Direct-Write Lithiation of Silicon Using a Focused Ion Beam of Li⁺

Abstract

Electrochemical processes that govern the performance of lithium ion batteries involve numerous parallel reactions and interfacial phenomena that complicate the microscopic understanding of these systems. To study the behavior of ion transport and reaction in these applications, we report the use of a focused ion beam of Li + to locally insert controlled quantities of lithium with high spatial-resolution into electrochemically relevant materials in vacuo. To benchmark the technique, we present results on direct-write lithiation of 35 nm thick crystalline silicon membranes using a 2 keV beam of Li + at doses up to 10 18 cm −2 (10 4 nm −2). We confirm quantitative sub-μm control of lithium insertion and characterize the concomitant morphological, structural and functional changes of the system using a combination of electron and scanning probe microscopy. We observe saturation of interstitial lithium in the silicon membrane at ≈ 10 % dopant number density and spillover of excess lithium onto the membrane's surface. The implanted Li + is demonstrated to remain electrochemically active. This technique will enable controlled studies and improve understanding of Li + ion interaction with local defect structures and interfaces in electrode and solid-electrolyte materials.

Phase Evolution Analysis During Real-Time Solid-State Chemical Lithiation of Crystalline Thin Window Silicon Membranes Using Low-Loss STEM-EELS Imaging

“…However, room temperature recrystallization of equilibrium intermetallic Li-Si phases appeared frustrated, and after the initial fast reaction step, the metastable silicide glass did not further evolve towards the Li-richest Li15Si4 phase. The obtained results are compared with liquid phase electrochemical lithiation of c-Si in a LiClO4-dimethyl carbonate electrolyte when a solid electrolyte interface is present [1] and direct injection of Li + ions into c-Si using focused Li + ion beams [4].…”

A High‐Resolution Versatile Focused Ion Implantation Platform for Nanoscale Engineering

“…Such systems have found many applications across a variety of disciplines, largely due to their milling capabilities. [ 2 ] Examples include the milling of arrayed nanopores for multicolor generation; [ 3 ] microfabrication and failure analysis; [ 4 ] nanoscale device prototyping [ 5 ] (including Fresnel zone plates for high‐resolution X‐ray imaging); [ 6 ] localized materials engineering of electrochemically active systems; [ 7 ] and when in conjunction with other processes, the creation of plasmonic nanoparticles for single photon sources. [ 8 ] The use of FIB systems specifically for low‐dose impurity‐ion doping has been limited, though its potential is substantial with applications in developing fields such as quantum technologies.…”

Disordering kinetics in monocrystalline and epitaxial Si upon energy deposition induced by dual-beam ion irradiation

“…Those elements are then used to design ever increasingly complex electronic devices. Therefore, Si-based materials are found in various fields of physics and materials science that include, to cite just a few, central processing units, energetic particle detectors (for instance in large-scale accelerator facilities) [5][6], sensors for space applications [7], photovoltaic cells [8] and lithium batteries [9][10]. For most of these uses, and also for functional design at the nanoscale such as nanobubble formation [11] or doping [1,12], silicon is subjected to ion irradiation, an operation during which complex energy deposition processes are involved.…”