Green mechanochemical Li foil surface reconstruction toward long-life Li-metal pouch cells

The uncontrollable growth of Li dendrites and high cost hinder the commercial application of Li metal batteries (LMBs). Herein, a low-cost Li foil surface-reconstruction strategy based on a mechanochemistry reaction between fumed silica and Li is proposed to realize a dendrite-free Li metal anode for practical Li metal pouch cells. Under the action of mechanical friction, fumed silica can break the primitive passivation layer on Li foil and undergo in situ lithiation, forming a multifunctional reconstructed surface with nanoscale dispersed high electrolyte wettability and nanoparticles with affinity to Li. Deep insight into the unique interfacial electrochemical mechanism indicates that the entire reconstructed surface of Li foil (ERS@Li) can not only induce uniform deposition and stripping of Li, enhancing the electrode dynamics, but also construct an anionphilic interface. As a result, applying an ERS@Li anode can effectively improve the low-temperature (-40 degrees C) and cycling performance of practical LMBs (93% after 500 cycles at 0.3 C/0.5 C for a 0.53 A h Li||LCO pouch cell, 97% after 49 cycles at 0.1 C/0.2 C for a 1.6 A h Li||S pouch cell and stability over 30 cycles for an Li||S pouch cell with 466.7 W h kg-1). This work provides a new idea for solving the practical problems of LMBs. A green mechanochemical surface treatment strategy endows practical Li metal pouch cells with excellent electrochemical performance, achieving high energy density, stable cycle performance and high security.

Automated summary

This study proposes a low-cost Li foil surface-reconstruction strategy using a mechanochemistry reaction between fumed silica and Li to achieve dendrite-free Li metal anode. The reconstructed surface enhances the electrode dynamics and constructs an anionphilic interface, leading to significantly improved low-temperature and cycling performance of Li metal batteries while maintaining high energy density and stable cycle performance.