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In order to solve the problem of capacity reduction of Schiff base monomer in lithium-ion batteries due to the dissolution of active substances, the Schiff base polymer(PI) with C=N bond was prepared by one-step condensation method using p-benzaldehyde and p-phenylenediamine as raw materials. Poly(Schiff base)/carbon nanotubes(PI/CNTs) composites with high conductivity were prepared by doping carbon nanotubes(CNTs). The composition, structure, micro morphology and electrochemical properties of the prepared materials were analyzed by using FT-IR, SEM, XRD, TG, XPS and electrochemical workstation. The results indicate that the PI/CNT material with 5%CNTs(mass fraction) is a three-dimensional frame structure, and shows excellent electrochemical performance. The first specific capacity of PI/CNT-3 material is 209.9 mAh·g-1. After 200 cycles, the cycle retention rate is 60.5%. When the rate of charge and discharge is 0.1 C, 0.2 C, 0.5 C, 1 C and 0.1 C, the specific capacity of PI/CNT-3 electrode materials is 182.4, 150.8, 129.8, 101.3 mAh·g-1 and 156.4 mAh·g-1 respectively, which has good cycle stability and rate performance.

Purpose – Many experts suggest that the human being explore marine resources and marine new energy sources to alleviate the shortage of land resources and the ecological degradation. However, island coastal zones are considered to be fragile ecosystems; their geographical location and natural characteristics, their biodiversity and associated ecosystems, and their exposure to diverse land and sea conditions all make them highly vulnerable to environmental changes and human activities. Therefore, it is necessary to achieve the goals of environmental protection and sustainable development on the basis of a comprehensive evaluation and understanding of islands. Design/methodology/approach – Due to the importance of island groups, this paper conducts evaluation studies on them. Using the Delphi, AHP and TOPSIS methods, this study evaluated quantitatively the comprehensive development level and comprehensive development potential of island groups in terms of resources, natural environment, economy and society. Innovatively using them as two subsystems, the present study combined the coupling coordination model and the obstacle factor calculation method. Findings – The prospective index of comprehensive development was applied to the Changdao Island Group in Yantai, Shandong Province as an example, and the final evaluation revealed that the comprehensive development prospect of this island group had an upward trend from 2010 to 2017. Future efforts should be made to improve its economic and social conditions and economic development status, apart from promoting its comprehensive development by improving human resources management, increasing the GDP growth rate, and improving fresh water and electricity supply. Originality/value – This study takes the integrated development level of the island and the integrated development potential of the island as two subsystems, and the innovative application of the coupling coordination degree model is used to calculate the integrated development index of the island to understand the development status of the island area. On the basis of this model, the obstacle factor identification method is designed to identify the main obstacle factors, and on the basis of evaluation and identification, specific measures to ensure the sustainable development of the island area are effectively proposed.