Recently, metallic zinc (Zn) is becoming a promising ideal anode material for rechargeable aqueous batteries by providing high theoretical capacity (820 mA h/g) with divalent reaction, environmental friendliness, earthy abundance, low cost, low toxicity, higher water compatibility, and low electrochemical potential (−0.762 V vs SHE). However, intensive growth of zinc dendrites while plating/stripping lowers its coulombic efficiency and shortens the cycle life of the rechargeable devices. Here, we report a concentrated aqueous electrolyte (4.2 M ZnSO4 + 0.1 M MnSO4) with improved cycling stability of zinc metal anode achieving an average coulombic efficiency (ACE) ∼99.21% cycling for more than 1000 h at 0.2 mA/cm2 current density using a Zn||Cu cell. However, a frequently used diluted electrolyte (2 M ZnSO4 + 0.1 M MnSO4) only produces ACE ≈ 97.54% with a relatively short life cycle. The developed concentrated electrolyte with strongly aggregated ion pairs shows the synergetic effects of the enhanced solvation/desolvation process, electrostatic shielding, and Le Chatelier’s principle. Consequently, the additives simultaneously suppress Zn dendrites and dissolution of Mn2+ ions from the MnO2 cathode. A highly stable and reversible Zn||MnO2 cell retaining about 88.37% retention capacity was obtained after cycling for more than 1200 cycles at 938 mA/g current density.

Rechargeable aqueous zinc-ion batteries (ZIBs) are emerging as alternative lithium-ion batteries for large-scale energy storage applications due to their safety and environmental friendliness. However, their applications are hindered by the...

Zinc metal is considered a promising anode material for aqueous zinc ion batteries. However, it suffers from dendrite growth, corrosion, and low coulombic efficiency (CE) during plating/stripping. Herein, a concentrated hybrid (4 m Zn(CF 3 SO 3 ) 2 + 2 m LiClO 4 ) aqueous electrolyte (CHAE) to overcome the challenges facing the Zn anode is reported. The developed electrolyte achieves dendrite-free Zn plating/stripping and obtains an excellent CE of ≈100%, surpassing the previously reported values. The combination of synchrotron-based in operando transmission X-ray microscopy, X-ray diffraction, and ex situ X-ray photoelectron spectroscopy analyses indicate that the denser, anion-derived passivation layer formed using the CHAE facilitates homogeneous current distribution and better prevents freshly deposited Zn from directly contacting the electrolyte than the looser, solvent-derived layers formed from a dilute hybrid aqueous electrolyte (DHAE). The beneficial effects of the CHAE on the compact, dense, and stable salt-anion-derived passivation layer can be attributed to its unique solvation structure, which suppresses the water-related side reactions and widens the electrochemical potential window. In the hybrid Zn||LiFePO 4 configuration, the CHAE-based cell delivered a stable performance of CE >99% and capacity retention >90% after 285 cycles. In contrast, the DHAE-based cell exhibits capacity retention of <65% after 170 cycles.

The low ionic conductivity, thermal stability and incompatibility of pellet-like solid-state electrolytes lead to low cycling performance in anode-free lithium metal batteries. Herein, we report an effective and feasible composite solid electrolyte-designing approach using the garnet (Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 , LLZTO)−polymer composite electrolyte (LLZTO/ PEO-CPE) laminated on both the anode and cathode surfaces with an ultrathin thickness of 7−10 μm by spin coating method. It is found that the LLZTO/PEO-CPE exhibits a high ionic conductivity of about 4.76 × 10 −4 S/ cm at room temperature, excellent thermal stability, and good compatibility. Moreover, it simplifies the preparation of solid electrolytes and reduces the interfacial and grain boundary resistances for ion transfer. The use of both anode and cathode laminating enables dendrite-free lithium plating on copper with a high average coulombic efficiency and cycling stability of 98.8 and 41.2%, respectively, after the 65 cycles at 0.2 mA/cm 2 and 55 °C in an anodefree battery. This work provides a new design of solid-state electrolytes (SSEs) to achieve safe and dendrite-free anode-free batteries.

A cell with doped LPS – Li1.5Al0.33Sc0.17Ge1.5(PO4)3 shows improved conductivity and a capacity retention of 83.6% for more than 80 cycles.