Inorganic solid-state electrolytes for lithium metal batteries have attracted considerable interest, but their brittle characteristics and weak electrolyte/electrode interface create a major difficulty in a widespread application in flexible electronics. Here, we propose the novel design of a flexible solid-state lithium metal battery with seamless interfaces that ensure compatible electrode/electrolyte interfaces even under extreme deformations and reduce electrode/electrolyte interfacial resistance. This new concept of Solid State Lithium Metal Batteries (SSLMB) is produced through a step-by-step printing process with the help of ultraviolet drying under ambient conditions, without complicated steps (high temperature/high pressure).
Change of FT-IR spectra corresponding to acrylic C=C double bonds of ETPTA before and after UV irradiation. Comparison of electronic resistivity change as a function of longitudinal compression cycling (bending radius = 1 mm): pCathode embedded in SUS versus cycling performance (with a charge/discharge current density = 0.5 C/0.5 C) of the SUS network- the embedded NCM811 printed cathode and the conventional cathode.
Comparison of the electronic resistance change as a function of the longitudinal compression cycle (bending radius = 2 mm): cPET-embedded Li vs. Galvanostatic Li deposition/stripping voltage profiles of Li║Cu-Li (5 mAh cm-2) and Li ║cPET/Ag-Li (5 mAh cm-2) cells during cycling at the current densities of 1mA cm-2 for 1 mAh cm-. a) Schematic illustration showing the fabrication procedure of pQSSLMB with good interface compatibility.
List of Tables
Introduction
- Introduction to lithium-ion batteries
- Issues of lithium-ion batteries and the advent of the solid-state lithium metal batteries Nowadays, the continuous development of flexible and wearable electronics is pushing the rapid
Lithium-ion batteries (LIBs) are a type of rechargeable battery that is gaining a lot of attention for portable electronic devices. LIBs consist of a cathode, an anode, and an electrolyte that helps transfer ions to the electrodes.1 When the battery is externally connected, electrons are transferred through the external charge and chemical reactions continue, leading to current generation. Lithium-ion battery issues and the advent of solid-state lithium metal batteries Nowadays, the continuous development of flexible and wearable electronics is rapidly pushing the Nowadays, the continuous development of flexible and wearable electronics is driving the rapid growth of flexible and secure energy sources.3 To satisfy the expanding market need for flexible devices, flexible LIBs have been significantly advanced over the past decades.
The most attractive solution is the use of lithium metal anode for the development of flexible lithium metal batteries (LMB). The mechanical stability of the solid electrolyte interface (SEI) layer becomes weak and leads to low coulombic efficiency.5, 6 Third, the use of conventional organic liquid electrolytes has potential hazards such as flammability and explosion. Moreover, it is difficult to effectively introduce the high voltage cathode due to the poor electrochemical stability of liquid electrolytes as the voltage is increased.
Solid state electrolytes are the most promising candidates in flexible LMBs, eliminating most safety concerns. The main key of solid-state electrolytes is that they enable the use of high-voltage cathode material due to their wide electrochemical window and confinement of Li dendrites. 7 Therefore, the most promising direction for flexible batteries is the development of lithium metal in solid state. batteries (SSLMB) to achieve the ultimate goal of high performance and safety.6.
Skeleton-Reinforced, Printed Flexible Quasi-Solid-State Lithium Metal Batteries with Seamless Interfaces
- Introduction
- Materials
- Design and Fabrication of printed QSSLMBs
- Characterization of printed QSSLMB
- Electrochemical measurements
- Characterization of the printed electrolyte membranes
- Fabrication and characterization of the printed cathodes
- Fabrication and characterization of the cPET/Ag-Li
- Electrochemical performance of the printed QSSLMBs
- Mechanical flexibility and thermal stability of the printed QSSLMBs
The printed cathodes consist of NCM811 powders and conductive additives (carbon black) and gel electrolytes. The isothermal mode (100 ℃ for 100 min) of TGA (Q500, TA) was applied to evaluate the weight loss of electrolytes over time. The composition ratio (PC/Al2O3 gel electrolyte) was 50/50 (w/w) for printability of the pQSSE paste.
The rheological properties of the pQSSE paste (i.e. before UV curing) showed shear-thinning fluid behavior (Figure 2.1b). This means that the printable QSSE paste has the thixotropic liquid which facilitates the printing process on the non-woven substrate. a) Schematic illustration depicting the fabrication procedure of the pQSSE membrane with non-flammable gel electrolyte. The thickness of the pQSSE membrane increases slightly to 30 µm, which is still much thinner than other SSEs.
The UV curing printing process with the well-matched rheological properties of the pQSSE paste improves the adhesion between the pQSSE paste and the nonwoven, which significantly improves the mechanical properties. The electrochemical impedance spectroscopy (EIS) was implemented to estimate the ionic conductivity of the pQSSE membrane from 25 to 80 oC (Figure 2.6a). This can be attributed to the well-formed ion transport channels in the non-woven matrix.
In contrast to the flammable behavior of the polyethylene separator wetted by a conventional liquid organic electrolyte (Figure 2.8b), the pQSSE membrane exhibited non-flammable properties (Figure 2.8a). In addition, the gel electrolyte in the pCathode provides sufficient ionic networks, especially for the high mass loading of the pCathode. Comparison of the electronic resistance change after the longitudinal compression cycle (bending radius = 1 mm): SUS embedded pCathode vs.
Cycling performance (at a charge/discharge current density = 0.5 C/0.5 C) of the SUS mesh-embedded pCathode and the conventional cathode. Due to the non-flexible properties of the conventional Cu foil as the current, Cu-Li does not resist mechanical fracture and breaks off. Comparison of the electronic resistance change as a function of the longitudinal compression cycle (bending radius = 1 mm): cPET-embedded Li vs.
The electrochemical performance of the printed QSSLMB with seamless interfaces was evaluated at room temperature and ambient pressure. The first charge/discharge profiles of the printed QSSLMB showed a charge capacity of 180.7 mAh g-1 and a high discharge capacity of 180 mAh g-1 with a Coulombic efficiency of 99.6 % (Figure 2.20b). Usually, the delamination of the active material of the current collector can lead to poor cell performance.
To elucidate the potential applications of printed QSSLMB for wearable devices, we evaluated its mechanical flexibility and safety at room temperature.
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