碳酸酯类电解液中Mg(NO3)2添加剂抑制锂枝晶生长的研究

在锂-硫化聚丙烯腈电池体系中,负极锂枝晶的形成和生长严重恶化了电池充放电性能,并给电池带来了安全隐患。而在更有利于稳定正极硫化聚丙烯腈材料的碳酸酯类电解液中,锂枝晶生长尤为严重。本文通过将硝酸镁添加到碳酸酯类电解液中,研究硝酸根和镁离子对锂金属表面改性的共同作用。实验数据发现,在硝酸根和镁离子共同作用下,锂枝晶生长被有效抑制。当硝酸镁浓度为100 mmol·L^-1时,锂铜半电池的库仑效率明显提高,并显著改善了锂-硫化聚丙烯腈电池的循环性能。300次循环后容量保持率为71%,远高于硝酸锂的61%和无添加剂的50%。

Study on Inhibition of Lithium Dendrite Growth by Mg(NO3)2 Additive in Carbonate Electrolyte

In the lithium-sulfurized polyacrylonitrile battery system, the formation and growth of lithium dendrites in the negative electrode seriously deteriorate the charge and discharge performance of the battery. If the growth of lithium dendrites pierces the separator and causes thermal runaway, it will also bring serious damage to the battery, causing potential safety risks. In the carbonate electrolyte that is more conducive to stabilizing the positive electrode sulfurized polyacrylonitrile material, the growth of lithium dendrites is particularly serious. In this paper, magnesium nitrate was added to the carbonate electrolyte to investigate the combined effect of nitrate and magnesium ions on the surface modification of lithium metal. Studies have found that during the cycle, magnesium ions were reduced on the surface of the lithium negative electrode to form a lithium-magnesium alloy layer, which reduced excessive side reactions between the electrolyte and the negative electrode. The reduction of magnesium ions into magnesium metal could guide the uniform deposition of lithium ions and reduce the formation of lithium dendrites; at the same time, nitrate could form an SEI film with high ionic conductivity rich in nitrogen oxides with lithium ions, which could make lithium ions at the interface that conducts quickly at the location, and under the combined action of the two, the formation and growth of lithium dendrites were inhibited, and the cycle performance of the battery was improved. The experimental data showed that under the combined action of nitrate and magnesium ions, the growth of lithium dendrites was effectively inhibited. When the concentration of magnesium nitrate was 100 mmol·L^-1, the coulombic efficiency of the lithium copper half-cell was significantly improved, and the cycle performance of lithium-sulfide polypropylene nitrile battery was also significantly enhanced. The capacity retention rate after 300 cycles was 71%, which was much higher than 61% of lithium nitrate and 50% without additives.