Here, we report a remarkable 15 Å nanolayered tin phosphate, Sn(HPO4)2·3H2O (SnP-H+ or SnP), and its clay-like gel, which are multifunctional and are prepared using earth-abundant Sn and P chemicals by a facile, environmentally benign and potentially cost-effective process. This new energy material is discovered here as the best proton conductor among all the known layered phosphates with a very high proton conductivity of over 1 × 10-2 S cm-1 at 100 °C for potential use in PEM fuel cells. But it is also a very good capacitor material with fast Li-storage kinetics (charging time of 13 s).