[0077] In other words, there are several conflicting factors that must be considered concurrently when it comes to the design and selection of a cathode or anode active material in terms of material type, size, electrode layer thickness, and active material mass loading. Thus far, there has been no effective solution offered by any prior art teaching to these often conflicting problems. We have solved these challeng› ing issues, which have troubled battery designers and elec› trochemists alike for more than 30 years, by developing a new process of producing lithium batteries as herein dis› closed. 

[0078] The prior art lithium battery cell is typically made by a process that includes the following steps: (a) The first step includes mixing particles of the anode active material ( e.g. Si nano particles or mesa-carbon micro-beads, MCMBs), a conductive filler (e.g. graphite flakes), a resin binder ( e.g. PVDF) in a solvent ( e.g. NMP) to form an anode slurry. On a separate basis, particles of the cathode active material (e.g. LFP particles), a conductive filler (e.g. acety› lene black), a resin binder (e.g. PVDF) are mixed and dispersed in a solvent ( e.g. NMP) to form a cathode slurry. (b) The second step includes coating the anode slurry onto one or both primary surfaces of an anode current collector (e.g. Cu foil), drying the coated layer by vaporizing the solvent ( e.g. NMP) to form a dried anode electrode coated on Cu foil. Similarly, the cathode slurry is coated and dried to form a dried cathode electrode coated on Al foil. Slurry coating is normally done in a roll-to-roll manner in a real manufacturing situation; (c) The third step includes lami› nating an anode/Cu foil sheet, a porous separator layer, and a cathode/Al foil sheet together to form a 3-layer or 5-layer assembly, which is cut and slit into desired sizes and stacked to form a rectangular structure (as an example of shape) or rolled into a cylindrical cell structure. ( d) The rectangular or cylindrical laminated structure is then encased in an alumi› num-plastic laminated envelope or steel casing. ( e) A liquid electrolyte is then injected into the laminated structure to make a lithium battery cell. 

[0079] There are several serious problems associated with the conventional process and the resulting lithium-ion bat› tery cell or sodium-ion cell: 

[0080] 1) It is very difficult to produce an electrode layer (anode layer or cathode layer) that is thicker than 200 µm (100 µm on each side of a solid current collector, such as Cu or Al foil). There are several reasons why this is the case. An electrode of 100 µm in thickness typically requires a heating zone of 50-100 meters long in a slurry coating facility, which is too time consuming, too energy intensive, and not cost› effective. For some electrode active materials, such as metal oxide particles, it has not been possible to pro› duce an electrode of good structural integrity that is thicker than 100 µmin a real manufacturing environ› ment on a continuous basis. The resulting electrodes are very fragile and brittle. Thicker electrodes have a high tendency to delaminate and crack. 

[0081] 2) With a conventional process, as depicted in FIG. l(A), the actual mass loadings of the electrodes and the apparent densities for the active materials are too low to achieve a gravimetric energy density of>200 Wh/kg. In most cases, the anode active material mass loading of the electrodes (areal density) is significantly lower than 25 mg/cm $^{2 }$and the apparent volume density or tap density of the active material is typically less 

than 1.2 g/cm 3 even for relatively large particles of graphite. The cathode active material mass loading of the electrodes (areal density) is significantly lower than 45 mg/cm 2 for lithium metal oxide-type inorganic materials and lower than 15 mg/cm 2 for organic or polymer materials. In addition, there are so many other non-active materials ( e.g. conductive additive and resin binder) that add additional weights and volumes to the electrode without contributing to the cell capacity. These low areal densities and low volume densities result in relatively low gravimetric energy density and low volumetric energy density. 

[0082] 3) The conventional process requires dispersing dry electrode active materials (anode active material or cathode active material) in a liquid solvent ( e.g. NMP) to make a slurry and, upon coating on a current collector surface, the liquid solvent has to be removed to dry the electrode layer. Once the anode and cathode layers, along with a separator layer, are laminated together and packaged in a housing to make a battery or supercapacitor cell, one then injects a liquid elec› trolyte into the cell. In actuality, one makes the two electrodes wet, then makes the electrodes dry, and finally makes them wet again. Such a wet-dry-wet process is clearly not a good process at all. 

[0083] 4) Current lithium-ion batteries still suffer from a relatively low gravimetric energy density and low volumetric energy density. Commercially available lithium-ion batteries exhibit a gravimetric energy den› sity of approximately 150-250 Wh/kg and a volumetric energy density of 450-650 Wh/L. 

[0084] In literature, the energy density data reported based on either the active material weight alone or the electrode weight cannot directly translate into the energy densities of a practical battery cell or device. The "overhead weight" or weights of other device components (binder, conductive additive, current collectors, separator, electrolyte, and packaging) must also be taken into account. The convention production process results in the weight proportion of the anode active material (e.g. graphite or carbon) in a lithium-ion battery being typically from 12% to 17%, and that of the cathode active material ( e.g. LiMn$_{2}$ 0 4 ) from 20% to 35%. 

[0085] The present invention provides a process for pro› ducing an electrode of an electrochemical cell ( e.g. alkali metal battery cell) having a high electrode thickness, high active material mass loading, low overhead weight and volume, high volumetric capacitance, and high volumetric energy density. In addition, the manufacturing costs of the batteries produced by the presently invented process are significantly lower than those by conventional processes. 

[0086] In some embodiments of the present invention, as illustrated in FIG. l(C), the invented process comprises continuously feeding an electrically conductive current col› lector 304 (e.g. Cu foil or Al foil) from a feeder roller (302, into an active material mixture deposition zone where a wet active material mixture 308 ( e.g. slurry, suspension, or polymer gel-like mass) of an electrode active material, a conductive additive, and a liquid or polymer gel electrolyte is delivered and deposited onto a surface of the current collector 308 to form a layer of wet electrode 310 thereon; basically a coating or casting procedure ( e.g. using a coating head 306). 

