Ion Loss Research Articles

High-energy LiNi0.90Co0.04Mn0.03Al0.03O2 cathode material with lithium-reactive Li0.34La0.56TiO3 coating and Li2NiO2 lithium supplying for enhanced performance lithium-ion batteries

In the work, we have focused on the surface variations of the LiNi0.90Co0.04Mn0.03Al0.03O2 induced by the lithium ion conductor Li0.34La0.56TiO3 and over-lithiated oxide Li2NiO2 double coverings. The influence of various covering materials on particles morphology, crystal structure and electrochemical properties have been explored. It is found that the Li0.34La0.56TiO3 firm layer could reduce the catalytic decomposition of electrolyte and further maintain the stable particles morphology and crystal structure of cathode after long-term cycling. In addition, the Li2NiO2 served as the lithium supplement additive could compensate the irreversible active lithium ions loss during cycling and then relieve the cyclic capacity attenuation. Comparatively, the cathodes after Li0.34La0.56TiO3 coating deliver the obvious enhanced rate capability, superior discharging capacity at low temperature and more stable cyclic performance than those of pristine LiNi0.90Co0.04Mn0.03Al0.03O2. Besides, the Li0.34La0.56TiO3 and Li2NiO2 co-coated sample demonstrates the superior safety performance and cyclic stability when applied in the pouch battery in comparison with the pristine cathode.

Enabling Long‐term Cycling Stability of Na3V2(PO4)3/C vs. Hard Carbon Full‐cells

AbstractSodium‐ion batteries are becoming an increasingly important complement to lithium‐ion batteries. However, while extensive knowledge on the preparation of Li‐ion batteries with excellent cycling behavior exists, studies on applicable long‐lasting sodium‐ion batteries are still limited. Therefore, this study focuses on the cycling stability of batteries composed of Na3V2(PO4)3/C based cathodes and hard carbon anodes. It is shown that full‐cells with a decent stability are obtained for ethylene carbonate/propylene carbonate electrolyte and the conducting salt NaPF6. With cathode loadings of 1.2 mAh/cm2, after cell formation discharge capacities up to 92.6 mAh/g are obtained, and capacity retentions >90 % over 1000 charge/discharge cycles at 0.5 C/0.5 C are observed. It is shown that both, the additive fluoroethylene carbonate and impurities in the electrolyte, negatively affect the overall discharge capacity and cycling stability and should therefore be avoided. Remarkably, the internal resistances of well‐balanced and well‐built cells did not increase over 1500 cycles and 5 months of testing, which is a very promising result regarding the possible lifespan of the cells. The initial loss of active sodium ions in hard carbon remains a major problem, which can only be partially reduced by proper balancing.

Novel PFAS-specific monitoring approach for highly impacted surface waters

In regulatory environmental monitoring programs, only a very small fraction of the vast number of per- and polyfluoroalkyl substances (PFAS) are investigated by target analysis. Therefore, non-target analysis (NTA) studies are increasingly conducted to detect unknown or unnoticed PFAS. These studies are often based on a few grab samples. Thus, discontinuously emitted PFAS from industrial batch processes might be easily overlooked. To address this deficiency and obtain in-depth information on the occurrence and temporal trend of PFAS in surface water impacted by treated industrial waste water, a comprehensive target and NTA study was implemented for 29 months.Elevated PFAS concentrations with up to 10.8 μg L−1 were detected in the river water by target analysis. In addition to PFAS target analysis, the water samples were analyzed by liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS/MS). Data processing strategies and various filtering steps were applied to prioritize PFAS. Substances were identified by comparing data to available internal and external PFAS suspect lists, a fragment ion and neutral loss list, and spectral libraries. Several compounds were unequivocally identified based on reference standards.Fifty-five PFAS were (tentatively) identified using NTA. Of those, 43 could be assigned to 13 different homologous series. Partly fluorinated short-chain carboxylic acids (H-PFCA) and sulfonic acids (H-PFSA) were predominantly found in addition to perfluoroalkyl carboxylic acids (PFCA) and the alkyl ether carboxylic acid DONA. To the best of our knowledge, 12 PFAS were reported in surface water for the first time. Signal intensities of individual PFAS and signal ratios varied widely over time, which may indicate batch operations leading to discontinuous emission. Results and insights from this screening approach on PFAS can be used to optimize forthcoming surface water monitoring programs by including newly identified PFAS and selecting appropriate sampling intervals.

