Lithium difluoro­(oxalato)borate tetra­methyl­ene sulfone disolvate

The title compound, Li+·C2BF2O4 −·2C4H8O2S, is a dimeric species, which resides across a crystallographic inversion center. The dimers form eight-membered rings containing two Li+ cations, which are joined by O2S sulfone linkages. The Li+ cations are ligated by four O atoms from the anions and solvent mol­ecules, forming a pseudo-tetra­hedral geometry. The exocyclic coordination sites are occupied by O atoms from the oxalate group of the difluoro­(oxalato)borate anion and an additional tetra­methyl­ene sulfone ligand

Proton conducting plastic crystal electrolytes based on pivalic acid

Peer reviewed: YesNRC publication: Ye

Multifunctional semi-interpenetrating polymer network-nanoencapsulated cathode materials for high-performance lithium-ion batteries

As a promising power source to boost up advent of next-generation ubiquitous era, high-energy density lithium-ion batteries with reliable electrochemical properties are urgently requested. Development of the advanced lithium ion-batteries, however, is staggering with thorny problems of performance deterioration and safety failures. This formidable challenge is highly concerned with electrochemical/thermal instability at electrode material-liquid electrolyte interface, in addition to structural/chemical deficiency of major cell components. Herein, as a new concept of surface engineering to address the abovementioned interfacial issue, multifunctional conformal nanoencapsulating layer based on semi-interpenetrating polymer network (semi-IPN) is presented. This unusual semi-IPN nanoencapsulating layer is composed of thermally-cured polyimide (PI) and polyvinyl pyrrolidone (PVP) bearing Lewis basic site. Owing to the combined effects of morphological uniqueness and chemical functionality (scavenging hydrofluoric acid that poses as a critical threat to trigger unwanted side reactions), the PI/PVP semi-IPN nanoencapsulated-cathode materials enable significant improvement in electrochemical performance and thermal stability of lithium-ion batteries.open

Manipulation of Disodium Rhodizonate: Factors for Fast-Charge and Fast-Discharge Sodium-Ion Batteries with Long-Term Cyclability

Organic sodium‐ion batteries (SIBs) are one of the most promising alternatives of current commercial inorganic lithium‐ion batteries (LIBs) especially in the foreseeable large‐scale flexible and wearable electronics. However, only a few reports are involving organic SIBs so far. To achieve fast‐charge and fast‐discharge performance and the long‐term cycling suitable for practical applications, is still challenging. Here, important factors for high performance SIBs especially with high capacity and long‐term cyclability under fast‐charge and fast‐discharge process are investigated. It is found that controlling the solubility through molecular design and determination of the electrochemical window is essential to eliminate dissolution of the electrode material, resulting in improved cyclability. The results show that poly(vinylidenedifluoride) will decompose during the charge/discharge process, indicating the significance of the binder for achieving high cyclability. Beside of these, it is also shown that decent charge transport and ionic diffusion are beneficial to the fast‐charge and fast‐discharge batteries. For instance, the flake morphology facilitates the ionic diffusion and thereby can lead to a capacitive effect that is favorable to fast charge and fast discharge

Binding MoSe2 with carbon constrained in carbonous nanosphere towards high-capacity and ultrafast Li/Na-ion storage

© 2018 Most of the reported MoSe 2 electrode materials are suffered from tended stacking, large volume expansion and relatively low capacity. As shown the experiences of Li/Na-Se batteries, the encapsulating of the exfoliated MoSe 2 into carbon nanospheres are successfully constructed with the introduction of C-O-Mo bonds and larger layer distance (0.89 nm). Interestingly, the C-O-Mo bonds stayed on the surface of the Se-O insulation layer can improve the rate of ions transfer and also promote the reversible conversion of MoSe 2 . The first-principles calculations demonstrated that the frontier molecular orbitals of C-O-Mo interface structure are mainly localized on the MoSe 2 sheet fragment with an appropriate HOMO-LUMO gap ( < 4 eV), proving that its conductivity is being greatly enhanced with higher stability. Utilized as an anode for LIBs, it delivers Li-storage capacities of 1208 mAh g −1 after 150 cycles at 1.0 A g −1 and 519 mAh g −1 after 200 cycles at 4.0 A g −1 . Also note that the Na-storage capacities are found to be 543, 491 mAh g −1 after 120 cycles at 0.1, 1.0 A g −1 , respectively. Through the analysis of CV, the reduced particles might improve the capacitive behaviors, further leading to the higher rate performances. Ex-situ techniques showed that the emerging Se during the electrochemical process was constrained uniformly in the carbon matrix. More greatly, the controlling of by-product Se plays key roles in achieving high-rate capability and cycling stability, which would open up a potential avenue for these metal-selenide anodes designs of battery storage systems

An ion conductive polyimide encapsulation: New insight and significant performance enhancement of sodium based P2 layered cathodes

The final publication is available at Elsevier via https://doi.org/10.1016/j.ensm.2019.07.010. © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/It is essential to stabilize the surface of P2 layered cathode materials at high cut-off voltages (>4.3 V) in order to construct high-energy sodium ion batteries (SIB) that are promising for commercial application. When the voltage exceeds 4.3 V, large volume changes due to phase transitions and active species dissolution affect the structural stability of high voltage cathodes. In this study, we report a novel method of enhancing the electrochemical cycling performance of P2-type Na2/3(Mn0.54Ni0.13Co0.13)O2 (NNMC) materials through ion-conductive polyimide (PI) encapsulation. The electrochemical performance of ultrathin PI coated NNMC (PI-NNMC) is one of the best reported in the literature among layered cathodes in terms of cyclic stability (82% after 100 cycles at 0.16 A g−1) at a high voltage range between 2 and 4.5 V, compared to the pristine (46%) and Al2O3-coated NNMC (70%). At high current (5C), the NNMC-PI electrode demonstrates superior cyclability by retaining 70% of its capacity after 500 cycles. The ultrathin PI layer possesses excellent surface protection, high ionic conductivity (vs Al2O3 coating) and facile ion transport, thus enabling a fast and durable redox electrochemistry in NNMC materials for high-performance sodium storage above 4.3 V.This work was financially supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the University of waterloo, and the Waterloo Institute for Nanotechnology and the 111 Project (No. D17007) and K.K acknowledges the financial support for this work from Henan Normal University, China