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Aims: Cardiac autonomic neuropathy (CAN) is a serious complication of diabetes and is associated with adipokines. The C1q tumor necrosis factor‐related protein 9 (CTRP9) is a newly discovered adipokine. This study aimed to evaluate the association of serum CTRP9 levels with the prevalence and severity of CAN in patients with type 2 diabetes mellitus. Materials and Methods: We enrolled 262 patients (aged ≥18 years) with type 2 diabetes mellitus into this study. Standard cardiovascular autonomic reflex tests (CARTs) were used to assess CAN and patients were divided into three groups accordingly: a non‐CAN group, an early CAN group, and a definite CAN group. Serum CTRP9 levels were measured by enzyme‐linked immunosorbent assay, and the tertiles were calculated. Results: Serum CTRP9 levels decreased significantly in the early CAN and definite CAN groups (P < 0.05). The percentage of definite CAN was the highest at the minimum tertile of serum CTRP9 level (T1; P < 0.05). Additionally, serum CTRP9 levels were negatively correlated with age, DM duration, hemoglobin A1c (HbA1c), and fasting plasma glucose (FPG) while positively correlated with high‐density lipoprotein cholesterol (HDL; P < 0.05). The level of CTRP9 was also significantly associated with the four indexes of CARTs (P < 0.05). Furthermore, CTRP9 was a protective factor for definite CAN (P < 0.05). Compared with the maximum tertile (T3) of the serum CTRP9 levels, a decreased level of serum CTRP9 in T1 significantly increased the prevalence ratio of definite CAN in patients with type 2 diabetes mellitus (P < 0.05). Conclusion: Serum CTRP9 levels were independently associated with definite CAN. CTRP9 represents a reliable biomarker for exploring CAN in patients with type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

The development of high energy density material is of great importance and urgency for new generation of energy storage system. However, electrolyte formula for high voltage system remains a challenge. The use of various functional additives gives rise to the complexity of electrolyte system and hinders completely understanding of the action mechanism of additives. Herein, we report the adaptability and mechanism of a single additive LiPO 2 F 2 added in the conventional LiPF 6 -based electrolyte system. The resulting conclusion displays a notable improvement in the cycling stability for 5 V-class cathode LiNi 0.5 Mn 1.5 O 4 , the capacity retention increase from 85.76% to 95.92%. It is comforting that the rate performance is not reduced due to the increase in cycle stability, and it also shows good advantages in terms of high rate and reversibility. Meanwhile, detailed analysis about interface mechanism for LiPO 2 F 2 by the surface testing (SEM, TEM and XPS) give the direct characterizations. Common ion effect of the decomposition product Li 3 PO 4 from additive is probed from the above characterization and combined with DFT calculations and some clever experiments to prove the positive effect of additives. The findings obtained from this work may provide a useful guidance for the research on electrolyte formulation for high voltage system. Unlabelled Image • LiPO 2 F 2 as film-formed additive for high voltage system • Li 3 PO 4 produced by LiPO 2 F 2 on the surface of cathode plays a key role in performance improvement by common ion effect. • Cycling performance for LNMO has been improved. [ABSTRACT FROM AUTHOR]

Recent works show the promise for lithium tetrafluoroborate (LiBF4) as an electrolyte salt for lithium‐ion batteries. In this paper, LiBF4 is synthesized by a novel reaction between the as‐prepared anhydrous Li2SO3 and (C2H5)2O⋅BF3 in an aprotic solvent. The moisture sensitivity and water‐removing method of LiBF4 materials which has been dried under vacuum for 2 h at different temperature, is studied by Fourier transform infrared spectroscopy measurements. Results show that almost all of the adsorbed water would be removed at above 65 °C. With the increase of drying temperature, crystal water will decrease slowly, and almost disappear completely at 170 °C. However, due to the thermal decomposition of LiBF4, LiF and BF2OH impurities are formed as the temperature reaches 165 °C. So, we determine that the proper drying temperature is 155 °C, though the trace water cannot be removed thoroughly. Besides, influences of trace water on the electrochemical performance of Li/MCMB half‐cell with LiBF4 as electrolyte salt has been investigated. Results show that discharge plateaus at about 1.5 V vs. Li/Li+ will be lengthened with the increase of water content. Subsequently, the so‐called solid‐electrolyte interphase (SEI) film will become thicker and more resistant, which leads to poor Li+ ion migration and bad cycling performance. [ABSTRACT FROM AUTHOR]

In order to optimize the electrolyte system of lithium difluoro (oxalato) borate (LiDFOB)-ethyl methyl carbonate (EMC)/ethylene carbonate (EC)/adiponitrile (ADN) to overcome the drawback of low discharge capacity at room temperature and the easily decomposition of ADN under lower potential, three sulfur-containing solvents, ethylene sulfite (ES), dimethyl sulfite (DMS) and sulfolane (SL) are introduced. AC impedances, cycling performance, cyclic voltammetry tests as well as compatibilities between electrolytes and positive/negative electrodes are evaluated, respectively. Both of the solution systems of 0.7 M LiDFOB-EMC/ES/ADN (49: 49: 2, vol. % ratio) and 0.7 M LiDFOB-EMC/SL/ADN (65.3: 32.7: 2, vol. % ratio) are recommended as alternative electrolytes for 5 V high-voltage lithium ion batteries, benefitting from the synergistic effect between LiDFOB salt and sulfur-containing solvents. Besides, the effect on the performance of sulfur-containing solvents on the positive and negative electrodes is studied by theoretical calculation. This paper provides a promising candidate for improving the electrochemical performance of the battery by optimization of electrolyte formula, especially by a combination of lithium salt and solvent mixture. [ABSTRACT FROM AUTHOR]

