Li-air Research Articles

Phthalocyanine-based bifunctional soluble hybrid catalyst for rechargeable lithium-oxygen batteries

A mixture of tetrabutylammonium lithium phthalocyanine (TBA-LiPc) and dilithium phthalocyanine (Li2Pc) (2:1 mol ratio) functions as a bifunctional soluble hybrid catalyst in tetraethylene glycol dimethyl ether (TEGDME) for a rechargeable lithium-oxygen cell. Cyclic voltammetry (CV) measurements of the hybrid catalyst in TEGDME show highly symmetrical peaks at 2.54 V and 3.22 V vs Li/Li+ corresponding to oxygen reduction and oxygen oxidation reactions, respectively. Long-term cycling of cells with PVP-modified graphene nanosheets (GNSs) coated hierarchical porous carbons (HPC) cathodes at a fixed capacity of 1200 mAh/g (carbon) exhibits 402 and 379 cycles in oxygen and dry-air, respectively.

Engineering single-atom Mn on nitrogen-doped carbon to regulate lithium-peroxide reaction kinetics for rechargeable lithium-oxygen batteries

Precision engineering of catalytic sites to guide more favorable pathways for Li2O2 nucleation and decomposition represents an enticing kinetic strategy for mitigating overpotential, enhancing discharge capacity, and improving recycling stability of Li-O2 batteries. In this work, we employ metal–organic frameworks (MOFs) derivation and ion substitution strategies to construct atomically dispersed Mn-N4 moieties on hierarchical porous nitrogen-doped carbon (Mn SAs-NC) with the aim of reducing the overpotential and improving the cycling stability of Li-O2 batteries. The porous structure provides more channels for mass transfer and exposes more highly active sites for electrocatalytic reactions, thus promoting the formation and decomposition of Li2O2. The Li-O2 batteries with Mn SAs-NC cathode achieve lower overpotential, higher specific capacity (14290 mA h g−1 at 100 mA g−1), and superior cycle stability (>100 cycles at 200 mA g−1) compared with the Mn NPs-NC and NC. Density functional theory (DFT) calculations reveal that the construction of Mn-N4 moiety tunes the charge distribution of the pyridinic N-rich vacancy and balances the affinity of the intermediates (LiO2 and Li2O2). The initial nucleation of Li2O2 on Mn SAs-NC favors the O2 → LiO2 → Li2O2 surface-adsorption pathway, which mitigates the overpotentials of the oxygen reduction (ORR) and oxygen evolution reaction (OER). As a result, Mn SAs-NC with Mn-N4 moiety effectively facilitates the Li2O2 nucleation and enables its reversible decomposition. This work establishes a methodology for constructing carbon-based electrocatalysts with high activity and selectivity for Li-O2 batteries.

Cation Vacancy Modulated Interfacial Electronic Interactions for Enhanced Electrocatalysis in Lithium–Oxygen Batteries

AbstractLi–O2 batteries deliver ultrahigh theoretical specific energy while suffering from low energy efficiency and poor cyclability due to sluggish kinetics of oxygen electrode reactions. Herein, a strategy of engineering interfacial electron structure of MXene‐based composites is presented to boost oxygen electrode reactions for advancing Li–O2 batteries with the cation vacancy‐rich CoSe@MXene (VCo‐CoSe2@MXene) as the case study. The formation of interfacial Co─C bond between VCo‐CoSe2 and Ti3C2 MXene and its enhanced covalency after introducing Co vacancy leads to promoted electron transfer from Ti3C2 MXene to CoSe2 and optimized electronic structure of interfacial Co sites, especially the second Co sites neighboring Co vacancy, which serve as the active centers for oxygen redox reactions. On this basis, VCo‐CoSe2@MXene‐based Li─O2 batteries exhibit low overpotential (0.35 V) and excellent cycling stability (250 cycles at 500 mA g−1). This work proposes an effective strategy to develop MXene‐based electrocatalysts for Li–O2 batteries by tailoring interfacial electron structure.

Hierarchically Interconnected 3D Catalyst Structure of Porous Multi-Metal Oxide Nanofibers for High-Performance Li-O2 Batteries.

