Optimizing the performance of lithium metal anode is required to enable next generation high energy density batteries. Anode-free cells are particularly attractive as they facilitate highest cell architecture. In this work, we investigate anode-free cycled under different protocols. We demonstrate impact charge and discharge current with three cycling conditions: a symmetric charge-discharge, an asymmetric faster slower charge. show that relative rate vs more important than absolute...

Inorganic surface coatings such as Al2O3 are commonly applied on positive electrode materials to improve the cycling stability and lifetime of lithium-ion cells. The beneficial effects typically attributed chemical scavenging corrosive HF physical blockage electrolyte components from reaching surface. present work combines published thermochemistry data with new density functional theory calculations propose a mechanism action: spontaneous reaction LiPF6 salt Al2O3-based coatings. Using 19F...

A set of LiNi0.5Mn0.3Co0.2O2/graphite lithium-ion cells underwent 750 charge-discharge cycles during about 8 months at 55°C to upper cutoff potentials 4.0, 4.1, 4.2, 4.3, and 4.4 V. The electrolyte in these was extracted using a centrifuge method studied gas chromatography/mass spectrometry determine the changes solvents by inductively coupled plasma-mass salt content electrolyte. negative electrodes from were harvested micro-X-ray fluorescence quantify amount transition metals which...

Single crystal Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 //graphite (NMC532) pouch cells with only sufficient graphite for operation to 3.80 V (rather than ≥4.2 V) were cycled charging either 3.65 or facilitate comparison LiFePO 4 (LFP) on the grounds of similar maximum potential and negative electrode utilization. The NMC532 cells, when constructed be charged V, have an energy density that exceeds LFP a cycle-life greatly at 40 °C, 55 °C 70 °C. Excellent lifetime high temperature is demonstrated...

With a potential to deliver 60% greater energy density than conventional lithium-ion batteries, the simple design of anode-free lithium metal cells with liquid electrolytes has generated significant research interest. However, without excess lithium, short lifetime and safety concerns for cycling make development particularly challenging. Herein, we investigate effect four different positive electrode materials on performance cells—LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532), LiNi 0.8 0.1 (NMC811),...

Fast-charging lithium-ion cells require electrolyte solutions that balance high ionic conductivity and chemical stability. The introduction of an organic ester co-solvent is one route can improve the rate capability a cell. Several new candidates were identified based on viscosity, permittivity (dielectric constant), DFT-calculated electrochemical stability windows. formate, nitrile, ketone, amide co-solvents are shown to increase lithium hexafluorophosphate in conventional...

LiFePO 4 (LFP) is an appealing cathode material for Li-ion batteries. Its superior safety and lack of expensive transition metals make LFP attractive even with the commercialization higher specific capacity materials. In this work performance LFP/graphite cells tested at various temperatures cycling protocols. The amount water contamination controlled to study impact on fade in LFP. Further, several additive systems that have been effective NMC/graphite chemistries are cells. presence excess...

Unwanted redox shuttles can lead to self-discharge and inefficiency in lithium-ion cells. This study investigates the generation of a shuttle LFP/graphite NMC811/graphite pouch cells with common alkyl carbonate electrolyte. Visual inspection electrolyte extracted after formation at temperatures between 25 70 °C reveals strong discoloration. Such electrolytes intense red brown color show relatively large shuttling currents Al/Li coin Two weight percent vinylene is effective preventing as...

Unwanted parasitic reactions in lithium-ion cells lead to self-discharge and inefficiency, especially at high temperatures. To understand the nature of those this study investigates open circuit storage losses LFP/graphite NMC811/graphite pouch with common alkyl carbonate electrolytes. The perform a test 40 °C 500 h period after formation temperatures between 70 °C. Cells formed elevated temperature showed reversible loss that could be assigned redox shuttle generated electrolyte during...

Transition metal dissolution from the positive electrode of Li-ion cells with subsequent deposition on graphite negative can contribute to failure cells. The transition various single crystal Li[Ni 1−x−y Mn x Co y ]O 2 and 1−x grades depostion is quantified using scanning micro X-ray fluorescence spectroscopy. Graphite electrodes were extracted /graphite (NMC/graphite) (NM/graphite) pouch after aggressive charge-discharge or storage protocols at 70 °C. In all cases, less than 1 μ g cm −2...

Liquid electrolytes for anode-free Li metal batteries (LMBs) provide a cost-effective path to high energy density. However, liquid are challenging due the reactivity of 0 with electrolyte and resulting loss, as well mossy deposits leading inactive dendrite formation. Thus, more research is needed develop capable 80 % capacity retention after 800 cycles meet electric vehicle (EV) demands. Here, we report cycle life results from 65 mixtures consisting various additives or co-solvents added...

The impact of graphite materials on capacity retention in Li-ion cells is important to understand since Li inventory loss due SEI formation, and cross-talk reactions between the positive negative electrodes, are cell failure mechanisms cells. Here, we investigate five from reputable suppliers performance NMC811/graphite We show that natural graphites (NG) here have a mixture 3R 2H phases, while artificial (AG) were only. find there differences N 2 BET surface area...

Many studies of Li-ion cells examine compositional changes to electrolyte and electrodes determine desirable or undesirable reactions that affect cell performance. Cells involved in these typically have a limited test lifetime due the resource intensive time-consuming nature experiments. Here, electrode analyses were performed on large matrix tested at various conditions with cycle lifetimes. The included LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532)/graphite 0.6 (NMC622)/graphite pouch excellent...