Exploring the mechanism of axial ion energy acquisition and loss in an magnetoplasmadynamic thruster plume

In order to investigate the mechanism of axial ion energy acquisition and loss in an applied-field magnetoplasmadynamic thruster (AF-MPDT) plume plasma, a 10 kW level MPDT was tested using a Gauss meter, a Langmuir probe, a Faraday probe, a retarding potential analyzer (RPA) and a thrust target stand. Axial ion energy (Eiz) and axial Lorentz force density (Fz) distributions are obtained and interconnected. In the R direction, a local peak in Eiz exists as a result of the presence of maximum Fz in proximity. This localized Fz surge is instigated by the diamagnetic current, a consequence of the abrupt density reduction near the beam edge. In the Z direction, Eiz first increases to a maximum and subsequently decreases. The increase is due to the dominant Fz in ion acceleration in the vicinity of the thruster exit. Further downstream, the Fz decreased and the effect of charge-exchange collisions became apparent, leading to the decrease of Eiz.

Surface-barrier detector with smoothly tunable thickness of depleted layer for study of ionization loss and dechanneling length of negatively charged particles channeling in a crystal

A new method for the experimental study of ionization loss of relativistic negatively charged particles moving in a crystal in the channeling regime using a semiconductor surface-barrier detector with smoothly tunable thickness of the depleted layer is proposed. The thickness of the depleted layer in a flat semiconductor detector can be smoothly regulated by the value of the bias voltage applied to the detector. Therefore, the energy distribution of the ionization loss of relativistic particles which cross the detector and move in the channeling regime in the detector crystal can be measured along the path of the particles by varying the bias voltage of the detector and the dechanneling length can be found. Available literature data on experimental and theoretical researches of the dechanneling length are reviewed. The significant disagreement between the experimental and theoretical data is noted. Comparison of experimental data obtained by the detector-target with smoothly tunable thickness of the depleted layer with calculations can help to develop theoretical description of the dynamics of motion of negatively charged particles channeling in a crystal. A better understanding of the dechanneling length properties can be useful in the production of positrons and other particles such as neutrons by an electron beam in crystals, as well as in the development of crystalline undulators, and in the crystal-based extraction of electron beams from a synchrotron.

Heat Load onto the Globus-M2 Tokamak Wall due to Fast Ion Loss during Development of Toroidal Alfvén Eigenmodes

Heat Load onto the Globus-M2 Tokamak Wall due to Fast Ion Loss during Development of Toroidal Alfvén Eigenmodes

Heat Load onto the Globus-M2 Tokamak Wall due to Fast Ion Loss during Development of Toroidal Alfvén Eigenmodes

The results of experiments are described, which were performed at the Globus-M2 tokamak andaimed at studying the fast ion loss at the outer tokamak wall due to fast ions interaction with the toroidalAlfvén eigenmodes. The local heating of carbon tiles was experimentally measured, and the correspondingheat flux was calculated. It was shown how simulations of the lost particle orbits can explain the characteristicfeatures of the spatial map of wall heating. The flux of lost fast particles onto the wall was studied as a functionof the instability amplitude. It has been demonstrated that the simulations predict similar dependence of thefast ion flux on the instability amplitude and also correlate its nature to the peculiarities of fast ions spatialdistribution.

Present and Future Generation of Secondary Batteries: A Review

AbstractMajor support for the future energy storage and application will benefit from lithium‐ion batteries (LIBs) with high energy density and high power. LIBs are currently the most common battery type for most applications, but soon a broader range of battery types and higher energy densities will be available. In the near future, hundreds of millions of electric vehicles are expected to be on the road, and a large amount of cobalt will be depleted. Various kinds of batteries are developed today to store energy, including Li‐ion, lead‐acid, Ni‐MH, redox flow, Na‐ion, Mg‐ion, Li‐air, Al‐ion, Li/S, NC‐based batteries, Al‐based batteries, metal‐air batteries, solid‐state batteries, etc. There are several types of battery components, such as electrodes, electrolytes, separators, etc. Cell chemistry and component diversity will continue to increase with future generations of batteries. Next‐generation LIBs and sodium‐ion batteries are explored for their ability to reduce active ion loss and increase energy density by pre‐lithiation. To maximize the electrochemical system's performance, various scientific and technological approaches are needed to maximize the potential of battery chemistry.

