Lithium, sodium, potassium and calcium amine-bis(phenolate) complexes in the ring-opening polymerization of rac-lactide.

Compounds of Li, Na, K and Ca of a tetradentate amino-bis(phenolato) ligand were prepared. Bimetallic compounds formulated as M[L](THF) (where M = Na, n = 1 (1·THF) or Li, n = 1 (2·THF)) were synthesized via the reaction of H[L] (where [L] = 2-pyridylmethylamino-N,N-bis(2-methylene-4-methoxy-6-tert-butylphenolato) with sodium hydride or n-butyllithium, respectively, in THF. Monometallic complexes MH[L](THF) (where M = Na, n = 1 (3·THF), Li, n = 0 (4) and K, n = 0 (5)) were obtained by reaction of H[L] with MN(SiMe) where M = Na, Li, or K.

Accelerated Stress Test Method for the Assessment of Membrane Lifetime in Vanadium Redox Flow Batteries.

An accelerated stress test (AST) method was developed to estimate the lifetime of ion-exchange membranes in a vanadium redox flow battery. The oxidative VO ions present in the charged positive electrolyte are the predominant stressor causing loss of functional groups and membrane conductivity. Membrane aging was accelerated in ex situ tests by exploiting elevated temperatures and the increased oxidative strength of Ce.

Tackling Capacity Fading in Vanadium Redox Flow Batteries with Amphoteric Polybenzimidazole/Nafion Bilayer Membranes.

Vanadium flow batteries are among the most promising technologies for stationary energy storage applications if their cost of storage can be further decreased. Capacity fading resulting from imbalanced vanadium crossover is a key operating cost component. Herein, a new approach is reported to avoid this cost by balancing electrolyte transport with amphoteric bilayer Nafion/meta-polybenzimidazole membranes.

Revealing the role of phosphoric acid in all-vanadium redox flow batteries with DFT calculations and in situ analysis.

The present work suggests the use of a mixed water-based electrolyte containing sulfuric and phosphoric acid for both negative and positive electrolytes of a vanadium redox flow battery. Computational and experimental investigations reveal insights on the possible interactions between the vanadium ions in all oxidation states and sulphate, bisulphate, dihydrogen phosphate ions and phosphoric acid. In situ cycling experiments and ion-specific electrochemical impedance measurements confirmed a significant lowering of the charge-transfer resistance for the reduction of V(iii) ions and, consequently, an increase of the voltaic efficiency associated with the negative side of the battery.