Thin-film lithium-ion battery
The thin film lithium-ion battery is a form of
Thin-film construction could lead to improvements in
Background
In a thin-film lithium battery the electrolyte is solid and the other components are deposited in layers on a
Components of thin film battery
Cathode materials
Cathode materials in thin film lithium ion batteries are the same as in classical lithium ion batteries. They are normally metal oxides that are deposited as a film by various methods.
Metal oxide materials are shown below as well as their relative specific capacities (Λ), open circuit voltages (Voc), and energy densities (DE).
Λ(Ah/kg) | VOC(V) | DE(Wh/kg) | |
---|---|---|---|
LiCoO2 | 145 | 4 | 580 |
LiMn2O4 | 148 | 4 | 592 |
LiFePO4 | 170 | 3.4 | 578 |
DE = Λ VOC |
Λ: capacity (mAh/g) |
VOC: Open circuit potential |
Deposition methods for cathode materials
There are various methods being used to deposit thin film cathode materials onto the current collector.
Pulsed Laser Deposition
In
Magnetron Sputtering
In Magnetron Sputtering the substrate is cooled for deposition.
Chemical Vapor Deposition
In
Sol-Gel Processing
Electrolyte
The greatest difference between classical lithium ion batteries and thin, flexible, lithium ion batteries is in the
Separator Material
Separator materials in lithium ion batteries must not block the transport of lithium ions while preventing the physical contact of the anode and cathode materials, e.g. short-circuiting. In a liquid cell, this separator would be a porous glass or polymer mesh that allows ion transport via the liquid electrolyte through the pores, but keeps the electrodes from contacting and shorting. However, in a thin film battery the electrolyte is a solid, which conveniently satisfies both the ion transportation and the physical separation requirements without the need for a dedicated separator.
Current Collector
Current collectors in thin film batteries must be flexible, have high surface area, and be cost-effective. Silver nanowires with improved surface area and loading weight have been shown to work as a current collector in these battery systems, but still are not as cost-effective as desired. Extending graphite technology to lithium ion batteries, solution processed
Advantages and challenges
Thin film lithium ion batteries offer improved performance by having a higher average output voltage, lighter weights thus higher energy density (3x), and longer cycling life (1200 cycles without degradation) and can work in a wider range of temperatures (between -20 and 60 °C)than typical rechargeable lithium-ion batteries.
Li-ion transfer cells are the most promising systems for satisfying the demand of high specific energy and high power and would be cheaper to manufacture.
In the thin film lithium ion battery, both electrodes are capable of reversible lithium insertion, thus forming a Li-ion transfer cell. In order to construct a thin film battery it is necessary to fabricate all the battery components, as an anode, a solid electrolyte, a cathode and current leads into multi-layered thin films by suitable technologies.
In a thin film based system, the electrolyte is normally a solid electrolyte, capable of conforming to the shape of the battery. This is in contrast to classical lithium ion batteries, which normally have liquid electrolyte material. Liquid electrolytes can be challenging to utilize if they are not compatible with the separator. Also liquid electrolytes in general call for an increase in the overall volume of the battery, which is not ideal for designing a system that has high energy density. Additionally, in a thin film flexible Li-ion battery, the electrolyte, which is normally polymer-based, can act as the electrolyte, separator, and binder material. This provides the ability to have flexible systems since the issue of electrolyte leakage is circumvented. Finally, solid systems can be packed together tightly which affords an increase in energy density when compared to classical liquid lithium ion batteries.
Separator materials in lithium ion batteries must have the ability to transport ions through their porous membranes while maintaining a physical separation between the anode and cathode materials in order to prevent short-circuiting. Furthermore, the separator must be resistant to degradation during the battery’s operation. In a thin film Li-ion battery, the separator must be a thin and flexible solid. Typically today, this material is a polymer-based material. Since thin film batteries are made of all solid materials, allows one to use simpler separator materials in these systems such as Xerox paper rather than in liquid based Li-ion batteries.
Scientific development
Development of thin solid state batteries allows for roll to roll type production of batteries to decrease production costs. Solid-state batteries can also afford increased energy density due to decrease in overall device weight, while the flexible nature allows for novel battery design and easier incorporation into electronics. Development is still required in cathode materials which will resist capacity reduction due to cycling.
