A nasicon-type phase as intercalation electrode: NaTi2(PO4)3

Reversible intercalation of sodium in NaTi2(PO4)3 at room temperature can be achieved either chemically or electrochemically. Na3Ti2(PO4)3 is obtained as final product via a two phase mechanism. The non-existence between both extreme compounds of a Na1+xTi2(PO4)3 solid solution seems to result from a topotactic demixtion reaction which requires only Na+ and e− transfers without skeleton bond breaking and recombination.