Tortuosity Effects in Lithium-Metal Host Anodes

Abstract

A strong correlation between host tortuosity and cycling reversibility of a hosted Li-metal anode is revealed for the first time. High tortuosity leads to preferential top-surface Li deposition based on locally enhanced current density and concentration gradient. This top-surface accumulated Li blocks inward ion transport and invalidates the internal electrode, further aggravating the uneven current distribution and non-uniform plating and stripping. Decreased electrode tortuosity can significantly improve the anodic Coulombic efficiency, uniformity of Li-metal stripping and plating, and cycling stability of the rGO host.

Tortuosity Modulation toward High‐Energy and High‐Power Lithium Metal Batteries

“…There are several approaches to achieve low-tortuous structures for hybrid lithium anodes, which can be categorized into microprocessing, [59][60] rolling-cutting, [61][62][63][64] templating, [65][66][67][68][69] direct growth, [70][71] and 3D printing [72] methods according to their synthesis processes. Microprocessing methods [59][60] usually involve laser or ion etching steps, which are highly dependent on the processing equipment, and have been used to generate vertically aligned microchannels on metallic foils.…”

“…Typical rolling-cutting method [61][62][63][64] consists of three steps: covering organic or inorganic films with lithium foil, rolling them into a cylinder, and then laterally cutting it into thin discs, i.e., hybrid lithium anodes, which is expected to be a favorable processing method for manufacturing low-tortuous arrays. Templating methods usually utilize wood, [65][66] ice crystal, [67][68] or anodized aluminum oxide [69] (AAO) as templates and convert conductive carbonaceous materials into low-tortuous arrays by positively or negatively replicating the microstructures of templates. Direct growth approaches include catalytic growth [70] and hydrothermal growth [71] method.…”

“…Conductive arrays including porous metallic foils, [59][60] oriented metallic foil, [63] and vertically aligned carbon arrays [67,[69][70] can incorporate into low-tortuous anodes and homogenize the distributions of electric field of anodes, efficiently regulating lithium plating. For instance, copper (Cu) foil with vertically aligned microchannels prepared via a laser microprocessing system was first developed as a host for lithium anode by Guo and co-workers.…”

Reversible Deposition of Lithium Particles Enabled by Ultraconformal and Stretchable Graphene Film for Lithium Metal Batteries

“…More significantly, the Li metal deposits beneath the stacked defect-free graphene layers in this work, while the stacked rGO layers reported in literature act as 3D host for the Li deposition. [39][40][41][42] This is because more negative voltage is required for the deposition of metallic Li on the defect-free few-layer graphene than on the rGO ( Figure S9, Supporting Information). Moreover, the thin defect-free graphene film acts as ultraconformal SEI, which enables fast Li-ion transfer for Li deposition on the Li metal surface beneath the film.…”

The Insights of Lithium Metal Plating/Stripping in Porous Hosts: Progress and Perspectives

“…In addition, the relationship between host tortuosity and cycling reversibility of composite Li anodes was first revealed by Cui and co‐workers. [ 94 ] Li metal tends to plate and strip on the upper surface in a highly tortuous anode because the ion transport path to the middle or bottom of the host is much longer. The accumulation of deposited Li further impedes the ion transmission over time, thus aggravating the growth of excessive Li deposition on the top, while the surface inside the anode cannot be utilized effectively.…”