To satisfy the need of 5 V high-voltage cathode materials, lithium difluoro(oxalato)borate (LiDFOB) with excellent film-forming property has been chosen as lithium salt, and adiponitrile (ADN) with stable electrochemical performance has been evaluated as functional additive. An electrochemical investigation of this novel electrolyte solution shows a wide electrochemical oxidation window of nearly 6.0 V vs Li + /Li. Due to the positive effect of ADN on the cathode/electrolyte interface, LiNi 0.5 Mn 1.5 O 4 /Li half-cell with ADN-adding electrolyte exhibits prominent rate capability and cyclability. It is believed that the improvement of electrochemical performances has benefitted greatly from interfacial impedance reducing. Two modeling hypotheses have been used to explain interfacial interaction between ADN and LiNi 0.5 Mn 1.5 O 4 , by the means of analysis of X-ray photoelectron spectroscopy and theoretical calculation. Results show that ADN can enrich the surface of cathode material to hinder the further decomposition of the electrolyte, and contribute to the formation of a cathode-electrolyte interface passivation film with protective and conductive properties. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) suffering from severe performance degradation because of the unstable solid electrolyte interphase (SEI) on the anode at low temperature restricts their practical applications. Herein, lithium difluorophosphate (LiDFP) as the additive is introduced into lithium bis(fluorosulfonyl) imide (LiFSI) based electrolyte to improve the electrochemical performance of graphite/Li half-cells at low temperature. Contrary to the popular perception, we reveal at low temperature that LiDFP attenuates the decomposition of LiFSI by competing the hydrolysis reaction with LiFSI to generate a SEI film rich in LiF and Li 3 PO 4 during prolonged cycling, rather than preferential decomposition. Additionally, the possible reaction equations and the interaction mechanism between LiDFP and LiFSI are proposed by combining in situ electrochemical impedance electrochemical (PRIs-EIS) tests, spectroscopic characterization techniques and density functional theory (DFT) calculations. It is demonstrated that the strong binding energy between LiF (from the decomposition of LiFSI) and LiDFP makes LiDFP easier deposit on the electrode surface. This work demonstrates the synergistic role combining the complementary advantage of film-forming additives and main lithium salts to improve the interfacial stability of LIBs at low temperature. Additionally, it can also pave the new pathway for the design of low temperature electrolytes in LIBs. [Display omitted] • The synergy effect of additive LiDFP and LiFSI improves the interface stability. • The competitive hydrolysis reaction of LiDFP and LiFSI is elucidated. • The strong binding energy between LiF and LiDFP enables LiDFP easier deposit. • The stable and robust interface can avoid the aggregation of organics. [ABSTRACT FROM AUTHOR]

The longevity of lithium-ion batteries is determined by the rate of chemical and electrochemical side reactions that limit their charge storage capacity. In particular, dissolution of transition metals from the cathode accelerates the blockage of Li x C 6 anodes, but few direct dissolution studies have been made to date. Although LiMn 2 O 4 (LMO) has been frequently used as a model electrode for dissolution studies, the cause and nature of dissolution and dissolution-free states are still unclear. By online inductively coupled plasma analysis, we detect dissolution from LMO electrodes in real time to reveal the role of surface versus bulk structure effects, electrode potential and degree of lithiation on Mn dissolution. We find that fully lithiated LMO, with an average Mn redox state of 3.5, readily dissolves when brought in contact with 0.2 M Li 2 SO 4 , but that on initial charging a dissolution–passivation event preceding delithiation abruptly stops further detectable dissolution, until well past fully delithiated λ-MnO 2. Dissolution reactivates on returning to the initial potential of pristine LMO, and increases exponentially in the overlithiation region. Our results provide access to much more detailed dissolution information than post-mortem battery analysis allows, enabling targeted materials screening and informing best practices in charging/discharging profiles. In particular, our data suggests that suitable potential conditioning of electrodes may mitigate dissolution, as an alternative or additional measure to the use of protective surface films or incorporation of dopants. [ABSTRACT FROM AUTHOR]

[Display omitted] Coating and single crystal are two common strategies for cobalt-free nickel-rich layered oxides to solve its poor rate performance and cycle stability. However, the action mechanism of different modification protocols to suppress the attenuation are unclear yet. Herein, the Li 2 MoO 4 layer-coated polycrystalline LiNi 0.9 Mn 0.1 O 2 (1.0 %-Mo + NM91) and single crystal LiNi 0.9 Mn 0.1 O 2 (SC-NM91) are prepared to investigate this difference, respectively. By focusing on the interior of particles, the relationship between structure evolution and electrochemical behavior is systematically studied, and the intrinsic mechanism of coating/single-crystallization modifications on suppressing the attenuation is clarified. The results show that microcracks in LiNi 0.9 Mn 0.1 O 2 (NM91) are the main culprit leading to the rate capability decay, and the coating can effectively prevent the radial diffusion of microcracks from the center to surface, inhibiting the generation of surface side reactions. Therefore, the coating has a more advantage in improving the rate performance at 5.0C, the discharge capacity of 1.0 %-Mo + NM91 (130.6 mAh/g) is 7.9 % higher than that of SC-NM91 (121.0 mAh/g). In contrast, the single-crystallization can effectively prevent the formation of intergranular cracks arising from the anisotropic stress in NM91, which causes the severe cycle degradation. Correspondingly, the grain boundary-free SC-NM91 shows superior cyclability. The capacity retention rate of SC-NM91 (80.8 %) at 0.2C after 100cycles is 6.3 % higher than that of 1.0 %-Mo + NM91 (74.5 %). This work concludes the effect difference of different modification methods on enhancing the electrochemical performance, which provides theoretical and technical guidance for the optimized and targeted modification design in the cobalt-free high nickel cathode materials. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks (COFs) are a kind of porous crystalline polymeric material. They are constructed by organic module units connected with strong covalent bonds extending in two or three dimensions. COFs possess the advantages of low-density, large specific surface area, high thermal stability, developed pore-structure, long-range order, good crystallinity, and the excellent tunability of the monomer units and the linking reticular chemistry. These features endowed COFs with the ability to be applied in a plethora of applications, ranging from adsorption and separation, sensing, catalysis, optoelectronics, energy storage, mass transport, etc. In this paper, we will review the recent progress of COFs materials applied in photocatalytic CO2 reduction. The state-of-the-art paragon examples and the current challenges will be discussed in detail. The future direction in this research field will be finally outlooked. [ABSTRACT FROM AUTHOR]

The importance of advanced energy-conversion devices such as water electrolysis has manifested dramatically over the past few decades because it is the current mainstay for the generation of green energy. Anodic oxygen evolution reaction (OER) in water splitting is one of the biggest obstacles because of its extremely high kinetic barrier. Conventional OER catalysts are mainly noble-metal oxides represented by IrO2 and RuO2, but these compounds tend to have poor sustainability. The attention on Prussian blue (PB) and its analogs (PBA) in the field of energy conversion systems was concentrated on their open-framework structure, as well as its varied composition comprised of Earth-abundant elements. The unique electronic structure of PBA enables its promising catalytic potential, and it can also be converted into many other talented compounds or structures as a precursor. This undoubtedly provides a new approach for the design of green OER catalysts. This article reviews the recent progress of the application of PBA and its derivatives in OER based on in-depth studies of characterization techniques. The structural design, synthetic strategy, and enhanced electrochemical properties are summarized to provide an outlook for its application in the field of OER. Moreover, due to the similarity of the reaction process of photo-driven electrolysis of water and the former one, the application of PBA in photoelectrolysis is also discussed. [ABSTRACT FROM AUTHOR]

