Spinel LiNi_0.5Mn_1.5O₄ (LNMO) cathode material doped with Ti and La co-doping were synthesized through a solid-state method. The bi-functions of the Ti and La co-doping is realized. On the one hand, the stability of the LiNi_0.5Mn_1.5O₄ crystal structure is enhanced and the Mn³⁺ interference inside the material is reduced by the Ti doping. On the other hand, the co-doped La contributes to the formation of Li_0.5La_0.5TiO₃ (LLTO) superionic conductor incorporated in the bulk LiNi_0.5Mn_1.5O₄ phase, thereby enhancing the Li diffusion. With the help of XRD, FTIR, SEM and STEM techniques, La and Ti in the crystallographic structure and the dispersion of the LLTO superionic conductor in the bulk LNMO spinel are discussed. At the optimized molar ratio of 20:1 between LNMO and LLTO, the composite exhibits the best electrochemical performances in terms of the reversible capacity, rate capability and cycling stability. The lithium ion diffusion coefficient in the bulk LNMO phase is tripled by the LLTO superionic conductor incorporation.

Potassium-ion batteries (KIBs) represent one of the most promising alternatives to lithium-ion batteries (LIBs) considering the potential low cost and abundant potassium resource. In this work, we demonstrate a core-shell structured sponge cathode for KIBs, where amorphous V₂O₅ uniformly coats on carbon nanotube (CNT) sponge via atomic layer deposition (ALD). The V₂O₅@CNT sponge shows several advantages as cathode: (1) the three-dimensional (3D) conductive network of CNT sponge offers a fast electron transport pathway, (2) the porous nature and high surface area of CNT sponge enables enough access for electrolyte to V₂O₅, (3) the amorphous structure of V₂O₅ offers a fast kinetics upon K-ion insertion/deinsertion. The V₂O₅@CNT sponge cathode delivers a high capacity of 206 mA h/g and moderate cycling and rate performance in common carbonate-based electrolyte system.