Non-aqueous lithium-oxygen batteries (LOBs) have emerged as a promising candidate due to their high theoretical energy density and eco-friendly cathode reaction materials. However, LOBs still suffer from high overpotential and poor cycling stability resulting from difficulties in the decomposition of discharge reaction Li2O2 products. Here, a 3D open network catalyst structure is proposed based on highly-thin and porous multi-metal oxide nanofibers (MMONFs) developed by a facile electrospinning approach coupled with a heat treatment process. The developed hierarchically interconnected 3D porous MMONFs catalyst structure with high specific surface area and porosity shows the enhanced electrochemical reaction kinetics associated with Li2O2 formation and decomposition on the cathode surface during the charge and discharge processes. The uniquely assembled cathode materials with MMONFs exhibit excellent electrochemical performance with energy efficiency of 82% at a current density of 50mAg-1 and a long-term cycling stability over 100 cycles at 200mAg-1 with a cut-off capacity of 500 mAhg-1. Moreover, the optimized cathode materials exhibit a remarkable energy density of 1013Whkg-1 at the 100th discharge and charge cycle, which is nearly four times higher than that of C/NMC721, which has the highest energy density among the cathode materials currently used in electric vehicles.

Design of multifunctional interfaces on ceramic solid electrolytes for high-performance lithium-air batteries

High-energy-density lithium (Li)–air cells have been considered a promising energy-storage system, but the liquid electrolyte-related safety and side-reaction problems seriously hinder their development. To address these above issues, solid-state Li–air batteries have been widely developed. However, many commonly-used solid electrolytes generally face huge interface impedance in Li–air cells and also show poor stability towards ambient air/Li electrodes. Herein, we fabricate a differentiating surface-regulated ceramic-based composite electrolyte (DSCCE) by constructing disparately LiI-containing polymethyl methacrylate (PMMA) coating and Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) layer on both sides of Li1.5Al0.5Ge1.5(PO4)3 (LAGP). The cathode-friendly LiI/PMMA layer displays excellent stability towards O2− and also greatly reduces the decomposition voltage of discharge products in Li–air system. Additionally, the anode-friendly PVDF-HFP coating shows low-resistance properties towards anodes. Moreover, Li dendrite/passivation derived from liquid electrolyte-induced side reactions and air/I-attacking can be obviously suppressed by the uniform and compact composite framework. As a result, the DSCCE-based Li–air batteries possess high capacity/low voltage polarization (11,836 mA h g−1/1.45 V under 500 mA g−1), good rate performance (capacity ratio under 1000 mA g−1/250 mA g−1 is 68.2%) and long-term stable cell operation (∼300 cycles at 750 mA g−1 with 750 mAh g−1) in ambient air.

An In Situ Gelled Polymer Electrolyte to Stabilize Lithium–Air Batteries

AbstractGel polymer‐based lithium batteries exhibit a unique combination of advantageous properties, including the favorable interfacial contact characteristic of liquid‐state batteries and the inherent stability of solid‐state batteries. For Li–air batteries operated in the semi‐open atmosphere, implementing in situ synthesized gel polymer electrolytes (GPEs) is effective in mitigating the environment‐induced challenges. In this study, a dimethyl sulfoxide (DMSO)‐based GPE in situ initiated by the toluene‐2,4‐diisocyanate (TDI) and 1,4‐benzenediboronic acid (BDBA) is designed to enable the stable operation of lithium–air batteries. The integration of in situ polymerization and polyvinyl alcohol's functional group engineering not only brings benefits to the interfacial contact and electrochemical stability of the battery but also mitigates the moisture sensitivity and volatility of the DMSO electrolyte in the ambient environment. In addition, the GPE can promote the formation of a robust protection film on the lithium surface. As a result, the designed GPE makes the batteries fully leverage their outstanding cycling stability in the ambient environment (241 cycles at 500 mA g−1 and 1000 mAh g−1). Moreover, an optimized Li–air pouch cell structure incorporating the GPE achieves a boasted energy density of 757.5 Wh kg−1, providing a significant technical pathway to bring Li–O2 batteries to practical Li–air batteries.

