Humans’ dependence on electronic products is fundamentally tied to power supply. In modern life, we use various electronic devices such as smartphones, computers, and electric cars, and the usage duration of these devices heavily relies on batteries, especially lithium-ion batteries. Imagine being able to drive an electric car for thousands of kilometers or use a smartphone for days without needing to recharge – the future of battery technology becomes crucial in such scenarios.
While lithium-ion batteries are widely used in modern electronic systems, there is a general consensus that current struggle to meet the growing energy storage demands of the future. Researchers are actively seeking higher-capacity, longer-lasting, and safer alternatives. In this article, TechSparks will explore the current limitations of lithium-ion batteries and their alternatives.
Why Look for Lithium-Ion Battery Alternatives
For commercial lithium-ion batteries, they typically consist of three key components:
- Lithium Cobalt Oxide Cathode: Serving as the battery’s cathode, it contains lithium cobalt oxide compounds. During charging, lithium ions detach from the cathode material and move into the electrolyte.
- Carbon Anode: Serving as the battery’s anode, it is made of carbon materials. During charging, lithium ions move to the anode and become embedded within the carbon structure. During discharge, they are released from the anode.
- Electrolyte: Serving as the medium between the cathode and anode, it is typically a liquid or gel that allows lithium ions to move during the charge and discharge processes.
During the battery’s charging process, current flows through the battery, causing lithium ions to move from the cathode to the anode, while electrons flow through an external circuit. This process stores energy in the battery. During discharge, when the battery is connected to an external device, the stored energy is released, with electrons flowing back to the cathode through the external circuit and lithium ions returning from the anode to the cathode. This continuous charge and discharge cycle enables the battery to provide reliable electrical energy.
At this stage, lithium-ion batteries mainly face three problems: Energy Density, Safety Hazards, and Cost.
Energy density is a key criterion for evaluating the performance of lithium-ion batteries. It represents how much electrical energy a battery can store per unit mass. Higher energy density typically signifies superior battery performance. However, one of the current challenges is the inadequacy of energy density, especially for high-power wearable electronic devices. These devices require smaller, lighter batteries to enhance portability. When the energy density of batteries falls short of the requirements, conflicts arise.
Furthermore, under high-power conditions, batteries require more frequent charging. However, lithium-ion batteries have a limited number of charge-discharge cycles, typically ranging from a few hundred to a few thousand cycles. This implies that they need periodic replacement, which can be inconvenient for users.
According to the plan released by the U.S. Department of Energy, they had originally aimed to achieve an energy density of 400 watt-hours per kilogram for lithium-ion batteries by 2017. This technological breakthrough would mean that electric vehicles could travel over 500 kilometers on a single charge. However, achieving higher energy density in battery technology takes time and ongoing research efforts. While today’s lithium-ion batteries have made significant strides in energy density, the ideal target is still a considerable distance away. So far, even the best commercial lithium-ion batteries can only reach around 200 watt-hours per kilogram.
Lithium-ion battery safety issues have been a subject of concern for users ever since their development, particularly after multiple incidents of Samsung smartphones exploding came to light. Below are some notable cases:
- In 2013, a four-year-old Australian girl died due to internal bleeding caused by swallowing a lithium battery.
- In 2013, the crash of Flight ET702 was attributed to a fire in the cargo hold, reportedly caused by lithium-ion batteries.
- In 2016, an accident occurred in Indiana, USA, involving a drunk driver crashing an electric car into a tree at high speed, with lithium-ion batteries considered one of the contributing factors to the fire.
- In 2016, Samsung’s smartphone, Galaxy Note 7, was recalled globally due to battery issues. Reports indicated that battery overheating led to multiple incidents of phone explosions and fires.
Despite several incidents involving lithium-ion batteries worldwide, many of these accidents were primarily caused by improper handling rather than inherent issues with the batteries themselves. Excessive concerns about safety may be unwarranted.
Since we cannot directly interact with lithium-ion batteries, incidents involving them tend to gain more attention. This is understandable, similar to how plane crashes are often perceived as less safe, even though the actual probability of such incidents is lower than that of car accidents. When used in accordance with regulations, lithium-ion batteries are relatively safe, just like other everyday objects such as knives.
To address concerns about lithium battery safety, manufacturers are implementing additional protective measures and electronic monitoring systems to minimize potential risks. One critical issue is the sensitivity of lithium batteries to high temperatures. To ensure safety and reliability, battery operating temperatures must be strictly controlled below 60°C. During manufacturing, factories conduct safety tests, including subjecting batteries to durability tests in an 80°C high-temperature environment. Only if there is no significant deformation or fire incidents in this environment can the batteries be used in devices. Additionally, more stringent thermal abuse tests, such as placing batteries in a 130°C test chamber, are required for extreme conditions. If no abnormal incidents, including fires, occur within half an hour, the batteries are considered to meet safety standards.
