Investigations on morphological and electrochemical changes of all-solid-state thin film battery cells under dynamic mechanical stress conditions

To design and manufacture high-performance energy storage devices with real mechanical flexibility is one of the main advantages of the solid-state battery technology. Mechanically flexible thin film, all solid-state Li-ion batteries are supposed to be the main power sources in emerging technologies such as flexible electronics, wearables, etc. However, if a flexible solid-state device is exposed to repeated external mechanical load, introducing additional aging mechanisms might be expected. In addition, externally introduced stress and strain to the battery functional components could influence lithiation kinetics of the respective electrode material. In the present study, the effect of the external mechanical load on the lithiation kinetics and the collateral mechanical fatigue of the full battery cell during dynamic bending were investigated in detail. Therefore, mechanically flexible, all solid-state MoO3/LiPON/Li battery cells were fabricated on a polymer substrate. Battery cells were exposed to static convex bending and it was ascertained that the bulk resistance of the positive electrode is largely dependent on the depth-of-discharge as well as mechanical stress state, while other processes such as charge transfer and electrolyte bulk resistance are less affected. Furthermore, battery cells were cycled galvanostatically, while they were bent repeatedly using different bending scenarios. Below a threshold bending frequency (f = 1/360 Hz), stable battery function was found, however mechanical aging of the battery cell was observed. As it was demonstrated, the metal current collector/positive electrode interface is highly prone to the physical degradation upon dynamic bending. As a result, delamination of the electrode and contact loss occur, causing capacity fading, accordingly. The present study shed light on the joint mechanical-electrochemical aging of mechanically flexible all solid-state Li-ion batteries

Mixed copper-zinc hexacyanoferrates as cathode materials for aqueous zinc-ion batteries

Aqueous rechargeable metal-ion batteries have become potentially advantageous for the integration of renewable energy sources into the electric power grid thanks to their high rate capability, low cost, environmental friendliness, and intrinsic safety. In this work, we tried to improve the electrochemical stability of CuHCF and prevent/postpone its aging upon cycling. At first we investigated the phase transformation occurring in CuHCF during intercalation of zinc using XRD, SEM and EDX. We observed that large particles are formed upon cycling, which are depleted from copper and are zinc- or iron-rich. In order to prevent this, we modified the CuHCF structure by partially substituting its transition metals with zinc ions during synthesis. We observed that CuZnHCF mixtures with Cu:Zn ratios of 93:7 exhibited an excellent cycle life up to 1000 cycles, with improved specific charge retention with respect to its CuHCF counterpart. Also in the case of CuZnHCF mixtures the formation of large particles upon cycling is observed, but less extended as in pure CuHCF. It appears that different morphologies of the particles show different compositions in term of zinc, iron and potassium

The influence of thinking styles on perceived price fairness: An experimental study

Customers expect pricing practices to be fair, they are specifically sensitive to price increase considered unfair or unacceptable, which eventually influences both behavioural intentions and emotions. Substantial investments are deployed in building positive associations with consumers, which can be subverted by the incident of price increase leading to unfairness perceptions. It is significantly important to mitigate the perceived unfairness perceptions, given the stakes involved. This article investigates the role that styles of thinking (holistic versus analytic) plays in perceived price fairness. The findings of this research show that styles of thinking play a significant role in influencing perceived price fairness. When exposed to negative and/or undesirable events such as price increase, styles of thinking influence cognitive attribution, which, in turn, influences price fairness perceptions. This research adds to the growing literature in price fairness by exploring the influence of thinking styles on perceived price fairness that has not been examined before. These findings suggest that strategies to influence styles of thinking could be useful in managing perceived unfairness perceptions. Marketers and managers could utilise marketing-management strategies based on findings of this research to maintain positive consumer’s perception of price, thereby will improve firms’ performance, in terms of, value, profitability and sales. © 2020, Springer Nature Singapore Pte Ltd