Batteries & Supercaps最新文献

Sulfur-polyacrylonitrile (SPAN) is a sulfur-based active material for next-generation lithium-sulfur battery cathodes. Due to the covalent bonding between sulfur chains and the polymeric backbone, the shuttle effect degrading classical sulfur-based cathodes can be suppressed while also achieving a high active material content in the cathode. In this paper, we investigate the processability of an industrially scalable SPAN active material with 38 wt.-% of sulfur in a water-based and scalable process route. The potential of the SPAN material for industrial adoption and the impact of the process route on the cell performance are discussed. We show that when processed correctly, the SPAN material delivers exceptional cycling stability and good C-rate performance with ether-based electrolytes. However, the performance of the SPAN cathode is influenced by the mixing characteristic. Using higher mixing intensities during the slurry preparation leads to deterioration of the electrochemical performance. This can be attributed to a decreasing carbon black percolation with increasing tip speed in combination with the kinetic limitation of sulfur cathodes during Li₂S₂ and Li₂S oxidation.

Lithium-sulfur batteries (LSBs) are discussed as the most promising post-lithium-ion battery technology due to the high theoretical energy density and the cost-efficient, environmental-friendly active material sulfur. Unfortunately, LSBs still suffer from several limitations such as cycle life and rate capability. To overcome these issues, the development of adapted electrolytes is one promising path. Consequently, in this study, we focus on the influence of the lithium salt on the performance of LSBs. In a fixed solvent system without employing LiNO₃, five different lithium salts are compared. The electrolyte properties as well as the influence of polysulfides are determined and discussed in relation with the battery performance. Interestingly, although the different salts lead to different electrolyte properties, only a minor influence of the salt is observed at low C-rates. By performing a rate capability test, however, a strong influence of the lithium salt is detected at high C-rates, with LiFSI outperforming the other salts. This correlates well with ionic conductivity and a suppressed influence of polysulfides in case of LiFSI. To verify the results, multi-layered pouch cells were tested under lean electrolyte conditions. The study emphasizes the significance of the lithium salt and provides guidance for electrolyte design under lean electrolyte conditions.

The Li-rich antifluorite-type oxides Li₅FeO₄, Li_5.5Fe_0.5Co_0.5O₄ and Li₆CoO₄ have been investigated as positive electrode materials for Li-ion batteries in a combined operando XANES and XRD experiment. All materials show a similar two-step behaviour upon initial charge (termed Stage I and Stage II), and reversibility of subsequent cycling depends upon whether the initial charge cycle is terminated following Stage I or allowed to proceed through Stage II. By tracking the energetic evolution of the XANES pre-edge feature present in both Fe and Co K-edge spectra, as well as the evolution of X-ray diffractograms during charge and discharge, we correlate the changes in chemical coordination and oxidation states in both species and the structural changes to the electrochemical potential profile, and infer the role of anionic redox processes.

The utilization of copper hexacyanoferrate (CuHCF) as positive electrode material in aqueous zinc-ion batteries (ZIBs) has gained significant attention due to its efficient (de−)intercalation of Zn²⁺ ions, cost-effective synthesis, low toxicity, and high working potential. One approach to improve its electrochemical performance is to coat the CuHCF particles with conductive polymers, such as poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT : PSS). In this study, we investigated the impact of the PEDOT : PSS as a coating on the electrochemical behavior and the cycle life of CuHCF for aqueous ZIB applications. Galvanostatic cycling performed at a current rate of 1 C relevant for the stationary application of the CuHCF/PEDOT : PSS electrodes having high mass loadings (10 mg cm⁻² of active material) revealed significantly longer cycle life while maintaining a high Coulombic efficiency (≥ 99.5 %). The longest cycle life was achieved with CuHCF coated using a 4.5 wt. % PEDOT : PSS aqueous coating dispersion. These findings demonstrate the potential of conductive polymer coatings as a practical approach to enhance the electrochemical performance of positive electrode materials in aqueous Zinc-ion batteries.

Silicon is a promising candidate for replacing graphite in anodes for advanced Li-ion batteries due to its high theoretical gravimetric energy density. However, silicon as an active anode material suffers from significant volume changes upon lithiation/delithiation, causing fast capacity fading. The performance of silicon anodes depends on the polymeric binders used, which form well-bound Si particles matrices that accommodate the strains developed during their repeated lithiation, thus maintaining their integrity.