Poly(ethylene oxide) (PEO) and Li6.75La3Zr1.75Ta0.25O12 (LLZTO)‐based composite polymer electrolytes (CPEs) are considered one of the most promising solid electrolyte systems. However, agglomeration of LLZTO within PEO and lack of Li+ channels result in poor electrochemical properties. Herein, a functional supramolecular combination (CD‐TFSI) consisting of active β‐cyclodextrin (CD) supramolecular with self‐assembled LiTFSI salt is selected as an interface modifier to coat LLZTO fillers. Benefiting from vast H‐bonds formed between β‐CD and PEO matrix and/or LLZTO, homogeneous dispersion and tight interface contact are obtained. Moreover, 6Li NMR spectra confirm a new Li+ transmission pathway from PEO matrix to LLZTO ceramic then to PEO matrix in the as‐prepared PEO/LLZTO@CD‐TFSI CPEs due to the typical cavity structure of β‐CD. As a proof, the conductivity is increased from 5.3 × 10−4 S cm−1 to 8.7 × 10−4 S cm−1 at 60 °C, the Li+ transference number is enhanced from 0.38 to 0.48, and the electrochemical stability window is extended to 5.1 V versus Li/Li+. Li‖LiFePO4 CR2032 coin full cells and pouch cells prove the practical application of the as‐prepared PEO/LLZTO@CD‐TFSI CPEs. This work offers a new strategy of interface modifying LLZTO fillers with functional supramolecular combination to optimize PEO/LLZTO CPEs for solid lithium batteries.
This paper extends the existing studies of cyclical fiscal policy by providing the first systematic theoretical and empirical study of cyclical quasi‐fiscal investment of state‐owned enterprises (SOEs) in China. Using data from Chinese listed companies and the System GMM method, the results show that: (1) both central and local SOEs exhibit expansion‐biased investment behaviours; (2) the expansion‐biased investment of central SOEs mainly goes to the tertiary industry and the western regions of China, while the expansion‐biased investment of local SOEs mainly occurs in the tertiary industry and the middle and western regions of China; (3) during the economic recession, the higher the local growth targets, the more bank credit central and local SOEs can obtain, and the more pronounced the expansion‐biased investment. The study shows that apart from the countercyclical fiscal policy implemented by central and local governments, the quasi‐fiscal function of central and local SOE investments is also key for the Chinese economy to quickly recover from recessions.
Surface functionalization is an effective strategy to reduce the chemical reactivity between a Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) electrolyte and Li metal anode and optimize the interfacial contact of different components. Herein, sodium itaconate (SI) is introduced to modify the surfaces of LATP particles (LATP@SI) via a self-polymerizing process, and a composite solid electrolyte (CSE) composed of poly(ethylene oxide) (PEO) and LATP@SI is fabricated. Benefiting from the protection of the SI nanolayer, LATP demonstrates chemical compatibility with the Li metal anode, while the reduced surface energy renders a good dispersion of LATP in PEO. Furthermore, abundant carboxyl groups in SI can offer a bridge between LATP and PEO to accelerate Li + transmission. As a result, the as-prepared PEO-LATP@SI-6 CSE exhibits a high ionic conductivity of 1.15 × 10 −4 S cm −1 at 30 °C and 1.20 × 10 −3 S cm −1 at 60 °C, a wide electrochemical stable window beyond 5.0 V, an improved Li + transference number of 0.41, and an optimized lithium compatibility over 1200 h with Li dendrite free. The as-assembled Li||PEO-LATP@SI-6 CSE||LiFePO 4 full battery delivers a high reversible capacity of 155 mAh g −1 and an outstanding capacity retention of 89% after 200 cycles. The Li|| LiFePO 4 pouch cell also successfully runs 50 cycles with a terminal discharge capacity of 116.6 mA h g −1 . This study opens a new avenue to protect LATP. The developed surface functionalization technique promises a facile and efficient method for interfacial engineering to accelerate the practical application of LATP in solid-state lithium batteries.
Microporous layer (MPL) is a vital component for proton-exchange membrane fuel cells (PEMFCs) to improve the cell performance. However, the conventional preparation of MPL, involving the mixing of carbon black with hydrophobic agent polytetrafluoroethylene (PTFE), followed by high-temperature annealing, is often complicated and costly. Herein, we present a facile and low-cost method to fabricate the MPL by functionalization of carbon black via covalent bonding with hydrophobic agent. Upon chemical grafting with fluoroalkylsilane (FAS-17), the water contact angle of carbon black is increased from 66.4 to 150.4°, resulting in superhydrophobicity. The MPL prepared with the resultant superhydrophobic carbon endows the PEMFC with enhanced gas and water permeability and hereby improved electrochemical performance over traditional MPL, and a maximum power density of 1211 mW cm −2 for the PEMFC can be obtained. This work offers a feasible strategy to construct an efficient MPL for the PEMFC via a chemical grafting approach.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.