Digital Manufacturing of Lithium-Ion Battery Utilizing Inkjet Technology
Background
There are demands for the automotive industry to promote the spread of electric vehicles to realize a decarbonized society and there are also demands for the spread of highly convenient devices to improve our quality of life. Lithium-ion batteries will play an important role in the advancement of both of these demands.
For example, it is essential that lithium-ion batteries for automotive use realize a longer cruising range, ensure higher safety to prevent ignition, and result in lower costs.
Batteries installed in an electric vehicle
Battery installed in a drone
Solutions
There are expectations for innovative digital manufacturing processes that combine the use of ink created by applying advanced dispersion techniques and the inkjet technology that has been cultivated over many years. It is expected that these processes will contribute to improved lithium-ion battery performance, greater automation of the production lines, and reduced environmental impact and material costs due to lower material losses.
Technical highlights
In addition to developing battery material inks suitable for inkjet printing and inkjet printheads suitable for battery materials, we have also developed equipment to realize mass production, so it has become possible to perform digital printing at any position, with any film thickness, and in any shape.
- It is possible to print with high precision in a target location
- The non-contact process has little impact on the substrate
- High-density nozzles eject micro-droplets (in pL units) at high speed
- The film thickness is highly uniform
- The printheads can be lined up to support higher speeds and wider widths
Digital data use for the printing of any pattern
The non-contact printing of micro-droplets
Micron-order film thickness control
Wider processing with printhead parallelization
1. Development of battery material ink suitable for inkjet printing
Conventional battery manufacturing includes the application of a coat of high-viscosity paste mixed with ceramic battery materials. We have completely renewed this processing by developing original low-viscosity inks that are suitable for inkjet printing. We are working to create inks for various applications, such as for the main electrode materials on the market, special separators, ceramics that add functionality, and solid electrolytes.
Ceramic ink
- The desired amount of ceramic ink can be printed anywhere on the battery configuration
- When there is abnormal heat generation, a printed ceramic layer acts as a resistance layer and improves safety
- A lineup of quick-drying inks helps customers reduce drying takt time
Sensing technology enables printing at any position
In the event of abnormal heat generation, such as due to an external shock, the ceramic ink acts as a resistance layer that improves safety
Quick-drying ink reduces drying takt time
Separator ink
- Printing highly heat-resistant separators anywhere on the electrodes or porous layers helps improve the battery productivity and safety
- Good battery performance is realized with a 3D mesh structure, the optimal design of porosity and hole sizes, and high electrolyte affinity
- The integrated formation of the separator with the electrode improves productivity by halving the number of layers processed and contributes to yield improvement reducing misalignment
Conceptual image of the roll-to-roll manufacturing process
High heat resistance (160°C or higher)
Cycle characteristics of the printed separator (the product developed)
Increased productivity and yield
Solid electrolyte ink
- Using inkjet technology to print the solid electrolyte layers on all-solid-state batteries, the promising next-generation battery
- The non-contact printing that is a characteristic of the inkjet process enables the printing of highly smooth thin films of solid electrolytes without damaging the substrate
- It is possible to perform remote operation using digital control that contributes to the construction of a minimal-sized dry atmosphere environment, which is the environment required for solid electrolytes
Higher energy density is realized with a thinner solid electrolyte layer
Thin-film printing of the solid electrolyte layer
Solid electrolyte ink
2. Development of inkjet printheads suitable for battery materials
The production of lithium-ion batteries with increasingly high capacities means that the electrode layer is becoming thicker. However, for the materials that do not contribute to battery capacity, such as separators, there are demands for thinner films. As printheads for battery materials, Ricoh has developed both printheads that support thicker films and printheads that support thinner films, and these are in use for battery manufacturing using inkjet technology.
Printhead for thin films and printhead for thick films
3. Development of equipment for mass production
One requirement for lithium-ion battery production lines is stable operation. Ricoh fully utilizes the inkjet technologies it has developed so far to achieve the production stability and reliability required for mass production lines.
Roll-to-roll inkjet (IJ) mass production equipment
Ricoh's vision
The inkjet technology that Ricoh has cultivated over many years is not limited to printing on paper and non-paper media as “display printing.” It also extends to “functional printing,” where new value is created by combining printing-related materials and process technologies.
This technology is an initiative that has realized “functional printing” by digitally printing functional materials to manufacture lithium-ion batteries. We will continue to provide new value for the manufacturing of lithium-ion batteries, which will become increasingly diversified in the future.