Poly(methyl methacrylate)-Based Gel Polymer Electrolyte for High-Performance Solid State Li–O₂ Battery with Enhanced Cycling Stability

Abstract

The lithium oxygen (Li–O2) battery is considered as one of the promising next-generation energy storage devices due to its high theoretic specific energy. However, some critical problems such as solvent evaporation, lithium dendrites, liquid electrolyte leakage, and liquid electrolyte decomposition under high voltage seriously hinder its application. To address these issues, a well-designed poly­(methyl methacrylate) (PMMA) and SiO2 composite gel polymer electrolyte (PMMA/SiO2/PP@GPE) is prepared by a phase inversion method followed by a gelation process. Benefitting from this unique architecture, the PMMA/SiO2/PP@GPE exhibits high liquid electrolyte uptake ability and adequate gelation degree, which result in well-enhanced electrochemical performances and interfacial stability. Compared with traditional polypropylene (PP) separator and liquid electrolyte systems, the electrochemical window of a solid state Li–O2 battery was widened to 4.9 V, and the lithium-ion transference number increased to 0.54. A lithium symmetrical battery displays an enhanced cycling stability due to improved interface compatibility. As a consequence, the solid state Li–O2 battery employing PMMA/SiO2/PP@GPE delivers the high first charge–discharge capacity of 6.8 mAh cm–2 and a stable cyclic performance of 116 cycles with 0.5 mAh cm–2.

1,2,3-Trimethoxypropane: a bio-sourced glyme as electrolyte for lithium–O2 batteries

“…Also, the authors recommend to potential future works based on TMP that cyclability performance in Li–O 2 could be greatly improve – for instance – by the use of a redox mediator, as proven in other works. 36,37 Overall, cells with TMP-based electrolytes exhibited a more moderated decay of capacity than cells using G4-based electrolytes, and similar cyclability was observed for both liquid and gel polymer electrolyte cells. Hence, these findings would confirm the capability of using TMP as the solvent or plasticizer in electrolytes for Li–O 2 cells.…”

Safe and Energy-Dense Flexible Solid-State Lithium–Oxygen Battery with a Structured Three-Dimensional Polymer Electrolyte

“…18−21 The addition of inorganic fillers and/or liquid plasticizers has proved to be a viable strategy to increase the ionic conductivity. 22,23 In addition, conventional polymer electrolytes are dual-ion conductors with a low lithium ion transference number (t Li + < 0.5), wherein both Li + cations and its counteranions are involved in the ion conduction process. 24 This will generate the concentration gradient and polarization phenomena, leading to the formation of lithium dendrites and premature battery failure.…”

“…Compared with inorganic solid electrolytes, polymer electrolytes display stronger processing adaptation and better flexibility and thus serve as a better candidate and have great potential applications on flexible power sources. − However, polymer electrolytes still present various concerns limiting their widespread use. Generally, ionic conductivity of polymer electrolytes (σ < 10 –5 S cm –1 , 25 °C) is far below that of liquid electrolytes (σ ≈ 10 –2 to 10 –3 S cm –1 , 25 °C), thus limiting the operation at ambient temperature. , Hybrid polymer electrolytes (HPEs), consisting of a polymer host, lithium salts, inorganic fillers, and/or liquid plasticizers, are expected to overcome this disadvantage. − The addition of inorganic fillers and/or liquid plasticizers has proved to be a viable strategy to increase the ionic conductivity. , In addition, conventional polymer electrolytes are dual-ion conductors with a low lithium ion transference number ( t Li + < 0.5), wherein both Li + cations and its counteranions are involved in the ion conduction process . This will generate the concentration gradient and polarization phenomena, leading to the formation of lithium dendrites and premature battery failure. , With the aim to increase t Li + , researchers have designed various polymer electrolytes to inhibit the transference of negative charge by covalently binding anions to the polymer backbone or setting anion traps .…”

Comparative Study of the Electrochemical Performance of Different Separators in Aprotic Li–O2 Batteries

“…They include polymer-based Celgard separators, 26−28 glass fiber separators (GF/A, GF/D, GF/F), 14,16,22,29−33 and gel polymer electrolyte separators (GPE). 23,34 The costs of these separators vary widely. In particular, the price of GF/F is approximately 5 times that of GF/D.…”