Next-Generation Energy Storage and Power Sources – Solid State Batteries

Under the trend of net zero carbon emissions, the promotion of renewable energy and electric vehicles has become an important green energy policy in various countries, but these two major applications rely on higher-standard energy storage/battery systems.

As far as battery technology is concerned, the following 6 items are generally required to have market development advantages: (1) High energy density: it has a smaller volume, lighter weight and can store more electrical energy. (2) Long service life: the number of charge and discharge times is large, and the generation of waste is also reduced. (3) Fast charging and discharging speed: Through relatively fast discharging and charging that does not require too long, it is possible to drive for a long distance again. (4) Heat and cold resistance: It can adapt to extreme climates and environments to ensure a stable power supply. (5) High safety: high temperature resistance, not easy to explode and ignite, and long cycle life at high temperature. (6) The cost to achieve commercialization: After investing in R&D and mass production, the cost can be reduced to a cost acceptable to consumers.

Traditional (liquid) lithium batteries dominate the market for a long time

At present, the only batteries that can meet all the above conditions are lithium batteries that have been developed for more than 30 years. Therefore, they are widely used in smart mobile devices, electric transportation vehicles, renewable energy storage systems and other fields, especially lithium iron phosphate. (LFP) and lithium ternary (NCM, NCA) batteries have captured almost all the energy storage battery and power battery markets, and are also the mainstream battery formulas of major global automotive groups at this stage.

The main structure of traditional (liquid) lithium batteries includes positive and negative electrodes, liquid electrolyte, separator and structural shell; the electrolyte can quickly conduct lithium ions, enabling lithium batteries to provide high current applications. However, the traditional electrolyte is easy to leak, easy to burn, and easy to oxidize at high voltage, which hinders the increase of energy density. At the same time, there are also concerns that the high temperature above 40 °C will lead to a sharp decrease in safety and life. In comparison, lithium ternary batteries have high energy density and can support fast charging, but have short lifespan and low safety; lithium iron phosphate batteries have long lifespan, high safety, and low cost, but low energy density.

In order to improve energy density, battery life, charge and discharge speed, safety, and lower costs, battery technology must make breakthroughs, and the use of solid electrolytes to replace organic electrolytes has become the mainstream market effort.

Solid-state batteries will be the stars of the future

The solid-state battery uses a solid-state electrolyte instead of the electrolyte of the traditional lithium battery, so the problem of liquid leakage can be avoided, and because the solid-state electrolyte has a strong blocking effect on the positive and negative electrodes, it is less likely to generate lithium dendrites and cause short circuits, and the safety is naturally higher. high. In the part of energy density, due to the safety of solid-state batteries, materials with higher energy density can be used for positive and negative electrodes, such as lithium metal for negative electrodes or NCMA mixture for positive electrodes, so that the energy density can exceed that of lithium ternary batteries; currently The energy density of mainstream liquid lithium-ion battery technology has approached the physical limit of 300Wh/kg, while the energy density of solid-state batteries can be as high as 500Wh/kg.

On the whole, the charge-discharge efficiency and energy density of solid-state batteries are more than 2 times higher than that of traditional lithium batteries, and the battery life will be extended by more than 2 times. With high safety, solid-state batteries have been regarded as a new generation of battery technology after liquid lithium batteries in recent years, attracting the industry to fully invest in research and development. Japan’s Toyota (Toyota) depot plans to launch cars equipped with solid-state batteries in 2025, and Bill Gates (Bill Gates) new venture QuantumScape also plans to mass-produce in 2024. However, the technology of solid-state batteries is still immature at present, and the average manufacturing cost is still several times higher than that of liquid lithium batteries, which cannot be popularized in the short term.

Taiwan strives to stay ahead

Solid-state batteries with various advantages have caused research institutes and manufacturers in various countries to compete for investment and aggressive entry. It is expected that solid-state batteries will be introduced to the commercial market in the next few years, especially in the mass consumer market such as electric vehicles. Its commercial potential will be faster accomplish. Just imagine, if an electric vehicle needs 1,000 batteries, when each battery can increase the energy by more than 20%, it can be reduced from 1,000 batteries to 800 batteries, which not only makes the vehicle lighter, but also lowers the manufacturing cost .

Taiwan is also not absent in this technology, starting from solid-state resin batteries, moving towards all-solid-state batteries and maintaining the advantages of the previous class. It is understood that the network polyamide epoxy resin (NAEPE) developed by ITRI is between colloidal and solid state. By adding polyamide epoxy resin additives (AEO) and initiators, liquid lithium batteries can be The existing electrolyte is modified without heating or UV light, and can be cured at room temperature, which not only maintains the high ionic conductivity of the original electrolyte, but also improves the high voltage stability. The solidified electrolyte has higher flash point temperature, and has the characteristics of flame retardancy and good high temperature cycle life. Using NAEPE’s solid-state lithium battery, the interior can be connected in series (cell to module) like building blocks, breaking through the limitation of a single structure of lithium batteries, reaching a high-voltage voltage of 12V for one battery, saving series and parallel components for the rear battery module, easy to Battery module design. This technology overcomes the current need for high-temperature curing of all-resin electrolytes, poor ionic conductivity and electrochemical stability, and accelerates the development of solid-state battery materials technology. It also provides the world with solid-state lithium batteries with high energy density and safety to promote green and sustainable development.

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