Jingchao Chai

High-voltage and free-standing poly(propylene carbonate)/Li6.75La3Zr1.75Ta0.25O12 composite solid electrolyte for wide temperature range and flexible solid lithium ion battery

Solid electrolyte is regarded as a perfect way to enhance safety issues and boost energy density of lithium batteries. Herein, we developed a type of free-standing poly(propylene carbonate)/Li6.75La3Zr1.75Ta0.25O12 composite solid electrolyte for ambient temperature and flexible solid-state lithium batteries. The composite solid electrolyte exhibited excellent comprehensive performance in terms of high ionic conductivity (5.2 × 10−4 S cm−1) at 20 °C, a wide electrochemical window (4.6 V), high ionic transference number (0.75) and satisfactory mechanical strength (6.8 MPa). When evaluated as solid electrolyte for an ambient-temperature solid lithium battery, such a composite electrolyte delivered excellent rate capability (5C) at 20 °C. This superior performance can be comparable to a liquid electrolyte-soaked PP separator-based lithium battery at room temperature. To our knowledge, this is the best rate capability of a solid composite electrolyte for a solid lithium battery at ambient temperature. Moreover, such a composite electrolyte-based flexible LiFePO4/Li4Ti5O12 lithium ion battery delivered excellent rate capability and superior cycling stability. All these fascinating features make poly(propylene carbonate)/Li6.75La3Zr1.75Ta0.25O12 a very promising all-solid-state electrolyte for flexible solid lithium batteries. Our study makes a big step into addressing the challenges of ambient-temperature solid lithium batteries.

In Situ Generation of Poly (Vinylene Carbonate) Based Solid Electrolyte with Interfacial Stability for LiCoO2 Lithium Batteries

Nowadays it is extremely urgent to seek high performance solid polymer electrolyte that possesses both interfacial stability toward lithium/graphitic anodes and high voltage cathodes for high energy density solid state batteries. Inspired by the positive interfacial effect of vinylene carbonate additive on solid electrolyte interface, a novel poly (vinylene carbonate) based solid polymer electrolyte is presented via a facile in situ polymerization process in this paper. It is manifested that poly (vinylene carbonate) based solid polymer electrolyte possess a superior electrochemical stability window up to 4.5 V versus Li/Li+ and considerable ionic conductivity of 9.82 × 10−5 S cm−1 at 50 °C. Moreover, it is demonstrated that high voltage LiCoO2/Li batteries using this solid polymer electrolyte display stable charge/discharge profiles, considerable rate capability, excellent cycling performance, and decent safety characteristic. It is believed that poly (vinylene carbonate) based electrolyte can be a very promising solid polymer electrolyte candidate for high energy density lithium batteries.

Progress in nitrile-based polymer electrolytes for high performance lithium batteries

Nitrile or cyano-based compounds have aroused interest in high performance battery electrolyte fields due to their unique characteristics such as a high dielectric constant, high anodic oxidization potential and favorable interaction with lithium ions. Particularly, owing to the presence of a unique plastic-crystalline phase, succinonitrile/salt-based solid electrolytes possess an ultra high ionic conductivity of more than 10−3 S cm−1 at room temperature. Herein, recent progress in nitrile-based polymer electrolytes has been reviewed in terms of their potential application in flexible, solid-state or high voltage lithium batteries. Factors affecting the ionic conductivity of nitrile-based electrolytes have also been summarized. We hope that fresh and established researchers can obtain a clear perspective of nitrile based polymer electrolytes and our mini review can spur more extensive interest for the exploration of high performance batteries.

A high-voltage poly(methylethyl α-cyanoacrylate) composite polymer electrolyte for 5 V lithium batteries

High-voltage lithium batteries have attracted increasing attention for large scale energy storage application in electric vehicles, smart grids and other electronic devices. However, a major bottleneck to achieve high-voltage lithium batteries is the anodic voltage stability of electrolytes. Herein, we fabricate a composite polymer electrolyte, comprised of poly(methylethyl α-cyanoacrylate), nonwoven polytetrafluoroethylene and lithium bis(oxalate)borate salt. The composite polymer electrolyte presents a wide electrochemical window, which is explored to address the above-mentioned bottleneck. It is demonstrated that such a composite polymer electrolyte exhibits a higher ionic conductivity (1.24 mS cm−1 at 25 °C), better dimensional thermal resistance (150 °C) and higher ion transference number (0.63) compared to those of commercially available liquid electrolytes with a polypropylene separator. In addition, LiNi0.5Mn1.5O4/Li batteries employing such a composite polymer electrolyte deliver excellent cycling performance and outstanding rate capability. So, it is demonstrated that the poly(methylethyl α-cyanoacrylate) based polymer electrolyte appears to be a promising candidate of high-voltage lithium battery electrolyte towards next generation high energy density batteries.

