PAPER BASED MATERIALS FOR THE STORAGE OF ELECTRICAL ENERGY

Abstract

The invention relates to coated paper where a base paper is coated at least on one side and where the coating comprises at least 5 wt. % carbon material and at least 5 wt. % of an open-framework material and at least 1 wt. % binder, a process for the manufacture of the means, a composition for coating paper, coated paper, a process for the manufacture of the coated paper, a means for storing electricity, use of the coated paper as well as a method for storing electricity.

Claims

1. A coated paper where a base paper is coated at least on one side and where the coating comprises at least 5 wt. % carbon material and at least 5 wt. % of an open-framework material and at least 1 wt. % binder.

2. The coated paper according to claim 1, wherein the open-framework material is a clay, a metal oxide or mixtures thereof, and/or comprised in the coating in an amount in a range from 50 to 80 wt. %.

3. The coated paper according to claim 1, wherein the carbon material is comprised in the coating in an amount in a range from 10 to 80 wt. %, and preferably is amorphous carbon and/or activated carbon.

4. The coated paper according to claim 1, wherein the base paper comprises 40 to 70 wt. % of mechanical pulp.

5. The coated paper according to claim 1, wherein the thickness of the base paper is in a range from 20 to 200 m.

6. The coated paper according to claim 1, wherein the width of the paper is in a range from 0.7 to 15 m.

7. A composition for coating paper, comprising water and at least 5 wt. % carbon material and at least 5 wt. % of an open-framework material and at least 1 wt. % binder.

8. The composition according to claim 7, wherein the weight ratio of open-framework material to carbon material is in a range from 4:1 to 1:1.

9. A process for manufacture of coated paper, wherein the composition according to claim 7 is coated onto a base paper.

10. The process according to claim 9, wherein the process is conducted on a paper machine.

11. The process according to claim 9, wherein com-position is coated onto the paper by an online or offline coating machine.

12. The process according to claim 9, wherein the paper is satinated online or offline after coating.

13. Means for storing electricity, comprising at least one anode and one cathode and at least one layer of coated paper according to claim 1 in an electrolyte.

14. The means according to claim 13, wherein one layer of the coated paper is the cathode.

15. The means according to claim 13, wherein the means is a battery or a supercapacitor.

16. The means according to claim 13, wherein the electrolyte is aqueous.

17. Batteries or Supercapacitors comprising the coated paper according to claim 1.

18. (canceled)

19. (canceled)

20. The coated paper according to claim 4 wherein the base paper comprises 40 to 70 wt. % of ground wood.

Description

FURTHER EMBODIMENTS

[0113] In a further embodiment, the problem according to the present invention is solved by the use of the coated paper according to the present invention to make batteries or supercapacitors.

[0114] In a further embodiment, the problem according to the present invention is solved by the use of the means according to the present invention to store electricity or to stabilize an electrical power network grid.

[0115] In a further embodiment, the problem according to the present invention is solved by a method for storing electricity, characterized in that the means according to the present invention is charged with electricity.

[0116] Preferably, the voltage for charging the means according to the present invention is in a range from 1.6 to 2.9 V per unit cell.

Example 1: the Paper

[0117] A paper coating composition with the following ingredients was prepared in an otherwise usual manner:

TABLE-US-00001 TABLE 1 air oven Solids dry dry content kg kg in % Water 162.5 0 0 CMC 0.9 0.8 90 (Carboxymethylcellulose) Calypso 78 (Kaolin) 67.2 40 59.5 PAK1000 (activated 52.6 50 95 carbon) Litex 9740 (styrene 14.0 7 50 butadiene binder) Luvitec K30 (PVP- 2.1 2 97 binder) Sterocoll XT (thickener) 0.7 0.2 27 Total 300.0 100 33

[0118] An alternative coating composition was prepared as follows:

TABLE-US-00002 air oven dry dry Solid kg kg content % Water 152.1 0 0 Calypso 78 (Kaolin) 90.8 54 59.5 PAK 1000 (activated carbon) 37.9 36 95 Litex 9740 (styrene 17.2 8.6 50 butadiene binder) Daicol (guar gum) 1.3 1.2 90 Sterocoll XT (thickener) 0.7 0.2 27 Total 300.0 100 33

[0119] The resulting aqueous coating composition had a solid content of 34%, viscosity of 380 mPas (measured with a Haake Viscotester C with the conditions mentioned above), a water retention of 150 g/m.sup.2 and could be coated on an industrial coating machine.

[0120] Base paper with a substance of 38.7 g/m.sup.2 (with 4% moisture, also comprising 0.65 wt. % PAAE based on the dry paper mass) was coated with this coating composition on a pilot coating machine with a width of 0.5 m using a roll applicator for pre-coating and a jet coater for top-coating. The coating was applied only on one side. The paper was satinated in two-nips of a pilot calender at a temperature of 120 C. and a pressure of 300 kN/m. The coating had a weight of 20 g/m.sup.2*. After drying in the oven, the total weight was 58.2 g/m.sup.2.

Example 2: Energy Storage Device of Zinc-Ion Hybrid Super Capacitors

[0121] This example is related to an energy storage device of zinc-ion hybrid super capacitors, in which one sheet of the activated carbon/clay loaded paper based material of example 1, Zn metal foil and ZnSO.sub.4 aqueous solution serve as cathode, anode and electrolyte, respectively.

[0122] Reversible ion adsorption/desorption on the activated carbon/clay loaded paper based materials cathode and Zn.sup.2+ deposition during charging and stripping during discharging on a Zinc foil anode enabled the device to repeatedly and rapidly store and deliver electrical energy, with a capacity of 121 mAh g.sup.1 (corresponding to an energy of 84 Wh kg.sup.1), a very large power output of 14.9 kW kg.sup.1 and an estimated cycling stability with 91% capacity retention over 10000 cycles.

