3D cellular graphene films with open porosity, high electrical conductivity, and good tensile strength, can be synthesized by a method combining freeze-casting and filtration. The resulting supercapacitors based on 3D porous reduced graphene oxide (RGO) film exhibit extremely high specific power densities and high energy densities. The fabrication process provides an effective means for controlling the pore size, electronic conductivity, and loading mass of the electrode materials, toward devices with high energy-storage performance.

Sodium is a promising anode material for batteries due to its low standard electrode potential, high abundance and low cost. In this work, we report a new rechargeable ~ 3.5 V sodium ion battery using Na anode, amorphous carbon-nanosphere cathode and a starting electrolyte comprised of AlCl 3 in SOCl 2 with uoride-based additives. The battery, exhibiting ultrahigh ~ 2800 mAh/g rst discharge capacity, could cycle with a high reversible capacity up to ~ 1000 mAh/g. Through battery cycling, the electrolyte evolved to contain NaCl, various sulfur and chlorine species that supported anode's Na/Na + redox and cathode's chloride/chlorine redox. Fluoride-rich additives were important in forming a solid-electrolyte interface, affording reversibility of the Na anode for a new class of high capacity secondary Na battery. Main TextDevising new battery concepts is important to meeting society's growing demand of energy storage.Different rechargeable batteries have been developed, including lithium ion batteries (LIBs), sodium ion batteries (SIBs) and aluminum ion batteries (AIBs) [1][2][3][4][5][6][7][8][9] . Prior to the invention of secondary LIBs, a primary Li-metal battery was developed in the 1970's using thionyl chloride (SOCl 2 ) as a catholyte, Li metal as anode and amorphous carbon as the positive electrode [10][11][12][13][14][15][16] . The Li-SOCl 2 battery was attractive due to its high energy density, but did not receive sustained interest due to the lack of rechargeability 17,18 . The battery discharges through Li anode oxidation and catholyte SOCl 2 reduction into sulfur (S), sulfur dioxide (SO 2 ), and chloride ion (Cl -) on the carbon electrode 19,20 . The Clions react with Li + stripped from

Electrocatalytic CO 2 reduction (CO 2 RR) to valuable fuels is a promising approach to mitigate energy and environmental problems, but controlling the reaction pathways and products remains challenging. Here a novel Cu 2 O nanoparticle film was synthesized by square-wave (SW) electrochemical redox cycling of high-purity Cu foils. The cathode afforded up to 98% Faradaic efficiency for electroreduction of CO 2 to nearly pure formate under ≥45 atm CO 2 in bicarbonate catholytes. When this cathode was paired with a newly developed NiFe hydroxide carbonate anode in KOH/borate anolyte, the resulting two-electrode high-pressure electrolysis cell achieved high energy conversion efficiencies of up to 55.8% stably for long-term formate production. While the high-pressure conditions drastically increased the solubility of CO 2 to enhance CO 2 reduction and suppress hydrogen evolution, the (111)-oriented Cu 2 O film was found to be important to afford nearly 100% CO 2 reduction to formate. The results have implications for CO 2 reduction to a single liquid product with high energy conversion efficiency.

We investigated rechargeable aluminum (Al) batteries composed of an Al negative electrode, a graphite positive electrode, and an ionic liquid (IL) electrolyte at temperatures down to -40 °C. The reversible battery discharge capacity at low temperatures could be superior to that at room temperature. In situ/operando electrochemical and synchrotron X-ray diffraction experiments combined with theoretical modeling revealed stable AlCl/graphite intercalation up to stage 3 at low temperatures, whereas intercalation was reversible up to stage 4 at room temperature (RT). The higher-degree anion/graphite intercalation at low temperatures affords rechargeable Al battery with higher discharge voltage (up to 2.5 V, a record for Al battery) and energy density. A remarkable cycle life of >20,000 cycles at a rate of 6C (10 minutes charge time) was achievable for Al battery operating at low temperatures, corresponding to a >50-year battery life if charged/discharged once daily.