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As a promising candidate for the flame‐retardant electrolyte, triethyl phosphate (TEP)/potassium bis(fluorosulfonyl)amide (KFSI)‐based electrolyte has drawn much attention in the K‐ion battery community. Although the TEP/KFSI formula at a moderate main salt concentration (normally, <3 m) enables the compatibility of the reactive K metal anode, the long‐standing oxidative instability of KFSI salt remains unsolved. Here, an additive strategy is reported to address the high‐voltage issue in the TEP/KFSI electrolyte, and generalize it to the other KFSI‐based electrolytes. The addition of potassium nitrate changes the surface charge distribution and effectively suppresses the decomposition of KFSI toward the high‐voltage cathode. The nitrate‐containing electrolyte enables superior stability of a 4.3 V‐class K‐ion battery, as evidenced by its 80% capacity retention over 2000 cycles (≈6 months) at the 1 C rate. Moreover, the long‐cycling stability of the graphite‐based full cell with Prussian Blue cathode is demonstrated. [ABSTRACT FROM AUTHOR]

Various electrolyte additives are developed to construct a cathode electrolyte interphase (CEI) layer for high‐voltage LiCoO2 since the cathode suffers severe interfacial degradation when increasing the cut‐off voltage over 4.55 V. However, the CEI derived from the additive sacrificial reaction faces the risk of rupture due to the corrosion reaction and the volumetric variation of the cathode. Herein, a non‐passivating cathode interface is realized for 4.6 V LiCoO2 with a non‐sacrificial electrolyte additive (TBAClO4) by regulating the solvent environment at the interface rather than the preferential decomposition for CEI formation. Owing to the novel protection mechanism, the cell performance shows little dependence on the CEI‐formation process. Therefore, an ultra‐high initial coulombic efficiency (96.63%) and excellent cycling stability (81% capacity retention after 300 cycles) are achieved in Li||LiCoO2 batteries. Moreover, even with the electrolyte containing 1000 ppm H2O, the remarkable water capture ability of the additive together with its interfacial regulation enables the 4.6 V Li||LiCoO2 battery to retain 80% capacity after 200 cycles. This non‐sacrificial strategy provides new insights into high‐voltage electrolyte additive design for high‐energy‐density lithium metal batteries. [ABSTRACT FROM AUTHOR]

Potassium ion batteries using graphite anode and high‐voltage cathodes are considered to be optimizing candidates for large‐scale energy storage. However, the lack of suitable electrolytes significantly hinders the development of high‐voltage potassium ion batteries. Herein, a dilute (0.8 m) fluorinated phosphate electrolyte is proposed, which exhibits extraordinary compatibility with both graphite anode and high‐voltage cathodes. The phosphate solvent, tris(2,2,2‐trifluoroethyl) phosphate (TFP), has weak solvating ability, which not only allows the formation of robust anion‐derived solid electrolyte interphase on graphite anode but also effectively suppresses the corrosion of Al current collector at high voltage. Meanwhile, the high oxidative stability of fluorinated TFP solvent enables stable ultrahigh‐voltage (4.95 V) cycling of a potassium vanadium fluorophosphate (KVPO4F) cathode. Using TFP‐based electrolyte, the 4.9 V‐class potassium ion full cell based on graphite anode and KVPO4F cathode shows rather remarkable cycling performance with a high capacity retention of 87.2% after 200 cycles. This study provides a route to develop dilute electrolytes for high‐voltage potassium ion batteries, by utilizing solvents with both weak solvating ability and high oxidative stability. [ABSTRACT FROM AUTHOR]

In the article "Non-Sacrificial Additive Enables a Non-Passivating Cathode Interface for 4.6 V Li||LiCoO2 Batteries," researchers Guang Feng, Dengyun Zhai, Feiyu Kang, and their colleagues propose a new method to stabilize a 4.6 V LiCoO2 cathode in lithium metal batteries. By using a non-sacrificial electrolyte additive, they are able to regulate the solvent environment at the cathode interface, reducing interfacial side reactions and improving the cycle life of the batteries. This research offers a promising approach to enhance the performance of high-voltage lithium-ion batteries. [Extracted from the article]

