There has been a widespread development of the Electric Vehicle (EV) Market in recent years due to technological advances. There was about an overall number of 7.2 million EVs on the roads in 2019, which is expected to reach about 140 million by 2030. Among all different types of secondary batteries, lithium-ion batteries (LIBs) play a significant role in the profitability of EVs for their high energy densities as well as their long service lives.
Having said that, current LIBs are not cost-effective due to limited ability to provide sufficient requirements of EV advancements. As an example, by a single charging, there is a short driving range you can achieve, and the customers should spend a lot of time on charging each time. Also, to achieve acceptable performance in comparison to vehicles with an internal combustion engine, LIBs with higher power and energy densities are to be developed. Moreover, the attempt to provide more efficient and powerful LIBs have brought safety challenges with it.
The tight packing of electrodes alongside their narrow separation increases the energy densities of LIBs but also increases their explosion risk. Thus, the horrible news of LIBs explosion or combustion in mobile phones, EVs, and energy storage systems has struck dear in its consumers' heart, possibly affecting the market demand for such EVs. As a result, safe LIBs are required for the further improvement of EV performance. The liquid organic electrolyte (LE) is the component of an LIB as the sole responsible for any combustion risk due to its high volatility as well as flammability. In particular, all-solid-state batteries (ASSBs), which solid electrolytes (SEs) are used in as substitutes for LEs, are known as efficient next-generation battery systems. In addition to their nonflammable feature, SEs have several pros compared with conventional LEs.
Solid-state technology. Image Credits: https://www.saftbatteries.com/media-resources/our-stories/solid-state-technology-quest-holy-grail
Today's LIBs have a low operating temperature range because of the LE; in which the ionic conductivity of the electrolyte is decreased and performance is at stake significantly at sub-zero temperatures, while, at above 60 °C, the high reactivity of LEs accelerates decomposition and the deterioration of other parts; Hence, increasing the chance of battery swelling or malfunction. Unlike LEs, SEs solid nature can operate at a wide temperature range between (−30 to 100 °C) performing well. In addition, the energy densities of ASSBs can significantly rise by using lithium metal as an anode, as the solid−solid contact between the lithium and electrolyte prohibits critical safety issues. Also, SEs acting as rigid physical barriers between the anodes and cathodes can help to optimize energy density and utilizing limited space . Thus, the great interest in developing solid electrolytes (SEs) and all-solid-state batteries (ASSBs) to provide safe and durable batteries can also play a vital role in the success of future electric vehicles (EVs). However, the development of SEs and ASSBs might be affected by constraints that come from problematic contact issues at numerous solid-solid interfaces .
On the other hand, conventional Li-ion batteries with flammable organic liquid electrolytes have several safety issues, which has limited their application in EVs. All-solid-state batteries (ASSBs) have replaced conventional batteries in large-scale energy storage fields such as intelligent power grids and electric vehicles, for their advantages in providing safety, energy density, and thermostability. Solid electrolytes determine the main properties of ASSBs. Different solid electrolytes, such as polymers and inorganic electrolytes, have received global attention in recent years. Among these alternatives, organic-inorganic composite solid electrolytes (CSEs) that take advantage of both types of electrolytes have been considered as the best alternative for high-performance ASSBs, being investigated in extensive studies in this regard .
As an aim to reduce the imports and improve the sustainability of battery manufacturing, it is essential to invest early in large-scale recycling infrastructure. Moreover, the changing international and political relations with countries owning natural reserves of key metals and raw materials alongside the fluctuation in prices of raw material in global markets can influence the battery prices. As one thing, a rise in the price of batteries can lead to an increase in the already high cost of electric vehicles, acting as an obstacle to the EVs market. Therefore, several EV companies have started considering this opportunity or already established/ announced plans for possible recycling operations .
The most important challenge in recycling these batteries is to identify their owner, whether it is the vehicle owner or the battery manufacturer. New regulations in China now force EV manufacturers to recover their batteries, making them set up recycling channels and service outlets where their old productions can be collected, stored, and transferred to recycling companies. Another point to be stipulated is the high cost of recycling in this case.
In addition, the safety risks related to collection, transport, and storage can impose problems with waste lithium batteries. The principle challenge is to provide safety throughout the whole battery recycling value chain, from collection to logistics, as well as controlling all emissions during recycling treatment .
All Solid-State Batteries. Image Credits: https://starzenergies.com/solid-state-batteries-challenges-and-opportunities/
All in all, it is clear that recycling electric-vehicle batteries at some stage are vital based on many grounds. The decision to recycle batteries is originally derived from the desire to avoid landfills and to ensure the supply of strategic elements. In many parts of the world, the key components of the batteries are not available, and access to resources is required in securing the supply chain. We all agree that EVs have turned out to be a beneficial secondary resource for critical materials. Careful resource management regarding electric-vehicle battery manufacturing—and their recycling process—is a key element of the future automotive industry's sustainability .
 Sun, Y.K., 2020. Promising All-Solid-State Batteries for Future Electric Vehicles.
 Lim, H.D., Park, J.H., Shin, H.J., Jeong, J., Kim, J.T., Nam, K.W., Jung, H.G. and Chung, K.Y., 2020. A review of challenges and issues concerning interfaces for all-solid-state batteries. Energy Storage Materials, 25, pp.224-250.
 Zhang, D., Xu, X., Qin, Y., Ji, S., Huo, Y., Wang, Z., Liu, Z., Shen, J. and Liu, J., 2020. Recent Progress in Organic–Inorganic Composite Solid Electrolytes for All‐Solid‐State Lithium Batteries. Chemistry–A European Journal, 26(8), pp.1720-1736.
 Harper, G., Sommerville, R., Kendrick, E., Driscoll, L., Slater, P., Stolkin, R., Walton, A., Christensen, P., Heidrich, O., Lambert, S. and Abbott, A., 2019. Recycling lithium-ion batteries from electric vehicles. Nature, 575(7781), pp.75-86.