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 in situ construct a Li3P@Co ion/electron conductive interface on every single CoP-C@CFC. Thanks to the high ionic conductive Li3P and electron-conductive Co nanoparticles, the rapid dispersion of Li+ and obviously reduced local current density can be achieved simultaneously. Furthermore, in situ optical microscopy observations display obvious depression for volume expansion and Li dendrites. As expected, a miraculous average Coulombic efficiency (CE) of 99.96% over 1100 cycles at 3 mA cm-2 and a low overpotential of 11.5 mV with prolonged cycling of over 3200 h 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 500 cycles at 2 C and excellent rate capability.An ion/electron redistributed 3D flexible host is designed by lithiophilic carbon fiber cloth modified with MOF-derived porous carbon sheath with embedded CoP nanoparticles (CoP-C@CFC). During the Li plating, the in situ formed Li3P@Co conductive interface on CoP-C@CFC realizes Li+/charge redistribution, which achieves highly average Coulombic efficiency of 99.96% over 1100 cycles at practical current density of 3 mA cm−2.