Study of High-Energy Proton Irradiation Effects in Top-Gate Graphene Field-Effect Transistors

In this article, the effects of high-energy proton irradiation on top-gate graphene field-effect transistors (GFETs) were investigated by using 20 MeV protons. The basic electrical parameters of the top-gate GFETs were measured before and after proton irradiation with a fluence of 1 × 1011 p/cm2 and 5 × 1011 p/cm2, respectively. Decreased saturation current, increased Dirac sheet resistance, and negative drift in the Dirac voltage in response to proton irradiation were observed. According to the transfer characteristic curves, it was found that the carrier mobility was reduced after proton irradiation. The analysis suggests that proton irradiation generates a large net positive charge in the gate oxide layer, which induces a negative drift in the Dirac voltage. Introducing defects and increased impurities at the gate oxide/graphene interface after proton irradiation resulted in enhanced Coulomb scattering and reduced mobility of the carriers, which in turn affects the Dirac sheet resistance and saturation current. After annealing at room temperature, the electrical characteristics of the devices were partially restored. The results of the technical computer-aided design (TCAD) simulation indicate that the reduction in carrier mobility is the main reason for the degradation of the electrical performance of the device. Monte Carlo simulations were conducted to determine the ionization and nonionization energy losses induced by proton incidence in top-gate GFET devices. The simulation data show that the ionization energy loss is the primary cause of the degradation of the electrical performance.

Guiding-centre orbit-following simulations of charge exchange loss of NBI ions with the finite Larmor radius effect

Guiding-centre orbit-following simulations of the charge exchange (CX) loss of neutral beam injection (NBI) ions are presented. The finite Larmor radius (FLR) effect in the fast ion–neutral collision can be included in guiding-centre orbit-following simulations by using the gyroaverage method. It is proved that the neutralization probability of fast ions computed by using the gyroaverage method in the guiding-centre orbit simulation is roughly the same as that computed in the full-orbit simulation when the time step in the guiding-centre simulation is the order of the gyroperiod. The CX losses of NBI fast ions for two NBIs in the EAST tokamak have been simulated by the guiding-centre orbit-following code GYCAVA, and the FLR effect in the fast ion–neutral collision on CX losses has been numerically studied. The CX effect of the fast ion–neutral collision can significantly enhance NBI ion losses on EAST. The FLR effect in the fast ion–neutral collision can enhance the CX loss. Vertical asymmetry of localized heat loads induced by CX losses is found, which is related to the FLR effect of fast ions and the strong radial gradient of the neutral density near the plasma edge. Heat loads induced by CX losses are localized in the regions near the poloidal angle $\theta =-60^\circ$ , because the likelihood of exchanging charge is the largest at gyrophase $\xi ={\rm \pi}$ , and this leads to fast downwards moving neutrals. Fast ion loss fractions induced by CX increase with the neutral density increasing.

Evaluation of Red Cell Deformability in Sickle Cell Disease Patients, Sickle Cell Carriers, and Healthy Controls Using Lorrca-Derived Parameters