The development of high energy density and power density battery is of increasing importance for new generation energy storage system. However, interface instability between cathode and electrolyte remains a challenge for taking advantage of battery consistency. The use of commercial LiPF 6 -based electrolyte still has the limitations in optimizing interface stability to reduce material performance degradation. Here, self-developed synthetic lithium difluorobis (oxalato) phosphate (LiDFBOP) additive acts as "interface modifier" is adopted in the traditional electrolyte system. The resulting optimized electrolyte formulation exhibits improved electrochemical properties and self-discharge inhibition at high temperatures. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and density functional theory (DFT) calculation is applied to detect the LiDFBOP effect mechanism and distribution of main components of the interface film. It can be demonstrated that the participation of LiDFBOP can lead to a change in the composition of the interface film, which increases the number of components that facilitate the transport of lithium ions. The analytical means for additive effect obtained from this work offer a new opportunity to make an in-depth analysis of film components between cathode and electrolyte. Image 1 • LiDFBOP as a novel additive is firstly synthesized and characterized. • LiDFBOP as film reconstructor can optimize the performance of LNMO/Li cells. • CEI film composition distribution is proven by the TOF-SIMS. • The effect mechanism of LiDFBOP is verified by the DFT calculation in detail. [ABSTRACT FROM AUTHOR]

The so-called solid-electrolyte interface (SEI) derived from the interaction between electrolyte and electrode plays a decisive role in Li-ion battery performance. Lithium difluoro(bisoxalato) phosphate (LiDFBOP) as the derivative of LiPF 6 has caused great attention among the researchers. However, the mechanism of effect for LiDFBOP salt has not yet revealed, which limits the findings for the fundamental cause of performance improvement. In this work, the effect of LiDFBOP on the mesocarbon microbead (MCMB) anode electrode has been investigated with aid of surface analysis technique, such as scanning electron microscope (SEM), X-ray photoelectron spectrum (XPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS). On the basis of the modification with LiDFBOP, the long-term cycling and degradation resistance of Li/MCMB half cells have been achieved, which results from the preferential decomposition of LiDFBOP regulating the decomposition law of the electrolyte system. The SEI film with layer structure has different composition distribution under the obstruction of LiDFBOP of the decomposition of LiPF 6. The more organic ingredients are distributed in the SEI film on the electrolyte side, which leads to low impedance and fast transportation of lithium ions. The special ingredient distribution is ascribed to the obstruction of LiDFBOP on the decomposition of LiPF 6. This work signifies the research of the effect of SEI film distribution on the battery performance. [ABSTRACT FROM AUTHOR]

With the large-scale retirement of new energy vehicles, it is particularly important to recycle and reuse retired lithium-ion batteries (LIBs). However, the current improper handling of spent electrolytes will cause serious environmental problems. Here, we propose a novel, simple and easy-to-implement method to realize the high-value utilization of recovered electrolytes from retired LIBs. Comparing with the initial content of LiPF6 (1 mol L−1 in a mixed carbonate solvent system, and about 1 g in a 18650 type LIB) in fresh batteries, a maximum leaching efficiency of 29% could be realized during the full-component resource reclamation of retired LIBs, using the selective mixed leaching solvent system of dimethyl carbonate + CHClF2 (1 : 1, v/v ratio). Then the water and HF impurities are reduced from 80.90 ppm to 4.56 ppm and from 1312.91 ppm to 291.52 ppm by pre-treatment with hexamethyl disilazane (C6H19NSi2). Although the purified electrolyte does not meet the standards for re-use in LIBs, it can be used as a synthetic raw material for lithium salt additives. As a typical case, the LiPF6 salt in a leached electrolyte is recycled into a salt additive of lithium difluorodioxalate phosphate (LiDFBOP) under the preferred reaction conditions (75 °C, 27 h, with a molar ratio of 1 : 3 for LiPF6 : bis (trimethylsilicon)oxalate), realizing closed-loop recycling. The electrochemical results show that the electrochemical performances of the graphite/Li and LNCA/Li half cells are significantly improved with the addition of the as-prepared LiDFBOP additive. This research gives a large-scale synthesis route to realize high-value utilization of low-quality LiPF6, and helps establish a full-component resource reclamation process of retired LIBs. It not only improves environmental friendliness, but also realizes the high efficiency utilization of resources. [ABSTRACT FROM AUTHOR]

Aims/Introduction: This study aimed to evaluate the association between time in range (TIR) obtained from continuous glucose monitoring and the prevalence and degree of painful diabetic neuropathy. Materials and Methods: A total of 364 individuals with diabetic peripheral neuropathy were enrolled in this study. Sensor‐based flash glucose monitoring systems were used to monitor the participants' glucose levels, and the glycemic variability metrics were calculated, including the TIR, glucose coefficient of variation, standard deviation and the mean amplitude of glycemic excursions. The participants were asked to record any form of pain during the 2 weeks of monitoring, and score the pain every day on a numerical rating scale. Based on the numerical rating scale, the patients were divided into the pain‐free group, mild pain group and moderate/severe pain group. Results: Overall, 51.92% (189/364) of the participants were diagnosed with painful diabetic neuropathy. Compared with the pain‐free group, the level of TIR decreased significantly in the mild pain and moderate/severe pain groups (P < 0.05). The prevalence of mild pain and moderate/severe pain decreased with increasing TIR quartiles (all P < 0.05). Multiple linear regression analysis showed that TIR was significantly negatively correlated with the numerical rating scale score after adjustment for glycated hemoglobin, glycemic variability indicators and other risk factors (P < 0.05). Logistic regression analysis showed that a decreasing level of TIR was significantly associated with an increasing risk of any pain and moderate/severe pain (P < 0.05). Conclusions: TIR is correlated with painful diabetic neuropathy and is underscored as a valuable clinical evaluation measure. [ABSTRACT FROM AUTHOR]

Bismuth(III) sulfide (Bi 2 S 3) is a promising cathode material for aqueous zinc ion batteries (ZIBs), yet suffers from serious capacity issues due to its poor electrical conductivity and microstructural degradations. In this work, Bi 2 S 3 anchored on reduced graphene oxide (rGO) is prepared through hydrothermal reaction and is used as cathode material for aqueous ZIBs. Raman and XPS characterizations confirmed that the oxygen bridge in Bi–O–C heterostructures is successfully created during the hydrothermal synthesis. These oxygen bridges are energy favourable in the Bi 2 S 3 /rGO composite materials and serve as the electron transfer channels for rapid charge compensation during Zn2+ incorporation/extraction. Rotating ring–disc electrode (RRDE) measurements demonstrate improved electrochemical stability of the Bi 2 S 3 /rGO composite material compared to pristine Bi 2 S 3. As a result of these improved characteristics, Bi 2 S 3 /rGO composite shows notably better rate performance and cycling stability than unsupported Bi 2 S 3. Ex-situ X-ray diffraction and XPS characterizations indicate that Zn2+ undergoes a reversible conversion reaction with Bi 2 S 3 to form ZnS/Bi0, rather than being intercalated into Bi 2 S 3 crystal interlayers. The rGO substrate forms chemical bonds with bismuth in the composite material, and the strongly anchored bismuth on the rGO through a Bi–O–C bridge enables a highly reversible conversion reaction. As a result, the Bi 2 S 3 /rGO composite with 8 wt% rGO can deliver a reversible capacity of ∼186 mAh g−1 at the current density of 500 mA g−1 after 150 cycles, showing high promise as Zn-ion battery material. [ABSTRACT FROM AUTHOR]

