent, trivalent, and quadrivalent
dopants for surfaces and grain boundaries. The magnitude of the segregation
potential also depended on the surface chemistry and grain boundary
structure, showing higher segregation energies for the Σ5 grain
boundary compared with the lower energy Σ3 boundary and higher
for the {104} surface compared to the {001}. Lanthanum-doped nanoparticles
were synthesized and imaged with scanning transmission electron microscopy-electron
energy loss spectroscopy (STEM-EELS) to validate the computational
results, revealing the predicted lanthanum enrichment at grain boundaries
and both the {001} and the {104} surfaces.