Toothpaste-like Electrode: A Novel Approach to Optimize the Interface for Solid-State Sodium-Ion Batteries with Ultralong Cycle Life

A non-sintered method with toothpaste electrode for improving electrode ionic conductivity and reducing interface impedance is introduced in solid-state rechargeable batteries. At 70 °C, this novel solid-state battery can deliver a capacity of 80 mAh g^-1 in a voltage range of 2.5-3.8 V at 0.1C rate using layered oxide Na_0.66Ni_0.33Mn_0.67O₂, Na-β″-Al₂O₃ and sodium metal as cathode, electrolyte and anode, respectively. Moreover, the battery shows a superior stability and high reversibility, with a capacity retention of 90% after 10 000 cycles at 6C rate and a capacity of 79 mAh g^-1 is recovered when the current rate is returned to 0.1C. Furthermore, a very thick electrode with active material mass loading of 6 mg cm^-2 also presents a reasonable electrochemical performance. These results demonstrate that this is a promising approach to solve the interface problem and would open a new route in designing the next generation solid-state battery.