Constructing efficient lithium salt dissociation solid-state electrolytes with high conductivity and transference number of Li ions for stable all-solid-state lithium batteries

The broad application of solid-state polymer electrolytes (SPEs) has been hindered by the extremely low transference number of lithium ions and ionic conductivities. This study innovatively introduces Co-doped Li4Ti5O12 (CLTO) into poly(ethylene oxide) (PEO) matrix, CLTO not only brings a stronger interaction with TFSI-, but also weakens the Li-O bond in Li4Ti5O12 and reduces the diffusion activation energy of Li+. Thus, CLTO introducing PEO-based polymer solid electrolytes could simultaneously promote the dissociation of Li+ from LiTFSI and Li4Ti5O12, constructing efficient dual lithium salt dissociation regions and rapid Li+ conduction channels. The experimental tests and density functional theory calculations have confirmed the operational mechanisms of CLTO within the polymer matrix. As a result, the obtained SPEs exhibit a high ionic conductivity (1.09 x 10(-4) S cm(-1)) and a quite large tLi+ of 0.83 at 60 degrees C. Moreover, the low (Highest Occupied Molecular Orbital) HOMO energy (-7.25 eV) of the CLTO-LiTFSI-PEO-10 (CLP-10) endow it can accommodate both the Li-metal anode and high-voltage cathodes. The all-solid-state LiFePO4||Li and NCM811|| Li batteries offer exceptional specific capacities of 164.61 and 194.95 mAh/g at 60 degrees C, respectively. In addition, the pouch cell assembled with CLP-10 works stably under extreme conditions such as bending and shearing.