BACKGROUND Red blood cell (RBC) deformability plays a critical role in RBC elongation and viscosity, and when reduced, perfusion of peripheral tissues and oxygen delivery are impaired. Intracellular ATP maintains water and ion homeostasis in RBCs; reduced ATP leads to water and ion loss, dehydration and loss of RBC elasticity. RBC dehydration increases mean corpuscular hemoglobin concentration (MCHC) and also affects distribution of RBC width (RDW). Patients with sickle cell disease (SCD) have reduced RBC ATP, and markedly reduced RBC deformability when compared to healthy individuals. Here, we employed Laser-Optical Rotational Red Cell Analyzer (LORRCA, RR Mechatronics) to evaluate deformability in RBCs from patients with SCD (HbSS) compared to RBCs from sickle cell carriers (HbAS) and ethnic-matched healthy controls (HbAA). We further analyzed how these LORRCA-derived parameters correlate with ATP, MCHC, and RDW. METHODS We enrolled adult subjects (age ≥ 18 years) of African-descent, and not recently transfused (within 8 weeks) under protocol NCT03685721 approved by the NHLBI Institutional Review Board. Fresh whole blood in EDTA was processed on the same day of collection. Cells were counted and diluted in polyvinylpyrrolidone (PVP) solution before undergoing LORRCA assays including deformability, osmoscan, and oxygenscan (HbSS subjects). The deformability assay uses the elongation Index (EI) to measure the cells' ability to undergo deformation with increasing shear stress at 0.95, 3, and 30 Pascals (Pa). The osmoscan assay measures the deformability under continuous osmotic changes (0-600mOsm/kg) and has several parameters: O min (RBC fragility); El max (maximum deformability and membrane flexibility); O max (osmolality where EI max is achieved) and O hyper (intracellular viscosity and maximum deformability in the hypertonic region). The oxygenscan assay measures the oxygen pressure at the time when RBCs start to become rigid (point of sickling). Whole blood levels of ATP were measured using LC-MS/MS with LLOQ at 50.0 μg/mL and converted to intracellular concentrations by dividing by the hematocrit (as a fraction). Descriptive statistics and correlation (Spearman) of ATP, RDW, and MCHC with each LORRCA parameter were performed using R (v4.2.3) and Prism(v9). RESULTS We studied 156 subjects which comprised of 63 HbSS (33 males), 61 HbAS (23 males) and 32 HbAA (8 males) genotypes. The average age in years (range) in HbSS was 32 (18-58); in HbAS, 43 (18-70), and in HbAA, 38 (19-72). As shear stress and osmotic pressure increased, the mean EI and osmolality were significantly (p<0.001, unpaired two-sample t-test) lower in the HbSS cohort compared to HbAS and HbAA (Figure 1). There was no significant difference in the mean EI and osmolality between HbAA and HbAS with increasing shear stresses and osmotic pressures. As shear stress increased, the correlation of deformability with reduced ATP got significantly stronger in the HbSS cohort (r= -0.351 at 0.95 Pa to r=-0.401 at 30 Pa) but the trend was reversed for the HbAS and HbAA cohort (Table 1). Under increasing osmotic pressure, a significant correlation was found between reduced ATP and maximal deformability (EI Max) in HbSS (p=0.008) compared to HbAS (p=0.896) and HbAA (p=0.114). MCHC was significantly correlated with RBC hydration state (O Hyper) in all 3 genotypic groups (HbSS, HbAS and HbAA). Similarly, RDW correlated with maximal deformability (EI Max) under increasing osmotic pressure in all 3 cohorts. In the HbSS subjects, there was a significant positive correlation of ATP and RDW with point of sickling (oxygenscan); MCHC was negatively correlated but was not significant. CONCLUSION RBC deformability was reduced in HbSS patients compared to HbAS and HbAA under increasing shear stress and osmotic pressure. ATP levels showed significant correlation with RBC deformability as measured by LORRCA, particularly in patients with SCD, suggesting increasing ATP levels as an important therapeutic strategy in patients with SCD. In keeping with published data, our analyses showed that RBC volume and size as well as intracellular hemoglobin concentration can affect deformability.

Investigation of lithium-ion battery nonlinear degradation by experiments and model-based simulation

Understanding the lithium-ion battery (LIB) nonlinear degradation is essential for battery full-lifespan usage and management. In this study, LIBs are cycled under conditions of low-temperature and high-current charging respectively. By designing a multi-battery parallel aging experiment, the evolution process and changing regulation of lithium ions (Li-ions) loss are quantified. The amount of irreversible lithium loss caused by two side reactions, i.e., the side reaction of SEI film growth and irreversible lithium plating, within the full lifespan of LIBs is measured and analyzed, which reveals that irreversible lithium plating is the dominant reason causing the battery nonlinear degradation. With the quantitative results above, an electrochemical aging coupled model is established, which agrees well with the experimental nonlinear aging. Furthermore, a simulation of the battery secondary capacity diving is conducted, and the formation of the nonlinear aging mechanism is revealed. A porosity reduction theory is proposed, in which the capacity diving of the battery is caused by the exponential growth of irreversible lithium plating, while the exponential growth phenomenon is due to the positive feedback loop formed by the porosity reduction of the negative electrode and the irreversible lithium plating.

A Critical Analysis of Target Ionization and Projectile Electron Loss in Neutral– and Ion–Atom Collisions

Electron removal (target ionization and/or projectile electron loss) in neutral–atom collisions is theoretically studied for the impact of H0, He0 and He+ beams on noble gases (He, Ne and Ar). These reactions are investigated theoretically within the Continuum Distorted Wave-Eikonal Initial State model. New features have been included in the theoretical model: (i) a scaled projectile charge depending on its velocity and charge, (ii) a dynamic projectile-effective-charge depending on the momentum transfer, and (iii) a dynamic target-effective-charge depending on the kinematics of the emitted electron. The energy and angular spectra of emitted electrons from the target and from the projectile are calculated and compared with the available experimental data. Also, the influence of each one of the corrections on the resulting spectra will be studied.