While the cost of lithium-ion batteries has been decreasing over the past few years, they are still considered relatively expensive. This is primarily influenced by several factors:
Expensive Raw Materials: The production of lithium-ion batteries requires a significant amount of raw materials, including lithium, cobalt, nickel, manganese, and lithium iron phosphate, among others. The prices of these materials fluctuate significantly and can experience sharp increases in a short period. For instance, in 2016, the price of lithium carbonate increased 2.5 times within six months. The volatility in raw material costs places greater pressure on manufacturers’ procurement and inventory management, making it challenging to reduce unit costs through bulk purchasing.
Lack of Economies of Scale: Currently, the lithium-ion battery market has not achieved significant economies of scale. Different manufacturers employ various production methods and technologies, resulting in inconsistent production costs. Tesla’s Gigafactory initiative is expected to change this landscape once completed, becoming the world’s largest lithium-ion battery manufacturing facility. It aims to reduce battery manufacturing costs through large-scale production. However, the factory is still in the construction phase, and it will take some time before it reaches full production capacity.
3 Lithium-Ion Battery Alternatives
Every technology has its flaws, and devising effective solutions is key. In this regard, upgrading technology and exploring alternatives is a better approach. We’ve discussed the challenges of lithium-ion battery technology in its current state, which requires more time to address, and rushing is not advisable. Therefore, it is recommended to compensate for the limitations of lithium-ion batteries by adopting alternatives. Some promising alternatives include sodium-ion batteries, multi-ion batteries, and lithium-air batteries. In the following sections.
Sodium-ion batteries, while fundamentally similar to lithium-ion batteries, differ primarily in their energy storage medium, replacing lithium ions with sodium ions. This change results in an increase in energy storage capacity, often several times that of lithium-ion batteries.
Furthermore, sodium-ion batteries are more cost-effective. The reason for this is the substitution of cheaper current collector materials. This is a critical component in batteries used to collect current and distribute it to external circuits. Lithium-ion batteries typically use electrolytes containing lithium salts, which can undergo chemical reactions when in contact with the metal electrode. In contrast, copper is more stable in this regard than aluminum, but it comes at a higher price, roughly three times more expensive. Sodium-ion batteries, on the other hand, do not have these concerns and can use cheaper aluminum as a current collector material.
However, it’s worth noting that sodium-ion battery systems also have some drawbacks.
Firstly, sodium ions have a significantly larger radius than lithium ions. This means that when moving back and forth between the positive and negative electrodes of the battery, more space is required to accommodate these larger ions. This could potentially lead to the deformation, damage, or collapse of the electrode materials, resulting in a rapid decrease in battery capacity.
Additionally, sodium ions have an atomic mass approximately three times that of lithium. Considering the concept of energy density mentioned earlier, this means that sodium-ion batteries of the same volume store relatively less energy.
The valence states of ions directly impact the amount of charge they carry, and this is one of the fundamental theories and principles of multi-ion batteries. For example, lithium ions have a valence state of +1, which means each lithium ion can carry only one charge, while aluminum ions have a valence state of +3 and can carry three charges. Therefore, in theory, multi-ion batteries can achieve higher energy density because they have the potential to store more charge.
Additionally, multi-ion batteries typically use electrolytes with high chemical stability, such as propylene carbonate and magnesium hexafluorophosphate, to enhance battery safety. These electrolytes are relatively stable, reducing the risk of battery fires compared to some organic electrolytes used in certain lithium-ion batteries, making them safer and more reliable.
However, it’s worth noting that high-valence ions often have slower migration speeds, which is a challenge for multi-ion batteries. This may limit the battery’s rate performance, i.e., the charging and discharging speed. This is not very friendly for today’s fast-paced society. After all, you wouldn’t want your phone to take 2 hours to charge before you can use it, right?
Based on the law of conservation of energy, combining materials with oxygen and burning them to obtain the required energy has been a commonly used method in the past, as exemplified by coal-burning trains. Is this design theory equally applicable in battery design? After all, oxygen in the air is abundant.
In fact, scientists are actively working on applying this principle to battery technology, giving rise to lithium-air batteries. Unlike traditional lithium-ion batteries, the negative electrode material in lithium-air batteries is metallic lithium, while the positive electrode is oxygen from the air. During battery discharge, the negative electrode releases lithium ions, which react with the oxygen in the positive electrode to form lithium oxide, accompanied by a charge transfer, thereby generating electrical energy. In theory, lithium-air batteries are a very promising energy storage solution, as their energy density can reach 12,000 watt-hours per kilogram, almost on par with traditional gasoline. This means that the energy storage capacity of lithium-air batteries could be 12 times that of traditional lithium-ion batteries.
However, lithium-air battery technology is still in the research and development stage. Although some laboratory studies and small-scale pilot projects have been conducted, it has not yet been widely commercialized or extensively applied. One of the challenges is the complexity of the reaction mechanism in lithium-air batteries, which has led to limited understanding of the actual reaction processes in the batteries. There have been reports of one prominent scientist achieving outstanding performance results in a paper, but other scientists have struggled to replicate those results.
Furthermore, lithium-air batteries require complex facilities to extract oxygen from the air, which increases cost and portability issues, limiting their competitiveness in large-scale applications.
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