Ion/Electron Redistributed 3D Flexible Host for Achieving Highly Reversible Li Metal Batteries.

Abstract

3D carbon frameworks are promising hosts to achieve highly reversible lithium (Li) metal anodes, whereas insufficient effects are attributed to their single electron conductivity causing local aggregating of electron/Li+ and uncontrollable Li dendrites. Herein, an ion/electron redistributed 3D flexible host is designed by lithiophilic carbon fiber cloth (CFC) modified with metal-organic framework (MOF)-derived porous carbon sheath with embedded CoP nanoparticles (CoP-C@CFC). Theory calculations demonstrate the strong binding energy and plenty of charge transfer from the reaction between CoP and Li atom are presented, which is beneficial to insitu construct a Li3 P@Co ion/electron conductive interface on every single CoP-C@CFC. Thanks to the high ionic conductive Li3 P and electron-conductive Co nanoparticles, the rapid dispersion of Li+ and obviously reduced local current density can be achieved simultaneously. Furthermore, insitu optical microscopy observations display obvious depression for volume expansion and Li dendrites. As expected, a miraculous average Coulombic efficiency (CE) of 99.96% over 1100cycles at 3mAcm-2 and a low overpotential of 11.5mV with prolonged cycling of over 3200h at 20% depth of discharge are successfully obtained. Consequently, the CoP-C@CFC-Li||LiFePO4 full cells maintain a capacity retention of 95.8% with high CE of 99.96% over 500cycles at 2 C and excellent rate capability.