FeNi nanoalloy-carbon nanotubes on defected graphene as an excellent electrocatalyst for lithium-oxygen batteries

Lithium-oxygen batteries (LOBs) promise high energy density but suffer from catalyst-related issues. We've developed FeNi-NCNT/DrGO, a novel catalyst, by integrating iron-nickel nanoalloys (FeNi) embedded in nitrogen-doped carbon nanotubes (NCNTs) grafted onto defect-rich reduced graphene oxide (DrGO). The fabrication involved freeze-drying, defect engineering, and thermal treatments. The FeNi nanoalloy within the catalyst demonstrates outstanding bifunctional activity, while the NCNTs serve as an excellent electronic conduction medium and DrGO enables favorable ion transport. The 3D open-space architecture of this catalyst provides a rapid diffusion path for the electrolyte and room for accommodating discharge products. As a result, the LOBs with FeNi-NCNT/DrGO exhibits exceptional electrochemical performance, achieving a deep discharge capacity of 21,153.6 mAh g−1 and a high round-trip efficiency of 98.7% at 200 mA g−1. Moreover, it demonstrates excellent cycling stability, exceeding 100 cycles at 200 mA g−1 with a cut-off capacity of 500 mAh g−1.

Cu3P Nanoarrays Derived from 7,7,8,8-Tetracyanoquinodimethane for High-Rate Electrocatalytic Oxygen Reactions of Lithium-Oxygen Batteries

Efficient electrocatalysis at the cathode is crucial for addressing the challenges faced by lithium-oxygen batteries (LOBs), including limited stability and low-rate capability. To develop an efficient cathode for aprotic LOBs, self-supported copper phosphide nanoarrays on carbon cloth are prepared at different heating rates via a phosphidation process using CuTCNQ nanoarrays. Different ramping rates have effects on particle size and intrinsic interaction, which in turn affect their catalytic properties. When phosphidation is carried out at a slow rate, it results in the formation of smaller, evenly distributed Cu3P particles on the nanoarrays (SG-Cu3P NAs/CC) compared to fast rate phosphidation (FG-Cu3P NAs/CC). As a result, SG-Cu3P NAs/CC exhibits lower resistance and a higher concentration of active sites than FG-Cu3P NAs/CC. The SG-Cu3P NAs/CC demonstrates LOBs with a low overpotential of 1.51 V at a high current rate of 1 mA cm−2 and a long cycle life of 115 cycles at 0.1 mA cm-2. The in situ Raman spectroscopy supports that Li2O2 is uniformly formed and decomposed on the SG-Cu3P NAs/CC surface. This study provides a compelling approach for the precise fabrication and analysis of binder-free, self-supported copper phosphides as highly efficient and stable materials for bifunctional oxygen electrocatalysis.

Recent Advances in Understanding of the Singlet Oxygen in Energy Storage and Conversion.

Singlet oxygen (term symbol 1Δg, hereafter 1O2), a reactive oxygen species, has recently attracted increasing interest in the field of rechargeable batteries and electrocatalysis and photocatalysis. These sustainable energy conversion and storage technologies are of vital significance to replace fossil fuels and promote carbon neutrality and finally tackle the energy crisis and climate change. Herein, the recent progresses of 1O2 for energy storage and conversion is summarized, including physical and chemical properties, formation mechanisms, detection technologies, side reactions in rechargeable batteries and corresponding inhibition strategies, and applications in electrocatalysis and photocatalysis. The formation mechanisms and inhibition strategies of 1O2 in particular aprotic lithium-oxygen (Li-O2) batteries are highlighted, and the applications of 1O2 in photocatalysis and electrocatalysis is also emphasized. Moreover, the confronting challenges and promising directions of 1O2 in energy conversion and storage systems are discussed.

A revolutionary design concept: full-sealed lithium-oxygen batteries

At this moment, non-aqueous rechargeable lithium-oxygen batteries (LOBs) with extremely high energy density are regarded as the most viable energy storage devices to potentially replace petroleum. One of the most crucial impediments to their implementation has been ensuring facile oxygen availability. Moreover, as semi-sealed systems, LOBs have confronted challenges including oxygen impurities, product degradation, anode corrosion, frequent side reactions, and mediocre cycling performance. In this work, utilizing the physical adsorption of porous (micro-, meso- and macro-porous) solid carbon materials, we incorporate an oxygen storage layer (OSL) with reversible oxygen ad/desorption capabilities into a LOB to develop novel fully-sealed lithium-oxygen batteries (F-S-LOBs). The results demonstrate mesoporous carbons exhibit optimal oxygen adsorption/desorption kinetics, rendering them highly suitable for F-S-LOBs without developing complex oxygen-permeable membranes or carrying oxygen tanks. The OSL fabricated with mesoporous carbon can sustain battery charge/discharge at various current densities with exceptional cycling performance. Additionally, we provide approximate pore size guidelines for oxygen storage materials to aid future research. This study is anticipated to offer a new robust research direction for metal-air batteries and to forge a new path toward promoting the commercialization and development of this technology.

