Cyclodextrin-Integrated PEO-Based Composite Solid Electrolytes for High-Rate and Ultrastable All-Solid-State Lithium Batteries

Abstract

Poly­(ethylene oxide) (PEO)-based composite solid electrolytes (CSEs) are considered as one of the most promising candidates for all-solid-state lithium batteries (ASSLBs). However, a key challenge for their further development is to solve the main issues of low ionic conductivity and poor mechanical strength, which can lead to insufficient capacity and stability. Herein, β-cyclodextrin (β-CD) is first demonstrated as a multifunctional filler that can form a continuous hydrogen bond network with the ether oxygen unit from the PEO matrix, thus improving the comprehensive performances of the PEO-based CSE. By relevant characterizations, it is demonstrated that β-CD is uniformly dispersed into the PEO substrate, inducing adequate dissociation of lithium salt and enhancing mechanical strength through hydrogen bond interactions. In a Li/Li symmetric battery, the β-CD-integrated PEO-based (PEO-LiTFSI-15% β-CD) CSE works well at a critical current density up to 1.0 mA cm–2 and retains stable lithium plating/stripping for more than 1000 h. Such reliable properties also enable its superior performance in LiFePO4-based ASSLBs, with specific capacities of 123.6 and 114.0 mA h g–1 as well as about 100 and 81.8% capacity retention over 300 and 700 cycles at 1 and 2 C (1 C = 170 mA g–1), respectively.

Interface Manipulation of Composite Solid Polymer Electrolyte with Polydopamine to Construct Durable and Fast Li+ Conduction Pathways

“…37,38 After adding the stoichiometric ratio of LiClO 4 as a preparation for Co 3 O 4 @PDA CPE, the downfield shift suggests a strong electric attraction between the labile hydrogen groups and the negative ClO 4 − anions of lithium salt. 39 Such a downfield shift is also found in the case of the DA monomer and LiClO 4 as shown in Figure S13b. 40 Thus, it is reasonable to speculate that the phenolic hydroxyl groups can serve as efficient Lewis-acid sites to interact with ClO 4…”

Rational design of a topological polymeric solid electrolyte for high-performance all-solid-state alkali metal batteries

“…For topological structures, fluoropolymers with multi-arm and three-dimensional spherical structures are preferred and exhibit peculiar physical properties and electrochemical behaviors unattainable by simple linear homopolymers 27 . Cyclodextrin ( α -type, β -type, and γ -type) reported by previous works has been demonstrated to be a suitable base material for post-functionalization or self-assembly, which could promote Li + migration or realize other potential functions 28 – 33 . Here, the food additive β -cyclodextrin ( β -CD) with 21 hydroxyl groups is selected as the “core” to obtain 21 functionalized arms, which is helpful to realize its high molecular size and high functionality.…”

Optimized functional additive enabled stable cathode and anode interfaces for high-voltage all-solid-state lithium batteries with significantly improved cycling performance

“…All the CSEs were fabricated through a solution pouring method. 58 Firstly, a certain mass ratio of poly(vinylidene uoride) (PVDF, HSV900, Guangdong Canrd New Energy Technology Co., Ltd), Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZTO, homemade), lithium bis(triuoromethane sulfonimide) (LiTFSI, 99%, Aladdin) and LiF (99.9%, Aladdin) was dissolved/dispersed in dimethylformamide (DMF, 99.8%, Aladdin), and then the mixture was stirred vigorously at 50 C for 5 h. Subsequently, a certain mass of poly(ethylene oxide) (PEO, M n ¼ 600 000, Aladdin) and a small amount of functional additive (LiDFOB or LiBODFP) were further added. Aer stirring for another 5 h, a highly viscous and brown slurry was formed, which was then poured into a homemade mold to evaporate most of the solvent at 50 C. Next, the prepared electrolyte lms were further dried in a vacuum drying oven at 80 C for 12 h. Finally, the electrolyte lms were cut into small discs with a diameter of 19 mm and then stored in a glovebox for later use.…”