Lithium (Li) metal is one of the most promising alternative anode materials of next‐generation high‐energy‐density batteries demanded for advanced energy storage in the coming fourth industrial ...revolution. Nevertheless, disordered Li deposition easily causes short lifespan and safety concerns and thus severely hinders the practical applications of Li metal batteries. Tremendous efforts are devoted to understanding the mechanism for Li deposition, while the final deposition morphology tightly relies on the Li nucleation and early growth. Here, the recent progress in insightful and influential models proposed to understand the process of Li deposition from nucleation to early growth, including the heterogeneous model, surface diffusion model, crystallography model, space charge model, and Li‐SEI model, are highlighted. Inspired by the abovementioned understanding on Li nucleation and early growth, diverse anode‐design strategies, which contribute to better batteries with superior electrochemical performance and dendrite‐free deposition behavior, are also summarized. This work broadens the horizon for practical Li metal batteries and also sheds light on more understanding of other important metal‐based batteries involving the metal deposition process.
Lithium (Li) nucleation and early growth processes significantly determine the final deposition behavior. The recent progress in influential models proposed to understand the process of Li nucleation and early growth is highlighted. Inspired by the abovementioned understanding, diverse anode‐design strategies, which contribute to better batteries with superior electrochemical performance and dendrite‐free deposition behavior, are also summarized.
Safe and rechargeable lithium metal batteries have been difficult to achieve because of the formation of lithium dendrites. Herein an emerging electrolyte based on a simple solvation strategy is ...proposed for highly stable lithium metal anodes in both coin and pouch cells. Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions, and forming a uniform solid electrolyte interphase (SEI), with an abundance of LiF and LiNxOy on a working lithium metal anode with dendrite‐free lithium deposition. Ultrahigh Coulombic efficiency (99.96 %) and long lifespans (1000 cycles) were achieved when the FEC/LiNO3 electrolyte was applied in working batteries. The solvation chemistry of electrolyte was further explored by molecular dynamics simulations and first‐principles calculations. This work provides insight into understanding the critical role of the solvation of lithium ions in forming the SEI and delivering an effective route to optimize electrolytes for safe lithium metal batteries.
Not dead ′Li′: Fluoroethylene carbonate (FEC) and lithium nitrate (LiNO3) were concurrently introduced into an electrolyte, thus altering the solvation sheath of lithium ions and forming a uniform solid electrolyte interphase (SEI). An abundance of LiF and LiNxOy is formed on the working lithium metal anode and contributes to dendrite‐free lithium deposition.
The lithium metal anode is regarded as a promising candidate in next‐generation energy storage devices. Lithium nitrate (LiNO3) is widely applied as an effective additive in ether electrolyte to ...increase the interfacial stability in batteries containing lithium metal anodes. However, because of its poor solubility LiNO3 is rarely utilized in the high‐voltage window provided by carbonate electrolyte. Dissolution of LiNO3 in carbonate electrolyte is realized through an effective solvation regulation strategy. LiNO3 can be directly dissolved in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding trace amounts of copper fluoride as a dissolution promoter. LiNO3 protects the Li metal anode in a working high‐voltage Li metal battery. When a LiNi0.80Co0.15Al0.05O2 cathode is paired with a Li metal anode, an extraordinary capacity retention of 53 % is achieved after 300 cycles (13 % after 200 cycles for LiNO3‐free electrolyte) and a very high average Coulombic efficiency above 99.5 % is achieved at 0.5 C. The solvation chemistry of LiNO3‐containing carbonate electrolyte may sustain high‐voltage Li metal anodes operating in corrosive carbonate electrolytes.
Liquid assets: LiNO3 can be dissolved directly in an ethylene carbonate/diethyl carbonate electrolyte mixture by adding a trace amount of copper fluoride to promote dissolution. The solvation structure of the electrolyte system protects the lithium metal anode in a working high‐voltage lithium metal battery. NCA=LiNi0.80Co0.15Al0.05O2.
