A sulfur-linked carbonyl-based poly(2,5-dihydroxyl-1,4-benzoquinonyl sulfide) (PDHBQS) compound is synthesized and used as cathode material for lithium-ion batteries (LIBs). Flexible binder-free composite cathode with single-wall carbon nanotubes (PDHBQS-SWCNTs) is then fabricated through vacuum filtration method with SWCNTs. Electrochemical measurements show that PDHBQS-SWCNTs cathode can deliver a discharge capacity of 182 mA h g (0.9 mA h cm ) at a current rate of 50 mA g and a potential window of 1.5 V-3.5 V. The cathode delivers a capacity of 75 mA h g (0.47 mA h cm ) at 5000 mA g , which confirms its good rate performance at high current density. PDHBQS-SWCNTs flexible cathode retains 89% of its initial capacity at 250 mA g after 500 charge-discharge cycles. Furthermore, large-area (28 cm ) flexible batteries based on PDHBQS-SWCNTs cathode and lithium foils anode are also assembled. The flexible battery shows good electrochemical activities with continuous bending, which retains 88% of its initial discharge capacity after 2000 bending cycles. The significant capacity, high rate performance, superior cyclic performance, and good flexibility make this material a promising candidate for a future application of flexible LIBs.

Owing to the increasing pressure on the ecological effect of solid waste disposal and developing the need for disposal of the corresponding hazardous metals, recovery of spent lithium ion batteries (LIBs) has gain worldwide attention in recent years. Much work has been done in this regard in the past few decades, and several new, interesting, and unique methods have been developed to recycle the cathode, anode, and electrolyte. Therefore, time has come to summarize the highlights in this emerging area to facilitate young researchers. In this review, starting from the current market demand and commercial value of lithium ion batteries, we have summarized the most recent progress in the direction of recycling the cathode and anode materials and electrolyte. At the beginning, an overview of the recycling techniques is presented to grasp understanding of the topic. Later, laboratory and industrial investigations and implementation are reviewed with emphasis on anode (graphite) and electrolyte recovery. Life cycle assessment of end-of-life LIB recycling, limitations, and future efforts have also mentioned to focus on improving the efficiency of metal extraction and separation with the sustainable and systematic recycling of spent lithium ion batteries.

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Advancement in mobile electronics is driving progress in lithium ion batteries. Recently, organic electrode materials have emerged as promising candidates for lithium ion batteries due to their high theoretical capacity, ease of synthesis, versatility of structure, and abundance. Polymerization is a strategy used to overcome the issues associated with small organic molecules for charge storage application. The focus of this review is on the most recent progress in the field of polymeric carbonyl materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Advantages of organic electrode materials, device architecture, and charge storage mechanism are discussed. Challenges associated with carbonyl‐based electrodes and some recent solutions are outlined. Later, a comparison of theoretical capacity, practical capacity, and cyclic life are presented for different carbonyl systems. Capacity‐fading phenomena and structural degradation during charging are discussed where necessary. Some key parameters for the design of flexible batteries are highlighted and an overview of some recent contributions of our group in this field are reported. Finally, some future prospects for researchers in this field are outlined.