Evaluating Ion Accumulation and Storage in Traveling Wave Based Structures for Lossless Ion Manipulations.

Structures for lossless ion manipulations (SLIM) technology has demonstrated high resolving power ion mobility separation and flexibility to integrate complex ion manipulations into a single experimental platform. To enable IMS separations, trapping/accumulating ions inside SLIM (or in-SLIM) prior to injection of a packet for separations provides ease of operation and reduces the need for dedicated ion traps external to SLIM. To fully characterize the ion accumulation process, we have evaluated the effect of TW amplitudes, ion collection times, and storage times on the "in-SLIM" accumulation process. The study utilized a SLIM module comprising 5 distinct tracks, each with a specific ion accumulation configuration. The effect of the TW conditions on the accumulation process was investigated for a 3-peptide mixture: kemptide, angiotensin II, and neurotensin at a TW speed of 106 m/s. The effect of ion accumulation time/collection time and storage time was investigated, in addition to TW amplitude. Overall, the signal of the analyte ions increased when the ion collection time increased from 49 to 163 ms but decreased when the ion collection time increased further to 652 ms due to the space charge effects. Ion losses were observed at high TW amplitudes (e.g., 15 Vp-p and 20 Vp-p). In addition, under space charge conditions (e.g., collection times of 163 and 652 ms), the signal of the analyte ions decreased with an increase in storage times for all TW amplitudes applied to the trapping region. For ion accumulation, the data indicate that gentler TW conditions must be utilized to minimize ion losses and fragments to benefit from the "in-SLIM" accumulation process. Wider SLIM tracks provided better performance than those with narrower tracks.

A hydrogen-vanadium rebalance cell based on ABPBI membrane operating at low hydrogen concentration to restore the capacity of VRFB

A hydrogen‑vanadium rebalance cell (HVRC) is developed to address the capacity degradation and hydrogen explosion risks in long-term operations of all‑vanadium liquid flow battery (VRFB). Different operating conditions was evaluated in this study to investigate the cell's performance focusing on low hydrogen concentrations (4 %). The HVRC achieved a stable rebalance process with a meager hydrogen stoichiometry ratio of 1.15 at 300 mA cm−2. The use of PFSA membranes was found to be problematic due to the contradictory issues of unstable battery operation without humidification and severe vanadium ion loss with humidification. Therefore, ABPBI membrane was used instead of PFSA membrane to reduce vanadium ion crossover and Pt catalyst corrosion. HVRC based on ABPBI membrane completed a 100 h stability test at 70 mA cm−2 with a stoichiometric ratio of hydrogen of 1.23. The vanadium ion crossover of ABPBI-HVRC was less than 1/6 that of PFSA-HVRC, and no significant platinum dissolution occurred during 100 h operation without humidification. The reliability of the ABPBI-HVRC in intermittent operation mode has also been verified. These results illustrate the HVRC offers a promising measure to eliminate safety issues and restore capacity in VRFB systems. Additionally, incorporating the ABPBI membrane in the HVRC holds greater promise for enhancing its stability.

LightGBM-Based Framework for Lithium-Ion Battery Remaining Useful Life Prediction Under Driving Conditions

The remaining useful life (RUL) degradation under driving conditions is complex. The features from incremental capacity-differential voltage (IC-DV) curves and electrochemical impedance spectroscopy (EIS) can be implemented to identify the battery degradation modes and predict RUL. This paper proposes a light gradient boosting machine (LightGBM) based framework with electro- chemical theory to achieve RUL prediction under driving conditions. The degradation modes are identified as loss of conductivity, loss of active material and loss of lithium ion, and the EIS is refined as ohmic resistance, charge transfer resistance, solid electrolyte interphase film resistance, and Warburg resistance. The LightGBM model is improved by the adaptive robust loss function to achieve multi-loss functions adaptive adjustment for different cases and limit the effect of measurement noise on gradients. Based on the perspective of multitask learning, the Pearson correlation is analyzed to design the sharing principle, which ensures full use of features and reduce experimental costs. The proposed framework is validated by the database under four vibration cases (static, X-axis, Y-axis, and Z-axis). Experimental results demonstrate that the proposed framework is capable of providing accurate and steady RUL prediction under driving conditions even with measurement noise. The proposed framework could guide periodic maintenance and stable operation to avoid risks.