Highly Stable Organic Molecular Porous Solid Electrolyte with One-Dimensional Ion Migration Channel for Solid-State Lithium-Oxygen Battery.

Solid-state lithium-oxygen (Li-O2 ) batteries have been widely recognized as one of the candidates for the next-generation of energy storage batteries. However, the development of solid-state Li-O2 batteries has been hindered by the lack of solid-state electrolyte (SSE) with high ionic conductivity at room temperature, high Li+ transference number, and the high stability to air. Herein, we developed the organic molecular porous solid cucurbit[7]uril (CB[7]) with one-dimensional (1D) ion migration channels as the SSE for solid-state Li-O2 batteries. Taking advantage of the 1D ion migration channel for Li+ conduction, CB[7] SSE achieved high ionic conductivity (2.45×10-4 S cm-1 at 25 °C). Moreover, the noncovalent interactions facilitated the immobilization of anions, realizing a high Li+ transference number (tLi + = 0.81) and Li+ uniform distribution. The CB[7] SSE also shows a wide electrochemical stability window of 0-4.65V and high thermal stability and chemical stability, as well as realizes stable Li+ plating/stripping (more than 1000h at 0.3mA cm-2 ). As a result, the CB[7] SSE endows solid-state Li-O2 batteries with superior rate capability and long-term discharge/charge stability (up to 500h). This design strategy of CB[7] SSE paves the way for stable and efficient solid-state Li-O2 batteries toward practical applications. This article is protected by copyright. All rights reserved.

Grain-refining Co0.85Se@CNT cathode catalyst with promoted Li2O2 growth kinetics for lithium-oxygen batteries

Highly active cathode catalysts for efficient formation/decomposition of Li2O2 are essential for the performance improvement of lithium-oxygen batteries (LOBs). In this study, a grain-refining Co0.85Se catalyst with a lattice spacing of 2.69 Å of (101) plane closely matching with the (100) plane (2.72 Å) of Li2O2 was applied for high-performance LOBs. Highly (101) plane exposed Co0.85Se@CNT was synthesized by a simple one-pot hydrothermal method. The Co0.85Se with the lattice matching effect not only led to the efficient conversion and polarized growth of Li2O2, but also prevented the formation of byproducts. Density functional theory (DFT) calculations reveal that Co0.85Se (101) plane has the intrinsic catalytic ability to generate/decompose Li2O2 during ORR/OER process, due to its homogeneous electron distribution, suitable adsorption energy, and promoted Li2O2 growth kinetics. As a consequence, the (101) plane highly exposed Co0.85Se@CNT-80 electrode exhibited remarkable cycle stability over 2400 h at 100 mA/g and 290 cycles at 500 mA/g, which is about 2 times longer than other electrodes.

Facile synthesis of nano-flower shaped NiCo2O4 and hexagonal prism shaped MoO3 composite materials as high-performance cathode materials for lithium-oxygen batteries

The development of lithium-oxygen batteries has a considerable positive impact on environmental protection and energy conservation. The cycling performance of lithium-oxygen batteries can be greatly improved by using a bifunctional cathode catalyst. In this study, composites of NiCo2O and h-MoO3 (named h-MoO3/NiCo2O4) were synthesized by a simple hydrothermal method and used as cathode catalysts for lithium-oxygen batteries. The h-MoO3/NiCo2O4 has large specific surface area (120 m2 g−1), low proportions of Ni2+/Ni3+ (0.41) and Co2+/Co3+ (0.91) and high proportions of Mo5+/Mo6+ (0.20) compared with those of h-MoO3/NiO and h-MoO3/Co3O4. The h-MoO3/NiCo2O4 composite provided a larger effective area for Li2O2 storage, resulting in low overpotential and high capacity. The first discharge capacities of h-MoO3/NiCo2O4 electrodes reached up to 9981.4 mA h g−1 and 8971.6 mA h g−1 at the current density of 500 mA g−1 and 700 mA g−1, respectively. The h-MoO3/NiCo2O4 electrodes exhibited good cyclic stability (133 cycles under a limited capacity of 500 mA h g−1 at 500 mA g−1) and low charge-discharge overpotential (only 0.84 V for the first cycle).