Prior Technology | Replacement Technology | Result |
---|---|---|
Solution based electrolyte | Solid state electrolyte | Increased safety and cycle life |
Polymer separators |
Paper separator | Decreased cost increased rate of ion conduction |
Metallic current collectors | Carbon nanotube current collectors | Decreased device weight, increased energy density |
Graphite anode | Carbon nanotube anode | Decreased device complexity |
Makers
Applications
The advancements made to the thin film lithium ion battery have allowed for many potential applications. The majority of these applications are aimed at improving the currently available consumer and medical products. Thin film lithium ion batteries can be used to make thinner portable electronics, because the thickness of the battery required to operate the device can be reduced greatly. These batteries have the ability to be an integral part of implantable medical devices, such as
Renewable energy storage devices
The thin film lithium ion battery can serve as a storage device for the energy collected from renewable sources with a variable generation rate, such as a solar cell or wind turbine. These batteries can be made to have a low self discharge rate, which means that these batteries can be stored for long periods of time without a major loss of the energy that was used to charge it. These fully charged batteries could then be used to power some or all of the other potential applications listed below, or provide more reliable power to an electric grid for general use.
Smart cards
Radio frequency identification tags
Radio-frequency identification tags can be used in many different applications. These tags can be used in packaging, inventory control, used to verify authenticity and even allow or deny access to something. These ID tags can even have other integrated sensors to allow for the physical environment to be monitored, such as temperature or shock during travel or shipping. Also, the distance required to read the information in the tag depends on the strength of the battery. The farther away you want to be able to read the information, the stronger the output will have to be and thus the greater the power supply to accomplish this output. As these tags get more and more complex, the battery requirements will need to keep up. Thin film lithium ion batteries have shown that they can fit into the designs of the tags because of the flexibility of the battery in size and shape and are sufficiently powerful enough to accomplish the goals of the tag. Low cost production methods, like roll to roll lamination, of these batteries may even allow for this kind of radio frequency identification technology to be implemented in disposable applications.[3]
Implantable Medical Devices
Implantable medical devices require batteries that can deliver a steady, reliable power source for as long as possible. These applications call for a battery that has a low self-discharge rate, for when it’s not in use, and a high power rate, for when it needs to be used, especially in the case of an implantable
Wireless Sensors
Wireless sensors need to be in use for the duration of their application, whether that may be in package shipping or in the detection of some unwanted compound, or controlling inventory in a warehouse. If the wireless sensor cannot transmit its data due to low or no battery power, the consequences could potentially be severe based on the application. Also, the wireless sensor must be adaptable to each application. Therefore the battery must be able to fit within the designed sensor. This means that the desired battery for these devices must be long-lasting, size specific, low cost, if they are going to be used in disposable technologies, and must meet the requirements of the data collection and transmission processes. Once again, thin film lithium ion batteries have shown the ability to meet all of these requirements.
See also
References
- ^ Jones, Kevin S.; Rudawski, Nicholas G.; Oladeji, Isaiah; Pitts, Roland; Fox, Richard (March 2012). "The state of solid-state batteries" (PDF). American Ceramic Society Bulletin. 91 (2).
...an alternative to the typical liquid-based LIBs has been actively pursued during the past 20 years. This alternative uses a solid-state electrolyte and, thus, is termed a solid-state or thin-film battery.
- PMID 27933836.
- ^ PMID 20836501.
- .
- ^ "Thin-Film Rechargeable Li-Ion Batteries". Solid State Division of Oak Ridge National Lab. 1995.
- .
- ^ "Laminated Type Lithium Ion Secondary Batteries". Murata Manufacturing. Retrieved November 11, 2022.
- ^ "Solid state thin-film lithium battery systems". Solid State & Materials Science: 479–482. 2008.
- ^ The Electrochemical Society Interface. 4: 44–48. 2008.
- ^ "Smart Cards". www.excellatron.com. Archived from the original on December 7, 2004. Retrieved 14 May 2023.
- .