Ultrathin Bilayer of Graphite/SiO₂ as Solid Interface for Reviving Li Metal Anode

Abstract

3860 mAh g −1 ), low redox potential (−3.04 V vs standard hydrogen electrode) and high capability to be coupled with high-voltage and/or high-capacity cathode materials. [1] However, the practical application of Li as an anode in rechargeable lithium batteries is still hindered by the uncontrollable growth of Li dendrites, low Coulombic efficiency (CE), and limited cycle life. [2] Numerous efforts have been made to address these issues. One of the strategies focuses on the design of suitable electrolytes by optimizing the concentration, [3] adding additives and fillers, [4] engineering highmodulus solid electrolytes and polymer electrolytes. [5] These advanced electrolytes are expected to have excellent electrochemical stability on the Li electrode and higher Young's modulus to resist the dendrite growth. [6] Further, developing stable host materials and nanostructured scaffolds to accommodate Li during the plating process has been employed to address the issues of large volume changes during lithium plating/stripping. [7] Recently, developing an artificial interfacial layer between the electrolyte and Li metal electrode has attracted tremendous attention in lithium metal batteries (LMBs). The interfacial layer can prevent side reactions, enable fast Li-ion diffusion, and suppress the Li dendrite growth for the efficient operation of Li metal anode. The side reactions and interfacial instability of Li metal lead to significant consumption of electrolyte. As a result, the resistance of the Li metal cell increases that leads to overpotential and ultimately short cell lifespan. Previous studies showed that various ceramics such as SiO 2 , TiO 2 , SnO 2 , and Al 2 O 3 are very promising interfacial layers to buffer the volumetric expansion of the anode. [8] Such ceramic layers are able to conduct Li + and block electron transport. [9] Lithiated multiwall carbon nanotubes and multilayered graphene with high mechanical rigidity have been reported as a controlled Li diffusion interface. [10] In addition, glass fibers, silica sandwiched between two separators, and silica@poly(methyl methacrylate) (SiO 2 @PMMA) nanosphere-modified Cu electrode has also been studied. [7c,11] These artificial layers improve wettability toward electrolyte, reduce the concentration of Li ions, and react with growing Li to suppress the dendrites. Organic/inorganic Lithium metal anodes are expected to drive practical applications that require high energy-density storage. However, the direct use of metallic lithium causes safety concerns, low rate capabilities, and poor cycling performance due to unstable solid electrolyte interphase (SEI) and undesired lithium dendrite growth. To address these issues, a radio frequency sputtered graphite-SiO 2 ultrathin bilayer on a Li metal chips is demonstrated, for the first time, as an effective SEI layer. This leads to a dendrite free uniform Li deposition to achieve a stable voltage profile and outstanding long hours plating/stripping compared to the bare Li. Compared to a bare Li anode, the graph...

In Situ Construction of a LiF‐Enriched Interface for Stable All‐Solid‐State Batteries and its Origin Revealed by Cryo‐TEM

“…The capacity increase of the first 15 cycles was related to the wetting process between the electrode and SPE interface. [53] The first coulombic efficiency was less than 90% when using PEO-LiTFSI-Li 2 S electrolyte, which was mainly attributed to two reasons: 1) Li consumption and SPE decomposition during the formation of SEI in the initial cycles, [54] 2) the side reaction of the Li 2 S redox transition into Li 2 S x (x > 2). [55,56] Figure 7d compared the rate performance of all-solid-state LMBs.…”

“…The capacity at a higher rate was higher in PEO-LiTFSI-Li 2 S compared to PEO-LiTFSI, which was due to the presence of Li 2 S that can help form a stable LiF-rich SEI to promote more dense and smooth Li deposition, increase the amount of transportable Li + , allow efficient transport of Li + , and enable uniform Li deposition. [54,57] When we further tracked the impedance after different cycles, the R ct at the interface for battery with PEO-LiTFSI electrolyte (Figure 7e) showed non-linear changes, but generally increased after prolonged cycles (290, 240, 250, 340, and 350 Ω after 10, 30, 70, 100, and 150 cycles, respectively). The increase in R ct is due to possible side reactions at the interface that destroy the Li metal and SPE, and lead to the formation of unstable SEI.…”

An Investigation of Titanium/Silicon Oxide‐CNTs Anode Material for Lithium‐Ion Batteries

“…The results are consistent with that in the CV characterization of Ti m Si n O l ‐CNTs. Over the topic material, there should not be reactions between the anode material and the electrolyte to consume the electrolyte (similar to that happened over the bare Li metal anode) . In the first discharge, (discharge to 0.10 V versus metal Li), both TiO 2 and SiO 2 could be reduced to lower valence states (SiO 2 starts to be reduced below 0.15 versus Li metal) .…”

“…The discharge/charge tests of the cells were carried out on a NEWARE CT‐3008‐5 V‐10 mA system. The voltage window is set as 0.10∼2.60 V (vs. Li / Li + ) to control the reduction level of SiO y to avoid over reduction of SiO y (over reduction of SiO y could lead to formation of too much of Li 2 O and Li 4 SiO 4 , which are harmful to electrode . The cycling voltammetry curves were recorded on an electrochemical workstation (CHI 660E, CHENHUA) at a scan rate of 0.1 mV s −1 within 0.10 V and 2.60 V (vs. Li/Li + ).…”

“…In the investigations of anode materials for lithium‐ion batteries (LIBs), three types of materials are reported. They are the intercalation type materials (e. g., graphite or lithium titanate), metal and alloy materials (e. g., lithium, tin, tin selenide, or silicon), and reduction/oxidation type materials (e. g., WO 3 and ReS 2 ) …”