A Superior Polymer Electrolyte with Rigid Cyclic Carbonate Backbone for Rechargeable Lithium Ion Batteries

The fabricating process of well-known Bellcore poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP)-based polymer electrolytes is very complicated, tedious, and expensive owing to containing a large amount of fluorine substituents. Herein, a novel kind of poly(vinylene carbonate) (PVCA)-based polymer electrolyte is developed via a facile in situ polymerization method, which possesses the merits of good interfacial compatibility with electrodes. In addition, this polymer electrolyte presents a high ionic conductivity of 5.59 × 10-4 S cm-1 and a wide electrochemical stability window exceeding 4.8 V vs Li+/Li at ambient temperature. In addition, the rigid cyclic carbonate backbone of poly(vinylene carbonate) endows polymer electrolyte a superior mechanical property. The LiFe0.2Mn0.8PO4/graphite lithium ion batteries using this polymer electrolyte deliver good rate capability and excellent cyclability at room temperature. The superior performance demonstrates that the PVCA-based electrolyte via in situ polymerization is a potential alternative polymer electrolyte for high-performance rechargeable lithium ion batteries.

High energy density hybrid Mg2+/Li+ battery with superior ultra-low temperature performance

The development of high energy density rechargeable Mg-based batteries operating in a wide electrochemical window and ultra-low temperature remains a great challenge owing to parasitic side reactions between electrolytes and battery components when examined at high operating potentials (above 2.0 V vs. Mg2+/Mg). Herein we propose a flexible pyrolytic graphitic film (GF) as a reliable current collector of high-voltage cathodes for a hybrid Mg2+/Li+ battery within a pouch cell configuration. The utilization of such a highly electrochemical stable GF unlocks the critical bottleneck of incompatibility among all battery parts, especially parasitic corrosive reactions between electrolytes and currently available current collectors, which takes a big step forward towards the practical applications of Mg-based batteries. With an operating potential of 2.4 V, the hybrid Mg2+/Li+ battery designed by us can deliver a maximum energy density of 382.2 W h kg(-1), which significantly surpasses that of the conventional Mg battery (about 60 W h kg(-1)), and the Al battery (about 40 W h kg(-1)) as well as the state-of-the-art hybrid Na/Mg and Li/Mg batteries. The electrochemical property of the hybrid Mg2+/Li+ battery is also characterized by higher rate capability (68.8 mA h g(-1) at 3.0C), higher coulombic efficiency of 99.5%, and better cyclic stability (98% capacity retention after 200 cycles at 1.0C). In addition, the designed hybrid battery delivers excellent electrochemical performance at an ultra-low temperature of -40 degrees C, at which it retains 77% capacity compared to that of room temperature. Our strategy opens up a new possibility for widespread applications of graphitic current collectors towards high energy rechargeable Mg-based hybrid batteries, especially applied in polar regions, aerospace, and deep offshore waters.

Facile and Reliable in Situ Polymerization of Poly(Ethyl Cyanoacrylate)-Based Polymer Electrolytes toward Flexible Lithium Batteries

Polycyanoacrylate is a very promising matrix for polymer electrolyte, which possesses advantages of strong binding and high electrochemical stability owing to the functional nitrile groups. Herein, a facile and reliable in situ polymerization strategy of poly(ethyl cyanoacrylate) (PECA) based gel polymer electrolytes (GPE) via a high efficient anionic polymerization was introduced consisting of PECA and 4 M LiClO4 in carbonate solvents. The in situ polymerized PECA gel polymer electrolyte achieved an excellent ionic conductivity (2.7 × 10-3 S cm-1) at room temperature, and exhibited a considerable electrochemical stability window up to 4.8 V vs Li/Li+. The LiFePO4/PECA-GPE/Li and LiNi1.5Mn0.5O4/PECA-GPE/Li batteries using this in-situ-polymerized GPE delivered stable charge/discharge profiles, considerable rate capability, and excellent cycling performance. These results demonstrated this reliable in situ polymerization process is a very promising strategy to prepare high performance polymer electrolytes for flexible thin-film batteries, micropower lithium batteries, and deformable lithium batteries for special purpose.

