Constructing Highly Conductive and Thermomechanical Stable Quasi‐Solid Electrolytes by Self‐Polymerization of Liquid Electrolytes within Porous Polyimide Nanofiber Films

Abstract

Solid electrolytes are being considered as an effective solution to replace liquid ones for building safer batteries, but they suffer either low ionic conductivity or large contact ohmic impedance. Here, a highly conductive and thermomechanically stable quasi‐solid electrolytes (QSE) by self‐polymerization of a commercially available liquid electrolytes (1,3‐dioxolane (DOL), 1,2‐dimethoxyethane (DME), lithium trifluoromethane sulfonimide (LiTFSI) and LiPF6) at room temperature in a porous polyimide nanofiber film are reported. LiPF6 initiates the ring‐opening reaction of DOL and LiTFSI promotes the self‐polymerization to form poly‐DOL (PDOL), while the plasticizer of DME solidifies the PDOL. On the other hand, polyimide has a great affinity with PDOL that facilitates to form stable QSE network. As a result, the QSE film shows a high room‐temperature ionic conductivity of 2.9 × 10−3 S cm−1, a high mechanical strength of 31 MPa, and high heat resistance to 160 °C. The LiFePO4||QSE||Li batteries with a high cathode loading of ≈18.7 mg cm−2 show great cycling performance and stable electrode/electrolyte interfaces at a high current rate of 0.5 C with a capacity retention of 91.8% over 200 cycles at room temperature.

High-Energy-Density and Long-Lifetime Lithium-Ion Battery Enabled by a Stabilized Li2O2 Cathode Prelithiation Additive

“…Impedance measurements in Figure S2c show that the carbonate electrolyte with 5.3 wt % PMMA still maintains an ionic conductivity of 0.98 mS cm −1 at 25 °C, comparable to that of the pristine electrolyte (1.00 mS cm −1 , Figure S2d). 38 The electrochemical stability window of the carbonate electrolyte with PMMA is similar to that of the pristine electrolyte by linear sweep voltammetry (LSV; Figure S2e). 39 As shown in Figure S2f, the freezing point of the electrolyte with PMMA is obtained via differential scanning calorimetry (DSC), which is comparable to that of the pristine electrolyte.…”

Advances in Nanofibrous Materials for Stable Lithium-Metal Anodes

“…143,144 As a typical example, Huang et al fabricated porous polyimide nanofiber films by electrospinning, and then added commercial electrolytes into the polyimide films. 145 Under the promotion of lithium bis-(trifluoromethane)sulfonimide (LiTFSI), the 1,3-dioxolane underwent self-polymerization, and finally a GPE with high room-temperature ion conductivity (2.9 × 10 −3 S cm −1 ), high strength (31 MPa), and high thermal stability (160 °C) was formed. To balance the mechanical strength and ionic conductivity of GPE, Zhou and co-workers designed an ultrathin (10 μm), flexible, and thermally stable single-ion conducting GPE.…”

“…For GPE, the use of three-dimensional nanofiber networks as a skeleton can effectively improve its mechanical strength and thermal stability. − In addition, the abundant nanoscale or microscale pore structures of nanofiber films provide sufficient space for retaining liquid electrolytes, preventing them from leaking while also providing good interfacial compatibility. , As a typical example, Huang et al fabricated porous polyimide nanofiber films by electrospinning, and then added commercial electrolytes into the polyimide films . Under the promotion of lithium bis­(trifluoromethane)­sulfonimide (LiTFSI), the 1,3-dioxolane underwent self-polymerization, and finally a GPE with high room-temperature ion conductivity (2.9 × 10 –3 S cm –1 ), high strength (31 MPa), and high thermal stability (160 °C) was formed.…”

Thermal‐Stable Separators: Design Principles and Strategies Towards Safe Lithium‐Ion Battery Operations

“…The Li/GPE/S battery was assembled with a discharge capacity of 741 mAh g À 1 after 500 cycles at 0.5 C and a capacity retention rate of 73.7 % (Figure 5h,i). Based on the same composition of the electrolyte, Yan and co-workers [117] prepared PI nanofiber porous membranes by sol-gel electrospinning, which carried out ring-opening thermal polymerization of LiPF 6 /DOL/LiTFSI/DME on the porous separator at room temperature to obtain the PI quasi-solid electrolytes (PIQSE) separator (Figure 6a). The imide ring in PI had a strong affinity for PDXL, which was beneficial to the formation of a network with uniform Li + conduction.…”