Rechargeable Li Metal Batteries Research Articles

Temperature Dependence of Dendritic Lithium Electrodeposition: A Mechanistic Study of the Role of Transport Limitations within the SEI

The accelerated failure of rechargeable Li-metal batteries due to dendritic Li electrodeposition particularly during charging at low temperatures is not well-understood. In this work, we investigate the effect of temperature on the initiation of Li dendrites during galvanostatic lithium electrodeposition. Using electrochemical measurements coupled with optical microscopy, we show that the dendrite onset time increases monotonically with temperature in the range 5 °C–35 °C. This observation is explained by incorporating temperature effects into an analytical transport model for Li dendrite initiation [J. Electrochem. Soc., 165, D696 (2018)], which considers solid state Li+ diffusion through a gradually thickening solid electrolyte interphase (SEI) layer. We conclude that sluggish Li+ transport at lower temperatures accelerates the depletion of Li+ at the Li-SEI interface, and this effect causes earlier initiation of dendrites at lower temperatures. Electrochemical impedance spectroscopy measurements of the temperature-dependent transport properties of the SEI, as well as plating efficiency measurements, are used to support the model.

Dendrite-free lithium metal anode with lithiophilic interphase from hierarchical frameworks by tuned nucleation

In the development of rechargeable Li metal batteries, current collectors with high porosity, rational pore structure and lithiophilic skeleton are essentially needed to suppress Li dendrite and accommodate the volume variation. Herein, 3D hierarchical porous collector activated from chemical dealloying of brass mesh is elaborately decorated with highly lithiophilic Sn layer via electroless plating method for dendrite-free Li metal anode. During Li plating process, the nucleation overpotential is remarkably reduced with the in-situ electrochemically generated Li–Sn alloy, realizing uniform Li nucleation/growth. Meanwhile, unique hierarchical porous structure with a high porosity of 60.2% ensures well dispersed current density for homogeneous Li deposition and accommodation. As expected, a high coulombic efficiency above 98% for 240 cycles at 1 ​mA ​cm−2 and a prolonged lifespan of symmetrical cells for 800 ​h ​at 1 ​mA ​cm−2 with lower polarization are achieved, which further renders the LiFePO4 based full cells with improved capacity retention up to 92.9% after 200 cycles at 0.5C. This work proposes a highly effective strategy to realize dendrite-free Li metal anode.

Lithium metal anodes: Present and future

Abstract Commercial lithium-ion (Li-ion) batteries based on graphite anodes are meeting their bottlenecks that are limited energy densities. In order to satisfy the large market demands of smaller and lighter rechargeable batteries, high-capacity metallic Li replacing low-specific-capacity graphite enables the higher energy density in next-generation rechargeable Li metal batteries (LMBs). However, Li metal anode has been suffering from dendritic problems, interfacial side reactions, volume change and low Coulombic efficiency. Therefore, performance enhancements of Li metal anodes are rather important to realize the high energy density characteristic of metallic Li. In this review, the annoying Li dendrite growth, unstable reaction interface and practical application issues of Li metal anodes are summarized and detailedly discussed to understand the current challenges concerning Li metal anodes. For overcoming such remaining challenges, the corresponding strategies and recent advances are covered and categorized. Finally, we discuss future opportunities and perspectives for developing high-performance Li metal anodes.

Eliminating Dendrites through Dynamically Engineering the Forces Applied during Li Deposition for Stable Lithium Metal Anodes

AbstractLithium metal anodes are considered the most promising anode for next‐generation high‐energy‐density batteries due to their high theoretical capacity and low electrochemical potential. However, intractable barriers, especially the notorious dendrite growth, severe volume expansion, and side reactions, have obstructed its large‐scale application. Numerous strategies from different points of view are explored to surmount these obstacles. Within these efforts, dynamically engineering the forces applied during the electrochemical process plays a significant role, as they can potentially eliminate the dendrite growth. In this Research News article, the relationship between different kinds of forces and the behavior of Li+/Li during the lithium deposition process is first explicated. Advanced strategies in building dendrite‐free Li anodes through dynamically engineering these forces are also summarized by sorting the Li deposition process into three stages: Li+ transport in electrolyte, Li+ reduction/Li atom surface migration, and Li bulk diffusion. Future perspectives and promising research directions for dendrite control are finally proposed. It is expected that dynamically engineering the forces applied during Li deposition will pave the way for next‐generation high‐energy‐density rechargeable Li metal batteries.

