@article {46255, title = {Dendrite growth suppression by Zn2+-integrated nafion ionomer membranes: beyond porous separators toward aqueous Zn/V2O5 batteries with extended cycle life }, journal = {Energy Technology}, volume = {7}, year = {2019}, month = {SEP}, type = {Article}, abstract = {

The dendritic/irregular growth of zinc deposits in the anode surface is often considered as a major intricacy limiting the lifespan of aqueous zinc-ion batteries. The effect of separators on the evolution of the surface morphology of the anode/cathode is never thoroughly studied. Herein, for the first time, the efficacy of the Zn2+-integrated Nafion ionomer membrane is demonstrated as a separator to effectively suppress the growth of irregular zinc deposits in the metallic anode of an aqueous Zn/V2O5 battery. The Zn2+-ions coordinated with the SO3- moieties in Nafion result in a high transference number of the Zn2+ cation, all the while facilitating a high ionic conductivity. The Zn2+-integrated Nafion membrane enables the Zn/V2O5 cell to deliver a high specific capacity of 510 mAh g(-1) at a current of 0.25 A g(-1), which is close to the theoretical capacity of anhydrous V2O5 (589 mAh g(-1)). Moreover, the same cell exhibits an excellent cycling stability of 88\% retention of the initial capacity even after 1800 charge-discharge cycles, superior to that of the Zn/V2O5 cells comprising conventional porous separators.

}, doi = {10.1002/ente.201900442}, author = {Ghosh, Meena and Vijayakumar, Vidyanand and Kurungot, Sreekumar} } @article {47006, title = {Dioxolanone-anchored poly(allyl ether)-based cross-linked dual-salt polymer electrolytes for high-voltage lithium metal batteries}, journal = {ACS Applied Materials \& Interfaces}, volume = {12}, year = {2020}, month = {JAN }, pages = {567-579}, type = {Article}, abstract = {

Novel cross-linked polymer electrolytes (XPEs) are synthesized by free-radical copolymerization induced by ultraviolet (UV)-light irradiation of a reactive solution, which is composed of a difunctional poly(ethylene glycol) diallyl ether oligomer (PEGDAE), a monofunctional reactive diluent 4-vinyl-1,3-dioxolan-2-one (VEC), and a stock solution containing lithium salt (lithium bis(trifluoromethanesulfonyl)imide, LiTFSI) in a carbonate-free nonvolatile plasticizer, poly(ethylene glycol) dimethyl ether (PEGDME). The resulting polymer matrix can be represented as a linear polyethylene chain functionalized with cyclic carbonate (dioxolanone) moieties and cross-linked by ethylene oxide units. A series of XPEs are prepared by varying the [O]/[Li] ratio (24 to 3) of the stock solution and thoroughly characterized using physicochemical (thermogravimetric analysis-mass spectrometry, differential scanning calorimetry, NMR, etc.) and electrochemical techniques. In addition, quantum chemical calculations are performed to elucidate the correlation between the electrochemical oxidation potential and the lithium ion-ethylene oxide coordination in the stock solution. Later, lithium bis(fluorosulfonyl)imide (LiFSI) salt is incorporated into the electrolyte system to produce a dual-salt XPE that exhibits improved electrochemical performance, a stable interface against lithium metal, and enhanced physical and chemical characteristics to be employed against high-voltage cathodes. The XPE membranes demonstrated excellent resistance against lithium dendrite growth even after reversibly plating and stripping lithium ions for more than 1000 h with a total capacity of 0.5 mAh cm(-2). Finally, the XPE films are assembled in a lab-scale lithium metal battery configuration by using carbon-coated LiFePO4 (LFP) or LiNi0.8Co0.15Al0.05O2 (NCA) as a cathode and galvanostatically cycled at 20, 40, and 60 degrees C. Remarkably, at 20 degrees C, the NCA-based lithium metal cells displayed excellent cycling stability and good capacity retention (\>50\%) even after 1000 cycles.

}, keywords = {cross-linked polymer electrolyte, dual-salt electrolyte, high-voltage cathode, lithium metal battery, solvent-free photopolymerization}, issn = {1944-8244}, doi = {10.1021/acsami.9b16348}, author = {Vijayakumar, Vidyanand and Diddens, Diddo and Heuer, Andreas and Kurungot, Sreekumar and Winter, Martin and Nair, Jijeesh Ravi} }