A new polymorph of Na2MnP2O7 as a 3.6 V cathode material for sodium-ion batteries

Exploring novel low-cost cathodes for sodium-ion batteries, here we unveil β-Na2MnP2O7, a new pyrophosphate cathode. Stabilizing into a triclinic structure, it was found to be electrochemically active, delivering a discharge capacity approaching 80 mA h g−1 along with the highest ever Mn3+/Mn2+ redox potential located at 3.6 V.