In today's life, mobile phones are not only communication tools, but also play an increasingly important role in work, leisure, and social interaction. When using a mobile phone, the most worrying thing is the low battery reminder on the mobile phone.
LG conducted a survey in 2016, and the results showed that 90% of people felt "panic" when their mobile phone battery was lower than 20%. Although major manufacturers are now working hard to expand the capacity of mobile phone batteries , with the increasing frequency and intensity of mobile phone use in daily life, most people have gradually changed from charging once a day to N charging a day, or even Many people bring a power bank with them when they go out for emergencies.
So, what can we do to extend the life of the mobile phone battery as much as possible when we use our mobile phones daily?
01 Lithium-ion battery working principle
The batteries used by most mobile phones on the market are Nobel Prize-level achievements - lithium-ion batteries. Compared with traditional batteries such as nickel metal hydride , zinc-manganese, and lead storage, lithium-ion batteries have the advantages of large capacity, small size, high voltage platform, and long cycle life. It is precisely because of these advantages that mobile phones Able to achieve a smaller appearance and longer battery life.
The lithium ion battery positive electrode in mobile phones usually uses LiCoO2 (lithium cobalt oxide), NCM, NCA materials; the negative electrode materials in mobile phones mainly include artificial graphite , natural graphite , MCMB, SiO, etc. During the charging process, lithium is deintercalated from the positive electrode in the form of lithium ions, and is finally embedded into the negative electrode through electrolyte movement, while the discharge process is exactly the opposite. Therefore, the charging and discharging process is a cycle in which lithium ions are constantly inserted/de-intercalated and inserted/de-inserted between the positive and negative electrodes, which is vividly called a "rocking chair battery".
The working principle of lithium batteries: Lithium ions continuously travel back and forth between the positive and negative electrodes as they are charged and discharged. The picture comes from the author
02 Reasons for the decline in lithium-ion battery life
The battery life of a newly purchased mobile phone is not bad at the beginning, but it will become less and less durable after being used for a period of time. For example: a new mobile phone is fully charged After that, it can probably be used for 36 to 48 hours, but after half a year, the same full battery can only last for 24 hours or even less.
What is the reason why mobile phone batteries "short life"? The main reasons are as follows:
① Overcharge and overdischarge
Lithium-ion batteries rely on the movement of lithium ions between the positive and negative electrodes to work. Therefore, the number of lithium ions that the positive and negative electrodes of a lithium-ion battery can hold is directly related to its capacity. . When a lithium-ion battery is deeply charged and discharged, the structure of its positive and negative electrode materials may be damaged. , the space that can accommodate lithium ions becomes less, and its capacity is also reduced, which is what we often call battery life. of reduction.
Before (a) After (b) LiCoO2 cathode material electron microscopy photography results after 50 deep charge and discharges
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Information: Popular Science China
Editor: Gao Qin
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