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1.
Chem Commun (Camb) ; 2020 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-32239070

RESUMO

The limited discharge capacity of LiCoO2 can be improved by increasing its working potential, but it suffers from Co4+ dissolution and decomposition of the electrolyte. Nitriles have attracted great interest as high-voltage electrolytes due to their wide electrochemical window. However, the cathodic interfacial stability of nitrile electrolytes with a high-voltage LiCoO2 cathode has yet to be explored. Herein, we adopted an SN-based deep eutectic electrolyte with SN as the only solvent and found that Co4+ could be reduced by the SN solvent on the interface of the LiCoO2 electrode, causing a reverse phase change of LiCoO2 and severe self-discharge of the LiCoO2|Li and LiCoO2|Li4Ti5O12 batteries. When LiDFOB was introduced into the electrolyte, the self-discharge behavior of cells could be largely decelerated. The series of characterizations performed in our work revealed that the cathode/electrolyte interface generated from the LiDFOB salt could stabilize the interface of LiCoO2 and suppress the dissolution of the ions of the transition metal Co.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32277864

RESUMO

Sluggish kinetics and poor reversibility of cathode chemistry is the major challenge for magnesium batteries to achieve high volumetric capacity. Introduction of the cuprous ion (Cu+ ) as a charge carrier can decouple the magnesiation related energy storage from the cathode electrochemistry. Cu+ is generated from a fast equilibrium between copper selenide electrode and Mg electrolyte during standing time, rather than in the electrochemical process. A reversible chemical magnesiation/de-magnesiation can be driven by this solid/liquid equilibrium. During a typical discharge process, Cu+ is reduced to Cu and drives the equilibrium to promote the magnesiation process. The reversible Cu to Cu+ redox promotes the recharge process. This novel Cu+ mediated cathode chemistry of Mg battery leads to a high reversible areal capacity of 12.5 mAh cm-2 with high mass loading (49.1 mg cm-2 ) of the electrode. 80 % capacity retention can be achieved for 200 cycles after a conditioning process.

3.
Artigo em Inglês | MEDLINE | ID: mdl-32293860

RESUMO

High voltage spinel manganese oxide LiNi0.5Mn1.5O4 (LNMO) cathodes are promising for practical applications owing to several strengths including high working voltages, excellent operating safety, low costs, and so on. However, LNMO-based lithium-ion batteries (LIBs) fade rapidly mainly owing to unqualified electrolytes, hence becoming a big obstacle toward practical applications. To tackle this roadblock, substantial progress has been made thus far, and yet challenges still remain, while rare reviews have systematically discussed the status quo and future development of electrolyte optimization coupling with LNMO cathodes. Here, we discuss cycling degradation mechanisms at the cathode/electrolyte interface and ideal requirements of electrolytes for LNMO cathode-equipped LIBs, as well as review the recent advance of electrolyte optimization for LNMO cathode-equipped LIBs in detail. And then, the perspectives regarding the future research opportunities in developing state-of-the-art electrolytes are also presented. The authors hope to shed light on the rational optimization of advanced organic electrolytes in order to boost the large-scale practical applications of high voltage LNMO cathode-based LIBs.

4.
Small ; 16(13): e1907163, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32133769

RESUMO

Lithium (Li) metal batteries (LMBs) are enjoying a renaissance due to the high energy densities. However, they still suffer from the problem of uncontrollable Li dendrite and pulverization caused by continuous cracking of solid electrolyte interphase (SEI) layers. To address these issues, developing spontaneously built robust polymer-reinforced SEI layers during electrochemical conditioning can be a simple yet effective solution. Herein, a robust homopolymer of cyclic carbonate urethane methacrylate is presented as the polymer matrix through an in situ polymerization method, in which cyclic carbonate units can participate in building a stable polymer-integrated SEI layer during cycling. The as-investigated gel polymer electrolyte (GPE) assembled LiCoO2 /Li metal batteries exhibit a fantastic cyclability with a capacity retention of 92% after 200 cycles at 0.5 C (1 C = 180 mAh g-1 ), evidently exceeding that of the counterpart using liquid electrolytes. It is noted that the anionic ring-opening polymerization of the cyclic carbonate units on the polymer close to the Li metal anodes enables a mechanically reinforced SEI layer, thus rendering excellent compatibility with Li anodes. The in situ formed polymer-reinforced SEI layers afford a splendid strategy for developing high voltage resistant GPEs compatible with Li metal anodes toward high energy LMBs.