Graphene-Modified 3D Copper Foam Current Collector for Dendrite-Free Lithium Deposition.

Lithium (Li) metal is regarded as the ideal anode for rechargeable Li-metal batteries such as Li-S and Li-air batteries. A series of problems caused by Li dendrites, such as low Coulombic efficiency (CE) and a short circuit, have limited the application of Li-metal batteries. In this study, a graphene-modified three-dimensional (3D) Copper (Cu) current collector is addressed to enable dendrite-free Li deposition. After Cu foam is immersed into graphene oxide (GO) suspension, a spontaneous reduction of GO, induced by Cu, generates reduced graphene oxide on a 3D Cu (rGO@Cu) substrate. The rGO@Cu foam not only provides large surface area to accommodate Li deposition for lowering the local effective current density, but also forms a rGO protective layer to effectively control the growth of Li dendrites. As current collector, the rGO@Cu foam shows superior properties than commercial Cu foam and planar Cu foil in terms of cycling stability and CE. The rGO@Cu foam delivers a CE as high as 98.5% for over 350 cycles at the current density of 1 mA cm−2. Furthermore, the full cell using LiFePO4 as cathode and Li metal as anode with rGO@Cu foam as current collector (LiFePO4/rGO@Cu-Li) is assembled to prove the admirable capacities and indicates commercialization of Li-metal batteries.

Towards better Li metal anodes: Challenges and strategies

Li metal batteries surpass the energy density of current Li-ion batteries, yet their developments suffer from challenges of Li dendrites and instability of solid electrolyte interphase layer. This review emphasizes problems, provides additional insights in advanced strategies for stabilizing Li metal anodes in liquid, polymer, ceramic and composite electrolytes and provides perspectives on the future development of Li metal anodes. Anode materials are key components of batteries that significantly impact their specific energy and power. Li metal is considered as the ultimate anode due to its high theoretical capacity (∼3860 mA h/g) and low redox potential (−3.04 V vs. standard hydrogen electrode). Specifically, rechargeable Li metal batteries (LMBs) with enabled safety promise to surpass the energy density of current Li-ion batteries. Unfortunately, the apparently inevitable growth of dendritic Li, electrolyte consumption, the severe volume changes and the connected potential safety risks of LMBs limit their practical application. Recent strategies based on manipulation of electrolyte chemistry, interface engineering, and structure modification of Li host have reportedly achieved improvement. At the moment, the trend is to move towards all-solid-state LMBs. However, there are serious challenges in terms of low ionic conductivity, poor interfacial contact, and sluggish kinetics. While there are excellent reviews available, this review emphasizes problems and provides additional insight in advanced strategies for stabilizing Li metal anodes in liquid, polymer, ceramic and composite electrolytes. New approaches and novel materials to overcome the above challenges are referred. This review aims at raising relevant questions and outlining future strategies for next-generation high-energy storage systems.

Enabling High-Energy Lithium Metal Batteries through Electrolyte Strategy

Lithium (Li) metal has been regarded as an ideal anode material for high-energy rechargeable batteries because metallic Li has an ultrahigh theoretical specific capacity (3860 mAh g-1) and a very low standard electrochemical redox potential (-3.040 V), thus the potential to double the specific energy density of the state-of-the-art Li ion batteries. However, the safety concern from Li dendrite growth and the short cycle life due to low Li Coulombic efficiency still hinder the application of rechargeable Li metal batteries. In the past six years, lots of great progresses have been made in stabilizing Li metal anode including smoothening Li deposition morphology and increasing Li Coulombic efficiency during repeated deposition/stripping processes, which have made the application of rechargeable Li metal batteries very promising although there are still many challenges to overcome. Among these progresses, one of the most important things is the development of electrolytes which can not only protect Li metal anode with high safety and good stability, but also to stabilize high voltage cathodes. The mechanisms for these advancements by the new electrolytes are the formation of high quality Li/electrolyte and cathode/electrolyte interface layers. More details of the electrolytes on advancing Li metal anodes and Li metal batteries will be discussed during the presentation.