The use of LiPF 6 in Li-ion battery electrolytes provides sufficient stability, conductivity, and cost most applications. However, has also been known to cause degradation cells, primarily from its thermal decomposition or hydrolysis form acidic species. This work considers the imide salts lithium bis(fluorosulfonyl)imide (LiFSI) bis(trifluoromethanesulfonyl)imide (LiTFSI) as an alternative LiFePO 4 /Graphite cells. LiFSI LiTFSI over improved cycling performance both control electrolyte (no...

Single-crystal LiNi x Mn y Co z O 2 (NMC) materials have recently garnered significant academic and commercial interest as they been shown to provide exceptional long-term charge-discharge cycling stability in Li-ion cells. Understanding the degradation mechanisms occurring conventional polycrystalline NMC comparison more stable single-crystal equivalents has become a topic of great importance. In this study, we demonstrate how multi-scale, situ computed tomography can be used characterize...

LiNi 0.5 Mn 0.3 Co 0.2 O 2 /graphite cells with two different electrolytes underwent charge-discharge cycling at 70 °C. The °C condition reduced the time it took for to lose significant capacity. Studies of changes electrolyte after by gas chromatography/mass spectrometry (GC/MS) and Nuclear Magnetic Resonance spectroscopy (NMR) suggest that same processes which cause cell failure degradation 40 55 occur °C, only an accelerated rate. Transition metal dissolution from positive electrode was...

This work examined the impact of depth discharge (DOD), C-rate, upper cut-off voltage (UCV), and temperature on lifetime single-crystal NMC811/Artificial Graphite (AG) cells. Cells were cycled at C/50, C/10, C/5, or C/3, 25, 50, 75, 100% DOD room (RT, 20 ± 2 °C) 40.0 0.1 °C. The UCVs 4.06 4.20 V. After 12000 hr cycling, experiments such as electrochemical impedance spectroscopy (EIS), Li-ion differential thermal analysis (DTA), ultrasonic mapping, X-ray fluorescence (XRF), capacity analysis,...

In an effort to better understand capacity loss mechanisms in LiFePO 4 (LFP)/graphite cells, this work considers carbon-coated LFP materials with different surface area and particle size. Cycling tests at room temperature (20 °C) elevated temperatures show more severe fade cells lower material. Measurements of Fe deposition on the negative electrode using micro X-ray fluorescence ( μ XRF) spectroscopy reveal graphite from low area. parasitic heat flow isothermal microcalorimetry marginally...

Unwanted self-discharge of LFP/AG and NMC811/AG cells can be caused by in situ generation a redox shuttle molecule after formation at elevated temperature with common alkyl carbonate electrolyte. This study investigates the for several electrolyte additives, e.g., vinylene lithium difluorophosphate, measuring additive reduction onset potential, first cycle inefficiency gas evolution during temperatures between 25 70 °C. After formation, is extracted from pouch visual inspection...

Abstract In recent years, LiFePO4 (LFP)/graphite cell chemistry has gained renewed interest for commercial use in electric vehicles and grid energy storage due to its low cost, utilization of an abundantly available transition metal, better intrinsic safety characteristics. However, LFP/graphite cells exhibit inferior cycling performance at high temperatures compared some Li[NixMnyCoz]O2 (NMC) type materials. This study evaluated three classes electrolyte additives - vinylene carbonate (VC),...

Lithium iron phosphate (LiFePO 4 , or LFP) is a widely used cathode material in Li-ion cells due to its improved safety and low cost relative other materials such as LiNi x Mn y Co z O 2 (x + = 1, NMC). To improve the calendar life of LFP cells, an investigation their failure mechanisms necessary. Herein, we use scanning micro X-ray fluorescence ( μ XRF) study Fe dissolution from deposition on graphite electrode, which thought be contributor capacity fade. The impacts vinylene carbonate (VC)...

Part II of this 2-part series examines the impact competitive graphite materials on NMC811 pouch cell performance using Ultra-High Precision Coulometry (UHPC), isothermal microcalorimetry, and in-situ stack growth. A simple lifetime projection best NMC811/graphite cells as a function operating temperature is made. We show that choice greatly impacts fractional fade, while charge endpoint capacity slippage was largely unchanged due to identical cathodes. an increase in 1st cycle efficiency...

A matrix of LiNi 0.5 Mn 0.3 Co 0.2 O 2 /graphite cells filled with 1.33 molal LiPF 6 in EC:EMC:DMC (ethylene carbonate: ethyl methyl dimethyl carbonate) (25:5:70 by volume) electrolyte and different weight percentages vinylene carbonate (VC) ethylene sulfate (DTD) additives underwent prolonged charge-discharge cycling at 20 °C 40 °C. The volume gas produced during formation cycle testing was measured. impedance spectra the before after After testing, extracted for study nuclear magnetic...

LiFePO 4 /graphite (LFP), Li[Ni 0.5 Mn 0.3 Co 0.2 ]O 2 (NMC3.8 V, balanced for 3.8 V cut-off), and 0.83 0.06 0.11 (Ni83, 4.06 cut-off) cells were tested at 85 °C. Three strategies used to improve cell lifetime all positive electrode materials 85°C. First, low voltage operation (<4.0 V) was limit the parasitic reactions electrode. Second, LiFSI (lithium bis(trifluoromethanesulfonyl)imide) as electrolyte salt its superior thermal stability over LiPF 6 hexafluorophosphate). The avoids...