Electroless Formation of Hybrid Lithium Anodes for Fast Interfacial Ion Transport

Abstract

Rechargeable batteries based on metallic anodes are of interest for fundamental and application-focused studies of chemical and physical kinetics of liquids at solid interfaces. Approaches that allow facile creation of uniform coatings on these metals to prevent physical contact with liquid electrolytes, while enabling fast ion transport, are essential to address chemical instability of the anodes.H ere,w er eport as imple electroless ion-exchange chemistry for creating coatings of indium on lithium. By means of joint density functional theory and interfacial characterization experiments,w es howt hat In coatings stabilizeL ib ym ultiple processes,i ncluding exceptionally fast surface diffusion of lithium ions and high chemical resistance to liquid electrolytes.I ndium coatings also undergo reversible alloying reactions with lithium ions,f acilitating design of high-capacity hybrid In-Li anodes that use both alloying and plating approaches for charge storage.Bymeans of direct visualization, we further show that the coatings enable remarkably compact and uniform electrodeposition. The resultant In-Li anodes are shown to exhibit minimal capacity fade in extended galvanostatic cycling when paired with commercial-grade cathodes.Secondary batteries comprising of metallic anodes (e.g.L i, Na, Al) have drawn significant recent attention due to their promise for enabling large (as high as ten-fold) increases in the anodic capacity,incomparison to state-of-art lithium-ion anode chemistry. [1,2] Am ajor barrier to the successful implementation of such anodes is the uneven electrodeposition of the metal in the charging process,w hich leads to formation of rough, so-called dendritic structures.T hese structures are diffusion-limited and as such under extended battery operation can grow to fill the inter-electrode space, short-circuiting the battery. [3][4][5] Previously,u sing continuum modeling,T ikekar et al. [6,7] proposed that dendrite-induced short-circuits can be prevented using electrolytes with moderate mechanical modulus (10 MPa) if afraction of the anions are tethered to prevent cell polarization at high current densities and to maintain electrolyte conductivity in the region near the anode.T here is also al arge body of experimental work showing that dendrite growth can be regulated using solid-state electrolytes, [8] nanoporous polymers or ceramics that host liquids in their pores, [9][10][11] crosslinked polymers, [12,13] as well as with high transference number gel-like electrolytes. [14][15][16][17] Although researchers are now able to address safety concerns associated with Li and Na metal anodes by av ariety of means,t his progress has uncovered difficult challenges associated with uncontrolled parasitic reactions between liquid electrolytes and ar eactive metal electrode. [18,19] In rechargeable batteries that employ metallic anodes, particularly those based on Li and Na, the electrolyte would ideally react with the metal surface to form astable and selflimiting passivation layer termed the solid-electrolyt...

An ion redistributor for dendrite-free lithium metal anodes

“…A mechanistic understanding of the dendritic growth is still lacking. If the transport behavior of Li ions and electrons can be rationally decoupled, a safe and long–life span Li metal battery is therefore highly expected ( 19 , 20 ). …”

Enabling reversible redox reactions in electrochemical cells using protected LiAl intermetallics as lithium metal anodes

“…Several effective approaches have been proposed to achieve efficient Li transport through the interphases formed on LiM anodes in aprotic liquid electrolytes and to enable high levels of reversibility in the electrochemical reactions that occur at the anodes' interphases (17)(18)(19). Among these approaches, we single out efforts that use alloying, such as Li-B, Li-Mg, and Li-In mechanisms (20)(21)(22)(23)(24)(25)(26), and coating processes to create stable and well-defined interphases on LiM (11,27,28) for their ability to create full electrochemical cells in which the anode and cathode capacity ratio (n/p ratio) is beginning to approach values required for a practical success of lithium metal batteries (LiMBs).…”

Confining electrodeposition of metals in structured electrolytes

“…Next, we systematically study the morphology of the lithiumelectrolyte interface in the cross-linked hairy nanoparticles soaked with liquid electrolyte using direct visualization of the lithium metal anode during electrodeposition in an optical cell. The cell comprises a lithium metal and stainless-steel electrodes separated by a chamber containing electrolyte of 1 M LiPF 6 -EC/ DMC (10). For the conditions used in the experiments, the diffusion-limited current density for the different membranes were calculated from the measured conductivity and transference number: J* = 2zc o FD app (t a L) −1 .…”

“…Such cells achieve this feat both by increasing the amount of electrical energy that can be stored on a mass or volume basis at the anode and by enabling more flexible material choices for the cathode (1)(2)(3)(4)(5)(6). Parasitic reactions between the chemically reactive anode (7)(8)(9)(10)(11) and proliferation of rough, dendritic/mossy electrodeposition at the metal anode during battery recharge have been reported to reduce stability of the cells by increasing the likelihood of failure by internal short circuits and by increasing the surface area of reactive metals in contact with electrolytes (12,13).…”

“…In all of the measurements the ratio between the weight of the composite material and liquid electrolyte (1 M LiPF 6 EC/DMC) was kept constant at 1:2. The details of the visualization cell for lithium deposition measurements were presented in a previous paper (10). The dendrite growth was done using a semiautomatic analysis in MATLAB, where the sizes of the focused dendrites are measured over time.…”