The high price of lithium salts hinders the sustainable development of high concentration electrolytes, while the poor electrochemical performance limits the large-scale application of low concentration electrolytes. Herein, the electrochemical performance of a low concentration electrolyte is improved via dual interfacial modification of the fluoroethylene carbonate (FEC) solvent and the lithium difluoro(oxalato)borate (LiODFB) additive. LiODFB is preferentially oxidized via a ring-opening path to generate a lithium fluoride (LiF)-rich inner layer on the surface of a ferrous lithium phosphate cathode, and then a large amount of C–F polycarbonate oligomers is generated in the outer layer via a reaction between LiODFB and FEC. LiF has a large bandgap and a low lithium ion (Li+) diffusion barrier, and the electronegative C–F groups provide the lithiophilic sites to reduce the interaction between Li+ and solvents, resulting in a repulsive force towards the C＝O dipole of the carbonate ester solvent to improve the oxidation stability of the electrolyte. The clever design of the multi-layer cathode electrolyte interphase suppresses the excessive decomposition of the electrolyte, improves the diffusion of Li+, and enables much-improved cycling stability of the cathodes. This work gives a fruitful insight into the key role of cathode electrolyte interphase components in Li+ diffusion and improves the performance of low-concentration electrolytes. [ABSTRACT FROM AUTHOR]

The surficial residual alkali is a key factor that leads to aggravated phase transition and decay in cobalt-free high-nickel cathode. In this paper, we develop a one-step in-situ modification technique to convert the residual alkali on the LiNi 0.9 Mn 0.1 O 2 (NM91) surface into Li 2 MoO 4 coating. As a fast ionic conductor, Li 2 MoO 4 coating not only facilitate Li+ diffusion, but also inhibits the transition from layered to rock salt phase on the cathode surface. Moreover, the multi-aperture architecture formed in the conversion promotes the high-valent Mo enter-into the lattice and realizes the gradient doping of Mo4+ through thermodynamic diffusion. Due to the pillar effect, Mo doping increases c-axis spacing, mitigates cation mixing, and reduces the irreversible H2-H3 phase transition. As a result, both the Li+ diffusion kinetics and thermodynamic stability are improved. Consequently, the as-prepared Mo modified NM91 exhibits an increased capacity retention from original 62.3–75.6 % (100 cycles, 0.2 C) and enhanced rate capability of 131.96 mAh g−1 at 5.0 C. This work provides a facile "reducing alkali" technological process, and lays foundation for the material design and performance optimization of high energy density cathodes in lithium-ion batteries. • Cobalt-free high nickel LiNi 0.9 Mn 0.1 O 2 cathode material was synthesized, and LiNi 0.9 Mn 0.1 O 2 was modified by doping and coating synergistically by one-step method to achieve a discharge capacity of 131.91 mAh g−1 at 5 C rate (LiNi 0.9 Mn 0.1 O 2 is only 77.7 mAh g−1) and a capacity retention rate of up to 75.6 % after 100 cycles at 0.2 C (LiNi 0.9 Mn 0.1 O 2 is only 62.3 %). • The mechanism of synergistic modification on the interfacial side reaction and structural stability of cobalt-free high nickel materials was clarified by characterization and DFT calculation. • The help of in-situ alkali reduction process to improve the stability of cobalt-free high nickel cathode materials was studied in a pioneering way, which laid a foundation for the correlation of interface stability and performance optimization of cobalt-free high nickel cathode materials, and had potential industrial application prospects. [ABSTRACT FROM AUTHOR]

• Directly introducing LiNO 3 into the Gr slurry overcomes its solubility limit. • Sustained releasing LiNO 3 from the Gr reservoir constitutes a virtuous circle in LCE. • Stronger bind of NO 3 –-Li+ weakens shielding effect, inhibiting solvents decomposition. • Increased interaction between anions and Li+ generates a Li 3 N&LiF-rich SEI. • Expanding the LCEs application by regulating the solvation and stabilizing interface. The high de-solvation energy derived from the solvent-rich Li+ solvation sheath and the resultant porous organic-rich electrode/electrolyte interface has hindered the commercialization of low-concentration electrolytes (LCEs). Here, unlike the common method so far reported, we invent an approach of sustained releasing LiNO 3 from the graphite (Gr) anode reservoir to optimize the solvation structure and form a stable interface in LCEs. The solubility limit can be overcome by introducing LiNO 3 directly in the Gr slurry. Moreover, the stronger binding energy between NO 3 – and Li+ drives NO 3 – enter the Li+ solvation sheath, weakening the shielding effect of solvent on Li+, and surprisingly increasing the coordination of PF 6 - to Li+. Thermodynamically, the corresponding lowest unoccupied molecular orbital energy levels of anions decrease, reducing the de-solvation energy of Li+ and forming a Li 3 N&LiF-rich solid electrolyte interface (SEI). This inorganic-rich SEI demonstrates advantages of inhibiting the decomposition of solvent and facilitating the transmission of Li+. As a result, the cell with Gr anode containing 1 wt% LiNO 3 exhibits superior cycle performance in LCE, almost no degradation within 200 cycles, even higher than that in conventional concentration electrolyte. More importantly, the continuous consumption of NO 3 – in turn promotes its sustained redissolution from the anode, constituting a virtuous circle of regulating solvation structure, stabilizing interface and improving battery performance. This work blazes a new trail to revive lithium salt additives with low solubility, and expands the design strategy and application prospect of LCEs by building the bridges between regulating the solvation structure and constructing favorable electrode/electrolyte interface. [ABSTRACT FROM AUTHOR]

The prevailing account attributes the positive effects of boron-based additives on solid electrolyte interface (SEI) layers to its solid products by prior decomposition. However, this study proves the BOF2− anion, a soluble product of film formation additive of lithium difluoro(oxalato)borate, plays a crucial role in improving the SEI layer. Specifically, BOF2− suppresses the excessive decomposition of salt anions by aggregating on the electrode surface. Meanwhile, it catalyzes the reduction of ethylene carbonate, leading to improving the stability of the interface. In the end, ultrasound shaking is used to generate more BOF2− anion and increase the cycle performance of cells at a high rate as excepted. This work helps to understand the effects of soluble products on the SEI forming process and provides new insights for improving the stability of electrode electrolyte interfaces. [Display omitted] • An effect mechanism of SEI formation is proved from the view of soluble product. • The soluble product of LiDFOB prevents its excessive decomposition. • The soluble product catalyzes the reduction of EC. [ABSTRACT FROM AUTHOR]

