Lithium Metal Anode Using Polyacrylonitrile Supported Metal Nitrates As an Additive in Carbonate-Based Electrolyte

As the demand for energy storage continues to rise, there is a growing need for research focused on developing high-energy-density and stable batteries. Among various anode materials for lithium batteries, lithium metal stands out as an ideal candidate due to its low redox potential and high specific capacity. Consequently, in the pursuit of post-lithium ion batteries with enhanced energy density, the utilization of lithium metal as an anode is inevitable. However, the stability and safety of lithium metal anodes are compromised by issues such as dendritic growth. When lithium metal comes into contact with organic electrolytes, it reacts to form a solid electrolyte interface (SEI). While the SEI prevents further electrolyte consumption, an unstable SEI layer can lead to uneven diffusion of lithium ions through the SEI and promote the growth of lithium dendrites. Therefore, achieving uniform lithium deposition and establishing a stable SEI is crucial for the safe operation of lithium metal batteries. Lithium nitrate (LiNO 3 ) is one of the promising electrolyte additives for Li metal anodes as reduction of LiNO 3 forms a highly Li + conductive lithium nitride (Li 3 N)-rich SEI. However, the application of nitrate additives in carbonate electrolyte has been limited due to poor solubility. Herein, metal nitrate (MNO 3 = LiNO 3 , AgNO 3 , RbNO 3 ) containing PAN interlayers are synthesized using electrospinning method and are adopted in cells using carbonate-based electrolyte. MNO 3 containing polymer interlayer can release additive constantly enabling nitrate act as an electrolyte additive. Despite the expected role of Ag + and Rb + cations in enhancing Li deposition morphology, LiNO 3 had the best cell performance. In the symmetric test, LiNO 3 /PAN had the longest cycle life of over 150 cycles whereas AgNO 3 /PAN and RbNO 3 /PAN lasted approximately 120 cycles. Furthermore, in full cell using NCM811 cathode, the cell with LiNO 3 /PAN show 90% retention after 100 cycles. Interestingly, in AgNO 3 /PAN cell, lithium nucleation overpotential disappeared and interfacial resistance alleviated only in earlier cycles but SEI composition was quite different from other samples probably due to Ag deposited on the Li anode. On the other hand, RbNO 3 /PAN cell show similar SEI composition and sufficient signs of NO 3 - reduction, but non-reacting Rb + is accumulated in the electrolyte and limit release of RbNO 3 from the interlayer.