A Concentrated Ternary‐Salts Electrolyte for High Reversible Li Metal Battery with Slight Excess Li

Abstract

Li metal can potentially deliver much higher specific capacity than commercially used anodes. Nevertheless, because of its poor reversibility, abundant excess Li (usually more than three times) is required in Li metal batteries, leading to higher costs and decreased energy density. Here, a concentrated lithium bis(trifluoromethane sulfonyl) imide (LiTFSI)–lithium nitrate (LiNO3)–lithium bis(fluorosulfonyl)imide (LiFSI) ternary‐salts electrolyte is introduced to realize a high stable Li metal full‐cell with only a slight excess of Li. LiNO3 and LiFSI contribute to the formation of stable Li2O–LiF‐rich solid electrolyte interface layers, and LiTFSI helps to stabilize the electrolyte under high concentration. Li metal in the electrolyte remains stable over 450 cycles and the average Coulombic efficiency reaches 99.1%. Moreover, with 0.5 × excess Li metal, the Coulombic efficiency of Li metal in the LiTFSI–LiNO3–LiFSI reaches 99.4%. The electrolyte also presents high stability to the LiFePO4 cathode, the capacity retention after 500 cycles is 92.0% and the Coulombic efficiency is 99.8%. A Li metal full‐cell with only 0.44 × excess Li is also assembled, it remains stable over 70 cycles and 83% of the initial capacity is maintained after 100 cycles.

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

“…However, its practical application is severely hindered by the problems of uncontrollable dendrite growth, low Coulombic efficiency (CE) and Li metal deactivation during the electrochemical plating and stripping process . Strategies such as electrolyte engineering, artificial solid electrolyte interphase (SEI), structured electrodes, and separator membrane modification, have been demonstrated to be effective in alleviating these issues via regulation of Li ion transport and/or interfacial properties …”

“…[2][3][4][5] Strategies such as electrolyte engineering, artificial solid electrolyte interphase (SEI), structured electrodes, and separator membrane modification, have been demonstrated to be effective in alleviating these issues via regulation of Li ion transport and/or interfacial properties. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Metal organic frameworks (MOFs), consisted of metal ions or clusters linked with organic molecules, have shown potential in advancing Li metal battery technology. With a large degree of variability in their ordered porous structure and chemical composition, [23] MOF materials offer a good platform for tuning Li ion transport properties and Li deposition/dissolution behavior.…”

Formulation of Blended‐Lithium‐Salt Electrolytes for Lithium Batteries

“…Zhou and co-workers reported a concentrated LiTFSI/LiFSI (DME/DOL) based blendedsalt electrolyte that was supported by LiNO 3 as an additive. [89] The additional LiFSI co-salt significantly enhanced the lithium-ion-transfer process and enabled homogenous Li deposition (Figure 4 d- More recently, a highly concentrated blended-salt electrolyte (4.6 m LiFSI + 2.3 m LiTFSI in DME) was formulated by Xu and co-workers to endow plated Li metal with a denser, more conformal morphology ( Figure 5 a-f), and this electrolyte also exhibited excellent oxidative stability ( Figure 5 g). [45] Furthermore, far more challenging 4.4 V LMBs of NCM622/ Li ( Figure 5 h) and NCM622/Cu (Figure 5 i) based on a cathode with a high Ni content, LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NCM622), showed unprecedented cyclability ( Figure 5 g-i), breaking the long-standing voltage limitation for ether-based electrolytes.…”

Formulierung von Elektrolyten mit gemischten Lithiumsalzen für Lithium‐Batterien

“…Zhou et al. berichteten über einen konzentrierten Gemischtsalz‐Elektrolyten auf der Basis von LiTFSI/LiFSI (DME/DOL), der durch den Zusatz von LiNO 3 unterstützt wird . Durch das zusätzliche Cosalz LiFSI wurde der Lithium‐Ionen‐Transfer erheblich verbessert und eine homogene Abscheidung von Lithium erreicht (Abbildung d–h).…”