The principle behind the first method of repairing lithium-ion batteries: Over time, the metal surface of lithium-ion batteries will oxidize to a certain extent, leading to poor contact between the battery and the phone, and a shorter battery life. Using an eraser or other cleaning tools can remove the rust on the surface, improving the contact between the battery and the phone.
The principle behind the second method of lithium-ion battery repair: Professor Ye Gaoxiang of the Department of Physics at Zhejiang University provides a professional explanation of this lithium-ion battery cryotherapy: Low temperatures cause changes in the electrolyte inside the lithium-ion battery, promoting chemical reactions in the battery that has just been frozen. The use of a lithium-ion battery is essentially a charging and discharging process. During this process, negative and positive charges collide with each other. The reason batteries become less durable is that at normal room temperature, the kinetic energy inside electrons is relatively high, making the battery more active and prone to leakage. Placing a lithium-ion battery in a low-temperature environment significantly changes the microstructure of the lithium film and electrolyte on the battery surface, as well as their interfaces, leading to temporary inactivity inside the battery and reduced leakage current. Therefore, after recharging, the phone's standby time will increase.
Lithium-ion batteries have a cycle life of approximately 600 cycles. With repeated charging, the thermal motion of molecules gradually disrupts the internal molecular structure, reducing charge storage efficiency. Freezing can damage the battery's original internal structure; while it might temporarily increase charge capacity, it's not effective in the long run. Professor Ye explains that once the microstructure of a lithium-ion battery is damaged, it's impossible to fully restore it, and using this method long-term will accelerate battery degradation.
The principle behind the third method of lithium-ion battery repair: Deeply discharging the phone, which depletes its internal energy to achieve a deeper recharge, requires some unconventional methods. Connect the phone to a 1.5V light bulb; the energy inside the lithium-ion battery will be transferred to the bulb until it is completely discharged. The phone will then slowly deplete its energy using a lower voltage. Normally, if the phone's voltage drops below its rated 3.6V after being connected to the power supply, it will automatically shut down. After being fully discharged, the recharged battery can be used for a longer period.
Mobile Phone Lithium-ion Battery Repair - A Complete Guide to Cryotherapy: This experiment used a Nokia BL-5C original lithium-ion battery purchased in April 2009. The battery had been used for nearly two years, and under normal use, the phone's standby time lasted about a day. If there were many calls, the battery life would be even shorter. If each call averaged 3 minutes, and the phone made or received 10 calls, the battery would be critically low.
Before the test, the phone was turned off and fully charged before being turned on again. Afterward, no calls were made or received, and no text messages were sent or received. Under no interference, the phone remained in standby mode for nearly three days until it completely ran out of battery.
Experimental Phase: The fully equipped mobile phone lithium-ion battery was placed in the freezer compartment (to prevent moisture, the phone was first tightly wrapped in cling film, ensuring a snug fit with three layers to create a vacuum. Then, three layers of newspaper were wrapped around the cling film to completely seal the battery). After 48 hours, the lithium-ion battery was removed, and the six layers of paper wrapping were removed one by one. The battery did not show any surface expansion or deformation due to freezing. After cooling for a period of time, the lithium-ion battery was fully charged and the phone was turned on. Under the same conditions, on the third day, the phone, which normally shuts down automatically, only showed one bar of battery remaining on the screen. A week later, one bar of battery remained on the screen. It wasn't until the ninth day that the phone emitted a low battery warning sound.
