Gassing in lithium-ion batteries (LIBs) is a serious challenge, especially at high voltage and elevated temperature. In this study, we use On-line Electrochemical Mass Spectrometry (OEMS) two-compartment cell with newly developed aluminum edge-seal to elucidate the origin of H2 evolution LIBs. We demonstrate that new sealing entirely impermeable for gaseous liquid species, thus allowing us measure true from H2O reduction graphite electrode, without interference lithium counter-electrode....

In the present work, extent and role of oxygen release during first charge lithium- manganese-rich Li1.17[Ni0.22Co0.12Mn0.66]0.83O2 (also referred to as HE-NCM) was investigated with on-line electrochemical mass spectrometry (OEMS). HE-NCM shows a unique voltage plateau at around 4.5 V in charge, which is often attributed decomposition reaction Li-rich component Li2MnO3. For this so-called "activation", it has been hypothesized that electrochemically inactive Li2MnO3 would convert into MnO2...

Washing is a commonly used method to remove surface impurities of cathode materials for lithium-ion batteries. However, clear mechanistic understanding the washing process missing in literature. In this study, we will investigate effect and subsequent drying nickel-rich NCM cathodes (85% nickel) with respect gassing impedance washed cathodes. By on-line electrochemical mass spectrometry (OEMS), show drastic reduction O2 release above 80% SOC deionized water, suggesting formation an...

Ni-rich layered oxides, like NCM-811, are promising lithium-ion battery cathode materials for applications such as electric vehicles. However, pronounced capacity fading, especially at high voltages, still lead to a limited cycle life, whereby the underlying degradation mechanisms, e.g. whether they detrimental reactions in bulk or surface, controversially discussed. Here, we investigate fading of NCM-811/graphite full-cells over 1000 cycles by combination situ synchrotron X-ray powder...

High-energy Li1.17Ni0.19Co0.10Mn0.54O2 (HE-NCM) is a lithium-rich layered oxide with alternating Li- and transition-metal (TM) layers in which excess lithium ions replace transition metals the host structure. HE-NCM offers capacity roughly 50 mAh g–1 higher compared to that of conventional oxides but suffers from loss voltage fade upon cycling. Differential plots (taken over 100 cycles) show origin fading phenomenon bulk issue rather than surface degradation. Although previous studies...

This study deals with the decomposition of ethylene carbonate (EC) by H2O in absence and presence catalytically active hydroxide ions (OH−) at reaction conditions close to lithium-ion battery operation. We use On-line Electrochemical Mass Spectrometry (OEMS) quantify CO2 evolved these reactions, referred as H2O-driven OH−-driven EC hydrolysis. By examining both reactions various temperatures (10 – 80°C) water concentrations (<20 ppm or 200, 1000, 5000 H2O) without OH− 1.5 M LiClO4, we...

In this study, we will show how the oxygen release depends on Li2MnO3 content of material and it affects actual voltage fading material. Thus, compared overlithiated NCMs (x • (1-x) LiMeO2; Me = Ni, Co, Mn) with x 0.33, 0.42 0.50, focusing electrochemical performance. We could that differs vastly for materials, while is similar, which leads to conclusion a chemical degradation, occurring at surface, bulk issue these materials. prove hypothesis by HRTEM, showing surface layer, dependent...

Apart from the often-described formation of interphases between electrodes and electrolyte in Li-ion batteries, changes bulk also occur during cycling. In this study, we use On-line Electrochemical Mass Spectrometry (OEMS) to measure gas evolution associated with initial cycles graphite/lithium half-cells an composed ethylene carbonate (EC), ethyl methyl (EMC), conducting salt LiPF6. The reduction at graphite surface within first cycle is accompanied by release lithium alkoxides (LiOR),...

Lithium-ion batteries operate predominantly at room temperature, but some applications such as electric vehicles also demand operation higher temperature. This is especially challenging for cathode active materials (CAMs), which undergo an accelerated failure elevated Here, we systematically compare the capacity fading of Ni-rich NCM-811 two different temperatures. The first dataset over 1000 cycles 22 °C stems from a former study, while NCM-811/graphite full-cells are investigated now under...

This study conducts a qualitative comparison between two methods for detecting side reactions - the voltage hold and decay using high precision coulometry (HPC) tester. The measurements were conducted with Si-G/NMC811 commercial cells three different temperatures four states of charge (SoC) in order to determine temperature dependency reactions. Here, we show that deliver comparable results when determining differential capacity an incremental analysis (ICA) instead single pulse method. Both...

Li- and Mn-rich layered oxides are a promising class of cathode active materials (CAMs) for future lithium-ion batteries. However, they suffer from fast capacity fading in standard EC-containing electrolytes, therefore fluorinated alternatives, such as FEC, required to improve their full-cell performance, which unfortunately increases the cost electrolyte. In this study, we will analyze reasons poor cycling performance electrolytes with CAMs that release lattice oxygen at high degrees...

