Periodic Reporting for period 1 - TOUGH (Toward Tough Amorphous Electrolytes and Stable Interfaces in Solid-State Batteries)
Reporting period: 2022-03-01 to 2024-02-29
Development of safe and efficient batteries is one of the key technologies for the sustainable society and world. While lithium-ion batteries have revolutionized the portable electronics, large-scale energy storage calls for improvements in battery performance, energy density, safety, and cost. A major research effort has focused on replacing the traditional liquid electrolytes with solid-state electrolytes to improve safety by avoiding the flammable liquid electrolyte, enable higher energy density and longer cycle lifetime. Among the different solid electrolyte candidates, amorphous (disordered) solid electrolytes show good ionic conductivity, interfacial contact, and compliant mechanical behavior. They also feature isotropic ionic conduction, zero grain-boundary resistance, easy film fabrication, and low cost. In general, the ionic conductivity of amorphous electrolytes is higher than that of crystalline electrolytes made of the same elements. Solid-state lithium metal batteries using a solid electrolyte show potential for providing improved safety as well as higher energy and power density compared with conventional lithium-ion batteries. However, two critical bottlenecks remain: the development of solid electrolytes with ionic conductivities comparable to those of conventional liquid electrolytes and the creation of stable interfaces between solid-state battery components. This project has focused on developing amorphous based solid-state electrolytes with high ionic conductivity and improving the mechanical reliability of interfaces in solid-state lithium metal batteries. This project elucidates the mechanical behavior of amorphous solid electrolyte/electrode interfaces to enable improved performance of all solid-state lithium metal batteries. Specifically, via the regulation of amorphous electrolyte composition and structure to improve the toughness, interface stability, and lithium-ion conductivity of amorphous based solid-state electrolytes. The ambitious goal has been achieved using a strategy based on both experiments and atomistic simulations to complement and advance each other.
Amorphous materials are some of the most promising electrolyte candidates for lithium metal batteries. The mechanical, electrochemical, chemical, and thermal properties can be regulated by modifying the compositions and structures of amorphous materials. Through understanding the working principles of amorphous materials as electrolytes/electrodes as well as providing more insights into constructing compatible electrolyte-electrode interfaces, superior amorphous materials-based batteries can be developed in the future. This project has prepared a novel polymer-based solid-state electrolyte using a ZIF-62 glass as a functional filler. The polymer-glass electrolyte shows uniform distribution of the functional filler and improvements in both ionic conductivity and mechanical properties. Upon addition of an ionic liquid (IL), the obtained polymer glass-IL electrolyte delivers high ionic conductivity, large electrochemical stability window, high lithium-ion transference number, and excellent inhibition of lithium dendrites growth. Moreover, full batteries based on the polymer-glass-IL electrolyte exhibit superior rate capability and cycle performance. Atomistic simulations demonstrate that the superior performance of this new composite electrolyte is attributed to the uniformly distributed defects on the surface of the ZIF-62 glass, giving rise to stronger interactions with the IL, which in turn leads to the formation of a less confined environment that facilitates ionic conductivity. A novel strategy of synthetic ZIF-62 glass layer has been proposed as a solution to improve the reversible lithium plating/stripping and suppress dendrite growth in lithium metal batteries. Simulations show that lithium ions have faster diffusion rate and smoother diffusion channels in ZIF-62 glass compared to ZIF-62 crystal. The performed experiments confirm that the ZIF-62 glass layer enables uniform Li-ion transport, achieving the rapid Li-ion infiltration/extraction, and promoting isotropic Li nucleation and growth. The fabricated lithium metal anode can operate for 300 h in symmetric batteries. Both LiFePO4 and high-voltage LiCoO2 based full batteries reveal high reversible capacities, superior rate performances, and long cycling stability properties up to 1000 cycles.
The project's outcomes have been disseminated within the scientific community through various channels. First, the research findings have been submitted or prepared for publication in peer-reviewed journals: (1) Metal-Organic Framework Glass as a Functional Filler Enables Enhanced Performance of Solid-State Polymer Electrolytes for Lithium Metal Batteries (Advanced Science, published); (2) Amorphous Materials for Lithium-Ion and Post-Lithium-Ion Batteries (Small, published); (3) High-Performance Dendrite-Free Lithium Metal Anode Based on Metal-organic Framework Glass (under review); (4) Amorphous Materials Based Heterostructure and Heterointerface for Rechargeable Batteries (in preparation). These papers will or have been disseminated within the academic community through various channels, including social media. Furthermore, the research has been presented at two prominent national/international conferences: (1) Annual Meeting of the Danish Electrochemical Society (Copenhagen, 2023); and (2) The 41st Annual International Battery Seminar & Exhibit (Orlando, 2024).
The project's outcomes have been disseminated within the scientific community through various channels. First, the research findings have been submitted or prepared for publication in peer-reviewed journals: (1) Metal-Organic Framework Glass as a Functional Filler Enables Enhanced Performance of Solid-State Polymer Electrolytes for Lithium Metal Batteries (Advanced Science, published); (2) Amorphous Materials for Lithium-Ion and Post-Lithium-Ion Batteries (Small, published); (3) High-Performance Dendrite-Free Lithium Metal Anode Based on Metal-organic Framework Glass (under review); (4) Amorphous Materials Based Heterostructure and Heterointerface for Rechargeable Batteries (in preparation). These papers will or have been disseminated within the academic community through various channels, including social media. Furthermore, the research has been presented at two prominent national/international conferences: (1) Annual Meeting of the Danish Electrochemical Society (Copenhagen, 2023); and (2) The 41st Annual International Battery Seminar & Exhibit (Orlando, 2024).
The newly emerged MOF glasses, of which some even maintain the porosity of their parent crystals, have the potential for a variety of applications, such as battery, gas separation, and drug delivery. However, the electrochemical properties of these glasses have not been well explored, which greatly hinders their applications in energy storage and conversion fields. Within this project, we demonstrated that the electrochemical activity of MOF glasses can be tuned by the system composition and post-processing routes, which ultimately regulate the battery performances. The developed strategies and results from this project will significantly benefit the researchers working on MOFs, glasses, batteries, and simulations. The outcomes of this project have been disseminated to the Danish and international glass industry through the visits to the glass company, and presentations at international conferences. The TOUGH project opens a new avenue for designing new type of glass-based batteries and provides fundamental knowledge to address the bottlenecks of MOF glasses and rechargeable batteries. The development of solid-state lithium batteries based on MOF glasses can lay technical support for a low-carbon and sustainable society and help achieve more efficient and safer solid-state batteries.