Stable Conversion Chemistry‐Based Lithium Metal Batteries Enabled by Hierarchical Multifunctional Polymer Electrolytes with Near‐Single Ion Conduction

Abstract

The lowC oulombic efficiency and serious safety issues resulting from uncontrollable dendrite growth have severely impeded the practical applications of lithium (Li) metal anodes.H erein we report as table quasi-solid-state Li metal battery by employingah ierarchical multifunctional polymer electrolyte (HMPE). This hybrid electrolyte was fabricated via in situ copolymerizing lithium 1-[3-(methacryloyloxy)propylsulfonyl]-1-(trifluoromethanesulfonyl)imide (LiMTFSI) and pentaerythritol tetraacrylate (PETEA) monomers in traditional liquid electrolyte,w hichi sa bsorbed in ap oly(3,3-dimethylacrylic acid lithium) (PDAALi)-coated glass fiber membrane.T he well-designed HMPE simultaneously exhibits high ionic conductivity (2.24 10 À3 Scm À1 at 25 8 8C), near-single ion conducting behavior (Li ion transference number of 0.75), good mechanical strength and remarkable suppression for Li dendrite growth. More intriguingly,t he cation permselective HMPE efficiently prevents the migration of negatively charged iodine (I) species,w hich provides the as-developed Li-I batteries with high capacity and long cycling stability.

Enabling a Durable Electrochemical Interface via an Artificial Amorphous Cathode Electrolyte Interphase for Hybrid Solid/Liquid Lithium‐Metal Batteries

“…Actually, when coupling with LiNi x Mn y Co 1− x − y O 2 (NCM) cathodes, there are inevitable side reactions that deteriorate interfacial stability, owing to the addition of commercial liquid electrolyte . Besides, the aggregation of space charge still exists across the cathode/polymer or cathode/ceramic interface, which is liable to hinder ionic transportation . A valid scenario is urgently required to ameliorate the above instability to extend the application of hybrid solid/liquid electrolytes.…”

“…Considering the demands for high energy density and security, solid electrolytes have the priority to replace liquid electrolytes when operated in Li-metal batteries, [1] and exhaustive efforts have been invested in the development of solid electrolytes with outstanding stability. [2] Solid electrolytes mainly fall into two categories: all-solid electrolytes and hybrid solid/liquid electrolytes, [3] and the latter concurrently contribute to benign interfacial contact and suppressed Li dendrite growth, [4] which is superior to the all-solid electrolytes with high electronic conductivity and insufficient contact, [5] hence filling the gap in high-safety Li metal batteries for ideal capacity output. However, the incompatibility caused by the inherent frail chemistry and electrochemistry on the cathode/electrolyte interface has usually been overlooked in recent hybrid solid/liquid battery systems.…”

A Single‐Ion Conducting Borate Network Polymer as a Viable Quasi‐Solid Electrolyte for Lithium Metal Batteries

“…Recent materials design efforts have focused on the development of ion‐selective solid polymer electrolytes that feature anionic groups immobilized onto the polymer backbone, wherein only Li + cations are free to move through the material. These single‐ion conductors can display Li + transport numbers approaching unity, but their room temperature ionic conductivities are typically less than 10 −5 S cm −1 , an order of magnitude lower than the minimum conductivity required for lithium battery operation .…”

A Polymer‐Reinforced SEI Layer Induced by a Cyclic Carbonate‐Based Polymer Electrolyte Boosting 4.45 V LiCoO2/Li Metal Batteries

“…Noted that a high t Li + would reduce electrode polarization by inhibiting the formation of a concentration gradient, which limits the available maximum current owing to the diffusion of ions generating important osmotic forces, and suppresses undesirable side reactions on the electrodes. [ 20 ] As can be seen from Figure 3b, the symmetric Li/PCUMA‐GPE/Li battery polarized at 5 mV for 7200 s presents a high t Li + of 0.44. Such a large t Li + of PCUMA‐GPE can be mainly attributed to cyclic carbonate with a high dielectric constant on PCUMA beneficial for the dissociation of Li salts and the interactions between N‐H on PCUMA with anions.…”