The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic vehicles. The emerging of intelligent control in kinds of devices brings new requirements for battery systems. The high-energy lithium batteries are expected to respond or react under different environmental conditions. In this work, a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium batteries. Specifically, the halide Li₃YBr₆ together with LiTFSI and LiNO₃ works as active fillers in a low-melting-point polymer matrix (polyethyleneglycol dimethyl ether (PEGDME) and polyethylene oxide (PEO)), which is further filled into the pre-lithiated alumina fiber skeleton. Above 60 ℃, the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface, effectively minimizing the interfacial resistance and leading to high discharge capacity in the cell. The electrolyte is changed into a solid state below 30 ℃ so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid interface. Therefore, by simply adjusting the temperature, the cell can be turned “ON” or “OFF” intentionally. This novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.

Lithium-sulfur batteries are recognized as one of the most promising next-generation energy storage devices, owing to the high theoretical energy density of 2600 Wh·kg^–1. However, their application has been seriously hindered by the sluggish electrochemical reaction kinetics of elemental sulfur and discharged products (Li₂S₂/Li₂S), and the notorious “shuttle effect” of soluble intermediate lithium polysulfide species, leading to poor cycle stability, low sulfur utilization and inferior coulombic efficiency. Introducing catalytic hosts into sulfur cathode is an efficient path to propel the conversion of sulfur-contained species, thus preventing the dissolution and loss of active-sulfur material in lithium-sulfur batteries. In this review, we summarize recent progresses on the uses of metals and alloys as the core catalytic host of sulfur, and demonstrate the catalytic mechanism in the conversion process of sulfur species with the help of metal and alloy hosts. Finally, future outlooks are proposed on the construction of catalytic hosts and the development of high-energy lithium-sulfur batteries.

Sulfur element possesses an ultrahigh theoretical specific capacity, while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products, limiting the enhancement on energy density of lithium–sulfur batteries. Herein, for the first time, Fe_0.24Co_0.26Ni_0.10Cu_0.15Mn_0.25 high-entropy alloy is introduced as the core catalytic host to activate the electrochemical performance of the sulfur cathode for lithium–sulfur batteries. It is manifested that Fe_0.24Co_0.26Ni_0.10Cu_0.15Mn_0.25 high-entropy alloy nanocrystallites distributed on nitrogen-doped carbon exhibit high electrocatalytic activity toward the conversion of solid sulfur to solid discharged products across soluble intermediate lithium polysulfides. In particular, benefiting from the accelerated kinetics by high-entropy alloy nanocrystallites and synergistic adsorption by nitrogen-doped carbon, the cathode exhibits high reversible capacity of 1079.5 mAh g_-cathode⁻¹ (high utilization of 89.4%) with the whole cathode as active material, instead of sulfur element. Moreover, under both lean electrolyte (3 μL mg⁻¹) and ultrahigh sulfur loading (27.0 mg cm⁻²) condition, the high discharge capacity of 868.2 mAh g_-cathode⁻¹ can be still achieved for the sulfur cathode. This strategy opens up a new path to explore catalytic host materials for enhancing the utilization of sulfur in the whole cathode for lithium–sulfur batteries.

High-Ni layered oxide cathodes hold a great promise for fabricating high-energy lithium-ion batteries. However, the oxygen evolution during cycling is a crucial factor in the structure deterioration, potential change, and capacity decay of cathodes, limiting the commercial application of high-Ni (Ni > 0.9) layered oxides in batteries. Herein, we demonstrate a feasible approach to enhance the stability of oxygen framework, through the surface oxygen immobilization with yttrium and bulk oxygen stabilization with aluminum in high-Ni layered oxides. As expected, benefiting from the oxygen-stabilized framework, the bulk structure deterioration, and interfacial parasitic reaction are mitigated obviously during battery operation, along with the improved thermal stability of cathode. Correspondingly, the as-prepared high-Ni oxide delivers high reversible capacity, impressive cycle ability, and low potential polarization upon cycling. Such significant improvement on the electrochemical performance is primarily attributed to the strong oxygen affinities of both yttrium at the surface layer and aluminum in the bulk, which synergistically stabilizes the oxygen framework of high-Ni oxide via raising the energy barrier for oxygen evolution. Therefore, building the stable oxygen framework is critical for enhancing the energy density output, cycle operation, and thermal stability of high-Ni oxide cathodes.

The exploration of new catalytic hosts is highly important to tackle the sluggish electrochemical kinetics of sulfur redox for achieving high energy density of lithium–sulfur batteries. Herein, for the first time, we present high-entropy oxide (HEO, (Mg_0.2Mn_0.2Ni_0.2Co_0.2Zn_0.2)Fe₂O₄) nanofibers as catalytic host of sulfur. The HEO nanofibers show a synergistic effect among multiple metal cations in spinel structure that enables strong chemical confinement of soluble polysulfides and fast kinetics for polysulfide conversion. Consequently, the S/HEO composite displays the high gravimetric capacity of 1368.7 mAh g⁻¹ at 0.1 C rate, excellent rate capability with the discharge capacity of 632.1 mAh g⁻¹ at 5 C rate, and desirable cycle stability. Furthermore, the S/HEO composite shows desirable sulfur utilization and good cycle stability under a harsh operating condition of high sulfur loading (4.6 mg cm⁻²) or low electrolyte/sulfur ratio (5 μL mg⁻¹). More impressively, the high volumetric capacity of 2627.9 mAh cm⁻³ is achieved simultaneously for the S/HEO composite due to the high tap density of 1.92 g cm⁻³, nearly 2.5 times of the conventional sulfur/carbon composite. Therefore, based on high-entropy oxide materials, this work affords a fresh concept of elevating the gravimetric/volumetric capacities of sulfur cathodes for lithium–sulfur batteries.

Solar cells hold a function of photovoltaic conversion, while rechargeable metal batteries have an advantage of high energy storage. The conventional charge mode of batteries is made based on complete utilization of electric energy. The combination of solar cells and rechargeable metal batteries brings a new opportunity for the development of photo-assisted rechargeable batteries, in which the solar energy can be utilized to partially achieve photo-charging with or without external electrical bias. This review highlights the working mechanism and structure design of photo-assisted rechargeable metal batteries according to the characteristics of rechargeable metal batteries and advantage of the photovoltaic technology. In particular, the recent advances are introduced for photo-assisted rechargeable batteries based on light-weight metal anodes, including metal lithium, metal sodium, and metal zinc. The working features of the integrated devices are also discussed for energy saving under photo-assisted charging mode. Finally, a future outlook is provided for further improving the performance of photo-assisted rechargeable metal batteries.