Electrode-Less MnO₂ -Metal Batteries with Deposition and Stripping Chemistry

Electrode materials are key components in typical batteries, where the electrodes are generally fabricated onto current collectors in solid forms and are isolated by a separator. However, the preparation of the electrodes increases the fabrication complexity, which speeds down their large-scale production. Here, series of static electrode-less MnO₂ -metal batteries are presented that are facilely fabricated by using carbon current collectors and electrolytes. The MnO₂ -metal batteries are operated in dual-deposition/stripping chemistries of Mn²⁺ /MnO₂ on the cathode and M/M^x+ on the anode. The MnO₂ -Cd/Zn/Cu batteries exhibit remarkable rates up to 200 C, excellent reversibility of 15 000 cycles, and realistic gravimetric and volumetric energy densities of 93.7 Wh kg^-1 and 134 Wh L^-1 , respectively. Impressively, the MnO₂ -Cd battery can achieve over 160 000 cycles in the high current pulse test, showing promises in the applications of electrical vehicle's start-stop and large-scale energy storage.