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Compressive sampling matching pursuit (CoSaMP), as a conventional algorithm requiring system sparsity and sensitive to step size, was improved in this paper by approximating the sparsity with adaptive variable step size. In the proposed algorithm (CoSaMP with variable step size abbreviated as Vss-CoSaMP), the idea of approximating sparsity with adaptive step size was borrowed from the sparsity adaptive matching pursuit (SAMP) algorithm to determine the sparsity for the CoSaMP algorithm. The applicability of the CoSaMP algorithm was therefore expanded considerably. On this basis, a step size reduction was added as the iteration termination condition of an orthogonal frequency division multiplexing (OFDM) system. An adaptive variable step size algorithm was then put forward to address the CoSaMP algorithm’s sensitivity to step size. It could realize the required precision at different initial step sizes. A simulation was carried out to analyze the influence of pilot number and step size in an OFDM system on the algorithm. The algorithms, including SAMP, CoSaMP, and Vss-CoSaMP, were compared with two sparse channels, revealing that the Vss-CoSaMP algorithm overcame the problem of the CoSaMP algorithm, that is, the impossibility to forecast the channel sparsity. With the adaptive step size, the proposed algorithm could reach and achieve better accuracy than the CoSaMP algorithm. Additionally, the proposed algorithm was superior over the SAMP algorithm in terms of reconstruction, mean square error (MSE), and bit error ratio (BER).

Covalent organic frameworks (COFs) have emerged as promising renewable electrode materials for LIBs and gained significant attention, but their capacity has been limited by the densely packed 2D layer structures, low active site availability, and poor electronic conductivity. Combining COFs with high-conductivity MXenes is an effective strategy to enhance their electrochemical performance. Nevertheless, simply gluing them without conformal growth and covalent linkage restricts the number of redox-active sites and the structural stability of the composite. Therefore, in this study, a covalently assembled 3D COF on Ti3C2 MXenes (Ti3C2@COF) is synthesized and serves as an ultralong cycling electrode material for LIBs. Due to the covalent bonding between the COF and Ti3C2, the Ti3C2@COF composite exhibits excellent stability, good conductivity, and a unique 3D cavity structure that enables stable Li+ storage and rapid ion transport. As a result, the Ti3C2-supported 3D COF nanosheets deliver a high specific capacity of 490 mAh g−1 at 0.1 A g−1, along with an ultralong cyclability of 10,000 cycles at 1 A g−1. This work may inspire a wide range of 3D COF designs for high-performance electrode materials. [ABSTRACT FROM AUTHOR]

Rechargeable metal‐ion batteries (MIBs) beyond lithium‐ion batteries based on Na, K, Mg, and Al metal electrodes which are earth‐abundant and low‐cost have been developed for large‐scale energy storage systems. MXenes, a type of transition metal carbides, nitrides, and carbonitrides, are discovered as electrodes for MIBs owing to their distinctive properties of large‐scale ultrathin conductive 2D structures, adjustable surface functional groups, regulable interlayer spacing, and high specific surface area. Herein, the properties of MXenes are summarized and the recent progress on MXene‐based materials for diversified MIBs (Li, Na, K, Mg, and Al‐ion batteries) is introduced. The main focus is on the synthesis and applications of MXene‐based materials in MIBs, and their roles in electrochemical reactions. Further examples are provided to demonstrate the significant function of MXene‐based composite as active materials, substrates, collectors, and precursors in different MIBs, highlighting the enormous potential of MXene‐based materials to construct advanced electrodes. This review expects to offer a deep understanding of the relationship between the electrochemical performance and the MXene‐based electrodes, which will promote more novel and creative breakthroughs in the MXenes‐based electrodes for MIBs. [ABSTRACT FROM AUTHOR]