In Situ Constructing Robust and Highly Conductive Solid Electrolyte with Tailored Interfacial Chemistry for Durable Li Metal Batteries

Abstract

Employing nanofiber framework for in situ polymerized solid‐state lithium metal batteries (SSLMBs) is impeded by the insufficient Li+ transport properties and severe dendritic Li growth. Both critical issues originate from the shortage of Li+ conduction highways and nonuniform Li+ flux, as randomly‐scattered nanofiber backbone is highly prone to slippage during battery assembly. Herein, a robust fabric of Li0.33La0.56Ce0.06Ti0.94O3‐δ/polyacrylonitrile framework (p‐LLCTO/PAN) with inbuilt Li+ transport channels and high interfacial Li+ flux is reported to manipulate the critical current density of SSLMBs. Upon the merits of defective LLCTO fillers, TFSI− confinement and linear alignment of Li+ conduction pathways are realized inside 1D p‐LLCTO/PAN tunnels, enabling remarkable ionic conductivity of 1.21 mS cm−1 (26 °C) and tLi+ of 0.93 for in situ polymerized polyvinylene carbonate (PVC) electrolyte. Specifically, molecular reinforcement protocol on PAN framework further rearranges the Li+ highway distribution on Li metal and alters Li dendrite nucleation pattern, boosting a homogeneous Li deposition behavior with favorable SEI interface chemistry. Accordingly, excellent capacity retention of 76.7% over 1000 cycles at 2 C for Li||LiFePO4 battery and 76.2% over 500 cycles at 1 C for Li||LiNi0.5Co0.2Mn0.3O2 battery are delivered by p‐LLCTO/PAN/PVC electrolyte, presenting feasible route in overcoming the bottleneck of dendrite penetration in in situ polymerized SSLMBs.

“Peapod-like” Fiber Network: A Universal Strategy for Composite Solid Electrolytes to Inhibit Lithium Dendrite Growth in Solid-State Lithium Metal Batteries

“…To further understand the dynamic evolution of the interface during the Li deposition, the distribution of Li + , TFSI – , and electric potential inside the Li symmetric cell was simulated using the finite element method (FEM). As shown in Figure b, the rapid Li depletion can be regarded as caused by the insufficient ionic conductivity of the PL and PLP and the unrestricted TFSI – motion. , Over time, the inhomogeneous electric field distribution within the PL and PLP electrolytes intensified, resulting in increasingly higher potentials proximal to the Li anode, accelerating the vertical growth of Li dendrites and ultimately leading to electrochemical instability. This phenomenon partly elucidates the occurrence of short-circuiting during cycling of the PL and PLP.…”

“…7−10 To address this, threedimensional (3D) network structures have been proposed, such as CSEs with continuous transport paths via a 3D ceramic network. 11,12 However, the brittleness of the ceramic skeleton poses challenges. 13,14 There is a need for a flexible 3D ionic conduction network to reinforce the polymer electrolyte.…”

“…However, a significant challenge arises in achieving a continuous conduction path in the polymer matrix solely through simple mechanical agitation of the fillers, as nanofillers often tend to agglomerate or precipitate. Furthermore, the mechanical properties of CSEs fabricated through this approach remain constrained. − To address this, three-dimensional (3D) network structures have been proposed, such as CSEs with continuous transport paths via a 3D ceramic network. , However, the brittleness of the ceramic skeleton poses challenges. , There is a need for a flexible 3D ionic conduction network to reinforce the polymer electrolyte. Additionally, thinning the electrolyte boosts weight/volume energy density, shortens ion transport distance, and enhances cell rate performance. − …”