• In-situ techniques identify soluble products limit LiBOB utilization efficiency. • Mechanism revelation that AC pulse promotes LiBOB complete decomposition. • AC pulse generates a reinforced SEI rich in inorganics and cross-linking polymers. • Synchronized achieving "amount reduction and efficiency increase" of additives. Lithium bis(oxalate)borate (LiBOB) is well known for its protection of graphite anodes in lithium-ion batteries (LIBs) by forming a passivated solid electrolyte interface (SEI) layer. However, the underlying film-formation mechanism of LiBOB remains poorly understood, thereby its utilization efficiency has received little attention. In this work, we resort to in situ techniques to determine the crux of limiting the complete decomposition of LiBOB during the initial SEI formation lies in the BOB-derived soluble products which accumulate on the graphite surface and hinder its subsequent sustained decomposition. Then alternating current pulse (AC) discharge technology is employed to promote the self-decomposition of LiBOB. The complementation results of electrochemical/physical characterizations and theoretical calculations reveal that AC not only facilitates the diffusion of soluble products, but also promotes the synergy reaction of the soluble products with LiPF 6 , generating a smooth and uniform SEI rich in inorganics (LiF and Li x PO y F z) and B-containing cross-linking polymers. More significantly, a thinner SEI is obtained in AC by reducing the LiBOB amount in half. The as-resulted cell exhibits higher rate performance (280 mAh g−1 at 2 C) and better cycling stability (320 mAh g−1 after 200 cycles at 1 C, 98 % capacity retention), synchronously achieving "amount reduction and efficiency increase" of expensive additives. This study provides an entirely novel method for reinforcing the SEI films using external electric fields, and enriches the strategies for improving the performance of LIBs via interfacial engineering. [ABSTRACT FROM AUTHOR]

The development of electrolytes with low cost and wide temperature range is important for the practical application of Zn-ion hybrid supercapacitors (ZHSCs). Low concentration electrolytes have significant advantages in terms of cost and viscosity, however, the ease of water electrolyte solidification at low temperatures and poor cycling stability hinder its application. Here, we developed a hybrid electrolyte with a reduced concentration to inhibit freezing of water at low temperatures using a polar small molecule cosolvent, and which can promote uniform deposition of Zn-ion and inhibit side reactions at the same time due to its strong interaction with Zn-ion. Based on the results, ZHSCs with relatively low concentration hybrid electrolyte have good cycle stability with more than 500 h of cycling and high specific capacities of 44 mAh g−1 at −20 °C, while maintaining the low-cost advantage of water electrolyte. This work provides a reasonable method for designing relatively low concentration electrolytes and is expected to realize the practical application of Zn-based energy storage equipment. The low viscosity of the 1 M ZnSO 4 /H 2 O/DMF at low temperature is conducive to the rapid migration of Zn-ion, and the participation of DMF in the solvation structure of Zn-ion significantly stabilizes the electrode/electrolyte interface. [Display omitted] • A relatively low concentration hybrid electrolyte formula was developed. • The freezing point of 1 M ZnSO 4 /H 2 O/DMF electrolyte is reduced to −20 °C. • The electrolyte formula can maintain ionic conductivity of 8.33 ms cm−1 at −20 °C. • The hybrid supercapacitor delivers exceeds 5000 cycles at −20 °C. • The action mechanism of DMF on Zn-ion and water molecules is revealed. [ABSTRACT FROM AUTHOR]

• The elements of Li, Ni, Co and Mn in Li-rich Mn-based cathode materials were replacing with Al. • Al-doped materials display different electrochemical performances. • The relationship between electrochemical characteristics and structure evolution has been systematically studied. Layered Li-rich Mn-based cathode materials have attracted immense interest for using in lithium-ion batteries, owing to their high energy density. However, the severe degradation of cycle and rate performances has impeded the actual commercial application. Herein, Al was selected as doping element to substitute for the metal elements of Li, Ni, Co and Mn in Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 material to promote electrochemical performances and optimize element proportion. Results indicate that when replacing Li with Al, it displays outstanding initial coulombic efficiency of 80.06%. Besides, Al-substitution for Co shows excellent rate performance of 147.3 mAh g−1 at 5.0 C. Particularly, the replacement of Mn not only shows the highest capacity and voltage retention within the potential range from 2.0 to 4.8 V, but also presents superior capacity retention up to the potential of 5.0 V. Unfortunately, the substitution of Ni displays the worst balanced electrochemical performance among Al-doped materials, which shows lower voltage retention than that of pristine. The reasons why Al-substitution for various cations displays difference on electrochemical performance were discussed from the perspective of migration, dissolution and valence reduction of transition metal ions to the structure evolution in detail. The proposed method and detected action mechanisms can provide guidance on how to optimize materials structure and composition for cathode materials in lithium-ion batteries to obtain electrode materials with excellent comprehensive electrochemical performance. [Display omitted] [ABSTRACT FROM AUTHOR]

Ni-rich LiNi0.8Co0.15Al0.05O2 materials have been successfully applied in electric vehicles due to the merits of high energy density which can meet the requirements for driving range. Nevertheless, the electrochemical performances of Ni-rich materials are limited by their structural instability. Herein, LiNi0.8Co0.15Al0.05O2 materials with the concentration-gradient structure of a Ni-rich core and a Co-rich surface were synthesized. The electrochemical results indicate that surface-concentration gradient LiNi0.8Co0.15Al0.05O2 provides improved electrochemical performance. It not only displays an initial Coulomb efficiency of 82.4%, and a capacity retention of 80.37% after 200 cycles at 25 °C, but also shows a capacity retention of 77.76% after 150 cycles at a high temperature of 55 °C. These excellent performances can be attributed to adjusting the distribution of Ni on the surface of the LiNi0.8Co0.15Al0.05O2 material, which inhibits the interfacial reaction between the material surface and electrolyte, lowers the consumption of active Li+ and decreases the interfacial film impedance. Moreover, less Ni content on the material surface is beneficial for reducing the formation of a NiO rock salt phase during the charging process and inhibits the surface structural evolution. The proposed method and detected mechanism will provide guidance for the design of cathode materials and their practical industrial applications. [ABSTRACT FROM AUTHOR]

