Yangyang Mao,Tianle Li,Siddig Abuelgasim,Xiaoqian Hao,Yupeng Xiao,Chongyang Li,Wenju Wang,Yuqian Li,Encai Bao
Previous studies revealed that LiNO 3 can enhance the cyclic stability of lithium‑sulfur (Li S) batteries by creating a solid electrolyte interface protecting the lithium electrode. However, this study investigated the effect of LiNO 3 and concentration in the electrolyte, first studied under low and high sulfur loading. It is confirmed that adding a small amount of LiNO 3 inhibits the shuttle effect phenomenon in Li S batteries, and the Coulombic efficiency was significantly improved. Appropriately increasing the concentration of LiNO 3 to 2 % could prolong the cycle life. However, when LiNO 3 is excessive, the rate and cycling performance decrease. The design of practical Li S batteries requires more research on the parameters of electrolyte additives under high‑sulfur-loading conditions. After gradient increasing the sulfur loading, the low concentration of LiNO 3 cannot play the best performance of the battery , so it is necessary to improve the concentration of LiNO 3 further. It is evident that adding LiNO 3 in Li S batteries has certain benefits, and the optimal amount of additive is related to the value of sulfur loading.
Solid polymer electrolytes (SPEs) with high ionic conductivity and electrochemical stability are crucial for the potential practical applications of solid-state lithium metal batteries. In SPEs based on polyvinylidene fluoride (PVDF), the addition of N , N -dimethylformamide (DMF) enhances ionic conductivity but reduces the electrochemical stable window. This work proposes a strategy to improve the stability of PVDF-based SPEs with high ionic conductivities using LiNO 3 additive. By adding 5% of LiNO 3 (comparing to the weight of LiTFSI lithium salt), the ionic conductivity of prepared PVDF-based SPEs achieves up to 10 −4 S cm −1 at 30 ℃. The assembled Li|SPE|NCM811 cells with the LiNO 3 -modified SPE film as separator maintained a capacity retention rate of 93.0% after 200 electrochemistry cycles induced at a current density of 0.5 C. The influence of LiNO 3 in the interface resistance, Li-ionic transfer number, solid electrolyte interface phase, and electrochemistry performance of LIBs is investigated.
Minglin Sun,Xiaofei Wang,Jia Wang,Hao Yang,Lina Wang,Tianxi Liu
It is generally understood that the reduction of nitrate on the metallic Li surface aids in the formation of a solid–electrolyte interphase. LiNO3 is, therefore, frequently used as an electrolyte additive to help suppress the polysulfide redox shuttle in lithium–sulfur (Li–S) batteries. Although LiNO3 enables cycling of cells with considerably improved Coulombic efficiency and cyclic performance, the self-discharge behavior has largely been neglected. We present in this work a basic but systematic study to assess self-discharge of Li–S batteries with electrolytes possessing LiNO3. Comparative electrochemical tests and interfacial analysis reveal that the redox shuttle is fast enough to cause cells to self-discharge at a relatively rapid rate with limited concentration of the LiNO3 additive. Despite the capacity loss of a full-charged cell under rest for one day can be controlled to 2% with LiNO3 concentration as high as 0.5 M, the development of a practically viable Li–S technology looks like a daunting challenge. Further increasing LiNO3 would potentially cause more irreversible reduction of LiNO3 on the cathode during the first discharge. Therefore, a possible pathway for a long shelf life and low self-discharge is offered as well by the synergic protection of the separator and stabilization of the Li anode surface. The cell using a nanosized Al2O3-coated microporous membrane and a LiNO3-possessing electrolyte exhibits an extremely suppressed self-discharge, providing an alternative perspective for the practical use of Li–S batteries.
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