There is a lot of research happening every day in the lithium battery sector to achieve increasingly higher performance and longer life, as well as shortening the charging time and ensuring greater range and power. As far as electric mobility is concerned, solid-state batteries may seem like the future's final frontier. Lithium-ion batteries use liquid electrolytes, while solid-state batteries use solid electrolytes.
Solid-state cells have a much different internal structure, as they are all solid. Solid-state batteries have liquid electrolytes, while traditional lithium batteries have liquid electrolytes:
- Typical cathode materials are LiFP, NMC, LMO, etc., which form the same positive electrode as a lithium-ion battery.
- As well as serving as the electrolyte, ceramics or solid polymers act as separators
- It contains lithium metal (pure lithium) as its anode
Solid-state separators like the gray central layer interact with the electrolyte and function as both separators and electrolytes. In addition to providing an electrical insulator and functioning as a mechanical separator between the anode and cathode, it is also a medium through which the ions move. This solid, resistant support allows the graphite structure on the anode to be removed, allowing lithium metal to accumulate directly on the anode. (Alternatively, semi-solid electrolytes can be used.)
What is the process of making a solid-state battery?
Lithium particles move between the cathode and anode's electrical contact when the cell is charging. They then move into the separator itself and create a solid layer of lithium. A lithium-ion technology anode, which contains graphite, will therefore have a smaller volume since it will only be composed of lithium particles. Solid-state batteries have the following advantages:
Safety is the most important factor
Unlike lithium-ion batteries, solid-state batteries don't contain a liquid electrolyte, which is volatile and therefore more flammable and is one of the most challenging safety components. This is replaced by a thicker separator layer made of a mechanically more resistant material (a ceramic composition containing additives); this increases the intrinsic safety of the cells by preventing short circuits even when the cells are misused or deteriorated, making them more reliable. Dendrites or sharp build-up of lithium that form between the cathode and anode are also less likely to form with this type of electrode. Lithium movement isn't uniform, and, in some extreme cases, it can pierce the separator due to points that grow like pins. A solid separator, on the other hand, is more resistant to dendrite piercing, which is what reduces the possibility of short circuits and gradual cell deterioration.
The highest density of energy
An anode made from pure metal can increase energy density by a significant amount due to its intrinsic safety. Lithium-ion batteries generally contain ions in the graphite anode, which can be removed by using metal anodes. As part of the transfer process, only the ions remain in a solid-state battery, and bulky, heavy compounds are removed that do not contribute to energy generation.
Recent studies have shown that solid-state batteries have an energy density that is 2-2.5 times greater than current lithium-ion battery technology, which would result in lighter and smaller batteries. We won't be able to be certain of the exact number until this technology becomes officially available, but we can be sure it would benefit electric mobility, which would benefit from a longer range and lighter weight.
Ultra-fast charge times
Compared to current technologies, solid-state batteries can charge up to 6 times faster than current technology. In addition, it is uncertain how this new technology will develop and how it will impact this number. Several prototype solid-state batteries are already available that charge very quickly but at the expense of other factors that make up a good performance. To assess the best alternative, including in terms of cost, we must weigh this advantage against other essential characteristics of these batteries.
The current consensus is that liquid electrolytes tend to be less efficient at high temperatures, while solid electrolytes respond better at high temperatures, as evidenced by their performance during fast charging, which has a much higher temperature.
Production is faster
The solid-state electrolyte theory, while understandable, has yet to be proved and will be done when this technology is truly mass-produced. This theory, while understandable, has yet to be proven as it is not liquid, thus allowing for a faster, easier production process.
In the present, however, we can certainly say that the process of filling the cell with electrolyte requires a great deal of time: you must begin by assembling the cell with an empty electrolyte space, and then, upon absorbing the electrolyte, you must refill it to restore it to the proper level before it can be sealed. As a result, solid-state technology could potentially contribute to a real improvement in this phase of the production process, but the actual production of this type of cell is needed before drawing sound conclusions.
How many solid-state batteries are there?
Could we all drive cars with solid-state batteries if we wanted to? A solid-state battery is also expensive, due partly to development costs but also to the difficulty of manufacturing on a large scale, which makes them expensive like other emerging technologies. Until solid-state batteries are ready for prime time, automakers and battery manufacturers still have a long way to go. Although solid electrolytes are advantageous over liquids, finding the right balance of materials for powering a car's electric motor is challenging.
The development of solid-state batteries is still in its infancy. Several other automakers are partnering with battery companies on their own projects to develop solid-state batteries, while Toyota plans to sell its first EV by 2030. A California-based company called QuantumScape has partnered with Volkswagen to develop battery technology that will be commercially available by 2024.
Solid-state battery research and development
Pure Silicone Anode Solid-State Battery
A new rechargeable solid-state battery is being developed by engineers at the University of California San Diego in partnership with LG Energy Solution. Anode and electrolyte are combined in a single device, replacing lithium and carbon completely.
During testing, the battery proved to be safe, durable, and highly energy-efficient. At room temperature, the prototype retained 80% capacity after 500 charge and discharge cycles. As a result of the technology, electric transportation, energy storage, and other fields have great prospects.
MIT's New Electrode Design
Mixed-ion-electronic conductors (MIECs) have also been developed at MIT, as well as lithium-ion insulators and electronic conductors. In this case, MIEC tubes are nanoscale and arranged in a honeycomb structure. Lithium forms the anode of the tubes.
A major discovery of this study was that lithium expands and contracts during charging and discharging because of its honeycomb structure. Battery cracks are prevented by this breathing of the anode. Tubes are protected from the solid electrolyte by the coating on their surfaces. By preventing liquids and gels from injecting into the battery, dendrites are eliminated.
Future Outlooks for Solid-State Batteries
Solid-state batteries have been seen as an important step in the development of electric vehicles for some time. Their lighter weight, greater energy storage, and reduced flammability make them a superior choice over liquids. There were two major obstacles to this development until recently - the cost of these batteries and their durability.
Furthermore, solid-state batteries are prone to chemical defects. It is because of tiny lithium dendrites, twig-like particles of lithium that form and grow inside the battery that they begin to degrade after a few charge/discharge cycles. This leads to short circuits and other problems.
Conclusion
Despite a few problems that need to be resolved, solid-state batteries are poised to enter the market soon and can be expected to be used widely in fields where energy density is a limiting factor because space does not allow them to store all the energy needed. As solid-state batteries have twice the energy density, they will double the range and are now viewed as the future of all transportation, including the automotive industry.
Both the industrial machinery and electric vehicle sectors are interested in how this new technology can be implemented: this is true for equipment that requires a lot of energy or a large range but whose volume is currently small compared to the energy it can generate.
It is certainly possible to expand the category of electrified vehicles through the introduction of solid-state battery technology. Solid-state cells could undoubtedly be a viable path to the future of industrial electrification if, in addition to their high energy density, they became competitive on all fronts.