The Fundamental Mechanism behind the Stability of Li Metal Anodes in Non-Aqueous Electrolytes

A stable and high efficiency Li metal anode (LMA) is critical rechargeable Li metal batteries (LMBs), including the batteries with various cathodes such as ion intercalation compounds and conversion materials (such as sulfur and oxygen). An ideal metal anode not only needs to have a very high Coulombic efficiency (CE), but also need to have a low concentration, high conductivity and low cost. [1-2] During the last a few years, various methods have been used to prevent dendrite growth and improve CE of LMA, including used of high concentration electrolytes (HCEs) Localized High-Concentration Electrolytes (LHCE) by diluting HCEs with electrochemically “inert” solvents or poorly solvating diluents. [3] However, the fundamental mechanism behind the stability of LMA in non-aqueous electrolyte is still not well understood. This work will report our recent investigations on the interaction between LMA and various non-aqueous electrolytes. Although LMA is kinetically unstable with non-aqueous electroltye, appropriate selection of non-aqueous electrolyte, including both salt and solvent will enable formation of a more stable SEI layer on LMA surface and largely minimize the side reaction between LMA and electrolyte, therefore enable a dynamically stable LMA for long term cycling of li metal batteries. Several high performance electrolytes that are stable at ~4.5V with a CE of more than 99.2% have enabled long term cycling of LMBs and will also be reported in this work. S. Whittingham, "History, Evolution, and Future Status of Energy Storage", proceedings of the IEEE(Volume: 100, Issue: Special Centennial Issue , May 13 2012).-G. Zhang, W. Xu and W. A., Henderson, Lithium Metal Anode and Rechargeable Li Metal Batteries. (Springer International Publishing), 249, (2017).Shuru Chen, Jianming Zheng, Donghai Mei, Kee Sung Han, Mark H. Engelhard, Wengao Zhao, Wu Xu, Jun Liu and Ji-Guang Zhang,” Mater. 2018, 30, 1706102.

(Invited) Electrochemical Fundamentals of Employing Li Metal Anode in the Next-Generation Battery Technologies

To significantly boost the cell-level energy of next-generation battery technologies, one of the most effective approaches is to replace graphite with Li metal which is ultralight but energy concentrated. However, the thermodynamic instability of Li metal leads to many well-known problems that prevent its implementation in realistic batteries. Although many approaches have been proposed to rescue Li metal anodes, most of the work are performed in small-scale coin cells and tested in conditions drastically different from the reality. A full knowledge of Li metal activities at the cell level is lacking but critical for the success of rechargeable Li metal batteries. This talk will discuss the electrochemical fundamentals underlying the formation of Li dendrites which is then correlated to the different Li metal failure mechanisms: cell short or electrolyte/Li depletion. A prototypic Li metal pouch cell with 350 Wh/kg energy has been demonstrated which shows more than 150 stable cycling. A series of fundamentally new insights will be discussed to inspire scientific innovations to take the real challenges of developing future battery technologies.

Dendrite-Free Epitaxial Growth of Lithium for Efficient Charging of Li–O2 Batteries with Improved Cycle Life

Realization of rechargeable Li-metal batteries with high energy density is hindered by uneven Li deposition leading to dendrite formation during repeated cycles. Uncontrolled dendrite growth induces internal short-circuits which limit the cell lifetime and generate ohmic heat leading to catastrophic failure when a volatile electrolyte is used. Several strategies have been conceived by the researchers to suppress dendritic growth and delay the premature death of the cell. These efforts include using electrolyte additives to form a porous ion-conducting solid electrolyte interphase (SEI) layer on metal preventing further reaction,1 implementing solid electrolytes with optimum mechanical properties,2 designing a Li matrix,3 reducing local space charge on the Li surface,4 and so on. Although considerable improvements have been achieved from these earlier studies, microscopically smooth Li surface covered with thin and uniform SEI layers is yet to be realized. Alternatively, here we show an unprecedented dendrite-free epitaxial electrodeposition of Li in the presence of LiBr–LiNO3/glyme ether electrolyte under O2 atmosphere. Stripping and plating of Li metal was investigated by using a symmetrical Li│Li cell and it has been found that in 1 M LiNO3+0.05 M LiBr/tetraglyme electrolyte the plating of Li metal shows dendrite-free epitaxial growth up to a thickness of >20 μm which is clearly observed by the scanning electron microscopic (SEM) images and electron backscatter diffraction (EBSD) signal in Figure 1. The epitaxial growth of Li metal seems to be benefited from the synergistic effect of the anions Br− and NO3 − forming a thin and homogeneous Li2O–rich solid electrolyte interphase (SEI) layer which is formed during the very first discharge (stripping) process, where the corrosive nature of Br− removes the original thick passivation layer on Li surface which is then again oxidized (passivated) by the NO3 − to prevent further reactions with the electrolyte. Because of this, the SEI layer remains thin and facilitates the electropolishing effect and gets ready for the epitaxial electroplating of Li in the following charge process. Similar epitaxial growths of Li have been observed for both symmetrical Li│Li cell and Li–O2 full cell resulting in a much improved performance with longer cycle life.5,6 However, in contrast, LiNO3 alone or other lithium salts, such as Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), Lithium trifluoromethanesulfonate (LiTf), do not exhibit any epitaxial Li deposition. This demonstrates the bi-functional activity of the dual anion electrolyte LiNO3–LiBr towards dendrite-free epitaxial growth of Li. The role of deposition rate, effect of electrolyte solvent and a detailed mechanism of epitaxial growth will be discussed in the presentation.

