Na3Ti2(PO4)3 as a sodium-bearing anode for rechargeable aqueous sodium-ion batteries

Na3Ti2(PO4)3 synthesized as fine carbon-coated powders is demonstrated for the first time to be a suitable sodium-bearing anode material for rechargeable aqueous sodium-ion batteries (ANaBs). Importantly, Na3Ti2(PO4)3 is found to be stable in deoxygenated water, enabling use of this material in aqueous systems. As a sodiated anode, it allows use of sodium-depleted cathode materials that require supply of sodium-ions from the anode. As an example, we demonstrate for the first time the use of olivine FePO4 as a cathode in an ANaB.