Very Stable Lithium Metal Stripping–Plating at a High Rate and High Areal Capacity in Fluoroethylene Carbonate-Based Organic Electrolyte Solution

Abstract

We report the highly stable galvanostatic cycling of lithium metal (Li) electrodes in a symmetrical Li|electrolyte solution| Li coin-cell configuration at a high rate and high areal capacity using fluoroethylene carbonate (FEC)-based electrolyte solutions [1 M LiPF 6 in FEC/dimethyl carbonate (DMC)]. The FEC-based electrolyte solution shows cycling behavior that is markedly better than that observed for the cells cycled with an ethylene carbonate (EC)-based electrolyte solution (1 M LiPF 6 in EC/DMC). With FEC-based electrolyte solution, Li|Li cells can be cycled at 2 mA cm −2 with an areal capacity of 3.3 mAh cm −2 for more than 1100 cycles, and full Li| LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NMC) cells with high areal loading cathode demonstrate stable cycling with the same capacity during 90 cycles. An increase in areal capacity up to 6 mA h cm −2 does not affect the shape of the voltage profile of the symmetric Li|Li cells. The reason for this high performance is the formation of a stable and efficient solid electrolyte interphase (SEI) on the surface of the Li metal electrodes cycled in the FEC-based solution. The composition of the SEI is analyzed by Fourier transform infrared spectroscopy.

A Sustainable Solid Electrolyte Interphase for High‐Energy‐Density Lithium Metal Batteries Under Practical Conditions

“…In F-SEI, LiF distributes uniformly at different depths (Figure 3a,d), which is mainly from the decomposition of FEC as reported. [45,52] LiF has been known to increase the uniformity of Li deposition. [35,58] In N-SEI, the content of LiF significantly reduces according to the atomic concentration of F( Supporting Information, Figure S13) because the formation of LiF only depends on the decomposition of LiPF 6 .The emerge of LiN x O y indicates that LiNO 3 engages in the formation of SEI, and thus sustainedrelease of LiNO 3 is effective in SEI modification (Figure 3b).…”

“…Among various approaches, LiF‐rich SEI (F‐SEI) and LiN x O y ‐contained SEI (N‐SEI) have arisen as exemplary methods to stabilize Li metal under mild conditions recently. F‐SEI is generated by fluorinated solvents or Li salts and N‐SEI is constructed by LiNO 3 additives in carbonate or ether electrolyte, respectively. Generally, F‐SEI and N‐SEI formed by additives as SEI precursors (<5 %, by weight or volume) cannot maintain sustainable due to irreversible exhaustion of limited additives under practical conditions .…”

“…[25][26][27][28][29] Tr emendous efforts have been devoted to constructing intrinsically uniform SEI by regulating the electrolyte solvation, i.e., the components and structure of electrolyte,such as concentrated electrolyte, [30][31][32][33][34] fluorinated electrolyte, [35][36][37] and sacrificial additives. [38][39][40] Among various approaches,LiF-rich SEI (F-SEI) and LiN x O y -contained SEI (N-SEI) have arisen as exemplary methods to stabilize Li metal under mild conditions recently.F -SEI is generated by fluorinated solvents or Li salts [37,[41][42][43][44][45] and N-SEI is constructed by LiNO 3 additives in carbonate or ether electrolyte, [40,[46][47][48][49][50][51] respectively. Generally,F -SEI and N-SEI formed by additives as SEI precursors (< 5%,b yw eight or volume) cannot maintain sustainable due to irreversible exhaustion of limited additives under practical conditions.…”

“…Generally,F -SEI and N-SEI formed by additives as SEI precursors (< 5%,b yw eight or volume) cannot maintain sustainable due to irreversible exhaustion of limited additives under practical conditions. [52,53] In order to avoid the rapid depletion, F-SEI induced by co-solvent [45] and N-SEI formed by sustained-release method [49,54] have been put forward. Nevertheless,t he sustainability of F-SEI or N-SEI under practical conditions (Figure 1a), including ultrathin Li anode (< 50 mm), high loading NCM523 cathode (> 4mAh cm À2 , measured value) and lean electrolytes (< 3gAh À1 ), has never been evaluated.…”

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 …”