Lithium metal batteries (LMBs) have been extensively investigated during the past decades because of their ultrahigh energy densities. With the increasing demand for energy density, however, the safety issue of LMBs has become a significant challenge. In particular, localized areas of increased temperature (namely, hotspots) may be induced and even exacerbated within LMBs by uneven current distribution, internal short circuits, or inadequate heat dissipation, which significantly sacrifices battery safety and cycle life. Here, we report the rational design and fabrication of a fast thermal responsive separator capable of inhibiting the growth of lithium dendrites and mitigating thermal propagation, thereby reducing the risk of thermal runaway. The as-achieved separator comprises both an electrospun membrane using a phase change material with superior thermal-storage ability and a thermally conductive modification layer of hexagonal boron nitride nanosheets with a fast heat-transfer feature. It is demonstrated that such a unique integration of heat conduction and heat storage enables the functional separator with attractive abilities to mitigate hotspots and inhibit the growth of lithium dendrites upon the cycling of LMBs. Moreover, pouch cells with the thermal-responsive separator, as well as numerical simulations, verify much enhanced safety and cycle life of LMBs. This work may offer a new conceptual design of intelligent separators that acts as a functional unit encapsulated within a single cell to boost in-situ thermal management, which will help to develop high-safety and energy-dense LMBs.

Silicon (Si) is one of the most promising anode materials for high-energy lithium-ion batteries. However, the widespread application of Si-based anodes is inhibited by large volume change, unstable solid electrolyte interphase, and poor electrical conductivity. During the past decade, significant efforts have been made to overcome these major challenges toward industrial applications. This review summarizes the recent development of microscale Si-based electrodes fabricated by Si microparticles or other industrial bulk materials from the perspective of industrialization. First, the challenges for microscale Si anodes are clarified. Second, structural design strategies of stable micro-sized Si materials are discussed. Third, other critical practical metrics, such as robust binder construction and electrolyte design, are also highlighted. Finally, future trends and perspectives on the commercialization of Si-based anodes are provided.

With the rapid development of lithium-ion batteries (LIBs), safety problems are the great obstacles that restrict large-scale applications of LIBs, especially for the high-energy-density electric vehicle industry. Developing component materials (e.g., cathode, anode, electrolyte, and separator) with high thermal stability and intrinsic safety is the ultimate solution to improve the safety of LIBs. Separators are crucial components that do not directly participate in electrochemical reactions during charging/discharging processes, but play a vital role in determining the electrochemical performance and safety of LIBs. In this review, the recent advances on traditional separators modified with ceramic materials and multifunctional separators ranging from the prevention of the thermal runaway to the flame retardant are summarized. The component–structure–performance relationship of separators and their effect on the comprehensive performance of LIBs are discussed in detail. Furthermore, the research challenges and future directions toward the advancement in separators for high-safety LIBs are also proposed.

A novel all-solid-state, coaxial, fiber-shaped asymmetric supercapacitor has been fabricated by wrapping a conducting carbon paper on a MnO₂-modified nanoporous gold wire. This energy wire exhibits high capacitance of 12 mF·cm^-2 and energy density of 5.4 μW·h·cm^-2 with excellent cycling stability. Hierarchical nanostructures and coaxial architectural design facilitate effective contacts between the two core@sheath electrodes and active layers with high flexibility and high performance. This work provides the first example of coaxial fibershaped asymmetric supercapacitors with an operation voltage of 1.8 V, and holds great potential for future flexible electronic devices.