Lithium metal batteries capable of stable operation at elevated temperature

Rechargeable lithium metal batteries have attracted wide attention due to high theoretical energy density. For practical applications, high-temperature performance of lithium batteries is essential due to complex application environments, in terms of safety and cycle life. However, it's difficult for normal operation of lithium metal batteries at high temperature above 55–60 °C using current lithium hexafluorophosphate (LiPF6) electrolyte systems. Herein, a kind of new electrolyte system is designed by adding two thermal-stable lithium salts together (i.e. lithium bis(trifluoromethanesulfonimide) (LiTFSI) and lithium difluoro(oxalato)borate (LiDFOB)) into carbonate solvents with high boiling/flashing point (i.e. ethylene carbonate (EC) and propylene carbonate(PC)). Small amount of LiPF6 is also added to prevent the corrosion of aluminum current collector. The results indicate that the new electrolyte possesses superior high-temperature performance, meanwhile, it effectively suppresses the formation of lithium dendrite by synergy effects of salts and solvents. Li/LiCoO2 cells with high LiCoO2 real capacity (2.4 mAh/cm2) using this kind of new electrolyte shows excellent cycling performance at elevated temperature up to 80 °C. Such performance is achieved for the first time for rechargeable Li metal battery using liquid organic electrolytes. It overcomes the operation temperature upper limit of traditional Li-ion batteries (i.e. 55–60 °C), which would effectively reduce thermal runaway risk and simplify the thermal management of Li metal batteries in reality.

Critical Parameters for Evaluating Coin Cells and Pouch Cells of Rechargeable Li-Metal Batteries

Summary Lithium (Li)-metal batteries have regained broad interest in the battery research community. Although many studies on Li anode have been published in recent years, it is difficult to evaluate and compare these advances for practical applications. A key challenge is a gap between materials and component properties and the achievable large-format cell-level performance. In this paper, we investigate the critical experimental parameters that determine the cycle number of coin cells to understand the performance variations reported in the literature. To define the range of cell parameters, we exemplify a representative Li-metal pouch cell with specific energy of 300 Wh/kg to provide an effective validation of electrode materials and accurate cell performance evaluations. Based on the pouch-cell-level requirements, we propose a set of coin-cell parameters and testing conditions to expedite the discovery of new materials and their full integration into realistic battery systems.

Pathways for practical high-energy long-cycling lithium metal batteries

State-of-the-art lithium (Li)-ion batteries are approaching their specific energy limits yet are challenged by the ever-increasing demand of today’s energy storage and power applications, especially for electric vehicles. Li metal is considered an ultimate anode material for future high-energy rechargeable batteries when combined with existing or emerging high-capacity cathode materials. However, much current research focuses on the battery materials level, and there have been very few accounts of cell design principles. Here we discuss crucial conditions needed to achieve a specific energy higher than 350 Wh kg−1, up to 500 Wh kg−1, for rechargeable Li metal batteries using high-nickel-content lithium nickel manganese cobalt oxides as cathode materials. We also provide an analysis of key factors such as cathode loading, electrolyte amount and Li foil thickness that impact the cell-level cycle life. Furthermore, we identify several important strategies to reduce electrolyte-Li reaction, protect Li surfaces and stabilize anode architectures for long-cycling high-specific-energy cells. Jun Liu and Battery500 Consortium colleagues contemplate the way forward towards high-energy and long-cycling practical batteries.

