Epitaxial growth of an atom-thin layer on a LiNi _0.5Mn _1.5O ₄ cathode for stable Li-ion battery cycling

Abstract

Transition metal dissolution in cathode active material for Li-based batteries is a critical aspect that limits the cycle life of these devices. Although several approaches have been proposed to tackle this issue, this detrimental process is not yet overcome. Here, benefitting from the knowledge developed in the semiconductor research field, we apply an epitaxial method to construct an atomic wetting layer of LaTMO ₃ (TM = Ni, Mn) on a LiNi _0.5Mn _1.5O ₄ cathode material. Experimental measurements and theoretical analyses confirm a Stranski–Krastanov growth, where the strained wetting layer forms under thermodynamic equilibrium, and it is self-limited to monoatomic thickness due to the competition between the surface energy and the elastic energy. Being atomically thin and crystallographically connected to the spinel host lattices, the LaTMO ₃ wetting layer offers long-term suppression of the transition metal dissolution from the cathode without impacting its dynamics. As a result, the epitaxially-engineered cathode material enables improved cycling stability (a capacity retention of about 77% after 1000 cycles at 290 mA g ⁻¹) when tested in combination with a graphitic carbon anode and a LiPF ₆-based non-aqueous electrolyte solution.

Abstract

Transition metal dissolution from cathode materials limits the cycle life of Li-ion batteries. Here, the authors report an atomic-thin protecting layer on the surface of a high-voltage cathode material, enabling long-term Li-ion battery cycling.