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The Power Behind Your Phone: How Batteries Work

The technology behind our phones is constantly advancing, but one aspect that remains crucial to the functionality of our devices is the battery. Without a reliable power source, our phones would be nothing more than expensive paperweights.

"When you talk about portable devices, whether a notebook, iPod, or phone, it's all about power; it's all about batteries." - Steve Jobs.

But have you ever wondered exactly how your phone's battery works? 

A battery is essentially a device that stores energy in the form of chemical reactions and releases it as electricity. The most common type of battery used in smartphones is the lithium-ion battery. These batteries are made up of a cathode, an anode, and an electrolyte. The cathode is typically made of lithium cobalt oxide, and the anode is made of graphite. The electrolyte is a liquid or gel that acts as a conductor between the cathode and anode.

When the battery is being charged, electrical energy flows into the battery, causing lithium ions to move from the anode to the cathode. This creates a positive charge on the cathode and a negative charge on the anode. Once the battery is fully charged, the lithium ions remain on the cathode, ready to be released as electricity when the battery is being used.

When the phone is turned on, and in use, the electrical energy stored in the lithium ions on the cathode flows through the circuit to power the phone. As the lithium ions flow back to the anode, the battery discharges, and the phone's power decreases.

What happens when the battery discharges

There are several key factors that determine the performance of a lithium-ion battery:

  1. Capacity: The capacity of a lithium-ion battery refers to the amount of energy that it can store. In the case of a lithium-ion battery, it is the amount of lithium ions that it can store. This is typically measured in milliampere-hours (mAh) or ampere-hours (Ah). A higher capacity battery will be able to store more energy and provide longer use between charges.
  2. Voltage: The voltage of a lithium-ion battery is a measure of the electrical potential stored within the battery. Lithium-ion batteries typically have a voltage of 3.7 volts to 4.2 volts.
  3. Energy density: Measure of the amount of energy stored in a given volume or weight of a battery. It is typically expressed in units of watt-hours per kilogram (Wh/kg) or watt-hours per liter (Wh/L). A higher energy density means that more energy can be stored in a smaller volume or weight of the battery, making it more efficient and suitable for portable devices where size and weight are important factors. The energy density of a battery is an important factor in determining its overall performance and suitability for a specific application.  Lithium-ion batteries have a higher energy density than other types of rechargeable batteries, making them ideal for portable devices such as phones and portable chargers where size and weight are important factors. 
  4. Self-discharge rate: The self-discharge rate of a lithium-ion battery refers to the rate at which the battery discharges when not in use. This rate can vary between different types of lithium-ion batteries and can have an impact on the overall cycle life of the battery.
  5. Cycle life: A battery cycle refers to the process of charging and discharging a battery. Every time a battery is charged and then discharged, it goes through one cycle. The number of cycles a battery can undergo before it reaches the end of its useful life is referred to as its cycle life.
  6. Operating temperature: The operating temperature of a lithium-ion battery is an important factor in determining its performance. High temperatures can cause the electrolyte to break down, reducing the battery's capacity and shortening its lifespan. On the other hand, low temperatures can make the electrolyte more viscous, reducing the battery's ability to charge and discharge quickly.
  7. Charging and discharging rate: The charging and discharging rate of a lithium-ion battery refers to the speed at which the battery can be charged and discharged.  It is typically expressed in units of current, such as amperes (A) or milliamperes (mA).  A higher charging and discharging rate mean that the battery can be charged or discharged more quickly. This can be beneficial for applications that require fast and convenient charging. But it can also have an impact on the overall life of the battery.
  8. Battery management system: The battery management system (BMS) is an important component of a lithium-ion battery that helps to regulate the battery's voltage and temperature to ensure optimal performance and safety. A high-quality BMS can help to extend the overall cycle life of the battery.

These factors, along with the specific design and construction of the battery, will determine the overall performance of a lithium-ion battery. It's important to consider these factors when evaluating the performance of a lithium-ion battery for a particular application.

For example, during the development of our Electron portable chargers, we prioritized size to make it as small as possible for convenience and speed of charging. We wanted to provide a quick boost on the go. It was important for us that Electrons are recharged and ready to go as fast as possible on our Supernova commercial cell phone charging station.

Electron portable charger and Supernova phone charging station

History of lithium-ion batteries

1912: The first step towards lithium batteries begins, with pioneering work started by G.N. Lewis.

The job was finished by John Goodenough, Stanley Whittingham, and Akira Yoshino.

1970s: Stanley Whittingham, working at Exxon, developed an early lithium battery using lithium titanium sulfide as the cathode and lithium metal as the anode.

1980: John Bannister Goodenough identifies and develops LixCoO2 as the cathode material of choice for the lithium-ion rechargeable battery, which is considered the single most important component of every lithium-ion battery.

1985: Akira Yoshino, an engineer at a Japanese company called Asahi Kasei, developed the first commercially viable lithium-ion battery using petroleum coke as the anode material and lithium cobalt oxide as the cathode. This battery was significantly safer than previous lithium batteries, which used lithium metal as the anode, which was highly reactive and prone to overheating.

These three scientists independently worked on the lithium-ion battery, each adding their own breakthroughs to the technology. They were later awarded the 2019 Nobel Prize in Chemistry for the development of lithium-ion batteries.