While the solid electrolyte interphase (SEI) film in carbonate-based lithium-ion batteries (LIBs) has been extensively studied, less is known about the formation of SEI due to the complexity and instability of interfacial chemical reactions between Li+ and solvent. This study presents new insights into the formation mechanism of SEI film on graphite anode in ethylene carbonate (EC) and dimethyl carbonate (DMC) co-solvent-based electrolytes. The potential-resolved in-situ electrochemical impedance spectroscopy technology and density functional theory calculations combined with multi-sweep cyclic voltammetry are utilized to confirm that EC prefers to solvate with Li+. Then, a large amount of Li+-EC and a small amount of Li+-DMC solvent molecules undergo solvent migration process and de-solvation at the electrode/electrolyte interface. It was found that Li+-DMC is preferentially de-solvation and reduced to form an unstable SEI film, while Li+-EC inhibits the reduction of DMC and turns the reduction process to be diffusion-controlled. This work provides a fresh perspective on the formation of SEI film by Li+-solvent interaction, which could guide the construction of a stable interface by regulating the Li+-solvation kinetic for high-performance LIBs. [ABSTRACT FROM AUTHOR]

High nickel LiNi 0.8 Co 0.15 Al 0.05 O 2 (NCA) cathode material has become one of the most promising cathode materials in the field of power batteries, but the side reaction between the conventional LiPF 6 -based electrolyte and the surface of the NCA material results in poor material interface stability. In this work, a compatible lithium difluoro(oxalate)borate (LiDFOB)-based electrolyte by the employment of sulfolane (SL) as a representative sulfur-containing solvent has been built to enhance the interfacial stability of NCA electrode. The composition, morphology and electrochemical properties are studied by X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy et al. Results show that the decomposition of LiDFOB on the surface of the positive electrode material contributes to forming a uniform cathode electrolyte interface (CEI) film, which subsequently reduces the dissolution of metal ions and hinders the structure transition of the material from the layered structure to spinel or rock-salt phases. Besides, the sulfur-containing products resulted from the decomposition of SL promote the conductivity of Li+ ions for CEI film, which makes up for shortcomings of LiDFOB. Moreover, more LiF has been formed due to the synergistic action between LiDFOB salt and SL solvent, improving the stability and density of CEI film, reducing the thickness of CEI film, and further improving the cycle performance of the battery. [ABSTRACT FROM AUTHOR]

A truncated octahedron structured LiNi0.5Mn1.5O4 (denoted as EG-LNMO) is synthesized by a graphite assisted calcination method. Herein, we introduce a possible growth model, graphite–ethanol synergism, for the formation of the truncated octahedral morphology LiNi0.5Mn1.5O4 based on a series of experimental results. The electrochemical test results indicate that EG-LNMO materials exhibit excellent electrochemical performances, attributed to the unique truncated octahedron structure. It has a high stability {111} crystal plane group and high lithium conductivity {100} crystal plane group, which can meet the requirements of large rate and long cycling performance. Moreover, the electrochemical properties of EG-LNMO under extreme conditions are tested (rapid charge–discharge performance and cycling performance at high rate). The results show that the capacity decay of the electrode material mainly depends on the later stage of the cycling process, which may be ascribed to the synergistic effect of the electrolyte decomposition and corrosion reaction, as well as the phase change inactivation of the electrode material. [ABSTRACT FROM AUTHOR]

The impurity of water, which should be controlled strictly during industrial production and storage processes, has a fatal influence on the performance of lithium ion batteries. Here, lithium bis(oxalato)borate is taken as an example to investigate the changes in properties of chelate-borate complexes when stored in a humid environment, using techniques of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric (TG) analysis and density functional theory (DFT) calculations. Besides, the effect of heating on remediation is studied with acidity test and electrochemical performance measurement. Results show that high relative humidity can accelerate the rate of increase in weight, though the same constant weight will be achieved in the end. The increase in weight is caused by a comprehensive action including the occurrence of hydrolytic reactions, and the formation of adsorbed water and crystal water. Further studies indicate that hydrolytic decomposition is spontaneous at room temperature, but the backward reaction cannot proceed with a heating method, namely, the remediation will be limited due to the formation of harmful hydrolysis products, though both the adsorbed water and the crystal water can be removed thoroughly. Moreover, we believe that the existence of hydrolysis products will lead to a sharp impedance increase of the so-called solid electrolyte interphase film, which will give rise to the deterioration of electrochemical performance sequentially. [ABSTRACT FROM AUTHOR]

The Al-doped modification strategy by substituting Al for different transition metal ions (TMs, TM = Mn, Ni, Co) has achieved excellent results in improving the cyclic performance of Li-rich Mn-based cathode materials (LRMs). However, the traditional explanation known as "pegging effect" is hard to distinguish how Al works in different TM substitutions. Herein, the electrochemical performances of Li 1.2 Mn 0.52 Ni 0.13 Co 0.13 Al 0.02 O 2 (LRM-Mn), Li 1.2 Mn 0.54 Ni 0.11 Co 0.13 Al 0.02 O 2 (LRM-Ni) and Li 1.2 Mn 0.54 Ni 0.13 Co 0.11 Al 0.02 O 2 (LRM-Co) are studied, and LRM-Mn shows the superior long-term cycling stability, especially at the high temperature of 55 °C. Density functional theory (DFT) reveals that LRM-Mn crystal structure has higher thermodynamic stability than any other sample, which is advantageous for inhibiting the transition of LRMs to low-energy stable phases during cycling (e.g., spinel phase and rock salt phase). Combined with density of states and Bader charge analyses, we think that the increased thermodynamic stability of LRM-Mn results from the reduction of the charge transfer of Mn and Co ions in a single delithiation process, which lowers the reactivity of TMs, alleviates the Li/TM mixing and inhibits the irreversible oxygen release. In addition, the biggest volume change during the delithiation process was observed when Al was substituted for Co, which results in the materials' premature production of fatigue stresses and intergranular cracking. This work comprehensively explains the modification mechanism of Al-doped in LRMs. It demonstrates practical significance for both the rational design of materials and the electrode electrochemical performance prediction. [Display omitted] [ABSTRACT FROM AUTHOR]

Preparing LiFePO 4 cathode from FeSO 4 ·7H 2 O waste residue, the by-product of TiO 2 production, can effectively reduce the LiFePO 4 cost and alleviate the environmental pollution problem. However, the inevitable Ti impurity may affect the structure and electrochemical performance of LiFePO 4. Based on the actual Ti content in FeSO 4 ·7 H 2 O waste residue, herein, we prepared the Ti-doped LiFePO 4 , which is expected to get the suitable Ti content. Importantly, Ti-doped with an appropriate amount can reduce the particle size of LiFePO 4 and shorten the migration distance of Li+ ions. Moreover, the impurity Ti as a dopant with an appropriate amount can modulate the band structures, improve the conductivity of LiFePO 4 and enhance the diffusion kinetics of Li+ ions. Hence, the sample with optimal Ti content (LFP-2) shows distinguished electrochemical performance with excellent rate capacity (93.5 mAh g−1 at 10 C) and stable long-term cycle performance (capacity retention of 94.9% after 300 cycles at 1 C with an initial capacity of 151.3 mAh g−1). This research is conducive to reducing the production cost of LiFePO 4 and solving the problem of environmental pollution. [Display omitted] • The effect of impurity Ti on LiFePO 4 is illustrated. • The sample with optimal impurity Ti content (LFP-2) endows the highest rate and cycle performance. • The result can be attributed to the diminution of particle size and the improvement of conductivity. [ABSTRACT FROM AUTHOR]

