Green Polymer Electrolytes Based on Polycaprolactones for Solid‐State High‐Voltage Lithium Metal Batteries

Abstract

Solid polymer electrolytes (SPEs) have attracted considerable attention for high energy solid-state lithium metal batteries (LMBs). In this work, potentially ecofriendly, solid-state poly(𝝐-caprolactone) (PCL)-based star polymer electrolytes with cross-linked structures (xBt-PCL) are introduced that robustly cycle against LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622) composite cathodes, affording long-term stability even at higher current densities. Their superior features allow for sufficient suppression of dendritic lithium deposits, as monitored by 7 Li solid-state NMR. Advantageous electrolyte|electrode interfacial properties derived from cathode impregnation with 1.5 wt% PCL enable decent cell performance until up to 500 cycles at rates of 1C (60 °C), illustrating the high potential of PCL-based SPEs for application in high-voltage LMBs. IntroductionAs essential component within lithium-based batteries, the electrolyte plays a vital role for achieving long-term electrochemical performance and safety. Despite their potential in providing high specific capacity, current lithium metal batteries (LMBs) are eventually limited by inhomogeneous lithium deposition (high-surface area lithium (HSAL)) or disadvantageous

Li+ Transport in Ethylene Carbonate Based Comb-Branched Solid Polymer Electrolyte: A Molecular Dynamics Simulation Study

“…The transference number of all systems lies in the range of 0.6 to 0.8, and the maximum value is observed for B 8 T 5 polymer with an insignificant difference between other polymer architectures. The B 4 T 5 system, which displays the highest total conductivity, has a transference number of 0.7 at 450 K. This value is superior to PEO, , PEO-blend, , and other solid polymer electrolytes. ,, …”

“…Molecular dynamics (MD) simulations were conducted using Atomistic Polarizable Potential for Liquid, Electrolytes, and Polymers (APPLE&P) which has been extensively used for modeling electrolytes with Li-ion salts. − In this force field, every force center is assigned an isotropic polarizability, and the induced point dipoles are computed using the self-consistent approach to minimize the electrostatic energy of the system. The Thole screening parameter of 0.2 was used to avoid the “polarization catastrophe” at short separations .…”

“…The B 4 T 5 system, which displays the highest total conductivity, has a transference number of 0.7 at 450 K. This value is superior to PEO, 61,62 PEO-blend, 63,64 and other solid polymer electrolytes. 35,65,66…”

Poly(Ether-Ester)-Based Solid Polymer Electrolytes with High Li-Ion Transference Number for High Voltage All-Solid-State Lithium Metal Batteries

“…24 Unfortunately, insufficient ionic conductivity (10 −6 −10 −7 S cm −1 ), low lithium ion transference number (t Li ature represent the main reasons restricting PEO-based SPEs' large-scale application, where the broadly accepted concept that the constrained segmental motion of PEO chains due to the semicrystallization nature of PEO and the limited Li + transport owing to the strong coordination between lithium ions and oxygen atoms could explain the its poor electrochemical performance. 25,26 In this context, the development of new polymer matrices to achieve high-performance LIBs is one of the research hotspots to SPEs-based LMBs.…”

“…Poly­(ε-caprolactone) (PCL) is one of typical aliphatic polyester that has been extensively studied on account of its excellent biodegradability, biocompatibility and processing ability . It is reported that the flexible polymer structure, relatively low glass transition temperature ( T g ∼ −60 °C), and the easier dissociation of lithium salts and weaker interaction between carbonyl groups and lithium ions may favor the migration of lithium ions .…”