Significantly improved electrochemical performance of the commercial lithium titanate (Li 4 Ti 5 O 12 ) achieved by using a novel current collector of cuprous iodide-modified copper foil

A novel finding that the electrochemical performance of the commercial lithium titanate (Li 4 Ti 5 O 12 , LTO) can be significantly improved by using a novel current collector of CuI particles modified copper foil is reported for the first time in this work. Firstly, a large number of particles with well-defined shapes were prepared on the commercial copper foil surface via a very simple soaking process, in which the soaking solution contained only CuSO 4 , H 2 SO 4 and [Bmim]I. As indicated by the XRD and XPS measurements, the particles observed on the surface of the copper foil were identified as CuI particles. That is, CuI particles modified copper foils (denoted as CuI/Cu) were successfully prepared at room temperature. CuI/Cu prepared in the presence of 0.4, 0.6 and 0.8 g of [Bmim]I were nominated as CF (copper foil) a, b and c, respectively. Inconceivably, as compared to the conventional LTO electrode, the LTO electrodes assembled using the newly prepared CFs exhibited a significantly improved electrochemical performance, i.e., all as-prepared CFs showed an evident promoting effect on the electrochemical performance of the traditional LTO electrodes. For instance, the initial discharge capacity (DC) of the LTO electrode assembled using CF b (called electrode b) at 0.2 C was 307 mAh g −1 , which was about 1.86 times higher than that of the LTO electrode prepared using the conventional copper foil current collector (165 mAh g −1 ). Particularly, as the applied current rate was as high as 10 C, the DC value of electrode b (117 mAh g −1 ), even after 100 cycles, was still about 2.54 times that of the traditional LTO electrode (46 mAh g −1 ). In this preliminary work, a new method for preparing CuI particles was developed, along with a novel approach to significantly improve the electrochemical properties of the commercial LTO electrode. The method did not require any strong oxidants or reducing agents, nor did it demand any additional energy expenditure during the preparation of CuI particles. Moreover, the approach did not require any changes in the assembly procedure for the LTO electrodes being studied. This work was very meaningful for the development of the CuI-related research field as well as for the electrochemical performance improvement of LTO-based lithium-ion batteries (LIBs).