Solid-state Li metal battery enabled by cold sintering at 120 °C

It is still a great challenge to fabricate dense solid electrolyte with high ionic conductivity using a facile and low-cost method for all solid-state rechargeable battery. In this context, a cold sintering process (CSP) is employed to prepare the ceramic solid electrolytes at an extremely low temperature of 120 °C, significantly suppressing the Li loss and impurity formation by traditionally high-temperature sintering. The low temperature prepared Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP)-LiClO 4 (10.0 wt%) composite electrolyte exhibits a high ionic conductivity of 6.35 × 10 −5  S/cm, low activation energy of 0.26 eV and high relative densities of 90%. The Li | CSP LAGP-LiClO 4 (10.0 wt%) | Li symmetric cell delivers a cycling time retention of over 350 h with a stabilized voltage overpotential at a current density of 0.2 mA/cm 2 . Moreover, the high Coulombic efficiency of 99.97% and capacity retention of 150 mAh/g are achieved after 130 cycles at 0.1C in Li | CSP LAGP-LiClO 4 (10.0 wt%) | LiFePO 4 solid cells. These good electrochemical performances are originated from the well-constructed solid electrolyte-electrode interfaces, where the electrochemically active interface demonstrates the powerful self-stabilization function to maintain the tight interface connection as well as the continuous Li ion transport. The CSP method sheds new light on the fabrication of solid electrolytes at a low temperature and inexpensive way, hence provides a rewarding avenue to fabricate better solid-state batteries and other electrochemical devices .