Analysis of Toroidal Alfven Eigenmode-Induced Fast Ion Losses in Globus-M2 Spherical Tokamak

Analysis of Toroidal Alfven Eigenmode-Induced Fast Ion Losses in Globus-M2 Spherical Tokamak

Impact of Simulated Acid Rain on Soil Base Cations Dissolution between Eucalyptus Pure Plantations and Eucalyptus–Castanopsis fissa Mixed Plantations

The soils of Eucalyptus pure plantations and Eucalyptus–Castanopsis fissa mixed plantations were studied using soil column leaching experiments with acid solutions to mimic the effects of acid rain on the soils. This helped researchers learn more about how soil base ions react to acid deposition and their ability to protect the soil from excessive acidity under pure and mixed-species plantations. The results showed that acid rain leaching increased the leaching loss, desorption, and desorption rate of soil base ions while decreasing the soil pH value, adsorption, and adsorption rate of soil base ions. The soil pH value and the leaching loss ranges of K+, Na+, and Mg2+ were all greater in the pure plantations than in the mixed plantations, while the leaching range of Ca2+ was greater in the mixed plantation than in the pure plantations. In the two types of plantations, the adsorption rates of Ca2+ and Na+ in the mixed plantations were higher than in the pure plantations, while K+ and Mg2+ showed higher adsorption rates in the pure plantations than in the mixed plantations. Therefore, soil pH and base ions were greatly affected by the pH value of acid rain. Compared with the pure plantations, the establishment of Eucalyptus–Castanopsis fissa mixed plantations can slow soil acidification and leaching of K+, Na+, and Mg2+ and contribute to the adsorption of Ca2+ and Na+, which is beneficial for the soil nutrient fixation of Eucalyptus plantations. The mixed plantations were found to increase the exchange reaction between H+ and base ions, thereby improving the acid buffer performance of the soil. This, in turn, helped to mitigate the decline in soil fertility. Therefore, establishment of Eucalyptus–Castanopsis fissa mixed-species plantations can slow down the impact of acid rain on soil acidification in artificial plantation land to a certain extent and play an important role in optimizing the plantation structure of Eucalyptus stands and maintaining their productivity.

Fast and reliable characterization of egg triacylglycerol profiles using atmospheric solids analysis probe tandem mass spectrometry (ASAP-MS/MS) combined with chemometric tools

In this study, the potential of atmospheric solid analysis probe tandem mass spectrometry (ASAP-MS/MS) was assessed as a green and rapid method combined with gas chromatography with flame ionization detection (GC-FID) and chemometrics to determine the triacylglycerol (TAG) profile of eggs from various housing systems, including indoor, cage-free, free-range, organic, and enriched systems. The most abundant ions were identified using the product ion and neutral loss scan. The fatty acid composition, mainly unsaturated, palmitic, and stearic acids of eggs was influenced by the housing systems. The optimal conditions of ASAP-MS for cone voltage, desolvation gas temperature, and desolvation gas flow were determined to be 40 V, 600 °C, and 1100 L h−1, respectively. The main TAGs (50:2, 50:1, 52:4, 52:3, 52:2, 52:1, 54:4, 54:3, 54:2, 54:1) were observed in the mass range m/z 830–890. Notable differences were observed for TAGs 54:1 and 52:4, which were found in significantly higher levels on WE and CE. The proposed methodology enables rapid and efficient TAG profiling of egg yolks, providing a solid foundation for future research in this field.

Robust stellarator optimization via flat mirror magnetic fields

Stellarator magnetic configurations need to be optimized in order to meet all the required properties of a fusion reactor. In this work, it is shown that a flat-mirror quasi-isodynamic (QI) configuration (i.e. a QI configuration with sufficiently small radial variation of the mirror term) can achieve small radial transport of energy and good confinement of bulk and fast ions even if it is not very close to perfect omnigeneity, and for a wide range of plasma scenarios, including low β and small radial electric field. This opens the door to constructing better stellarator reactors. On the one hand, they would be easier to design, as they would be robust against error fields. On the other hand, they would be easier to operate since, both during startup and steady-state operation, they would require less auxiliary power, and the heat loads on plasma-facing components caused by fast ion losses would be reduced to acceptable levels.