Stabilizing Lithium-Oxygen Batteries through In Situ Generated Phenyl/LiF-Rich Hybrid SEI Layer with Sulfonyl Fluoride Electrolyte Additive

Lithium-oxygen batteries have a wide application due to their ultra-high theoretical energy density. However, uncontrollable lithium dendrites and highly reactive oxygen species greatly cause the corrosion of lithium anodes and the degradation of the electrolytes. In our work, we introduce 4-Methylbenzenesulfonyl Fluoride (4-MBSF) as a highly efficient film-forming additive. It can form a stable inorganic-organic composite solid electrolyte interfacial layer and inhibit the growth of lithium dendrites to stabilize the lithium anode, thus dramatically enhancing the lives of lithium-oxygen batteries. The sulfonyl fluoride group of 4-MBSF can react with LiOH to form a LiF-rich protective layer on the lithium metal surface, which can improve stripping/deposition stability and ionic conductivity. Besides, the π-conjugation of the benzene ring can improve the flexibility of the SEI layer to accommodate volume changes of the lithium anode during cycling and inhibit the attacks of the reactive oxygen species. The cycle life of lithium-oxygen batteries with 4-MBSF is prolonged to 400 cycles.

A systematic review of nanotechnology for electric vehicles battery

Abstract Nanotechnology has increased electric vehicle (EV) battery production, efficiency and use. Nanotechnology is explored in this electric car battery illustration. Nanoscale materials and topologies research has increased battery energy density, charge time and cycle life. Nanotubes, graphene and metal oxides improve energy storage, flow and charging/discharge. Solid-state and lithium-air high-energy batteries are safer, more energy dense and more stable using nanoscale catalysts. Nanotechnology improves battery parts. Nanostructured fluids reduce lithium dendrite, improving batteries. Nanocoating electrodes may reduce damage and extend battery life. Nanotechnology benefits the planet. Nanomaterials allow battery parts to employ ordinary, safe materials instead of rare, harmful ones. Nanotechnology promotes battery recycling, reducing waste. Change does not influence stable, cost-effective or scalable items. Business opportunities for nanotechnology-based EV batteries need more research. High-performance, robust and environmentally friendly batteries might make electric cars more popular and transportation more sustainable with research and development. An outline of EV battery nanotechnology researchexamines the publication patterns, notable articles, collaborators and contributions. This issue was researched extensively, indicating interest. Research focuses on anode materials, energy storage and battery performance. A research landscape assessment demonstrates EV battery nanotechnology’s growth and future. A comprehensive literature review examined nanosensors in EVs. Our study provides a solid foundation for understanding the current state of research, identifying major trends and discovering nanotechnology breakthroughs in EV sensors by carefully reviewing, characterizing and rating important papers.

Characteristic analysis of lithium–oxygen batteries considering the discontinuous deposit and electrolyte degradation effects during discharge

The modeling research plays a crucial role in grasping the reaction mechanisms and forecasting the performance of lithium‑oxygen (LiO2) batteries. A transient LiO2 battery model including continuity, transportation, and reaction kinetics by simultaneously considering the discontinuous deposit of discharge product Li2O2 and the formation of by-product Li2CO3 due to electrolyte degradation, is developed to reveal the discharge phenomena. The effects of operating conditions and electrolyte and electrode properties on the discharge behaviors including voltage-capacity curve, energy density, profiles of O2 concentration (CO2) and porosity (ɛ) at the cathode are quantitatively studied. It is found that enhancing O2 solubility (SO2) and diffusivity (DO2) significantly improves discharge capacity and voltage plateau; the promotion of voltage plateau will be inconspicuous as electrolyte conductivity (κ) is enlarged over 1 S/m. With the rise of ɛ from 0.73 to 0.93, the specific capacity is boosted from 874 to 6122 mAh/g‑carbon, and the corresponding specific energy upgrades from 2260 to 15,610 mWh/g‑carbon. Shortening cathode thickness (Lca) facilitates the efficient utilization of carbon cathode material but this comes at the expense of lowering the mass loading of carbon, the practical energy drops 59.4 % as Lca reduces from 750 μm to 100 μm. After 20 consecutive charge-discharge cycles, the capacity retention obtained is 36.884 %, accompanied by a 13.8 % volume fraction of Li2CO3 formation inside the cathode. This work may guide in designing electrodes and electrolytes and provide performance regulation strategies for LiO2 batteries.

