Rational Design of High-Loading Electrodes with Superior Performances Toward Practical Application for Energy Storage Devices.

High-loading electrodes play a crucial role in designing practical high-energy batteries as they reduce the proportion of non-active materials, such as current separators, collectors, and battery packaging components. This design approach not only enhances battery performance but also facilitates faster processing and assembly, ultimately leading to reduced production costs. Despite the existing strategies to improve rechargeable battery performance, which mainly focus on novel electrode materials and high-performance electrolyte, most reported high electrochemical performances are achieved with low loading of active materials (<2 mg cm-2). Such low loading, however, fails to meet application requirements. Moreover, when attempting to scale up the loading of active materials, significant challenges are identified, including sluggish ion diffusion and electron conduction kinetics, volume expansion, high reaction barriers, and limitations associated with conventional electrode preparation processes. Unfortunately, these issues are often overlooked. In this review, the mechanisms responsible for the decay in the electrochemical performance of high-loading electrodes are thoroughly discussed. Additionally, efficient solutions, such as doping and structural design, are summarized to address these challenges. Drawing from the current achievements, this review proposes future directions for development and identifies technological challenges that must be tackled to facilitate the commercialization of high-energy-density rechargeable batteries.

Constructing Dual-Phase Co9S8-CoMo2S4 Heterostructure as an Efficient Trifunctional Electrocatalyst for Oxygen Reduction, Oxygen Evolution and Hydrogen Evolution Reactions.

Designing robust, efficient and inexpensive trifunctional electrocatalysts for the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is significant for rechargeable zinc-air batteries and water-splitting devices. To this end, constructing heterogenous structures based on transition metals stands out as an effective strategy. Herein, a dual-phase Co9S8-CoMo2S4 heterostructure grown on porous N, S-codoped carbon substrate (Co9S8-CoMo2S4/NSC) via a one-pot synthesis is investigated as the trifunctional ORR/OER/HER electrocatalyst. The optimized Co9S8-CoMo2S4/NSC2 exhibits that ORR has a half-wave potential of 0.86 V (vs. RHE) and the overpotentials at 10 mA cm-2 for OER and HER are 280 and 89 mV, respectively, superior to most transition-metal based trifunctional electrocatalysts reported to date. The Co9S8-CoMo2S4/NSC2-based zinc-air battery (ZAB) has a high open-circuit voltage (1.41 V), large capacity (804 mA h g-1) and highly stable cyclability (97 h at 10 mA cm-2). In addition, the prepared Co9S8-CoMo2S4/NSC2-based ZAB in series can self-drive the corresponding water electrolyzer. The dual-phase Co9S8-CoMo2S4 heterostructure provides not only multi-type active sites to drive the ORR, OER and HER, but also high-speed charge transfer channels between two phases to improve the synergistic effect and reaction kinetics.

An Ultrahigh-Mass-Loading Integrated Free-Standing Functional All-Carbon Positive Electrode Prepared using an Architecture Tailoring Strategy for High-Energy-Density Dual-Ion Batteries.

Dual-ion batteries (DIBs) have been attracting great attention for the storage of stationary energy due to their low cost, environmental friendliness, and high working voltage. However, most reports on DIBs involve low-mass-loading electrodes (<2.5 mg), while the use of high mass-loading electrodes (>10 mg cm-2 ), which are critical for practical application, is overlooked. Herein, an integrated free-standing functional carbon positive electrode (named MSCG) with a "point-line-plane" hierarchical architecture at the practical level of ultrahigh mass-loading (>50 mg cm-2 ) is developed for high-energy-density DIBs. The rationally designed microstructure and the advanced assembly method that is adopted produce a well-interconnected ion/electron transport channel in the MSCG electrode, which confers rapid ion/electron kinetic properties while maintaining good mechanical properties. Consequently, the DIBs with ultrahigh-mass-loading MSCG electrodes exhibits a high discharge capacity of 100.5 mAh g-1 at 0.5 C (loading mass of 50 mg cm-2 ) and a long-term cycling performance with a capacity retention of 87.7% at 1 C after 500 cycles (loading mass of 23 mg cm-2 ). Moreover, the DIB with the ultrahigh-mass-loading positive electrode achieves a high energy density of 379 Wh kg-1 based on the mass of electrode materials, the highest value recorded to date for any DIBs.