The commercialization of potassium‐ion batteries requires promising anodes with excellent reversible capacity and cycle stability. Graphite anodes have attracted extensive research owing to the formation of stable intercalation compounds, which also helps to focus attention on low‐cost carbon‐based anodes. However, the slow diffusion of potassium ion (K+) and structural damage of graphite caused by large size may lead to capacity decay. Herein, the modification strategies have been summarized, including microstructure regulation, heteroatom doping and building stable solid electrolyte interphase. And the opportunities and challenges faced by these improvement methods are proposed. Meanwhile, carbon‐based materials used as hosts or conductive carriers to improve the performance of other anodes are also summarized. [ABSTRACT FROM AUTHOR]

Nitrogen-doped ordered mesoporous carbon spheres (N-OMCS) were prepared by a facile one-pot soft-templating and one-step pyrolysis method. The as-obtained N-OMCS possesses an average diameter of around 300 nm, a moderate specific surface area of 439 m 2 g −1 and uniform mesopore size at around 5.0 nm. Owing to the ordered meso-structure and nitrogen doping, the N-OMCS materials, when used as supercapacitor electrodes, delivers a high specific capacitance of 288 F g −1 at a current density of 0.1 A g −1 . More remarkably, the N-OMCS electrode shows excellent rate capability with 66% capacitance retention at an ultrahigh current density of 50 A g −1 and outstanding cycling stability with almost no degradation over 25,000 cycles. The work would open up a new avenue to synthesize carbon spheres with mesoporous structure and nitrogen doping for high-performance supercapacitor applications. [ABSTRACT FROM AUTHOR]

Understanding the electrochemical property of superoxides in alkali metal oxygen batteries is critical for the design of a stable oxygen battery with high capacity and long cycle performance. In this work, a KO 2 -decorated binder-free cathode is fabricated by a simple and efficient electrochemical strategy. KO 2 nanoparticles are uniformly coated on the carbon nanotube film (CNT-f) through a controllable discharge process in the K-O 2 battery, and the KO 2 -decorated CNT-f is innovatively introduced into the Li-O 2 battery as the O 2 diffusion electrode. The Li-O 2 battery based on the KO 2 -decorated CNT-f cathode can deliver enhanced discharge capacity, reduced charge overpotential, and more stable cycle performance compared with the battery in the absence of KO 2 . In situ formed KO 2 particles on the surface of CNT-f cathode assist to form Li 2 O 2 nanosheets in the Li-O 2 battery, which contributes to the improvement of discharge capacity and cycle life. Interestingly, the analysis of KO 2 -decorated CNT-f cathodes, after discharge and cycle tests, reveals that the electrochemically synthesized KO 2 seems not a conventional electrocatalyst but a partially dissolvable and decomposable promoter in Li-O 2 batteries.

The formation of the insulated film-like discharge products (Li 2 O 2 ) on the surface of the carbon cathode gradually hinders the oxygen reduction reaction (ORR) process, which usually leads to the premature death of the Li-O 2 battery. In this work, by introducing the molecular sieve powder into the ether electrolyte, the Li-O 2 battery exhibits a largely improved discharge capacity (63 times) compared with the one in the absence of this inorganic oxide additive. Meanwhile, XRD and SEM results qualitatively demonstrate the generation of the toroid Li 2 O 2 as the dominated discharge products, and the chemical titration quantifies a higher yield of the Li 2 O 2 with the presence of the molecular sieve additive. The addition of the molecular sieve controls the amount of the free water in the electrolyte, which distinguishes the effect of the molecular sieve and the free water on the discharge process. Hence, a possible mechanism has been proposed that the adsorption of the molecular sieves toward the soluble lithium superoxides improves the disproportionation of the lithium superoxides and consequently enhances the solution-growth of the lithium peroxides in the low donor number ether electrolyte. In general, the application of the molecular sieve triggers further studies concerning the improvement of the discharge performance in the Li-O 2 battery by adding the inorganic additives.