Detrimental Effects of Chemical Cross-Talk in Rechargeable Lithium Metal Batteries

The energy density of conventional Li-ion batteries (LIBs) has eventually reached their theoretical limit. Increasing worldwide efforts have been made towards the next generation of energy storage systems including batteries using Li metal anode in combination with various cathodes, including intercalation compounds (such as NMC) or conversion materials (such as oxygen (O2) and sulfur (S)). For a full demonstration of new battery chemistries, the interfacial stability is essential to long cycle lifespan and battery performance. In general, batteries suffer from “cross-talk” processes upon cycling by the crossover of parasitic chemicals through the electrolyte media [1]. Indeed, "cross-talk" phenomena in Li-ion batteries, such as Mn2+ crossover from the cathode and contaminate graphite anode has been well established [2]. Li-S and Li-O2 batteries also have the shuttle issues of soluble redox-active materials, polysulfides and superoxide radical anions, respectively. However, the similar characteristics in Li metal batteries (LMBs) with conventional Li ion intercalation cathodes have rarely been studied. Therefore, an in-depth understanding of how a Li metal anode affects the cathode interface chemistry is critical to ensure the long-term cycling stability of LMBs. Here, we report the cathode failure triggered by the chemical “cross-talk” between the electrode pair in rechargeable LMBs. In sharp contrast to LIBs, the cathode in LMBs suffers more significant and irreversible capacity fade during cycling, and its capacity cannot be fully recovered in spite of repeated replacement with new Li metal in the successive cycling. In-depth characterizations of the cathode surface reveal severe deterioration of cathode electrolyte interphase related to the significant accumulation of highly resistive polymeric components and lithium fluoride. Extensive salt-anion decomposition at Li metal surface can cause the chemical aging of the electrolyte allowing the migration of soluble byproducts toward the cathode side, resulting in the severe deterioration of cathode and separator surfaces. A selective Li-ion permeable separator with polydopamine coating has been developed to mitigate the detrimental chemical crossover and enhance the cathode stability. [1] Mikhaylik, Y. V.; Akridge, J. R., Polysulfide Shuttle Study in the Li/S Battery System. J. Electrochem. Soc. 2004, 151 (11), A1969-A1976 [2] Vetter, J.; Novák, P.; Wagner, M. R.; Veit, C.; Möller, K. C.; Besenhard, J. O.; Winter, M.; Wohlfahrt-Mehrens, M.; Vogler, C.; Hammouche, A. Ageing mechanisms in lithium-ion batteries. J. Power Sources 2005, 147 (1), 269-281. Figure 1

Effects of Separators on Lithium Metal Batteries

The separator is an essential inactive component in liquid-electrolyte based batteries, with the function of separating the positive electrode from the negative electrode to avoid the electronic flow but enable the free ionic transport. The major commercial separators are thin, porous polymeric membranes with single layer or multilayers, and the polymer materials are typically polyolefins, polyesters, and so on. In recent years, separators with surface modifications have also been reported and produced for lithium (Li)-ion batteries, with the purposes of improving the mechanical strength, wettability, cell performance and safety tolerance under various abuse conditions. A lot of positive results have been achieved in Li-ion batteries. In recent years, with the demand for higher energy density than that from the state-of-the-art Li-ion batteries, the research and development of rechargeable Li metal batteries has been revived. However, the effects of the separators on the stability of Li metal anode and the performance of Li metal batteries have seldom reported. In this work, we have comprehensively studied the chemical and electrochemical stabilities of commercially available separators with Li metal anode in two kinds of liquid electrolytes, and found that the separators do have different stabilities with Li metal anode especially in conventional LiPF6-based electrolytes. The details of the investigations will be reported at the presentation.

Suppressing Li dendrite by a protective biopolymeric film from tamarind seed polysaccharide for high-performance Li metal anode

Li metal, which is a promising anode for Li based batteries, still suffers from the Li dendritic generation and interfacial instability. Herein, for the first time, tamarind seed polysaccharide (TSP), a natural polymer with ultrahigh degree of backbone substitution, high viscosity and hardness, excellent elasticity and remarkable stability in organic electrolytes, was employed for Li metal anode protection. Using such biopolymer, an even TSP protective film with optimal thickness was facile coated on the Cu foil (TSP-Cu), which could favor the homogeneous electrodeposition of Li metal on the Cu foil and successfully inhibits the formation of dendrite during prolonged cycles. Thus-coated Li@TSP-Cu anode can deliver a stable cycling performance for more than 90 cycles with a low over-potential even at a high current density of 5 mA cm−2 with a total capacity of 2 mAh cm−2, whereas the bare anode, i.e., Li@Cu, becomes unstable in initial cycle. Furthermore, the coated electrode could maintain a coulomb efficiency of 98.5% even after cycling for more than 100 cycles under a current density of 1 mA cm−2 with capacity of 1 mAh cm−2, superior to the bare Cu electrode which drops below 40% within less than 50 cycles under the same conditions. Electrochemical impedance analysis, SEM and XPS characterizations of the cycled anodes further confirmed the role of the TSP protective layer in blocking the repetitive regeneration of the SEI layer and in stabilizing the electrode interface. Our work demonstrated the promising perspective of biopolymeric protective films for construction of stable and dendrite-free Li metal anode in high-energy-density rechargeable Li metal batteries.

