Printable MnO2 Based Rechargeable Sodium Batteries
The inkjet-printed MnO2 electrode can serve as a cathode material for high performance rechargeable sodium batteries. The as-assembled full cell could reach maximum energy and power densities of 147 Wh·kg-1total and 4.6 kW·kg-1total with average working voltage of 2.3V and ca.100% capacity retention after 100 cycles, which could be anticipated for practical energy applications. The MnO2 based electrode could achieve simultaneously and unprecedentedly a working voltage of 2.5V, maximum energy and power densities of 587 Wh·kg−1cathode and 75 kW·kg−1cathode respectively with a 99.5% capacity retention for 500 cycles at 1 A·g−1. These values are approaching the targeted sodium ion batteries.
The long-neglected kinetically limitation effect is found to be effective in controlling the redox mechanism. The inkjet-printed MnO2 electrode shows an enhanced redox activity of Mn4+/Mn3+ couple, along with a fully suppressed redox activity of Mn3+/Mn2+ couple. Owing to the earth-abundant and low cost of sodium (Na) as compared to Li, sodium secondary batteries are envisioned to be a viable alternative to replace the current lithium (Li) based battery industry