• Formation of lif-rich cathode-electrolyte interphase via potentiostatic reduction. • The lif-rich CEI inhibits the corrosion of FSI− anion on aluminum collector. • The electrochemical performances of l -std-F reach the level of 1.0 m LiPF6-DEC/EC. The low concentration electrolyte shows the advantages of low viscosity and low cost, but the formation of porous and soluble organic cathode-electrolyte interphase (CEI) limits its performance. Herein, the electrochemical performance of the low concentration electrolyte of 0.45 M LiPF 6 ‑diethyl carbonate (DEC)/ ethylene carbonate (EC) (1:1, in volume ratio) is improved by 0.05 M bis(fluorosulfonyl)imide (LiFSI) additive, aided by the antecedent process of potentiostatic reduction at a low potential of 1.5 V. Results show that LiFSI is preferentially reduced via breaking the structure of FSI− anion to form a robust LiF-rich CEI on the surface of LiFePO 4 (LFP) cathode, solving the problem that it is difficult to form inorganic LiF on the cathode surface. In the subsequent cycling of LFP/Li half-battery, the as-formed CEI inhibits the corrosion of aluminum collector, suppresses the excessive decomposition of the electrolyte and improves the diffusion of Li+, resulting in a much-enhanced cycle stability of the cathode. Therefore, the cyclic performance of the LFP/Li half-battery using the modified low concentration electrolyte with the antecedent process of potentiostatic reduction is on a par with that using the standard electrolyte (1.0 M LiPF 6 -DEC/EC). Compared with the traditional electrolyte engineering of constructing a LiF-rich CEI by the direct oxidation defluorination of fluorinated anions, this strategy needs a lower reaction energy and can play a positive role at a lower reaction potential. This work provides an effective way to construct LiF-rich CEI which helps to improve the performance of low concentration electrolytes. [Display omitted] [ABSTRACT FROM AUTHOR]

Complexes of lithium bis(oxalato)borate (LiBOB), lithium difluoro(oxalato)borate (LiODFB) and lithium difluorobis(oxalato) phosphate (LiDFBOP) are the promising additives for advanced lithium ion batteries because of their high reactivity and easy synthesis, in which the changeable central atom and ligand bring diverse properties for salts. In this study, their structure-function relationship has been surveyed by exploring the reduction pathways. According to the analysis of experiments and quantum chemistry calculations, we have established that the steric-hindrance effect of ligands is the key effect on the bond-broken of these lithium salts. Specifically, more oxalate ligands are beneficial to the breaking of C–O and the bond of the central atom (M) with O atom, resulting in CO and CO 2 release as well as the generation of MO 2 -type soluble products. The as-generated MO 2 -type soluble products undergo a further self-aggregate process to form macromolecular complexes. In contrast, fewer oxalate ligands just encourage the bond breaking of the M − O bond, leading to CO 2 release and the generation of MF 2 -type soluble products. In addition, the universal promoting effect of soluble products on ethylene carbonate decomposition is verified. These results offer theoretic support for the molecular design of advanced functional chelae lithium salts. • Steric-hindrance effects of ligands affect complex salts decomposition mechanism. • More ligands always lead to the prior C–O bond break in oxalic acid rings. • Fewer ligands always lead to the prior break of the bond between central atoms and O. [ABSTRACT FROM AUTHOR]

Efficient energy storage of lithium-ion batteries plays a significant role across lots of sectors including consumer electronics, electric and hybrid electric vehicles and a smart grid accommodating intermittent renewable energy sources. Nanostructured cathode materials present fascinating opportunities for high-performance lithium-ion batteries, but intrinsic problems linked with the high surface area to volume ratios in the nanometer-range have restricted their adoption for practical applications. We demonstrate processing platform that realize high-performance nanostructured-LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM) layer cathode with carbon coating as a conductive additive. In this paper, we first presented a green, novel, economic and controllable chemical vapor deposition (CVD) method with sucrose as carbon source to coating NCM. Sol-gel synthesized NCM of carbon coated with optimized thickness by this formula are shown to have outstanding rate performance and robust cycle lifetime. The thickness - optimized sample of discharge capacity is as high as 104.5 mAh g −1 for 10 C (6s). High capacity retentions of 94.29% and 94.78% after 100 cycles for 0.1 C, respectively. Compared with the heat evaporation method, with the CVD method has better uniformity and higher quality. This approach further improves evidently the NCM of electrochemical performance and thus promotes lithium-ion battery development technology into unprecedented regimes of operation. [ABSTRACT FROM AUTHOR]

Water has a fatal influence on the performance of lithium ion batteries. In this work, Lithium hexafluoro phosphate(LiPF 6 )-ethylene carbonate (EC)/diethyl carbonate (DEC) and lithium bis(oxalato)borate (LiBOB)-tetramethylene sulfone (SL)/DEC are taken as examples to investigate the influences of water concentration for electrochemical window, acidity, impedance and cycling performance for lithium ion batteries by adjusting water concentrations in the electrolytes. Results show that LiBOB-based electrolyte has better water tolerance compared with LiPF 6 -based system, due to the formation of LiBOB·xH 2 O compounds by consuming the additive trace water. Besides, inductively coupled plasma test result shows that Mn ion dissolution in LiPF 6 systems is extremely severe, which is mainly caused by the corrosive reaction between LiMn 2 O 4 and by-product HF acid. And we believe that Mn ion dissolution and the following deposition should be responsible for failure work of LiPF 6 -based cells. But for LiBOB-based cells, stable SEI layers and good electrochemical performances have been obtained, benefitting from the synergistic effect between LiBOB salt and SL solvent. And the presence of high-resistance B(C 2 O 4 ) (OH) and LiB(C 2 O 4 ) (OH) 2 products on surface of graphite electrode is the main reason for a small number of capacity fading. [ABSTRACT FROM AUTHOR]

