kinetics), and to more effectively pack active material par› ticles in the pores of the foamed current collectors. 

[0221] Shown in FIG. 10 are Ragone plots of sodium metal batteries containing a sodium foil as the anode active material, disodium rhodizonate (Na$_{2}$C$_{6}$O$_{6}$ ) as the cathode active material, and lithium salt (NaPF $_{6}$)-PC/DEC as organic liquid electrolyte. The data are for both sodium metal cells prepared by the presently invented method and those by the conventional slurry coating of electrodes. These data indicate that both the gravimetric and volumetric energy densities and power densities of the sodium metal cells prepared by the presently invented method are signifi› cantly higher than those of their counterparts prepared via the conventional method. Again, the differences are huge and are likely due to the significantly higher active material mass loading associated with the presently invented cells, reduced proportion of overhead (non-active) components relative to the active material weight/volume, no need to have a binder resin, surprisingly better utilization of the electrode active material (most, if not all, of the active material contributing to the sodium ion storage capacity; no dry pockets or ineffective spots in the electrode, particularly under high charge/discharge rate conditions), and the sur› prising ability of the inventive method to more effectively pack active material particles in the pores of the foamed current collector. 

[0222] Quite noteworthy and unexpected is the observa› tion that the gravimetric energy density of the presently invented sodium metal-organic cathode cell is as high as 310 Wh/kg, higher than those of all rechargeable sodium metal or sodium-ion batteries ever reported (recall that current Na-ion batteries typically store 100-150 Wh/kg based on the total cell weight). Furthermore, for organic cathode active material-based sodium batteries (even for corresponding lithium batteries), a gravimetric power density of 1,250 W/kg and volumetric power density of 2,508 W/L would have been un-thinkable. 

[0223] It is of significance to point out that reporting the energy and power densities per weight of active material alone on a Ragone plot, as did by many researchers, may not give a realistic picture of the performance of the assembled battery cell. The weights of other device components also must be taken into account. These overhead components, including current collectors, electrolyte, separator, binder, connectors, and packaging, are non-active materials and do not contribute to the charge storage amounts. They only add weights and volumes to the device. Hence, it is desirable to reduce the relative proportion of overhead component weights and increase the active material proportion. How› ever, it has not been possible to achieve this objective using conventional battery production processes. The present invention overcomes this long-standing, most serious prob› lem in the art of lithium batteries. 

[0224] In commercial lithium-ion batteries having an elec› trode thickness of 150 µm, the weight proportion of the anode active material (e.g. graphite or carbon) in a lithium› ion battery is typically from 12% to 17%, and that of the cathode active material (for inorganic material, such as LiMn$_{2 }$0 $_{4}$ ) from 22% to 41 %, or from 10% to 15% for organic or polymeric. The corresponding weight fractions in Na-ion batteries are expected to be very similar since both the anode active materials and cathode active materials have similar physical densities between two types of batteries and the ratio of cathode specific capacity to the anode specific 

capacity is also similar. Hence, a factor of3 to 4 may be used to extrapolate the energy or power densities of the sodium cell from the properties based on the active material weight alone. In most of the scientific papers, the properties reported are typically based on the active material weight alone and the electrodes are typically very thin (<<100 µm and mostly <<50 µm). The active material weight is typi› cally from 5% to 10% of the total device weight, which implies that the actual cell (device) energy or power densi› ties may be obtained by dividing the corresponding active material weight-based values by a factor of 10 to 20. After this factor is taken into account, the properties reported in these papers do not really look any better than those of commercial batteries. Thus, one must be very careful when it comes to read and interpret the performance data of batteries reported in the scientific papers and patent appli› cations. 

[0225] The Ragone plot of a series of K-ion cells prepared by the conventional slurry coating process and the Ragone plot of corresponding K-ion cells prepared by the presently invented process are summarized and contrasted in FIG. 11. These data again confirm that the presently invented process works well for making both Na and K metal batteries having ultra-high energy densities and power densities. Similarly, lithium-ion capacitors or sodium-ion capacitors prepared according to the instant process also deliver a higher energy density and higher power density. 

We claim: 

1. A process for producing an electrochemical cell, said process comprising: 

(A) continuously depositing a wet cathode active material mixture onto at least a surface of a cathode current collector to form a wet cathode electrode, wherein said wet cathode active material mixture contains 30% to 85% by volume of a cathode active material and 0% to 15% by volume of a conductive additive dispersed in a first liquid or polymer gel electrolyte; 

(B) continuously depositing a wet anode active material mixture onto at least a surface of an anode current collector to form a wet anode electrode, wherein said wet anode active material mixture contains 30% to 85% by weight of an anode active material and 0% to 15% by volume of a conductive additive dispersed in a second liquid or polymer gel electrolytes; and 

(C) combining said wet cathode electrode or a portion thereof and said wet anode electrode or a portion thereof to form said electrochemical cell; 

wherein said anode electrode and/or said cathode elec› trode has a thickness from 200 µm to 3,000 µm. 

2. The process of claim 1, wherein step (A) includes delivering, continuously or intermittently on demand, said wet cathode active material mixture to said at least a surface through spraying, printing, coating, casting, conveyor film delivery, and/or roller surface delivery; and/or wherein step (B) includes delivering, continuously or intermittently on demand, said wet anode active material mixture to said at least a surface through spraying, printing, coating, casting, conveyor film delivery, and/or roller surface delivery. 

3. A process for producing an electrochemical cell, said process comprising: 

(A) continuously depositing a first wet electrode active material mixture onto at least a surface of a first current collector to form a first wet electrode, wherein said first wet electrode active material mixture contains a first 