Lithium‐ion batteries with routine carbonate electrolytes cannot exhibit satisfactory fast‐charging performance and lithium plating is widely observed at low temperatures. Herein we demonstrate that ...a localized high‐concentration electrolyte consisting of 1.5 M lithium bis(fluorosulfonyl)imide in dimethoxyethane with bis(2,2,2‐trifluoroethyl) ether as the diluent, enables fast‐charging of working batteries. A uniform and robust solid electrolyte interphase (SEI) can be achieved on graphite surface through the preferential decomposition of anions. The established SEI can significantly inhibit ether solvent co‐intercalation into graphite and achieve highly reversible Li+ intercalation/de‐intercalation. The graphite | Li cells exhibit fast‐charging potential (340 mAh g−1 at 0.2 C and 220 mAh g−1 at 4 C), excellent cycling stability (ca. 85.5 % initial capacity retention for 200 cycles at 4 C), and impressive low‐temperature performance.
The unique solvation structure in a localized high‐concentration electrolyte can suppress co‐intercalation of ether solvent into the graphite interlayers and render fast‐charging of practical lithium‐ion batteries.
Understanding the electrode/electrolyte interfacial chemistry is the cornerstone of designing lithium-ion batteries (LIBs) with superior performance. Graphite has been exclusively utilized as the ...anode material in state-of-the-art LIBs, whose interfacial chemistry has a profound impact on battery life and power delivery. However, current understanding of the graphite/electrolyte interface is still incomplete because of its intricate nature, which has driven unremitting explorations and breakthroughs in the past few decades. On the one hand, the applications of emerging experimental and computational tools have led researchers to re-examine several decades-old problems, such as the underlying mechanism of solid electrolyte interphase (SEI) formation and the co-intercalation mystery. On the other hand, from anion-derived interfacial chemistry to artificial interphases, novel interfacial chemistry for graphite is being proposed to replace the traditional ethylene carbonate-derived SEI for better performances. By summarizing the latest advances in the emerging interfacial chemistry of graphite anodes in LIBs, this review affords a fresh perspective on interface science and engineering towards next-generation energy storage devices.
Emerging interfacial chemistry of the graphite anode in today's lithium-ion batteries paves the way to next-generation, high-performance energy storage devices.
High‐energy‐density Li metal batteries suffer from a short lifespan under practical conditions, such as limited lithium, high loading cathode, and lean electrolytes, owing to the absence of ...appropriate solid electrolyte interphase (SEI). Herein, a sustainable SEI was designed rationally by combining fluorinated co‐solvents with sustained‐release additives for practical challenges. The intrinsic uniformity of SEI and the constant supplements of building blocks of SEI jointly afford to sustainable SEI. Specific spatial distributions and abundant heterogeneous grain boundaries of LiF, LiNxOy, and Li2O effectively regulate uniformity of Li deposition. In a Li metal battery with an ultrathin Li anode (33 μm), a high‐loading LiNi0.5Co0.2Mn0.3O2 cathode (4.4 mAh cm−2), and lean electrolytes (6.1 g Ah−1), 83 % of initial capacity retains after 150 cycles. A pouch cell (3.5 Ah) demonstrated a specific energy of 340 Wh kg−1 for 60 cycles with lean electrolytes (2.3 g Ah−1).
A solid electrolyte interphase (SEI) was proposed for practical high‐energy‐density Li batteries. The intrinsic uniformity and the constant supplements of building blocks of SEI jointly afford a sustainable SEI. A pouch cell with a specific energy of 340 Wh kg−1 underwent 60 cycles with a retention of 90 %.
The persistent efforts to reveal the formation and evolution mechanisms of solid electrolyte interphase (SEI) are of fundamental significance for the rational regulation. In this work, through ...combined theoretical and experimental model investigations, we elucidate that the electric double layer (EDL) chemistry at the electrode/electrolyte interface beyond the thermodynamic stability of electrolyte components predominately controls the competitive reduction reactions during SEI construction on Li metal anode. Specifically, the negatively‐charged surface of Li metal will prompt substantial cation enrichment and anion deficiency within the EDL. Necessarily, only the species participating in the solvation shell of cations could be electrostatically accumulated in proximity of Li metal surface and thereafter be preferentially reduced during sustained dynamic cycling. Incorporating multi‐valent cation additives to more effectively drag the favorable anionic SEI enablers into EDL is validated as a promising strategy to upgrade the Li protection performance. The conclusions drawn herein afford deeper understandings to bridge the EDL principle, cation solvation, and SEI formation, shedding fresh light on the targeted regulation of reactive alkali metal interfaces.
The electric double layer chemistry and structure are identified to play a predominate role in governing the competitive reactions during solid electrolyte interphase formation on lithium‐metal anodes. This knowledge affords critical guidance on the targeted interface design to enable a stable working lithium anode.