The evolution of gases is often associated with the decomposition electrolyte or active materials. Thus, its detection can be powerful for understanding degradation mechanisms in Li-ion batteries (LIBs). Here, we present an evaluation method gas and quantification by on-line electrochemical mass spectrometry (OEMS) when using volatile electrolytes (e.g., linear alkyl carbonates) a new OEMS cell design improved leak tightness. With significant fraction head-space being vapor, observe...

Li- and Mn-rich layered oxides are a promising next-generation cathode active material (CAM) for automotive applications. Beyond well-known challenges such as voltage fading oxygen release, their commercialization also depends on practical considerations including cost energy density. While the requirement these materials could be satisfied by eliminating cobalt, volumetric density might imply transition from most widely used porous structure to more densely packed structure. Here, we...

Li- and Mn-rich layered oxides (LMR-NCMs) are promising cathode active materials (CAMs) in future lithium-ion batteries (LIBs) due to their high energy density. However, the material undergoes a unique open circuit voltage (OCV) hysteresis between charge discharge after activation, which compromises its roundtrip efficiency affects thermal management requirements for LIB system. The is believed be caused by transition metal (TM) migration and/or oxygen redox activities. Using in-situ X-ray...

IrO 2 has been widely used as the anode co-catalyst for mitigating cell voltage reversal damages in proton exchange membrane fuel cells (PEMFCs). However, under PEMFC operation conditions, conventionally prepared catalysts are reduced by H , forming metallic Ir on their surface, which is prone to dissolution during start-up/shut-down (SUSD) cycles. The dissolved n+ ions can permeate through cathode electrode, poisoning oxygen reduction reaction (ORR) activity of Pt/C catalyst. In this study,...

Li-ion batteries (LiBs) are known to evolve gases during their first few formation cycles due the of a solid electrolyte interphase (SEI) at anode active material particle surface. Simultaneously, can react by other mechanisms leading volatile species. 1,2 At high state-of-charge, cathode also release reactive oxygen which causes CO and 2 from oxidative decomposition electrolyte. 3,4 Consequently, analysis evolved gas species one study effect additives, reveal substantial degradation...

High energy Li-Ion batteries rely on the pairing of a transition metal oxide cathode with graphite anode. Pushing upper cut-off voltage and state charge (SOC) to higher values, cycle-life battery is drastically reduced. Besides electrochemical electrolyte oxidation leading poor coulombic efficiencies large growth cell impedance, leaching ions from active materials one major obstacles increase power density without change materials. While capacity loss which can be ascribed overall material...

Graphite is the most widely used anode material in Li-ion batteries due to its excellent lithium storage capability as well long-term and cycle stability. Carbonate-based electrolytes are reduced on graphite surface form a solid electrolyte interface (SEI) within first few cycles. The passivating layer inhibits continuous decomposition by blocking electron transport while allowing Li-ions pass through. Additives often influence SEI chemistry [1]. Most studies focus composition of investigate...

Recently, many research activities have been devoted to the development of near 5 V cathode materials, e.g. LiMn 1.5 Ni 0.5 O 4 spinel, in order raise energy density lithium-ion batteries and allow for longer driving ranges battery electric vehicles. 1 However, enhanced degradation carbon electrolyte by use these high-voltage cathodes could not be mitigated so far. It was demonstrated recently On-line Electrochemical Mass Spectrometry (OEMS), 2 that anodic oxidation conductive carbon,...

Ni-rich layered oxides, like NCM-811 (Li 1+δ [Ni 0.8 Co 0.1 Mn ] 1-δ O 2 ), are promising cathode active materials for lithium-ion-batteries used in applications such as portable devices and battery electric vehicles. An increased Ni-content typically allows a higher reversible lithium usage at given cell potential, thereby improving the specific capacity. However, pronounced capacity fading, especially high voltages elevated temperatures, still leads to limited cycle life. 1 The underlying...

Layered lithium transition metal oxides, typically containing nickel, cobalt and manganese (NCM, Li 1+δ [Ni x Co y Mn z ] 1-δ O 2 with x+y+z=1), are the most widely used cathode active material (CAM) in Li-ion batteries for portable devices battery electric vehicles. 1 The class of NCM materials has several advantageous properties such as high energy power densities good cycling stability. However, depending on Ni:Co:Mn ratio, electrochemical performance characteristics can differ...

As a potential next generation cathode material, Li- and Mn-rich layered oxides, also referred to as High-Energy NCM (HE-NCM), offer high reversible capacities of ≈250 mAh/g. Despite the capacity relatively low material cost compared state-of-the-art materials, use HE-NCM is still challenged by issues such voltage fading, large charge-discharge hysteresis, impedance. Gassing, especially oxygen carbon dioxide release during initial formation cycles with HE-NCM, has been studied before [1]...

The cell voltage reversal that can occur during the transient operation of a proton exchange membrane fuel (PEMFC) stack leads to substantial degradation anode catalyst. During reversal, potential increases (&gt;&gt;1 V vs. reversible hydrogen electrode (RHE)), causing severe oxidation catalyst carbon support, which collapse layer and failure. One strategy mitigate damages H 2 starvation is addition co-catalyst electrode, catalyzes oxygen evolution reaction (OER), so non-damaging OER rather...