Nanoconfined phosphorus in mesoporous carbon as an electrode for Li-ion batteries: performance and mechanism

Phosphorus-mesoporous carbon composites have been prepared by direct vaporization-condensation of phosphorus onto mesoporous carbon. The as-prepared P-1-C-1 composite showed improved performance in batteries vs. Li compared with classical P mainly due to the electronic modification of the nanoconfined P. By combining the electrochemical analysis with P-31 and Li-7 NMR, in situ X-ray diffraction and Raman spectroscopy we have characterized the electrochemical mechanism of the P-1-C-1 composite vs. Li in the battery. Such activated P is able to react reversibly with Li to form Li3P and this reaction takes place at higher potential than that of classical P. This study demonstrates that the effects of nano-confinement of an active material (AM) (here P) on mesoporous carbons paves a way (i) to stabilize different polymorphs of an active element (vs. Li) that present a modified reactivity vs. Li and (ii) to enhance the electrochemical performance of AM vs. Li. Last but not least it is demonstrated that the nature of carbon is determinant for the electrochemical performance.