Self-Supporting Dendritic Copper Porous Film Inducing the Lateral Growth of Metallic Lithium for Highly Stable Li Metal Battery

Lithium metal is recognized as the most promising anode candidate for advanced high-energy-density batteries. However, uncontrolled vertical growth of Li dendrites will induce short-circuit and cause rapid capacity loss, which hinders the practical application of rechargeable Li-metal batteries. The regulation of Li dendrites from vertical to lateral growth may be an effective strategy to solve the problems. Herein, a self-supporting dendritic copper porous film as host matrix of lithium is constructed by a one-step facile and cost-effective electrodeposition on gas-liquid-solid interface to inhibit the vertical growth of Li dendrites. Li nucleates on the surface of copper nanoparticles and grows laterally by the induced action of lateral copper dendrites consisting of nanoparticles. Meanwhile, copper porous film with dendritic walls provides more nucleation sites for uniform Li deposition and space for Li storage. On this basis, high and stable Coulombic efficiency of 98% after 600 cycles at 1 mA cm−2 and prolong lifespan of 2400 h in the symmetric cell are achieved. Coupled with a LiFePO4 cathode, the full cell exhibits good rate performance and cycle stability with capacity retention of 82.4% for 250 cycles at 1 C. It provides a simple but effective way to realize a stable Li metal-based anode.

Lithium metal anode on a copper dendritic superstructure

Li-metal is one of the most promising anode materials for electrochemical energy storage. However, the growth of Li dendrites during electrochemical deposition leads to low Coulombic efficiency and safety concerns and has long hindered the application of rechargeable Li-metal batteries. In this study, we designed a Cu dendritic superstructure with macropores as an anode-free three-dimensional current collector, which can significantly improve the electrochemical plating/stripping behavior of Li. The Li-metal anodes are accommodated by a Cu dendritic superstructure with no uncontrollable Li dendrites. This anode can operate for more than 600 h without a short-circuit and exhibits a low level of voltage hysteresis (~20 mV). The anode-free dendritic superstructure demonstrates exceptional performance and highlights the importance of rational design for a current collector that can accommodate Li anodes and provide a long lifespan.

Dendrite-free lithium metal anode enabled by separator engineering via uniform loading of lithiophilic nucleation sites

Despite promising high-capacity of lithium metal anode, one major obstacle for its wide application is the uncontrolled dendrite growth, causing low Coulombic efficiency (CE), irreversible capacity loss and short circuit. Here, we report a facile separator engineering to suppress Li dendrites growth through single-side deposition of magnesium (Mg) nanoparticles. The lithiophilic Mg nanoparticles on the separator, servering as heterogeneous nucleation sites, exhibits a strong guiding effect to form inerratic Li crystal seeds in the early plating process, resulting in a dense Li anode with dendrite-free morphology after long cycling. The unique characteristics of this functional separator are further demonstrated in Li|LiCoO2 full cells with a high capacity retention (>80% after 400 cycles). Accordingly, our strategy offers a scalable low-cost and efficient approach for advanced rechargeable Li metal batteries.

Impacts of lean electrolyte on cycle life for rechargeable Li metal batteries

Strong demand for higher energy batteries for extended range electric vehicles has driven battery technology development toward Li metal batteries. One limitation of Li metal batteries is cycle life. At odds are the amount of electrolyte to fulfill high energy and the amount needed to achieve long cycle life. Here we employ an electrochemical model and design of experiment to understand impacts on cycle life and failure as electrolyte content is reduced to levels needed to achieve reasonably high specific energy. With lean electrolyte, a gap exists in achieving long cycle life with a reduction by a factor of 6.5 when electrolyte amount is reduced from 37.0 g Ah−1 to 6.0 g Ah−1. Two primary failure routes are identified with differences between lean and high electrolyte quantities. The results suggest that reporting and performing experiments for high energy cell designs requires that amount of electrolyte be considered a critical parameter.