Synchronous Redox Reactions in Copper Oxalate Enable High-Capacity Anode for Proton Battery

Proton batteries have emerged as a promising solution for grid‐scale energy storage benefiting their high safety and abundant raw materials. The battery chemistry based on proton‐ions is intrinsically advantageous in integrating fast diffusion kinetics and high capacities, thus offering great potential to break through the energy limit of capacitors and the power limit of traditional batteries. Significant efforts have been dedicated to advancing proton batteries, leading to successive milestones in recent years. Herein, the recent progress of proton batteries is summarized and insights into the challenges in electrodes, electrolytes and future opportunities for enhancing full‐cell applications are provided. The fundamentals of electrochemical proton storage and representative faradaic electrodes are discussed, delving into their current limitations in mechanism studies and electrochemical performances. Subsequently, the classification, challenges, and strategies for improving protonic electrolytes are addressed. Finally, the state‐of‐the‐art proton full‐cells are explored, and views on the rational design of proton battery devices for achieving high‐performance aqueous energy storage are offered.

Challenges and Opportunities for Proton Batteries: From Electrodes, Electrolytes to Full‐Cell Applications

Wu,

Guo,

Zhao

2024

Porous Structure‐Electrochemical Performance Relationship of Carbonaceous Electrode‐Based Zinc Ion Capacitors

Xiao,

Jiang,

Zeng

et al. 2024

The porous structure is critical for carbonaceous electrode‐based zinc‐ion capacitors (ZICs) to achieve excellent electrochemical performance, but the corresponding porous structure‐electrochemical performance relationship is yet to be fully understand. Herein, three types of N‐doped carbons with different porous structures are developed to investigate the relationship between the pore size distribution and the electrochemical performance of the devices. The optimized porous carbon (LVCR) exhibits large electrochemical surface area, plentiful oxygen functional groups, and hierarchical porous structure that facilitates electron transfer and ion diffusion. Consequently, the LVCR‐based ZIC exhibits a remarkable peak power density of 31.4 kW kg−1 and an impressive specific energy density of 126.6 Wh kg−1. Moreover, it demonstrates exceptional longevity, retaining the capacitance of 97.7% even after undergoing 50 000 cycles. Systematic characterization demonstrates that the macroporous and mesoporous structures determine the different stages of Zn2+ storage kinetics. The excellent Zn2+ storage and electrochemical performance of LVCR are attributed to the fast ion transport channels provided by the hierarchical porous structure and facilitated reversible chemisorption and desorption. This work not only deepens the understanding of charge storage mechanism, but also provides guidelines for rationally designing carbonaceous materials toward high‐performance ZICs in the view of porous structure‐electrochemical performance relationship.

Conjugated Enhanced Polyimide Enables High‐Capacity Ammonium Ion Storage

Huang,

Zhao,

Guo

et al. 2024

Aqueous ammonium ion batteries (AIBs) have emerged as a promising next‐generation rechargeable battery due to their safety, sustainability, abundant resources, and superior electrochemical performance. However, organic anode materials, particularly polyimide anode materials, suffer from low specific capacity caused by limited active sites. Herein, the study has developed a micro‐granular‐structured π‐conjugated enhanced polyimide (PTPD) as the anode material for AIBs. The large π‐conjugated enhanced structure enables long‐range electron delocalization, decreased bandgap, and reduced spatial steric hindrance, resulting in increased active sites capable of storing NH4+ ions. PTPD exhibits reversible oxidation and reduction reaction in (NH4)2SO4 solution, delivering a high specific capacity of 206.67 mAh g−1 at a current density of 0.5 A g−1, exceptional rate capability, and excellent cycling stability with a capacity retention of 74.28% after 2500 cycles at a current density of 10 A g−1. Furthermore, theoretical simulations and materials analysis demonstrate that PTPD undergoes enol‐keto transformation of carbonyl groups, effectively capturing NH4+ to store charges. This study provides an effective strategy for designing polymer‐based AIBs anodes with high specific capacity and cycling stability.