Enery storage is a vital issue to be solved for the efficient utilization of renewable energies such as solar, wind and tidal energy. In terms of rechargeable battery energy storage,...

The lithium-sulfur (Li-S) battery has received a lot of attention because it is characterized by high theoretical energy density (2,600 Wh/kg) and low cost. Though many works on the "shuttle effect" of polysulfide have been investigated, lithium metal anode is a more challenging problem, which leads to a short life, low coulombic efficiency, and safety issues related to dendrites. As a result, the amelioration of lithium metal anode is an important means to improve the performance of lithium sulfur battery. In this paper, improvement methods on lithium metal anode for lithium sulfur batteries, including adding electrolyte additives, using solid, and/or gel polymer electrolyte, modifying separators, applying a protective coating, and providing host materials for lithium deposition, are mainly reviewed. In addition, some challenging problems, and further promising directions are also pointed out for future research and development of lithium metal for Li-S batteries.

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Traditional aqueous energy storage devices are difficult to operate at low temperatures owing to the poor ionic conductivity and sluggish interfacial dynamics in frozen electrolytes. Herein, the low-cost brine refrigerants for food freezing and preservation as electrolytes, and unexpectedly realize high ionic conductivity and stable operation of an aqueous storage device at low temperatures are demonstrated. A CaCl 2 brine refrigerant electrolyte (BRE) with a low freezing point −55 °C and high ionic conductivity (10.1 mS cm −1 at −50 °C) is developed for supercapacitors (SCs), which retains 80% of the room temperature capacity at −50 °C and exhibits ultra-long cycle life with excellent capacity retention of 92% over 98,500 cycles, outperforming the other SCs which can be operated below −40 °C in literature. Moreover, the SCs with MgCl 2 and NaCl BREs can also be operated successfully with excellent cycle stability and high-capacity retention at low temperatures of −30 and −20 °C, respectively. Fundamental correlation between various cations and their effect on the freezing point reduction of aqueous electrolytes is revealed via Raman investigation and molecular dynamics simulations. This study provides a rational design strategy for green, inexpensive, and safe low-temperature aqueous electrolytes for energy storage devices.

An artificial mixed electronic–ionic conductive coating layer relieves dendrites and side effects.