Packed to capacity: The incorporation of mesoporous structures as a buffer layer enhances the structural stability of tin phosphate and alleviates the volume expansion of the tin phosphate anode during Li alloying/dealloying (see TEM image). The mesoporous tin phosphate/Sn2P2O 7 composite anode shows a large initial capacity (721 mAhg -1) and excellent cyclability (587 mAhg-1 at the 30th cycle.