Surface modified Li₄Ti₅O₁₂ by paper templated approach for enhanced interfacial Li⁺ charge transfer in Li-ion...

The Li₄Ti₅O₁₂ (LTO) and lithium silicate (LS) surface modified LTO have been demonstrated by a unique paper templated method. Comparative study of structural characterization with electrochemical analysis was demonstrated for pristine and modified Li₄Ti₅O₁₂. Structural and morphological study shows the existence of the cubic spinel structure with highly crystalline 250-300 nm size particles. The LS modified LTO shows the deposition of 10-20 nm sized LS nanoparticles on cuboidal LTO. Further, X-ray photoelectron spectroscopy (XPS) confirms the existence of Li₂SiO₃ (LS) in the modified LTO. The electrochemical performance was investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge. The modified LTO with 2% LS (LTS2) exhibited excellent rate capability compare to pristine LTO i.e. 182 mA h g^-1 specific capacity at a current rate, 50 mA g^-1 with remarkable cycling stability up to 1100 cycles at a current rate of 800 mA g^-1. The lithium ion full cell of modified LTO with LS as an anode and LiCoO₂ as a cathode exhibited a remarkably reversible specific capacity i.e. 110 mA h g^-1. Both electronic and ionic conductivities of pristine LTO are observed to be enhanced by incorporation of appropriate amount of LS in LTO due to a larger surface contact at the interface of electrode and electrolyte. More significantly, the versatile paper templated synthesis approach of modified LTO with LS provides densely packed highly crystalline particles. Additionally, it exhibits lower Warburg coefficient and higher Li ion diffusion coefficient which in turn accelerate the interfacial charge transfer process, which is responsible for enhanced stable electrochemical performance. The detailed mechanism is expressed and elaborated for better understanding of enhanced electrochemical performance due to the surface modification.