No abstract

The growth and proliferation of Li dendrites during repeated Li cycling has long been a crucial issue that hinders the development of secondary Li-metal batteries. Building a stable and robust solid state electrolyte interphase (SEI) on the Li-anode surface is regarded as a promising strategy to overcome the dendrite issues. In this work, we report a simple strategy to engineer the interface chemistry of Li-metal anodes by using tiny amounts of dimethyl sulfate (DMS, CHSO) as the SEI-forming additive. With the preferential reduction of DMS, an SEI layer composed of LiS/LiO forms on the Li surface. This inorganic SEI layer features high structural modulus and low interfacial resistant, enabling a dense and dendrite-free Li deposition as evidenced by scanning electron microscopy, atomic force microscopy, and in situ optical images. In addition, this SEI layer can prevent the deposited Li from direct contact with corrosive electrolytes, thus rendering an improved cycling stability of Li anodes with an average Coulombic efficiency of 97% for up to 150 cycles. When the DMS additive is introduced into a Li/NCM full cell, the cycle life of Li-metal batteries can be also improved significantly. This work demonstrates a feasible route to suppress Li dendrite growth by designing appropriate film-forming additives to regulate the interfacial properties of the SEI layer, and also the sulfonyl-based derivatives revealed in this work represent a large variety of new film-forming molecules, providing a broad selectivity for constructing high efficiency and cycle-stable Li anodes to address the intrinsic problems of rechargeable Li-metal batteries.

Rechargeable lithium metal batteries are regarded as the “Holy Grail” of energy storage systems but suffer from poor cycling stability and severe safety concerns caused by notorious Li dendrite growth. Herein, we have achieved a record-breaking cycling life of high-voltage Li metal full cells simply by constructing a mesoporous silica reinforced hybrid polymer artificial layer on the Li surface. The inorganic mesoporous SiO2 filler plays a critical role in regulating Li+ ion migration and strengthening the mechanical rigidity, while the polymeric PVDF matrix endows the artificial SEI with structural integrity and stretchable flexibility, thereby significantly stabilizing the fluid Li anode–electrolyte interface. A remarkably extended cycling life could be achieved for modified Li anodes when coupled with various high-voltage cathodes (4.5 V class LiNi0.5Co0.2Mn0.3O2 and LiNi0.8Co0.1Mn0.1O2 and 5 V class LiNi0.5Mn1.5O4) under practical and even harsh operating conditions. Our work clears the obstacles on the way to a practical Li metal anode and provides guidance for the development of high-energy batteries.

Dendritic Li growth is a detrimental killer that threatens the safe operation and wide application of rechargeable Li-metal batteries (LMBs). Tuning the nucleation and growth behavior of Li plating process is, therefore, essential to tackle the dendrite growth problem. Here, we demonstrate a flaky and dense Li growth behavior simply by creating a nanoporous Cu layer on the surface of Li metal anode. Highresolution SEM and AFM measurements reveal that the Li deposits first nucleate as nanoflakes within the pores of Cu layer, then these flakes continuously grow thicker until they fuse together and eventually evolve into an ultra-smooth and dense Li layer. Such a unique Li growth behavior is derived from the nanoporous Cu surface layer, which triggers a synergistic regulation of the electrodeposition kinetics by providing a uniformly distributed electric field, sufficiently enhanced Li + diffusion flux, and also appropriately regulated lithium nucleation kinetics. As a result, stable cycling of the Li|Li symmetric cell and Li metal full cells (Li|LTO/LFP/NCM) can be achieved under high current densities and high deposition capacities. These findings illustrate the feasibility to tailor the Li deposition microstructure, which help to create a highly reversible, nondendritic, and safer Li metal anode for LMB applications.

No abstract