Materials containing confined water can be easily synthesized via hydrothermal or sol-gel methods, and the confined water can be removed by thermal treatment. Typically, the weight loss occurs in stages (Figure ), and three types of water exist based on the differences in the activation energy (Table , Supporting Information). They are 1) surface-adsorbed water , 2) nanoconfined water , which is water molecule that constitutes the crystal structure, and 3) nanoconfined pseudo-water , which is hydrogen-containing species with an H:O stoichiometry other than 2:1, such as -OH group , hydroxide and hydronium (Figure ). Here H-Ti-O compound containing a large amount of confined water is first synthesized via hydrothermal reaction, resulting in a layered structure (denoted as HTO, Figure , Supporting Information). Then a Li-H-Ti-O layered structure (denoted as LHTO-pre) was obtained by an ionic exchange treatment of HTO in a LiOH solution. Finally, LHTO-pre is heat-treated at a low temperature (200 °C). At this temperature, all the surface-adsorbed water and part of nano-confined water can be removed. The resulted compound is denoted as LHTO. The weight loss of this process is illustrated in Figure . According to thermogravimetry analysis (TGA) and elemental analysis, the chemical formulars of LHTO-pre and LHTO are determined as Li1.81H0.19Ti2O5•H2O, and Li1.81H1.13Ti2O5.15-σ, respectively. The phase transformation of LHTO-pre during the dehydration process is further studied by X-ray diffraction (XRD) (Figure ). When the temperature is increased to 200 °C, a possible intermediate phase (LHTO) appears with decreased interlayer spacing from 0.8 nm to 0.6 nm (Figure , Supporting Information). FTIR shows hydrogen exists mainly in the form of Ti-OH (Figure , Supporting Information), confirming the presence of nano-confined pseudo-water. Scanning electron microscopy (SEM) images show the LHTO-pre has a nanowire morphology, which is maintained during the heattreatment at 200 °C (Figure ). High-resolution transmission electron microscopy (HRTEM) (Figure , f) images show more lattice distortion and defects appearing in LHTO than LHTO-pre, which would benefit the Li-ion transport . Further increasing the temperature leads to the loss of all confined water (Figure ) and the collapse of the layered structure. XRD shows the sharp peaks associated with the high-temperature Li4Ti5O12 phase (LTO, Figure ) and the amorphous-glassy phase disappears (Figure , Supporting Information).