Comonomer-Tuned Gel Electrolyte Enables Ultralong Cycle Life of Solid-State Lithium Metal Batteries

Abstract

Rechargeable lithium metal batteries (LMBs) are considered the “holy grail” of energy storage systems. Unfortunately, uncontrollable dendritic lithium growth inherent in these batteries has prevented their practical applications. The benefits of solid-state electrolyte for LMBs are limited due to the common compromise between ionic conductivity and mechanical property. This work proposes a mechanism for simultaneous improvement in ionic conductivity and mechanical strength of gel polymer electrolyte (GPE) which is based on tunable cross-linked polymer network through adjusting monomer ratios. With increasing bisphenol A ethoxylate dimethacrylate (E2BADMA) and poly­(ethylene glycol) diacrylate (PEGDA) mass ratios in GPE precursors, the formed polymer network experienced a composition evolution from a 3D cross-linked mono PEGDA network to triple PEGDA, E2BADMA, and PEGDA/E2BADMA networks and then to dual E2BADMA and PEGDA/E2BADMA networks, accompanied by the increase in both storage modulus (from 6 to 37 MPa) and ionic conductivity (from 0.06 to 0.44 mS cm–1). As a result, the E2BADMA/PEGDA mass ratio of 2:1 facilitates the successful fabrication of a dual-network-supported GPE (PEEPL-12) with a mechanical strength of 37 MPa and superior electrochemical properties (a high ionic conductivity of 0.44 mS cm–1 and a wide electrochemical stability window of 4.85 V vs Li/Li+). Such polymer electrolyte-based symmetric lithium metal batteries delivered a long cycle life (2000 h at 0.1 mA cm–2 and 0.1 mAh cm–2), and the Li|PEEPL-12|LiFePO4 cell delivered a high capacity of 140 mAh g–1 at the 100th cycle at the current density of 0.1 C (1 C = 170 mAh g–1). A more thorough investigation indicated the formation of a stable solid electrolyte interphase layer on a lithium metal anode. These extraordinary features open up a venue for fabrication of advanced polymer electrolyte for long-cycle-life lithium metal batteries.

Bioinspired, Ultra‐Sensitive Flexible Strain Sensor Based on Ceramic Fiber Paper With Superhydrophobic and High‐Temperature‐Resistant Properties

“…[ 9–11 ] Over the past decade, numerous efforts have been made to continuously improve their performances, such as the strain sensitivity, detection range, and cycling stability, of strain sensors. [ 12–14 ] Among them, sensitivity is one of the significant parameters as it endows the device with the ability to sense extremely weak mechanical signals. [ 13,15 ] To this end, researchers have been devoted to exploring the proper selection and combination of functional materials (e.g., MXene, low‐dimensional carbon materials, nanoparticles (NPs), and nanowires and their hybrid structures) and flexible substrates (e.g., polyethylene terephthalate (PET), polyurethane (PU), polydimethylsiloxane (PDMS), silk and fabric) to construct strain sensors with excellent performance.…”