The lithium (Li) metal anode is confronted by severe interfacial issues that strongly hinder its practical deployment. The unstable interfaces directly induce unfavorable low cycling efficiency, ...dendritic Li deposition, and even strong safety concerns. An advanced artificial protective layer with single‐ion pathways holds great promise for enabling a spatially homogeneous ionic and electric field distribution over Li metal surface, therefore well protecting the Li metal anode during long‐term working conditions. Herein, a robust dual‐phase artificial interface is constructed, where not only the single‐ion‐conducting nature, but also high mechanical rigidity and considerable deformability can be fulfilled simultaneously by the rational integration of a garnet Al‐doped Li6.75La3Zr1.75Ta0.25O12‐based bottom layer and a lithiated Nafion top layer. The as‐constructed artificial solid electrolyte interphase is demonstrated to significantly stabilize the repeated cell charging/discharging process via regulating a facile Li‐ion transport and a compact Li plating behavior, hence contributing to a higher coulombic efficiency and a considerably enhanced cyclability of lithium metal batteries. This work highlights the significance of rational manipulation of the interfacial properties of a working Li metal anode and affords fresh insights into achieving dendrite‐free Li deposition behavior in a working battery.
A single‐ion‐conducting interface consisting of dual‐layer architecture is proposed to regulate a homogeneous ionic and electric field distribution while achieving a superior mechanical feature at the surface of a lithium‐metal anode simultaneously, synergistically enabling a highly efficient cell performance of working lithium‐metal batteries.
Lithium (Li) metal is regarded as a “Holy Grail” electrode for next‐generation high‐energy‐density batteries. However, the electrochemical behavior of the Li anode under a practical working state is ...poorly understood, leading to a gap in the design strategy and the aim of efficient Li anodes. The electrochemical diagram to reveal failure mechanisms of ultrathin Li in pouch cells is demonstrated. The working mode of the Li metal anode ranging from 1.0 mA cm−2/1.0 mAh cm−2 (28.0 mA/28.0 mAh) to 10.0 mA cm−2/10.0 mAh cm−2 (280.0 mA/280.0 mAh) is investigated and divided into three categories: polarization, transition, and short‐circuit zones. Powdering and the induced polarization are the main reasons for the failure of the Li electrode at small current density and capacity, while short‐circuit occurs with the damage of the separator leading to safety concerns being dominant at large current and capacity. The electrochemical diagram is attributed from the distinctive plating/stripping behaviors of Li metal, accompanied by dendrites thickening and/or lengthening, and heterogeneous distribution of dendrites. A clear understanding in the electrochemical diagram of ultrathin Li is the primary step to rationally design an effective Li electrode and render a Li metal battery with high energy density, long lifespan, and enhanced safety.
The failure mechanisms of ultrathin lithium in pouch cells can be divided into three categories: polarization, transition, and short‐circuit. A clear working pattern for ultrathin Li metal in pouch cells is established, which can potentially assist in designing a promising strategy for an advanced Li metal anodes.
Lithium (Li) metal has been considered as an important substitute for the graphite anode to further boost the energy density of Li‐ion batteries. However, Li dendrite growth during Li ...plating/stripping causes safety concern and poor lifespan of Li metal batteries (LMB). Herein, fluoroethylene carbonate (FEC) additives are used to form a LiF‐rich solid electrolyte interphase (SEI). The FEC‐induced SEI layer is compact and stable, and thus beneficial to obtain a uniform morphology of Li deposits. This uniform and dendrite‐free morphology renders a significantly improved Coulombic efficiency of 98% within 100 cycles in a Li | Cu half‐cell. When the FEC‐protected Li metal anode matches a high‐loading LiNi0.5Co0.2Mn0.3O2 (NMC) cathode (12 mg cm−2), a high initial capacity of 154 mAh g−1 (1.9 mAh cm−2) at 180.0 mA g−1 is obtained. This LMB with conversion‐type Li metal anode and intercalation‐type NMC cathode affords an emerging energy storage system to probe the energy chemistry of Li metal protection and demonstrates the material engineering of batteries with very high energy density.
Fluoroethylene carbonate (FEC) additive is used to form a LiF‐rich solid electrolyte interphase (SEI). The FEC‐induced SEI layer is compact and stable, and therefore beneficial to obtain a uniform morphology of Li deposits. When the FEC‐protected Li metal anode matches a high‐loading oxide cathode, a high initial capacity and stable cycling are achieved.
