image: Ultrathin solid electrolyte fabricating process.
Credit: Tianshou Zhao, Lin Zeng and Meisheng Han from Southern University of Science and Technology.
A research team from the Southern University of Science and Technology has developed an electrochemically stable and ultrathin polymer-based solid electrolytes. Enhancing interfacial contact with lithium metal anode and constructing lithium-ion pathways, this innovative approach exhibits over 2100 hours of stable battery cycling in Li-symmetric cells. The study may offer a new approach for fabricating ultrathin solid electrolytes and provide insights into the mechanisms of dendrite-free formation, guiding the development of high-performance solid electrolytes.
All solid-state lithium-metal batteries (ASSLMBs) catch a lot of attention because they are safe, stable, and have a high theoretical capacity. Lithium has a high theoretical capacity (3860 mAh g-1) and lithium is calculated enough for civils around the world to use. However, it is also challenging to tackle the severe problems in solid-solid interfacial contact. The wettability between solid electrolyte and Li metal is proposed as the crucial feature in ASSLMBs, which determines the charge and ion distribution across the interface. In addition, in polymer electrolytes, the lithium salt and the chemical properties of polymer limit the ionic conductivity, even if they offer desirable properties such as flexibility and the available thin film casting method. Therefore, tackling the overall impedance and interfacial contact on the lithium surface is essential to achieve long-life, stable, high-performance ASSLMBs.
The Solution: The researchers reported a new ultrathin solid electrolyte for the development of ASSLMBs with stable performance. The results of the study suggest that the lithium metal anode circulating in this solid electrolyte forms a stable nitrile-rich layer, which promotes the deposition of lithium across the interface and prevents the growth of lithium dendrites in a vertical direction which may lead to a short-circuit. In addition, the impressive thickness of 12.4 μm also decreases internal resistances to 140 Ω in the Li-symmetric cells. Symmetric cells assembled with this solid electrolyte stably operate for over 2100 hours at 0.1 mA cm-2. In addition, the POLL possesses a stable Li+ conduction pathway, a low energy barrier for Li+ transfer, and a high oxidation voltage of 5.5 V due to the vital dehydrocyanation reaction with nitrile groups in the PAN. The Li-LiFePO4 battery has an initial discharge capacity of 156.1 mAh g-1, retaining 76.6% of its initial capacity after 100 cycles. The electrolyte exhibits excellent rate performance, with discharge capacities of 150.0, 153.1, 153.5, 144.2, and 118.5 mAh g-1 at 0.05, 0.1, 0.2, 0.5, and 1 C, respectively. The charge and discharge curves exhibit minimal side reactions, with a voltage difference of 0.07 V at 0.1 C and 0.04 V at 0.05 C, indicating high energy efficiency. These results highlight the promising commercial potential of the all-solid-state battery. This work offers a detailed analysis of the intrinsic properties of solid electrolytes and a reliable method for manufacturing ultrathin electrolytes.
The Future: Future research will explore more about the stable layer at the interface and pretreatment of solid electrolytes to avoid lithium consumption.
The all-solid-state lithium-metal battery featuring this ultrathin solid polymer-based electrolyte demonstrates the formation of a stabilization layer on lithium, promoting uniform lithium distribution, mitigating dendrite penetration, and enhancing battery cycle life. Li-symmetric batteries with this electrolyte demonstrate long cycling performance, keeping stability over 2100 hours. In addition, the full cells provide low potential difference in the charge/discharge curve and a high volumetric energy density of 338.3 Wh L-1 at 0.1 C.
The Impact: This work offers a promising method for achieving reliable ultrathin solid electrolytes and discusses more about the interfacial layer for stabilization in all-solid-state lithium-metal batteries.
The research has been recently published in the online edition of Materials Futures, a prominent international journal in the field of interdisciplinary materials science research.
Reference
Fenghua Yu, Yongbiao Mu, Meisheng Han, Jie Liu, Kunxiong Zheng, Zhiyu Zou, Hengyuan Hu, Quanyan Man, Wenjia Li, Lei Wei, Lin Zeng, Tianshou Zhao. Electrochemically Stable and Ultrathin Polymer-Based Solid Electrolytes for Dendrite-Free All-Solid-State Lithium-Metal Batteries[J]. Materials Futures. DOI: 10.1088/2752-5724/ada0cc
Journal
Materials Futures