ENERGY STORAGE DEVICES BASED ON HYBRID CARBON ELECTRODE SYSTEMS
The present application is directed to energy storage materials and devices, e.g. ion capacitors such as Li-ion capacitors, that employ more than one carbon-based electrodes comprising carbons with enhanced purity levels, e.g. below 500 ppm, wherein the carbon based electrodes have different properties, such as different surface areas, and/or different capability to intercalate vs. surface absorb electrolyte ions.
1 . An ion capacitor comprising two or more electrodes, wherein one or more of the electrodes comprises ultrapure synthetic carbon.
2 . The device of claim 1 , wherein both the anode and cathode comprise ultrapure carbon, and wherein the anode stores electrolyte ions through intercalation while the cathode stores electrolyte ions through a surface EDLC mechanism.
3 . The device according to claim 1 , wherein the anode comprises a hard carbon.
4 . The device of claim 3 , wherein the hard carbon exhibits a surface area of greater than 50 m 2 /g, an initial lithium insertion of greater than 800 mAh/g and a first cycle efficiency of greater than 75%.
5 . The device according to claim 1 , where the cathode comprises a mesoporous carbon
6 . The device according to claim 1 , wherein the total energy density of the device as normalized per mass of total carbon active material ranges from 50 Wh/kg to 150 Wh/kg.
7 . The device according to claim 1 , wherein the total power density of the device as normalized per mass of total carbon active material ranges from 10000 W/kg to 100000 W/kg.
8 . The device according to claim 1 , wherein the ratio of active carbon mass in the anode to active carbon mass in the cathode ranges from 1:3 to 1:1.
9 . The device according to claim 1 , wherein the ratio of skeletal active carbon volume in the cathode to skeletal active carbon volume in the anode ranges from 1:1 to 3:1.
10 . The device according to claim 1 , wherein the ratio of carbon surface area in the anode to carbon surface area in the cathode is less than 0.007:1
11 . The device according to claim 1 , wherein the anode comprises graphite.
12 . The device according to claim 1 , where the anode comprises nitrogen, phosphorus, or a combination thereof at a level of greater than 1 wt %.
13 . The device according to 1, where the cathode comprises a mesoporous carbon with greater than 1500 m 2 /g specific surface area and greater than 0.8 cc/g pore volume.
14 . The device according to claim 1 , wherein one or more electrodes comprises a hard carbon material that is capable of 60 mAh/g of lithium extraction at a rate of 3.6 seconds
15 . The device according to claim 1 , further comprising an aqueous or organic solvent with dissolved electrolyte ions selected from lithium, sodium, aluminum, magnesium and combinations thereof.
16 . The device according to claim 1 , wherein the packing efficiency in the anode or cathode, or both, is greater than 90% of the theoretical maximum packing density.