A non-carbonaceous titanium-based materials of Na 2 Ti 3 O 7 have been considered as an attractive anode material for sodium ion battery (SIBs), due to its low charge potential and high energy density. However, the selection of preferred sodium salts in liquid electrolyte is still a challenge to improve battery performance. Herein, the compatibility of Na 2 Ti 3 O 7 @C anode material with sodium perchlorate (NaClO 4)-based and sodium trifluoromethyl sulfonate (NaCF 3 SO 3)-based electrolytes are studied, respectively. The results show that solid electrolyte interphase (SEI) film formed by NaCF 3 SO 3 -based electrolyte is thin, compact and uniform, which can effectively reduce the transmission energy barrier of Na+. Different from that, the SEI film derived in NaClO 4 -based electrolyte contains more Na 2 CO 3 and NaF, caused by the continuous decomposition of NaClO 4 salt in carbonate solvent. It makes the SEI film thicker and the interface impedance larger, which results in the decline of battery cycle performance. In addition, more sulfur-containing compounds with good sodium conductivity and stability are generated due to the decomposed of NaCF 3 SO 3 salt in carbonate solvent, which improves interfacial transport performance of materials, and inhibits the increase of the SEI film thickness and thus improves the cycling and rate performance of batteries. This study provides a reference method for designing advanced SIBs. [Display omitted] • NaCF 3 SO 3 improves the initial coulomb efficiency of the material. • NaClO 4 promotes the formation of a thick but soft SEI film containing more Na 2 CO 3. • A thin but hard SEI film derived NaCF 3 SO 3 contains more stable inorganic species. • NaCF 3 SO 3 -based electrolyte is more conducive to performance promotion of Na 2 Ti 3 O 7 @C. • Direct visualization information of the formation of SEI film is provided. [ABSTRACT FROM AUTHOR]

Study Question: Does autologous transplantation of menstrual blood-derived stromal cells (menSCs) regenerate endometrium to support pregnancy in patients with severe Asherman's syndrome (AS)?Summary Answer: Autologous menSCs transplantation significantly increases endometrial thickness (ET) for women with severe AS.What Is Known Already: AS is a major cause of secondary infertility in women. Cell transplantation has been tried in a few clinical cases with encouraging results.Study Design, Size, Duration: In this experimental, non-controlled and prospective 3-year clinical study involving seven patients with AS, autologous menSCs were isolated and cultured from menstrual blood of each patient within ~2 weeks and then transplanted back into their uterus. Endometrial growth and pregnancy were assessed after cell therapy.Participants/materials, Setting, Method: Infertile women, aged 20-40 years, diagnosed with severe AS (Grade III-V) by hysteroscopy and with menstrual fluid were recruited at the Shengjing Hospital affiliated to China Medical University. Autologous menSCs transplantation was conducted followed by HRT. Endometrial thickness was monitored with frozen embryo transfer (FET) as needed.Main Results and the Role Of Chance: We successfully cultured menSCs from seven patients and transferred the autologous cells back to their uterus. Our results showed that the ET was significantly (P = 0.0002) increased to 7 mm in five women, which ensured embryo implantation. Four patients underwent FET and two of them conceived successfully. One patient had spontaneous pregnancy after second menSCs transplantation.Limitations, Reasons For Caution: Limited sample size, lack of rigorous controls or knowledge of underlying mechanism.Wider Implications Of the Findings: Autologous menSCs transplantation is a potential option for treating women with severe AS.Study Funding/competing Interests: This study was supported by Liaoning Provincial Science and Technology Program. The sponsor and authors declare no conflicts of interest.Trial Registration Number: Registered in the Chinese Clinical Trial Registry (ChiCTR-ONB-15007464). [ABSTRACT FROM AUTHOR]

[Display omitted] • A potential resolved in-situ electrochemical impedance technique was built. • The solid electrolyte interface layer still be formed and decomposed after long cycle. • The contribution of the interface layer compounds to impedance was distinguished. An understanding of the formation and evolution of the solid electrolyte interface (SEI) layer is still a challenge for lithium ion batteries due to its complexity and non-uniformity. Herein, an in-situ electrochemical technique, named potential resolved in-situ electrochemical impedance spectroscopy (PRIs-EIS), have developed to correlate the Nyquist and Bode plot changes with the voltammetric scan, which is then used to determine the correspondence between circuit components and SEI layer composition. Moreover, the formation and re-oxidation of organic compounds in the SEI layer are studied in conjunction with the electrochemical quartz crystal microbalance characteristics. In particular, it is shown that more inorganic compounds accumulate in the SEI layer as the cycle continues, repairing the pore structure, but decreasing the toughness of the SEI layer. The PRIs-EIS technique is shown to be a powerful, useful and cost-effective tool to illuminate the interfacial reaction mechanism, and the results from this technique aid in the evaluation and design of electrolyte systems. [ABSTRACT FROM AUTHOR]

The dissolution, migration, and deposition of transition metal (TM) ions are the main reasons for the capacity degradation of lithium-ion batteries, which significantly affect their comprehensive electrochemical performance and safety. In this work, the effects of different TM ions (Mn2+, Co2+, and Ni2+) on the electrochemical performance of lithium/mesocarbon microbeads half-cell were compared, and the mechanism was discussed. It is found that Mn2+ ions inhibit the decomposition of lithium salt and promote the decomposition of solvents, resulting in the crack of electrode material and solid electrolyte interface (SEI) film and the increase of capacity degradation. In contrast, Ni2+ ions promote the decomposition of lithium salts to a certain extent, thus inhibiting the excessive damage to the SEI film and electrode material. This study can provide theoretical support and research direction for the design of the electrolytes that can alleviate the damage of TM ions to the anode and the SEI film. [Display omitted] [ABSTRACT FROM AUTHOR]

High-voltage LiNi 0.5 Mn 1.5 O 4 materials with working voltage of 4.7 V vs. Li/Li+ can be used in lithium-ion batteries to meet the demands of high-voltage applications. However, these materials tend to undergo capacity degradation with cycling, and exhibit low coulombic efficiency. The redox reactions of the transition metals in LiNi 0.5 Mn 1.5 O 4 are related to voltage plateaus, which have an important influence on the electrochemical performance of lithium-ion batteries. In this work, we investigated the effects of two voltage plateaus for LiNi 0.5 Mn 1.5 O 4 cathode (4.0 V vs. Li+/Li and 4.7 V vs. Li+/Li) on the capacity degradation and coulombic efficiency, through the charging of half-cells to different cut-off potentials. We find that the redox reactions of manganese at the 4.0 V plateau play a negligible role in the capacity loss, while the increase in manganese content in the cathode material can significantly affect the coulombic efficiency. By contrast, when the cell was charged to cut-off potentials ≥4.8 V with a plateau at 4.7 V for nickel, the cell capacity degraded rapidly. Interestingly, when the cells were charged to 5.0 V, the content of P, F, Ni, and Mn increased with the thickness of the SEI film, indicating accelerated decomposition of the electrolyte due to the contribution of nickel. Thus, this work verifies the dependence of the capacity degradation and coulombic efficiency on the voltage plateau, and provides important information for further investigation of the effect of voltage plateaus on the characteristics and behavior of cathode materials. • Cells charged below 4.7 V with a 4.0 V plateau show high capacity retention. • The 4.7 V plateau with Ni contribute to most of the capacity but rapid capacity loss. • High manganese content expressed by charging time degrade the coulombic efficiency. [ABSTRACT FROM AUTHOR]