Retarding Li dendrites growth via introducing porous g-C3N4 into polymer electrolytes for solid-state lithium metal batteries

Solid polymer electrolytes (SPEs) based solid-state lithium metal batteries (SSLMBs) are widespreadly practiced as one of the main technical routes aiming for chemically essential safety with acceptable energy density . However, uncontrollable Li dendrites growth and sluggish Li + transport remain obstacles to the further development of SPEs-based SSLMBs. Herein, a porous g-C 3 N 4 (PCN) is designed and introduced into polyethylene oxide (PEO). Within the following synthesized PEO-based composite solid electrolyte (PEO/PCN/LiTFSI CSE), PCN is found to be an attractive multifunctional filler. For its porous morphology and high specific surface area, abundant Lewis basic active sites are exposed, which facilitates Li + to be uniformly distributed in PEO/PCN/LiTFSI CSE and thus more effectively mitigates the Li dendrites growth comparing to those with bulk g-C 3 N 4 filler, making PCN-involved Li symmetrical cell (Li|PEO/PCN/LiTFSI|Li) run steadily for 1400 h under the current density of 0.1 mA cm −2 at 60 °C. PCN also accelerates Li + transport in the manner of reducing PEO crystallinity and promoting LiTFSI dissociation. The Li + conductivity of PEO/PCN/LiTFSI CSE reaches 3.47 × 10 −4 S cm −1 at 60 °C. Therefore, long life span and high rate performances are together achieved in SSLMB assembled with PEO/PCN/LiTFSI CSE. This work reveals a feasible strategy to fabricate dendrite-free SSLMBs cycling within a fairly long time.