5.
Artigo em Inglês | MEDLINE | ID: mdl-32003965

RESUMO

Due to its highly in-plane oriented crystal structure, flexible graphite film (GF) possesses excellent electrochemical corrosion resistance, high planar electrical conductivity and considerable mechanical strength. In this work, laser-drilled integrated graphite film (porous-GF, PGF) is unprecedentedly used as a key to fabricate a high performance high-energy 5 V-class flexible PGF/PGF-LiNi0.5Mn1.5O4 full-cell, where flexible PGF is a self-standing flexible graphite anode for lithium ion intercalation/deintercalation and a high-voltage resistance cathode current collector. This unique designing based on flexible PGF will endow the future flexible batteries with excellent characteristics of thin, lightweight, simple fabrication and high-energy. More encouragingly, unlike previously reported flexible electrodes using carbon nanomaterials as non-metal current collector, the mass production and processability of flexible GF and PGF is feasible with the aid of commercially available roll-to-roll laser-drilling technology.

6.
Artigo em Inglês | MEDLINE | ID: mdl-32100988

RESUMO

The liquid electrolytes in lithium-air (oxygen) batteries are prone to volatilize, leak, flame, and cause uneven deposition of lithium during cycling, which makes the batteries to face serious problems in terms of safety and cycling stability. A novel Janus quasi-solid composite polymer electrolyte was fabricated by perfluorosulfonic acid (Nafion) membranes with tunable thickness and poly(vinylidene fluoride)-hexafluoropropylene (PVDF-HFP). The Nafion membranes not only guarantee the mechanical strength of the composites but also effectively prevent the migration of certain anions and macromolecules. The results indicate that Janus quasi-solid composite polymer electrolytes have excellent thermal stability, high lithium-ion migration number, and wide electrochemical window. Lithium-oxygen batteries using the novel quasi-solid composite electrolytes perform lower polarization and better cycling stability. The excellent properties of the quasi-solid composite electrolytes make it one of the effective materials for improving the cycling stability of lithium-air (oxygen) batteries.

7.
Adv Mater ; 32(14): e1907526, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32080916

RESUMO

There is a long-standing consciousness that the rhombohedral NASICON-type compounds as promising cathodes for Li+ /Na+ batteries should have inactive M1(6b) sites with ion (de)intercalation occurring only in the M2 (18e) sites. Of particular significance is that M1 sites active for charge/discharge are commonly considered undesirable because the ion diffusion tends to be disrupted by the irregular occupation of channels, which accelerates the deterioration of battery. However, it is found that the structural stability can be substantially improved by the mixed occupation of Na+ /Zn2+ at both M1 and M2 when using NaV2 (PO4 )3 (NVP) as a cathode for Zn-ion batteries. The results of atomic-scale scanning transmission electron microscopy, analysis of ab initio molecular dynamics simulations, and an accurate bond-valence-based structural model reveal that the improvement is due to the facile migration of Zn2+ in NVP, which is enabled by a concerted Na+ /Zn2+ transfer mechanism. In addition, significant improvement of the electronic conductivity and mechanical properties is achieved in Zn2+ -intercalated ZnNaV2 (PO4 )3 in comparison with those of Na3 V2 (PO4 )3 . This work not only provides in-depth insight into Zn2+ intercalation and dynamics in NVP unlocked by activating the M1 sites, but also opens a new route toward design of improved NASICON cathodes.