[0123] The paper of example 1 was used as a cathode and supported with stainless steel mesh as current collector. Zinc metal foil possessing a thickness of 20 m was purchased from Sigma Aldrich and directly used as anode electrode. The paper cathode//ZnSO.sub.4 (aq)//Zn anode energy storage devices were assembled with electrolyte of 2 M ZnSO.sub.4 aqueous solution, separator of two layers of air-laid paper (between the cathode and the anode) and a CR2032 coin battery shell. Cyclic voltammetry (CV) and Galvanostatic charge-discharge (GCD) techniques were applied to evaluate electrochemical behaviors of the energy storage devices. The tests were performed on an EG and G Princeton 273 potentiostat. In the CV tests with a voltage range of 0.21.8 V, the start voltage was set as 0.2 V, and then the voltage increased to 1.8 V and decreased to 0.2 V subsequently. Cycling stability was estimated after rate capability tests (i.e., charge/discharge for 5 cycles at each current of 0.1, 0.2, 0.5, 1, 2, 5, 10 and 20 A g.sup.1).

[0124] CV curves showed that the energy storage system was rechargeable and able to work in a voltage range of 0.2-1.8 V (in a wider voltage range, e.g., 0.1-1.9 V, generation of oxygen and hydrogen occurs).

[0125] For the system, the CV curves did not display severe deformation at large scan rates (e.g., 200-1000 mV s.sup.1), implying that the system possesses rapid kinetics during electrochemical reactions and therefore fast energy storage.

[0126] A GCD technique was applied to measure capacity, energy density and power output of the system. At current density of 0.1 A g.sup.1, discharge capacity and energy density of the system (calculated based on cathode mass, which is 0.7-0.8 mg cm.sup.2) was 121 mAh g.sup.1 and 84 Wh kg.sup.1, respectively. In addition, the system was rapidly charged/discharged within 15 seconds at a current of 20 A g.sup.1, and in this case, discharge capacity still reached 41 mAh g.sup.1, accompanying with a very high power output of 14.9 kW kg.sup.1 and an energy of 30 Wh kg.sup.1.

[0127] A safe, environmentally friendly, high-rate and long-life rechargeable energy storage system was produced. Environmental safety was suggested by the utilization of nontoxic electrode materials and aqueous electrolyte. The working voltage was in the range of 0.2-1.8 V and it was capable of delivering a high capacity of 121 mAh g.sup.1, a large energy density of 84 Wh kg.sup.1 and power density of 14.9 kW kg.sup.1.

[0128] The device possessed good rate capability and was charged and discharged very quickly within 15 seconds. The cycling stability was expected to be 91% capacity retention over 10000 cycles. Reversible ion adsorption/desorption on AC cathode and Zn.sup.2+ deposition/stripping on Zn anode were considered to be the core mechanism for energy storage.

Example 3 Energy Storage Device of Zinc-Ion Hybrid Super Capacitors

[0129] This example is related to an energy storage device of zinc-ion hybrid super capacitors, in which activated carbon/clay loaded paper-based materials, Zn metal foil and ZnSO.sub.4 aqueous solution serve as cathode, anode and electrolyte, respectively.

[0130] A highly reversible aqueous Zn/MnO.sub.2 battery with a the MnO.sub.2 cathode was fabricated by in situ electrodeposition of MnO.sub.2 onto the carbon component of the device from example 2 in mild acidic ZnSO.sub.4+MnSO.sub.4 electrolyte yielding the new storage device (Zn/MnO.sub.2 battery) that required no modification to production procedures, an addition to existing electrolyte of example 2 of MnSO.sub.4 and a forming process.

[0131] Rechargeable aqueous Zn/MnO.sub.2 battery chemistry in a neutral or mildly acidic electrolyte are attractive because all the components (anode, cathode, and electrolyte) in a Zn/MnO.sub.2 battery are safe, abundant, and sustainable. Electrochemical and structural analysis identify that the MnO.sub.2 cathode experiences a consequent H+ and Zn.sup.2+ insertion/extraction process with high reversibility and cycling stability.

[0132] The Zn/MnO.sub.2 battery delivered a cycling performance with a low capacity decay rate of 0.007% per cycle for 10 000 cycles at a high rate of 6.5 C.

[0133] The device showed a stable capacity of 50-70 mAh g.sup.1 for 10 000 cycles, reaching a high Coulombic efficiency of nearly 100%.

[0134] The Zn/MnO.sub.2 battery achieved a discharge capacity of 290 mAh g.sup.1 at a current density of 90 mA g.sup.1 between 1.0 and 1.8 V in 2 M ZnSO.sub.4+0.2 M MnSO.sub.4 electrolyte, which was considered as the maximum discharge capacity to define 1 C rate as 290 mA g.sup.1. And the discharge curves in both the first and second cycle showed sloping plateaus at 1.4 V followed with the long flat plateau at around 1.3 V. The overpotential difference was quite small during the first two cycles.

[0135] The features of the invention disclosed in the present description as well as in the claims can be essential for the realization of the invention in its various embodiments, both individually and in any combination. The invention is not limited to the described embodiments. It can be varied within the scope of the claims and taking into account the knowledge of the person skilled in the art.

[0136] The highly reversible Zn/MnO.sub.2 battery using in situ deposited MnO.sub.2 on the carbon component of the activated carbon/clay loaded paper based material that formed the cathode was working stable up to 10 000 cycles at 6.5 C with a low capacity decay rate of 0.007% per cycle and a stable capacity of 50-70 mAh g.sup.1 for 10 000 cycles, reaching a high Coulombic efficiency of nearly 100%. The in situ formed Zn/MnO.sub.2 battery simplified the battery fabrication process and reduced cost.