In Situ Formation of Polysulfonamide Supported Poly(ethylene glycol) Divinyl Ether Based Polymer Electrolyte toward Monolithic Sodium Ion Batteries

Sodium ion battery is one of the promising rechargeable batteries due to the low-cost and abundant sodium sources. In this work, a monolithic sodium ion battery based on a Na3 V2 (PO4 )3 cathode, MoS2 layered anode, and polyether-based polymer electrolyte is reported. In addition, a new kind of polysulfonamide-supported poly(ethylene glycol) divinyl ether based polymer electrolyte is also demonstrated for monolithic sodium ion battery via in situ preparation. The resultant polymer electrolyte exhibits relatively high ionic conductivity (1.2 mS cm-1 ) at ambient temperature, wide electrochemical window (4.7 V), and favorable mechanical strength (25 MPa). Moreover, such a monolithic Na3 V2 (PO4 )3 /MoS2 sodium ion battery using this polymer electrolyte delivers outstanding rate capability (up to 10 C) and superior cyclic stability (84%) after 1000 cycles at 0.5 C. What is more essential, such a polymer electrolyte based soft-package monolithic sodium ion cell can still power a red light emitting diode lamp and run finite times without suffering from any internal short-circuit failures, even in the case of a bended and wrinkled state. Considering these aspects, this work no doubt provides a new approach for the design of a high-performance polymer electrolyte toward monolithic sodium ion battery with exceptional rate capability and high safety.

Multifunctional Sandwich‐Structured Electrolyte for High‐Performance Lithium–Sulfur Batteries

Abstract Due to its high theoretical energy density (2600 Wh kg−1), low cost, and environmental benignity, the lithium–sulfur (Li‐S) battery is attracting strong interest among the various electrochemical energy storage systems. However, its practical application is seriously hampered by the so‐called shuttle effect of the highly soluble polysulfides. Herein, a novel design of multifunctional sandwich‐structured polymer electrolyte (polymer/cellulose nonwoven/nanocarbon) for high‐performance Li‐S batteries is demonstrated. It is verified that Li‐S battery with this sandwich‐structured polymer electrolyte delivers excellent cycling stability (only 0.039% capacity decay cycle−1 on average exceeding 1500 cycles at 0.5 C) and rate capability (with a reversible capacity of 594 mA h g−1 at 4 C). These electrochemical performances are attributed to the synergistic effect of each layer in this unique sandwich‐structured polymer electrolyte including steady lithium stripping/plating, strong polysulfide absorption ability, and increased redox reaction sites. More importantly, even with high sulfur loading of 4.9 mg cm−2, Li‐S battery with this sandwich‐structured polymer electrolyte can deliver high initial areal capacity of 5.1 mA h cm−2. This demonstrated strategy here may open up a new era of designing hierarchical structured polymer electrolytes for high‐performance Li‐S batteries.

An interpenetrating network poly(diethylene glycol carbonate)-based polymer electrolyte for solid state lithium batteries

Polycarbonate-based polymer electrolytes possess superior ionic conductivity at room temperature, higher lithium ion transference number and wider electrochemical stability window when compared with conventional poly(ethylene oxide)-based polymer electrolytes. Herein, the poly(diethylene glycol carbonate) dimethacrylate macromonomer (PDEC-DMA) was synthesized and the resultant interpenetrating network IPN-PDEC polymer electrolyte was developed via free radical in situ polymerization for polymer electrolyte Li metal batteries. This IPN-PDEC polymer electrolyte exhibited a decent ionic conductivity of 1.64 × 10−4 S cm−1 at room temperature and a wide electrochemical stability window (up to 4.5 V vs. Li+/Li). The LiFePO4/IPN-PDEC/Li and LiFe0.2Mn0.8PO4/IPN-PDEC/Li cells delivered excellent rate capability and cycling performance at room temperature. An all solid state lithium battery was also demonstrated by applying the as-prepared solid polymer electrolyte (SPE-PDEC) at a temperature of 100 °C, which displayed a superior cycling performance. Therefore, the IPN-PDEC network is a promising polymer electrolyte for solid state lithium batteries.