Position‐Responsive SEI Layer in Bicomponent‐Bidirectional Gradient Current Collector Induces Homogenized Ion Flux for Highly Reversible Li Metal Anode

Abstract

AbstractA gradient current collector (GCC) can encourage preferential Li metal deposition on the more lithiophilic/conductive bottom of 3D anodes, enhancing the reversibility of the battery. However, as the deposition proceeds, the reduction of lithophilicity/conductivity easily causes the disturbance of Li+ flux. Herein, a brand‐new bicomponent‐bidirectional gradient current collector (BGCC) is proposed. The BGCC constructs slow‐release additives with reverse gradient distribution (SA gradient) based on GCC, allowing it to build a position‐responsive solid electrolyte interface layer. Additionally, as the deposition amount increases, the slow‐release additives will release more and present a stronger ability to regulate Li+ flux, ensuring the anodereversibility under large deposition amounts conditions. Consequently, asymmetric cells can exhibit high reversibility with an average coulomb efficiency (CE) of 97.8% and sustain over 200 cycles using carbonate‐based electrolytes. The Li@BGCC||LiFePO4 full cells hold a capacity retention of 94.8% over 400 cycles with thin Li. Notably, even at low temperatures, the Li@BGCC anodes can exhibit a CE as high as 98.46% and excellent capacity retention of 97.8% after 100 cycles paired with NCM811 cathodes. This strategy opens up a new direction for the development of 3D current collectors.