Electronegative graphene film based interface-chemistry regulation for stable lithium metal batteries

To achieve practical application of lithium (Li) metal anodes for high-energy–density batteries, the primary challenges of the inhomogeneous solid electrolyte interphase (SEI) and irregular Li electrochemical stripping/depositing behaviors should been surmounted. So as to homogenize Li+ distribution and stabilize the SEI layer, herein, we reported a partially reduced graphene oxide (PrGO) film with a manageable electronegativity as an ideal Li host to construct composite electrode (PrGO@Li). The fabricated PrGO with tunable oxygen amount and negatively charge can achieve controllable Li capacity avoiding excess Li. More importantly, the electronegative PrGO film matrix can cause an electrostatic force and thereby regulate the Li+ distribution pattern and diffusion kinetics, which induces a homogeneous and stable LiF-rich SEI and highly conformal Li+ stripping/deposition behaviors without Li dendrites. As a result, the optimal PrGO@Li electrode delivers long-term reversible Li+ stripping/depositing processes with an extremely low overpotential (7 mV) after 2000 h cycling at 20 mA cm−2 and 10 mAh cm−2. Moreover, the full battery based on this anode paired with LiFePO4 cathode exhibits outstanding cycling stability, high rate capacity and excellent flexibility characters. Meanwhile, the controllable PrGO films can also be loading with sulfur as cathodes for satisfactory Li/sulfur batteries. This research deeply analyzes the intermediation mechanism between the graphene host and Li+ on the electrochemical behaviors, and offers universal guidance for the development of high-performance Li-metal batteries.