Outstanding capacity assimilated from lithium-rich manganese nickel oxide flexible cathode material relies on CNT-wrapped carbon fibers for flexible lithium-ion batteries

Abstract

The extraction of two Li-ions per formula unit from the Li-rich cathode materials is still far from reality due to the intense structural changes that occur in this type of material after some initial cycles. Here, we expound on Ni incorporation in Li₂MnO₃ cathode materials and their assimilation onto the CVD-grown 3D vertical CNT-wrapped carbon fibrils without disturbing their rudimentary structural features to procure high capacity and striking rate capabilities. The 3D morphological topographies of the Li-rich Li₂(Mn_1−xNi_x)O_3−δ (LRMNO) cathode material have been disclosed by high-resolution SEM and STEM analysis. When cycled within a voltage range of 3.5–4.9 V, the spray-coated 3D LRMNO wrapped on the surface of CNT (LRMNO@CNT-CC) exhibits a high capacity of up to 208 mA h g⁻¹ (after 10 initial cycles) at 1C rate and a surprising capacity retention of 91% after 200 cycles and 71% after 1000 cycles. The well-defined redox peaks that occur within the voltage range of 3.8–4.2 V and 4.6–4.9 V in the cyclic voltammetric curves and the differential capacity plot establish the strong structural elasticity of the sample with two Li⁺ extraction processes during a single charge–discharge cycle. The full Li flexible pouch cell batteries with spray-coated Mn₃O₄ nanoparticles on carbon fabrics as the anode material also exhibit superior electrochemical performances of 3D-flexible LRMNO@CNT-CC cathode materials. The careful Ni incorporation, the uniform 3-dimensional framework of the CNT support, and the synergistic interaction between the highly graphitised CNTs and the LRMNO nanoparticles highlight the extremely structurally sensitive Li₂MnO₃ cathode material to facilitate stable electrochemical performances and achieve sustainability.