8.
Small ; 16(5): e1905737, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31916670

RESUMO

Conventional lithium-sulfur batteries often suffer from fatal problems such as high flammability, polysulfide shuttling, and lithium dendrites growth. Here, highly-safe lithium-sulfur batteries based on flame-retardant electrolyte (dimethoxyether/1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether) coupled with functional separator (nanoconductive carbon-coated cellulose nonwoven) to resolve aforementioned bottle-neck issues are demonstrated. It is found that this flame-retardant electrolyte exhibits excellent flame retardancy and low solubility of polysulfide. In addition, Li/Li symmetrical cells using such flame-retardant electrolyte deliver extraordinary long-term cycling stability (less than 10 mV overpotential) for over 2500 h at 1.0 mA cm-2 and 1.0 mAh cm-2 . Moreover, bare sulfur cathode-based lithium-sulfur batteries using this flame retardant electrolyte coupled with nanoconductive carbon-coated cellulose separator can retain 83.6% discharge capacity after 200 cycles at 0.5 C. Under high charge/discharge rate (4 C), lithium-sulfur cells still show high charge/discharge capacity of ≈350 mAh g-1 . Even at an elevated temperature of 60 °C, discharge capacity of 870 mAh g-1 can be retained. More importantly, high-loading bare sulfur cathode (4 mg cm-2 )-based lithium-sulfur batteries can also deliver high charge/discharge capacity over 806 mAh g-1 after 56 cycles. Undoubtedly, the strategy of flame retardant electrolyte coupled with carbon-coated separator enlightens highly safe lithium-sulfur batteries at a wide range of temperature.

9.
Angew Chem Int Ed Engl ; 59(9): 3400-3415, 2020 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-31332946

RESUMO

Blended-salt electrolytes showing synergistic effects have been formulated by simply mixing several lithium salts in an electrolyte. In the burgeoning field of next-generation lithium batteries, blended-salt electrolytes have enabled great progress to be made. In this Review, the development of such blended-salt electrolytes is examined in detail. The reasons for formulating blended-salt electrolytes for lithium batteries include improvement of thermal stability (safety), inhibition of aluminum-foil corrosion of the cathode current collector, enhancement of performance over a wide temperature range (or at a high or low temperature), formation of favorable interfacial layers on both electrodes, protection of the lithium metal anode, and attainment of high ionic conductivity. Herein, we highlight key scientific issues related to the formulation of blended-salt electrolytes for lithium batteries.

10.
J Chem Inf Model ; 60(1): 11-16, 2020 Jan 27.
Artigo em Inglês | MEDLINE | ID: mdl-31874032

RESUMO

Relative binding affinity prediction is a critical component in computer aided drug design. A significant amount of effort has been dedicated to developing rapid and reliable in silico methods. However, robust assessment of their performance is still a complicated issue, as it requires a performance measure applicable in the prospective setting and more importantly a true null model that defines the expected performance of being random in an objective manner. Although many performance metrics, such as the Pearson correlation coefficient (r), mean unsigned error (MUE), and root-mean-square error (RMSE), are frequently used in the literature, a true and nontrivial null model has yet been identified. To address this problem, here we introduce an interval estimate as an additional measure, namely, the prediction interval (PI), which can be estimated from the error distribution of the predictions. The benefits of using the interval estimate are (1) it provides the uncertainty range in the predicted activities, which is important in prospective applications, and (2) a true null model with well-defined PI can be established. We provide one such example termed the Gaussian Random Affinity Model (GRAM), which is based on the empirical observation that the affinity change in a typical lead optimization effort has the tendency to distribute normally N (0, σ). Having an analytically defined PI that only depends on the variation in the activities, GRAM should, in principle, allow us to compare the performance of relative binding affinity prediction methods in a standard way, ultimately critical to measuring the progress made in algorithm development.

11.
Adv Mater ; 32(6): e1904987, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31850607

RESUMO

Rechargeable magnesium (Mg) metal batteries are a promising candidate for "post-Li-ion batteries" due to their high capacity, high abundance, and most importantly, highly reversible and dendrite-free Mg metal anode. However, the formation of passivating surface film rather than Mg2+ -conducting solid electrolyte interphase (SEI) on Mg anode surface has always restricted the development of rechargeable Mg batteries. A stable SEI is constructed on the surface of Mg metal anode by the partial decomposition of a pristine Li electrolyte in the electrochemical process. This Li electrolyte is easily prepared by dissolving lithium tetrakis(hexafluoroisopropyloxy)borate (Li[B(hfip)4 ]) in dimethoxyethane. It is noteworthy that Mg2+ can be directly introduced into this Li electrolyte during the initial electrochemical cycles for in situ forming a hybrid Mg2+ /Li+ electrolyte, and then the cycled electrolyte can conduct Mg-ion smoothly. The existence of this as-formed SEI blocks the further parasitic reaction of Mg metal anode with electrolyte and enables this electrolyte enduring long-term electrochemical cycles stably. This approach of constructing superior SEI on Mg anode surface and exploiting novel Mg electrolyte provides a new avenue for practical application of high-performance rechargeable Mg batteries.

