Shielded electric field-boosted lithiophilic Sites: A Janus interface toward stable lithium metal anodes

[Display omitted] •A Janus interface structure to improve the cycling stability of Li metal anode.•A shielded electric field enabled by the nano-diamond particles.•Boosted Li cyclability by the nano-diamond/lithiophilic material composite. Uncontrolled volume expansion with spiky lithium (Li) deposits is the major challenge for high-energy–density Li metal batteries to achieve long-term and safe cycling. The roughness or protrusion induced uneven electric field on the Li plating substrate is the main cause for the Li deposition heterogeneity. Lithiophilic sites are widely employed to guide Li deposition with high Li affinity, however also suffer from the restricted electrochemical regions by the uneven electric field for Li plating/stripping. Herein, a strategy of shielding the interfacial electric field to boost the functionality of lithiophilic sites is proposed beyond the single use of lithiophilic sites. A Janus composite of nanodiamond (ND) particles imbedded lithiophilic copper oxides (CuxO) is used to decorate the Li deposition substrate. The evenly distributed ND particles play a critical role to readjust the electric field on the electrode surface, and in turn homogenize the conversion process of CuxO sites to guide uniform Li deposition throughout the entire electrode surface. Consequently, the Li cyclability on the CuxO/ND decorated electrode significantly outperforms those on bare or CuxO decorated electrodes for practical cycling conditions, proving the designing principle of the shielded electric field-boosted lithiophilic sites interface for stable Li metal anodes.