In Situ Visualization of Atmosphere-Dependent Relaxation and Failure in Energy Storage Electrodes

Ultrahigh-Speed Aqueous Copper Electrodes Stabilized by Phosphorylated Interphase

High-energy metal anodes for large-scale reversible batteries with inexpensive and nonflammable aqueous electrolytes promise the capability of supporting higher current density, satisfactory lifetime, nontoxicity, and low-cost commercial manufacturing, yet remain out of reach due to the lack of reliable electrode-electrolyte interphase engineering. Herein, in situ formed robust interphase on copper metal electrodes (CMEs) induced by a trace amount of potassium dihydrogen phosphate (0.05 m in 1 m CuSO4 -H2 O electrolyte) to fulfill all aforementioned requirements is demonstrated. Impressively, an unprecedented ultrahigh-speed copper plating/stripping capability is achieved at 100 mA cm-2  for over 12 000 cycles, corresponding to an accumulative areal capacity up to tens of times higher than previously reported CMEs. The use of solid-electrolyte interface-protection strategy brings at least an order of magnitude improvement in cycling stability for symmetric cells (Cu||Cu, 2800 h) and full batteries with CMEs using either sulfur cathodes (S||Cu, 1000 cycles without capacity decay) or zinc anodes (Cu||Zn with all-metal electrodes, discharge voltage ≈1.02 V). The comprehensive analysis reveals that the hydrophilic phosphate-rich interphase nanostructures homogenize copper-ion deposition and suppress nucleation overpotential, enabling dendrite-free CMEs with sustainability and ability to tolerate unusual-high power densities. The findings represent an elegant forerunner toward the promising goal of metal electrode applications.

Soft Carbon as Cathode with High Rate Performance for Dual-Ion Batteries via Fast PF6 - Intercalation Improved by Surface Effect

Dual-ion battery is a new type of battery in which both anions and cations participate in the energy storage process. However, this unique battery configuration imposes high requirements on the cathode, which typically presents a poor rate performance due to the sluggish diffusion dynamics and intercalation reaction kinetics of anions. Herein, we report petroleum coke-based soft carbon as the cathode for dual-ion batteries, exhibiting a superior rate performance with a specific capacity of 96 mAh g-1 at a rate of 2 C and 72 mAh g-1 remained even at 50 C. In situ XRD and Raman demonstrate that the anions can directly form lower-stage graphite intercalation compounds during the charge process owing to the surface effect, skipping the long evolutionary process from higher to lower stage, thus significantly improving the rate performance. This study highlights the impact of the surface effect and provides a promising perspective for dual-ion batteries.