“Tree‐Trunk” Design for Flexible Quasi‐Solid‐State Electrolytes with Hierarchical Ion‐Channels Enabling Ultralong‐Life Lithium‐Metal Batteries

Abstract

theoretical energy density, low reduction potential of metallic Li, and their inherent safety provided by the solid-state electrolyte (SSE), [1][2][3] As the core component, the development of SSE with superior lithium-ion conductivity and stability plays a critical role in the realization of such batteries. [4][5][6] Compared to oxide or sulfidebased inorganic SSEs which are brittle and difficult to process, organic SSEs, such as poly(ethylene oxide), received wide attention due to their advantages including lightweight, flexible, scalable, and good interfacial compatibility with electrodes. [7,8] However, poor mechanical strength, insufficient thermal stability, and low ionic conductivity at room temperature (RT) of 10 −6 to 10 −5 S cm −1 reduce their commercial viability. [9,10] Despite various strategies including chemical crosslinking, [11] block copolymerization, [12] grafting, [13][14][15] filling with liquid plasticizers, [16][17][18] or combining with inert fillers, [19][20][21][22][23][24][25] to solve the aforementioned drawbacks for polymeric SSEs, the performance compromise between ion conductivity, transference number, mechanical strength, and satisfied lifespan has persisted for decades. [7] More efforts such as the development of novel materials and/or improved architectures, and even dramatical transformation of conventional polymeric SSEs and corresponding Li + -transport mechanism, are necessary and urgent to satisfy future energy storage needs. [4] The polymetric electrolytes with small amounts of liquid electrolyte to form a quasi-solid-state electrolyte (QSSE) might be an available strategy to improve the safety and electrochemical performance simultaneously.A common idea gaining popularity in scientific and technical societies is to learn from nature and thereby gain inspiration for material design. [26] Such an example can be found in trees, which possess an efficient internal nutrition delivery system and a robust mechanical structure that allows them to adapt to their natural environment. For instance, a tree trunk is mostly composed of inside xylem, middle cambium, and outside bark (Figure 1a and Figure S1, Supporting Information). [27] The inner xylem (sapwood and heartwood) acts as the framework to provide structural support with robust mechanical strength. [27][28][29] The bark (living phloem and outmost bark) that outer covers the tree's trunk and branches can transport nutriment formed throughThe construction of robust (quasi)-solid-state electrolyte (SSE) for flexible lithium-metal batteries is desirable but extremely challenging. Herein, a novel, flexible, and robust quasi-solid-state electrolyte (QSSE) with a "tree-trunk" design is reported for ultralong-life lithium-metal batteries (LMBs). An in-situgrown metal-organic framework (MOF) layer covers the cellulose-based framework to form hierarchical ion-channels, enabling rapid ionic transfer kinetics and excellent durability. A conductivity of 1.36 × 10 −3 S cm −1 , a transference number of 0.72, an electrochemical window of 5.2...

Sulfide-Based All-Solid-State Lithium–Sulfur Batteries: Challenges and Perspectives

“…However, a limited number of polymer types such as PTFE binder are suitable for this method [ 62 , 63 ]. Additionally, developing mechanically flexible electrolytes that can accommodate volume changes of sulfur could be another effective strategy to gain highly mechanically stable ASSLSBs [ 64 , 65 ].…”

Hollow‐Particles Quasi‐Solid‐State Electrolytes with Biomimetic Ion Channels for High‐Performance Lithium‐Metal Batteries

“…[16] QSSE may be an effective strategy to improve both safety and electrochemical performance. [17] Hou et al [18] identified solvent-assisted jumping as the main route of lithium-ion transport in the MOF-688 material and explained the key role of solvents. Yang et al [19] used the molecule-anion coordination to promote the dissociation of lithium salts, increase the concentration of free lithium ions, and achieve the fixation of anions, which weakened the dynamic traction of lithium ions when moving, and greatly enhanced the transport dynamics of lithium ions.…”

Cellulose-Assisted Vertically Heterostructured PEO-Based Solid Electrolytes Mitigating Li-Succinonitrile Corrosion for Lithium Metal Batteries

“…Vertically heterostructured PEO-based solid electrolytes (HPSE) are hybrid multilayered solid ion conductors with homogeneous composition in each layer . At the side of the Li anode, nanofillers can be added to enhance the mechanical properties of PEO, such as SiO 2 , , Al 2 O 3 , , BN, , MOFs (metal–organic frameworks), − and Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 . ,, At the cathode side, the flexibility and ionic conductivities of PEO-based SPEs can be increased by introducing plastic crystals, such as succinonitrile (SN), , which has attracted great attention as a typical solid plastic crystal. In 2004, Armand et al first introduced SN as a universal matrix for solid-state ionic conductors and found that the ionic conductivity of SN-lithium bis­(trifluoromethane)­sulfonimide (LiTFSI) could reach 3 mS cm –1 .…”