In recent years, lithium batteries using conventional organic liquid electrolytes have been found to possess a series of safety concerns. Because of this, solid polymer electrolytes, benefiting from shape versatility, flexibility, low-weight and low processing costs, are being investigated as promising candidates to replace currently available organic liquid electrolytes in lithium batteries. However, the inferior ion diffusion and poor mechanical performance of these promising solid polymer electrolytes remain a challenge. To resolve these challenges and improve overall comprehensive performance, polymers are being coordinated with other components, including liquid electrolytes, polymers and inorganic fillers, to form polymer-based composite electrolytes. In this review, recent advancements in polymer-based composite electrolytes including polymer/liquid hybrid electrolytes, polymer/polymer coordinating electrolytes and polymer/inorganic composite electrolytes are reviewed; exploring the benefits, synergistic mechanisms, design methods, and developments and outlooks for each individual composite strategy. This review will also provide discussions aimed toward presenting perspectives for the strategic design of polymer-based composite electrolytes as well as building a foundation for the future research and development of high-performance solid polymer electrolytes.

Carbon is a key component in current electrochemical energy storage (EES) devices and plays a crucial role in the improvement in energy and power densities for the future EES devices. As the simplest carbon and the basic unit of all sp ² carbons, graphene is widely used in EES devices because of its fascinating and outstanding physicochemical properties; however, when assembled in the macroscale, graphene-derived materials do not demonstrate their excellence as individual sheets mostly because of unavoidable stacking. This review proposal shows to engineer graphene nanosheets from the nano- to the macroscale in a well-designed and controllable way and discusses how the performance of the graphene-derived carbons depends on the individual graphene sheets, nanostructures, and macrotextures. Graphene-derived carbons in EES applications are comprehensively reviewed with three representative devices, supercapacitors, lithium-ion batteries, and lithium–sulfur batteries. The review concludes with a comment on the opportunities and challenges for graphene-derived carbons in the rapidly growing EES research area.

Due to the large reserves, low cost, high security and high energy density, rechargeable multivalent batteries have attracted extensive research enthusiasm for a long time. Multivalent batteries are also supposed as the potential candidates to Li-ion batteries in portable electronic devices and large-scale energy storage units. Unfortunately, most commercial cathode materials in Li-ion batteries cannot be applied in multivalent batteries because of the intensive polarization problem of multivalent intercalated ions (Mg²⁺, Zn²⁺, Al³⁺). Choosing and synthesizing the appropriate cathode materials are the main issues in overcoming the intensive polarization problem. Vanadium-based materials often possess many kinds of oxidation states because of the mutable vanadium element, which can facilitate achieving local electroneutrality and relieve the polarization problem of multivalent ions. In this review, we summarize the researches about the vanadium-based cathode materials for multivalent batteries and highlight the intercalation mechanism of multivalent ions to vanadium-based materials. In addition, different kinds of optimizing strategies are extracted from the literatures. On the basis of our review, progresses and future challenges of vanadium-based cathode materials in rechargeable multivalent batteries are more explicit.

Sodium-ion batteries have been emerging as attractive technologies for large-scale electrical energy storage and conversion, owing to the natural abundance and low cost of sodium resources. However, the development of sodium-ion batteries faces tremendous challenges, which is mainly due to the difficulty to identify appropriate cathode materials and anode materials. In this review, the research progresses on cathode and anode materials for sodium-ion batteries are comprehensively reviewed. We focus on the structural considerations for cathode materials and sodium storage mechanisms for anode materials. With the worldwide effort, high-performance sodium-ion batteries will be fully developed for practical applications.

The original version of this article unfortunately contained mistakes. The title was incorrect. The corrected title is given above.