All solid state batteries, as a new type of battery technology, have received widespread attention and research in recent years. Compared to traditional liquid state batteries, all solid state batteries have higher energy density, faster charging and discharging speeds, and better safety performance.
However, all solid state batteries face some challenging issues in their development, among which solving the interface issues becomes crucial, including interface side reactions and interface stability between the solid electrolyte and electrode materials. In addition, the manufacturing cost and cycle life of all solid state batteries also need to be further optimized and improved.
The application of 3D printing technology in the field of batteries
As a new manufacturing technology, 3D printing can accurately control the shape and structure from micro to macro without relying on any template, thereby improving the energy density and power density of batteries. With the rapid development of 3D printing technology, more and more researchers are trying to use 3D printing technology to prepare all solid state batteries, providing more possibilities for the mass production of solid state batteries.
Overview of 3D printed battery materials and processes
It has significant advantages in the following aspects: (1) the complex structure required for manufacturing; (2) Accurate control of electrode shape and thickness; (3) Printing solid-state electrolyte structure with high stability and safe operation; (4) Low cost, environmentally friendly, and easy to operate; (5) Eliminate device assembly and packaging steps by directly integrating batteries and other electronic products.
3D printing technology
At present, the 3D printing technologies used for solid-state batteries mainly include binder (or slurry) injection molding, powder laser sintering technology SLS, and photo curing molding SLA \ DLP.
Adhesive (or slurry) spray molding
The adhesive can be selectively sprayed onto the surface of the electrode powder on the current collector through a nozzle, and then the powder material can be bonded together to form a solid layer, layer by layer bonding, and finally forming a 3D electrode. By going back and forth two or three times, a thin layer of electrode can be bonded, and the next layer of powder can be the same material or electrolyte material. In order to achieve the manufacturing of dry electrodes or all solid state batteries, any shape of electrodes or batteries can be manufactured by continuously bonding each plane layer by layer.
Powder laser sintering technology SLS
The printing process of SLS is achieved by irradiating sintered powder materials with a high-power laser beam. The area where the laser is irradiated will quickly melt and bond into shape, while the powder that is not irradiated can still be recycled. Multiple electrode plates can be manufactured on such a printing platform.
This method, along with the binder (or slurry) spray forming technology, is expected to achieve the manufacturing of dry electrodes.
UV curing SLA/DLP
The principle is to irradiate the polymer electrolyte or organic-inorganic mixed electrolyte of solid-state batteries with ultraviolet light or light surface, making them solidify layer by layer and superimpose into shape. However, due to the incomplete development of materials, it is necessary to add some non functional photopolymerization materials, which will reduce battery performance, so the application scope is limited.
3D printing solid-state batteries
3D printing is a promising technology in the application of solid-state batteries. Due to the ability of this technology to use different types of printing materials, researchers can alter the three-dimensional structure of electrodes, electrolytes, separators, and stacking in batteries.
Positive electrode design
The use of 3D printing technology can design positive electrode materials for lithium batteries, achieving controllable transformation from two-dimensional electrodes to three-dimensional electrodes, improving electrode surface activity, shortening ion transport distance, and achieving high load positive electrode preparation. In addition, the controllability of the thickness of the positive electrode material can achieve adjustable quality of the active material, ultimately achieving the goal of high energy density and high power density lithium batteries.
3D printing battery positive and negative electrodes
Structured negative electrode
In the application of lithium battery negative electrodes, constructing structured lithium metal negative electrodes through 3D printing can increase the specific surface area of the electrode, evenly distribute the total electric field throughout the porous electrode, achieve the goal of reducing effective current density, uniform deposition, and suppressing electrode volume expansion, thereby improving the cycling stability and safety of the battery. In addition, 3D printing technology can be used to achieve controllable printing material morphology and template design. Electrochemical deposition or melting methods can effectively control the deposition/dissolution behavior of metallic lithium, suppress lithium dendrite growth, and achieve the goal of long life cycle of lithium metal batteries, solving the problem of battery short circuits.
Diaphragm/Solid Electrolyte Design
With the continuous development of 3D printing technology, the electrolyte of batteries can also be directly printed, thereby reducing manufacturing procedures, time, and costs. However, due to limitations in air stability, sulfide and halide electrolytes may not be suitable for printing. Therefore, polymer and oxide electrolytes are a type of solid-state electrolyte that has the potential for 3D printing in all solid state batteries.
3D printing membranes can achieve rational design of membrane structure and uniform ion flux, reducing the formation of lithium dendrites. In order to achieve high ion conductivity in solid-state lithium batteries, it is usually necessary to incorporate solid electrolytes into the active material of the positive electrode. This solid-solid interface must be seamless and have sufficient flexibility to meet the geometric changes caused by the charging and discharging process. 3D printing can finely optimize the interface structure to meet the stringent solid-solid interface requirements in solid-state lithium metal batteries.
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