Low-Temperature and Fast-Charging Lithium Metal Batteries Enabled by Solvent-Solvent Interaction Mediated Electrolyte.

Lithium metal batteries utilizing lithium metal as the anode can achieve a greater energy density. However, it remains challenging to improve low-temperature performance and fast-charging features. Herein, we introduce an electrolyte solvation chemistry strategy to regulate the properties of ethylene carbonate (EC)-based electrolytes through intermolecular interactions, utilizing weakly solvated fluoroethylene carbonate (FEC) to replace EC, and incorporating the low-melting-point solvent 1,2-difluorobenzene (2FB) as a diluent. We identified that the intermolecular interaction between 2FB and solvent can facilitate Li+ desolvation and lower the freezing point of the electrolyte effectively. The resulting electrolyte enables the LiNi0.8Co0.1Mn0.1O2||Li cell to operate at -30 °C for more than 100 cycles while delivering a high capacity of 154 mAh g-1 at 5.0C. We present a solvation structure and interfacial model to analyze the behavior of the formulated electrolyte composition, establishing a relationship with cell performance and also providing insights for the electrolyte design under extreme conditions.

Design and fabrication of high performance supercapacitor with cellulosic paper electrode and plant-derived redox active molecules.

As a promising substrate, cellulose fibers were widely investigated in supercapacitors for their low cost and sustainability. However, the low performance created great barrier for the future applications of the cellulosic paper-based supercapacitors. The performance of paper-based supercapaciors may be improved by the addition of redox active molecule. As a plant derived redox active molecule, Alizarin red S was used to improve the performance of PEDOT paper-based electrode via a simple post-treatment process. By combination of the treated paper electrode and the redox electrolyte, a symmetric paper-based supercapacitor with a superior performance of 2191.3 m F/cm2 (at 5 mA/cm2) and 4.87 mW h/cm3 (at power density of 36 mW/cm3) were fabricated. The charge and mass transfer mechanisms of paper electrode were detailed discussed. The simple and efficient strategy developed in this work opens up new doors for the development of other cellulose related high performance energy storage devices.