1991: The first commercial use of lithium-ion batteries was in Sony's Handycam video camera in 1991. It was the first consumer electronic device to use a lithium-ion battery, which allowed it to be smaller and lighter than previous camcorders that used nickel-cadmium batteries. This was a major milestone for the lithium-ion battery, as it demonstrated the technology's potential for use in portable consumer electronics.

Sony revolutionized the electronics market.  After that, the use of lithium-ion batteries quickly spread to other portable electronics such as laptops, smartphones, and tablets. The high energy density, long life, and low self-discharge rate of lithium-ion batteries made them ideal for these applications. Today, lithium-ion batteries are used in a wide range of devices, from small portable electronics to portable chargers, cell phone charging stations, electric vehicles, and large scale energy storage systems.

What are potential future technologies to make batteries last longer?

The challenge with batteries is that we want them to last for longer periods, potentially even for weeks.

There are several potential technologies that are being researched and developed to make batteries last longer. Some of the most promising include:

  1. Lithium-sulfur batteries: These batteries have the potential to have up to five times the energy density of current lithium-ion batteries, which would allow for longer battery life in devices.
  2. Lithium-air batteries: These batteries use oxygen from the air as the cathode material, which could increase the energy density of the battery.
  3. Solid-state batteries: These batteries use a solid electrolyte rather than a liquid one, which could improve safety and increase the energy density of the battery.
  4. Sodium-ion batteries: These batteries use sodium, which is abundant and inexpensive, instead of lithium. This could lead to lower costs and more sustainable batteries.
  5. Flow batteries: These batteries use liquid electrolytes that are stored in external tanks and pumped through the cell, which allows for very large-scale energy storage.
  6. Hybrid batteries: These batteries combine different types of batteries to achieve the best of all worlds, such as Lithium-ion with solid-state batteries.

At the moment, it's difficult to say which technology has the most promise for use in portable devices, as most of them are still in the research and development phase. However, solid-state batteries and lithium-sulfur batteries are considered to be among the most promising technologies for portable devices.

Solid-state batteries use a solid electrolyte instead of a liquid one, which increases safety and energy density. This could lead to smaller and lighter batteries for portable devices with longer run times.

basic-lithium-ion-and solid state battery

Lithium-sulfur batteries also have a high energy density which could lead to longer battery life in portable devices. They also have the potential to be less expensive to produce than lithium-ion batteries.

It's worth noting that each technology has its own unique set of challenges that need to be addressed before it can be commercialized. For example, lithium-sulfur batteries have shorter cycle lives than lithium-ion batteries, and researchers are still working on how to improve their performance and cycle life. It's likely that a combination of different technologies will be used to achieve the best performance in portable devices in the future.

What is the environmental impact of phone batteries?

The environmental impact of phone batteries can be significant. 

The most significant impact is the environmental damage caused by mining and processing the raw materials used in batteries, such as lithium, cobalt, nickel, and rare earth metals. These mining activities can cause habitat destruction, water pollution, and human rights violations. Additionally, the chemicals used in the battery production process can be toxic and harmful to the environment if not properly disposed of.

Another significant impact is the disposal of used batteries. Many phone batteries are not properly recycled and end up in landfills, where they can release toxic chemicals into the environment. Even when batteries are recycled, it's not a simple and clean process, it can still have an impact on the environment, and it's not a 100% environmentally friendly solution.

Finally, the production and disposal of batteries are also a source of carbon emissions, which contribute to climate change. The production of batteries is energy-intensive, and the mining, refining, and transportation of raw materials also contribute to carbon emissions.

Overall, it's important to be aware of the environmental impact of phone batteries and to take steps to reduce it. This includes properly recycling used batteries, supporting companies that use sustainable and responsible sourcing practices, and considering the environmental impact when buying new devices. Consider checking reading our blog: Reducing E-Waste and Promoting Sustainability Through Electron® Phone Charging Stations

Is there any risk to phone users from the batteries in modern smartphones?

Lithium-ion batteries, which are used in most smartphones, can be a fire hazard if they are damaged or defective. In rare cases, a battery can overheat and catch fire, potentially causing injury or damage to property.

If a battery is punctured or damaged, it can release dangerous chemicals that can cause injury if they come into contact with the skin or eyes or if they are inhaled. Be especially careful if you are replacing the phone battery by yourself.

battery is punctured or damaged

To minimize the risk of danger from batteries in smartphones, it's important to use the device as intended and follow the manufacturer's instructions. This includes charging the device using the correct charger, not leaving the device in hot or humid environments, and not puncturing or damaging the battery.

It's important to note that modern smartphone batteries are designed with safety features to prevent overheating and fire. Also, most manufacturers have strict quality control and testing standards to minimize the risk of defective batteries.

However, if you notice any unusual behavior with your device, such as overheating, swelling, or leakage, it's important to stop using the device immediately, contact the manufacturer or a professional and dispose of the battery properly.

We demystified some of the most popular battery myths in our blog: Myths About Cell Phone Battery Life vs Truths


In conclusion, batteries play a crucial role in powering our modern devices, including smartphones. From nickel-cadmium to lithium-ion, the technology behind batteries has evolved significantly, providing us with more efficient and longer-lasting power sources. The environmental impact of battery production and disposal remains a concern, but there are several initiatives on the way to address this. With the growing demand for longer-lasting and more efficient batteries, it's an exciting time for the battery industry, and we can look forward to even more advancements in the future.