12.
Nat Commun ; 10(1): 5374, 2019 11 26.
Artigo em Inglês | MEDLINE | ID: mdl-31772177

RESUMO

The surface chemistry of solid electrolyte interphase is one of the critical factors that govern the cycling life of rechargeable batteries. However, this chemistry is less explored for zinc anodes, owing to their relatively high redox potential and limited choices in electrolyte. Here, we report the observation of a zinc fluoride-rich organic/inorganic hybrid solid electrolyte interphase on zinc anode, based on an acetamide-Zn(TFSI)2 eutectic electrolyte. A combination of experimental and modeling investigations reveals that the presence of anion-complexing zinc species with markedly lowered decomposition energies contributes to the in situ formation of an interphase. The as-protected anode enables reversible (~100% Coulombic efficiency) and dendrite-free zinc plating/stripping even at high areal capacities (>2.5 mAh cm‒2), endowed by the fast ion migration coupled with high mechanical strength of the protective interphase. With this interphasial design the assembled zinc batteries exhibit excellent cycling stability with negligible capacity loss at both low and high rates.

13.
Adv Sci (Weinh) ; 6(22): 1901036, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31763139

RESUMO

Low ionic conductivity at room temperature and limited electrochemical window of poly(ethylene oxide) (PEO) are the bottlenecks restricting its further application in high-energy density lithium metal battery. Herein, a differentiated salt designed multilayered PEO-based solid polymer electrolyte (DSM-SPE) is exploited to achieve excellent electrochemical performance toward both the high-voltage LiCoO2 cathode and the lithium metal anode. The LiCoO2/Li metal battery with DSM-SPE displays a capacity retention of 83.3% after 100 cycles at 60 °C with challenging voltage range of 2.5 to 4.3 V, which is the best cycling performance for high-voltage (≥4.3 V) LiCoO2/Li metal battery with PEO-based electrolytes up to now. Moreover, the Li/Li symmetrical cells present stable and low polarization plating/stripping behavior (less than 80 mV over 600 h) at current density of 0.25 mA cm-2 (0.25 mAh cm-2). Even under a high-area capacity of 2 mAh cm-2, the profiles still maintain stable. The pouch cell with DSM-SPE exhibits no volume expansion, voltage decline, ignition or explosion after being impaled and cut at a fully charged state, proving the excellent safety characteristic of the DSM-SPE-based lithium metal battery.

14.
Chem Commun (Camb) ; 55(76): 11370-11373, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31478549

RESUMO

We demonstrated a novel single molecule - tetrakis(4-carboxyphenyl) porphyrin (TCPP) with a large π-conjugated system as a high-performance organic anode of lithium batteries. It was found that this TCPP displayed relatively low solubility (<0.1 mg mL-1) in a 1 M LiDFOB/PC electrolyte, high reversible specific capacity (ca. 1200 mA h g-1 at 358 mA g-1), excellent rate capability (548.4 mA h g-1 at 8 A g-1) and superior cycling performance (capacity retention of 89% after 2500 cycles at 6 A g-1).

15.
Nanoscale ; 11(38): 17913-17919, 2019 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-31553019

RESUMO

Conical silver nanocavity arrays are fabricated by directly depositing Ag on porous alumina templates with V-shaped nanopores. By controlling the thickness of deposited Ag, complete and cracked cavity arrays are constructed respectively. The cracked cavity arrays with the cavity wall consisting of Ag nanoparticles are demonstrated to exhibit higher surface enhanced Raman scattering (SERS) activity than the complete one. Numerical simulation reveals that an effective coupling of the cavity modes with the surface plasmons of Ag nanoparticles (NPs) generates a significantly enhanced local electric field on the cavity wall responsible for the high SERS activity. The optimized cavity array presents an enhancement factor (EF) of ∼7.4 × 106 and an excellent uniformity with a relative standard deviation (RSD) as small as ∼5% for rhodamine 6G (R6G) molecules. Moreover, a good linear correlation between the logarithmic Raman intensity and the molecular concentration endows the array with quantitative analysis ability. These cavity arrays therefore are of great potential for qualitative and quantitative chemical and biomedical analysis with high sensitivity and reproducibility.

