Antimony trisulfide-based materials have drawn growing attention as promising anode candidates for potassium-ion batteries (PIBs) because of their high capacity and good working potential. Despite the extensive investigations on their electrochemical properties, the fundamental reaction mechanisms of Sb 2 S 3 anodes, especially the reaction kinetics, structural changes, and phase evolutions, remain controversial or even largely unknown. Here, using in situ transmission electron microscopy, the entire potassiationdepotassiation cycles of carbon-coated Sb 2 S 3 single-crystal nanowires are tracked in real time at the atomic scale. The potassiation of Sb 2 S 3 involves multistep reactions including intercalation, conversion, and two-step alloying, and the final products are identified as cubic K 2 S and hexagonal K 3 Sb. These findings are confirmed by density functional theory calculations. Interestingly, a rocket-launching-like nanoparticle growth behavior is observed during alloying reactions, which is driven by the K + concentration gradient and release of stress. More impressively, the potassiated products (i.e., K 3 Sb and K 2 S) can transform into the original Sb 2 S 3 phase during depotassiation, indicating a reversible phase transformation process, as distinct from other metal chalcogenide based electrodes. This work reveals the detailed potassiation/depotassiation mechanisms of Sb 2 S 3-based anodes and can facilitate the analysis of the mechanisms of other metal chalcogenide anodes in PIBs.

Aqueous zinc iodide (Zn−I 2 ) batteries are promising large-scale energy-storage devices. However, the uncontrollable diffuse away/shuttle of soluble I 3 − leads to energy loss (low Coulombic efficiency, CE), and poor reversibility (self-discharge). Herein, we employ an ordered framework window within a zeolite molecular sieve to restrain I 3 − crossover and prepare zeolite molecular sieve particles into compact, large-scale, and flexible membranes at the engineering level. The as-prepared membrane can confine I 3 − within the catholyte region and restrain its irreversible escape, which is proved via space-resolution and electrochemical in situ time-resolution Raman technologies. As a result, overcharge/self-discharge and Zn corrosion are effectively controlled by zeolite separator. After replacing the typically used glass fiber separator to a zeolite membrane, the CE of Zn−I 2 battery improves from 78.9 to 98.6% at 0.2 A/g. Besides, after aging at the fully charged state for 5.0 h, self-discharge is restrained and CE is enhanced from 44.0 to 85.65%. Moreover, the Zn−I 2 cell maintains 91.0% capacity over 30,000 cycles at 4.0 A/g.

Developing high-performance lithium ion batteries (LIBs) requires optimization of every battery component. Currently, the main problems lie in the mismatch of electrode capacities, especially the excessively low capacity of cathodes compared with that of anodes. Due to the anisotropy of the crystal structure, different crystal planes play different roles in the transmission of lithium ions. Among these, the {010} facets of layered-structure materials, the (110) planes of spinel cathodes and the (010) planes of olivine cathodes can provide open surface structures, which furnish express channels for the rapid and efficient transmission of lithium ions, leading to enhanced rate performance. However, due to the high-energy surfaces of these crystal planes, they tend to disappear in the synthetic process, forming thermodynamic equilibrium products dominated by low-energy and electrochemically-inactive planes. From the structure design of the material itself, preparing functional materials with specific morphologies and crystal structures is considered to be the most effective way to improve the cyclability and rate performance of LIB cathodes. In this review, we highlight the latest developments in selectively exposing the crystal planes of LIB cathode materials. The synthetic method, the corresponding electrochemical performance, especially the rate capability, and the growth mechanism have been systematically summarized for layered-structure cathodes of LiCoO2, LiNixCoyMn1-x-yO2 and Li2MnO3·LiMO2, spinel cathodes of LiMn2O4 and LiNi0.5Mn1.5O4, and olivine cathodes of LiFePO4. This in-depth discussion and understanding is beneficial for the rational design of well-performing LIB cathodes and can provide direction and perspectives for future work.

Extending the charge cutoff voltage of cathode (e.g., LiCoO2) is a promising way to increase the energy density of Li-ion batteries, but critical challenges lie in the threats triggered by structural distortion and an unstable electrode/electrolyte interface. The general approach to enhance the stability of the cathode/electrolyte interface (CEI) consists of replacing the decomposition or sacrificing sources of carbonate solvents (e.g., EC) with concentrated or fluorinated electrolyte strategies. Herein, without following typical replacement strategies, we introduce a trace electrolyte additive and refine the dehydrogenation process of the original carbonate solvents, resulting in an enhanced CEI and long-term cycling stability of LiCoO2 up to 4.65 V. We demonstrate that cathode structure distortion, LiPF6 hydrolysis, and Co dissolution and shuttling have been simultaneously restrained. With the achievement of a long-life 250 and 270 Wh/kg pouch cells (assembled with a commercial graphite and SiO anodes), the refinement of the “old-school” electrolyte additive strategy opens up avenues toward the design of practical high-voltage full-cell systems.