Synergy of strong/weak interface adhesion forces and Li2S additive enabling high performance full anode-free lithium–metal batteries

Abstract

Anode-free Li–metal batteries (AFLBs) are receiving intense attention due to their high theoretical capacity and the absence of Li metal. To attain AFLBs in practice, it is crucial to homogeneously plate Li on the Cu collector and develop an additional Li source. Controllable Li plating has been shown by an inorganic nanoparticle-based double-component solid electrolyte interface (SEI). However, the complicated and batch-to-batch non-reproducible fabrication process is the major obstacle to its application. What's worse, the full AFLBs only depending on homogeneous Li plating/stripping generally show poor performance due to their less than 100% coulombic efficiency. Thus, researchers are still keeping a discreet attitude toward the practicability of AFLBs. Herein, we present a polar crosslinked tripropylene glycol diacrylate nanoparticle (CTN) prepared by an organic molecule confinement reaction, which gives precisely controllable physicochemical properties by a reproducible process. The double-component SEI on the Cu collector is fabricated by blending CTN and PVDF at the weight ratio of 60/40, i.e., CTN-60. Owing to a facilitated Li⁺ transfer and the strong/weak adhesion force with the Cu collector of CTN-60, homogeneous Li plating is achieved. The result indicates a high coulombic efficiency of 96.08% after 200 cycles at a current density of 0.5 mA cm⁻² and an areal capacity of 1 mA h cm⁻² in half-cell AFLBs. In LiFePO₄-based full ALIBs with CTN-60, the suspended Li₂S electrolyte is used for the generation of Li at the first charge. The high performance is achieved at 171 mA h g⁻¹ at 0.1C, 84 mA h g⁻¹ at 0.5C, and 82 mA h g⁻¹ at 2C after 100 cycles.