16.
Adv Sci (Weinh) ; 6(12): 1900355, 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31380171

RESUMO

Although the theoretical specific capacity of LiCoO2 is as high as 274 mAh g-1, the superior electrochemical performances of LiCoO2 can be barely achieved due to the issues of severe structure destruction and LiCoO2/electrolyte interface side reactions when the upper cutoff voltage exceeds 4.5 V. Here, a bifunctional self-stabilized strategy involving Al+Ti bulk codoping and gradient surface Mg doping is first proposed to synchronously enhance the high-voltage (4.6 V) performances of LiCoO2. The comodified LiCoO2 (CMLCO) shows an initial discharge capacity of 224.9 mAh g-1 and 78% capacity retention after 200 cycles between 3.0 and 4.6 V. Excitingly, the CMLCO also exhibits a specific capacity of up to 142 mAh g-1 even at 10 C. Moreover, the long-term cyclability of CMLCO/mesocarbon microbeads full cells is also enhanced significantly even at high temperature of 60 °C. The synergistic effects of this bifunctional self-stabilized strategy on structural reversibility and interfacial stability are demonstrated by investigating the phase transitions and interface characteristics of cycled LiCoO2. This work will be a milestone breakthrough in the development of high-voltage LiCoO2. It will also present an instructive contribution for resolving the big structural and interfacial challenges in other high-energy-density rechargeable batteries.

17.
Chem Commun (Camb) ; 55(74): 11059-11062, 2019 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-31453991

RESUMO

The addition of a polar-hydrophobic methylammonium trifluoroacetate ionic liquid tailors the hydrophobicity of halide-perovskite precursor solutions and assists in grain growth. This unique additive also functionalizes the grain boundaries via polar-polar interactions, thereby enhancing the optoelectronic properties and chemical stability of perovskites. This study opens the door to the solution hydrophobicity control towards high-performance perovskite devices.

18.
Adv Mater ; 31(50): e1902029, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31441147

RESUMO

Solid polymer electrolytes (SPEs) have aroused wide interest in lithium batteries because of their sufficient mechanical properties, superior safety performances, and excellent processability. However, ionic conductivity and high-voltage compatibility of SPEs are still yet to meet the requirement of future energy-storage systems, representing significant barriers to progress. In this regard, intermolecular interactions in SPEs have attracted attention, and they can significantly impact on the Li+ motion and frontier orbital energy level of SPEs. Recent advances in improving electrochemcial performance of SPEs are reviewed, and the underlying mechanism of these proposed strategies related to intermolecular interaction is discussed, including ion-dipole, hydrogen bonds, π-π stacking, and Lewis acid-base interactions. It is hoped that this review can inspire a deeper consideration on this critical issue, which can pave new pathway to improve ionic conductivity and high-voltage performance of SPEs.

19.
Chem Commun (Camb) ; 55(66): 9785-9788, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31355842

RESUMO

We report a strategy employing a concentrated electrolyte to boost the cycling stability of LiCoO2/graphite cells at 90 °C for the first time. Such a concentrated electrolyte provides the cells with superb cycling stability (97% after 160 cycles) at 90 °C. Further investigations unveil that the concentrated electrolyte participates in the formation of a compact LiF-rich CEI layer, which effectively inhibits the decomposition of electrolyte solvent and the dissolution of Co2+, maintaining the structural integrity of the LiCoO2 cathode.

20.
Bioorg Med Chem Lett ; 29(16): 2410-2414, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31160176

RESUMO

The discovery of a novel series of peptide deformylase inhibitors incorporating a piperazic acid amino acid found in nature is described. These compounds demonstrated potent in vitro enzymatic potency and antimicrobial activity. Crystal structure analysis revealed the piperazic acid optimized a key contact with the PDF protein that accounted for the increased enzymatic potency of these compounds. We describe lead optimization of the P3' region of the series that resulted in a compound with good potency against three target organisms. One molecule showed in vivo efficacy in a rat respiratory infection model but ultimately did not meet candidate progression criteria.

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