Ternary modification of polymer-derived carbon from disposable diapers for advanced energy storage: Three birds with one stone

In order to improve the energy storage capacity of carbon materials, exploring advanced preparation and modification technologies for carbon materials has always been the primary challenge in this field. Herein, we report a novel and diversified modification strategy for carbon materials, which can simultaneously satisfy pore regulation, catalytic graphitization, and heteroatoms doping. By modifying the carbon materials derived from super absorbent polymer in baby disposable diapers, both supercapacitors and lithium-oxygen batteries have achieved excellent electrochemical performance. In the application of supercapacitors, it shows a large specific capacitance of 384.1 F g−1 at 0.5 A g−1 and an outstanding ultrastability with a capacitance retention of 99 % over 10,0000 cycles at 20 A g−1. For the application in lithium-oxygen batteries, a high discharge capacity of 13,589 mAh g−1 can be achieved. These attractive electrochemical properties demonstrate enormous potential for practical applications of the as-developed ternary-modified carbon materials.

Interfacial structure and transport properties of concentrated lithium chloride solutions under an electrostatic field

Efficient moisture exchange between liquid desiccants and air is essential for optimizing dehumidification and air-conditioning systems, with the interfacial layer playing a critical role. This work investigates the influence of electrostatic fields (E-fields) on the structural and transport properties of the liquid-vapor interface between aqueous lithium chloride solutions and air at a microscopic scale using molecular dynamics (MD) simulations. Our research reveals that negative normal E-fields deplete ions within the interfacial layer, weakening their interactions with water molecules. Conversely, positive normal E-fields enrich surface ions, attracting a higher concentration of water molecules to the interface. The E-field enhances interactions between water molecules, increasing hydrogen bonds (H-bonds) at the interface. This weakens cohesion between water molecules and the liquid phase, ultimately reducing surface tension and the associated interfacial free energy barrier, facilitating the departure of water molecules from the liquid phase. Negative normal E-fields demonstrate greater advantages due to their pronounced alteration of the interface structure and the polarization of water molecules.

Graphene-supported single atom catalysts for high performance lithium-oxygen batteries

The optimal choice of d-block metals in single atom catalysts (SACs) is crucial for designing efficient electrocatalysts for activating the Oxygen reduction reaction (ORR)/ Oxygen evolution reaction (OER) in lithium-oxygen batteries (LOBs). Herein, we used the Quantum Mechanics methods to understand the origin of reactivity for a series of 16 d-block metals supported on nitrogen-doped graphene as SACs for ORR and OER in LOBs. Based on the Gibbs free energy calculations, we found that among the 16 SACs investigated, Zn-SAC exhibits the highest electrochemical activity with the lowest overpotential of 0.17 V. We then used machine learning (ML) to develop an intrinsic descriptor, Φ, that correlates the catalytic activity with electronic and chemical properties of the catalytic centers at the M-N4 active site on graphene surface. We established a linear relationship between Φ and the catalytic activity that provides guidance for designing efficient SACs for electrocatalysis in LOBs. To validate these predictions, we report electrochemical measurements showing that Zn-SAC exhibits an ultra-stable cyclability with reduced overpotentials over Mo-SAC and nitrogen-doped graphene (NG), confirming our theoretical prediction. This fundamental work provides a deep understanding on the rational design of efficient SACs for OER/ ORR in LOBs.

Determinants of the Surface Film during the Discharging Process in Lithium-Oxygen Batteries.

Lithium-oxygen batteries have one of the highest theoretical capacities and specific energies, but several challenges remain. One of them is premature death caused by a passivation layer with poor conductivities (both electronic and ionic) on the electrode surface during the discharge process. Once this thin layer forms on the surface of the catalyst and substrate, the overpotential significantly increases and causes early cell death. Therefore, understanding this thin layer is crucial to achieving high specific energy lithium-oxygen batteries. Herein, we quantitatively compared the ratio of lithium carbonate to lithium peroxide during the discharge process in a flow cell at different potentials. We found that the ratio rapidly increased at low potential and high flow rates. The surface route led to significant byproducts on the Au electrodes, and consequently, a 3 nm thick discharge product film passivates the electrode surface in a flow cell.