What is the effect of low temperature on lithium batteries?

Many people outside the use of mobile phones found that mobile phone battery power consumption is very fast when the weather is cold, and sometimes there will be a crash, failure to touch screen. Professionals remind that low temperature has a great impact on the phone battery, when use mobile phones in cold weather, there are some ways to improve the battery durability.

Current cell phone batteries are typically lithium, and the speed of the battery's chemical reaction is affected by the temperature. Mobile phone for a long time in the low temperature environment, will make the battery chemical reaction slow, resulting in the battery discharge current smaller, reduce the capacity of the battery, it may be used quickly, black screen, dead, touch screen failure, unable to access the Internet and other circumstances. When entering a warm room from a cold outdoor environment, the temperature change may also cause the phone to condense into water mist, resulting in circuit board short circuit or other faults.

When you go out in cold weather, try to keep your phone fully charged and reduce the number of power-hungry apps such as playing games, watching movies and listening to music. It is better to put the mobile phone in the pocket, backpack and other relatively warm places, call, answer the phone can use headphones, try to avoid the mobile phone directly exposed to the cold air. Do not use your cell phone in low temperatures for long periods of time. After entering the room from the outside, put the mobile phone for a period of time, and then use it after the water mist evaporates.

If the phone breaks down temporarily in a cold environment, you can shut it down and stop using it, and then let the phone get used to it in a slightly warmer environment for a while, and the situation will improve.

Is low temperature a problem for lithium batteries?

A lithium-ion battery works by changing the electrolyte inside it through a chemical reaction, creating a potential difference between the positive and negative electrodes that generates a current. In low temperature environment, the electrolyte moves very slowly, which affects the transfer activity of lithium ions between the positive and negative electrodes, resulting in the decline of battery charge-discharge performance.

Simply put, at low temperatures, it's not that the lithium batteries are truly dead, but that they're charged and can't be released.

According to the analysis data, the capacity of ordinary lithium battery will be reduced by 20% at zero degree Celsius, and it may only be about half when it reaches minus 10 degree Celsius.

Most cell phone batteries work in the normal range of 0 to 35 degrees Celsius, below or above this temperature, may be abnormal.

Low temperature is not good for lithium battery, if coupled with low power, that damage is worse, so apple in order to protect the lithium battery, added a "self-protection" mechanism -- encountered "low temperature + low power" automatically shut down and unable to boot use.

To this, we look at the instructions given apple, the iPhone's ideal working environment temperature 0 ℃ to 35 ℃. When the room temperature to a certain temperature (10 ℃ or so), apple will automatically power off.

Effect of low temperature on lithium iron phosphate battery

At present, lithium iron phosphate battery is the most widely used battery in electric vehicles. This kind of battery has high safety and long individual life. However, lithium iron phosphate has a fatal shortcoming. Low temperature has an effect on the positive and negative electrodes, electrolytes and adhesives of lithium iron phosphate. For example, the positive electrode of lithium iron phosphate itself has poor electronic conductivity, and is prone to generate polarization at low temperature, thus reducing the battery capacity. Due to the influence of low temperature, the speed of lithium inlaid graphite decreases, and lithium metal is easy to precipitate out on the surface of the negative electrode. If it is put into use due to insufficient shelf-life after charging, lithium metal cannot be embedded into the graphite again. At low temperature, the viscosity of electrolyte will increase, and the migration impedance of lithium ion will also increase. In addition, in the production process of lithium iron phosphate, the adhesive is also a very key factor; low temperature will also have a great impact on the performance of the adhesive.

Effect of low temperature on lithium titanate battery

Also lithium battery, lithium titanate battery low temperature resistance is better. The lithium titanate negative electrode material of spinal structure has a lithium potential of about 1.5v and will not form lithium dendrite. The volume strain is less than 1% in the process of charging and discharging. Nano-sized lithium titanate battery can be charged and discharged in large current, which can realize quick charging at low temperature and guarantee the durability and safety of the battery at the same time. Main titanium acid lithium batteries, for example, new energy of silver, its products have normal charging and discharging ability in - 50 to 60 ℃. Lithium titanate battery has the advantage of material, it can still achieve fast charge at low temperature, this kind of capricious, other material battery is difficult to learn.

Why does charge need temperature more than discharge?

Many battery products of enterprises can discharge normally at low temperature, but at the same temperature, it is difficult to achieve normal charging, or even unable to charge. On the contrary, when Li+ dissociates the graphite material into the solution, there will be a solvation process, and the solvation does not consume energy, Li+ can quickly dissociate the graphite. Therefore, the charge acceptability of graphite material is obviously inferior to that of discharge.

Charging batteries at low temperatures has its risks. As the temperature decreases, the dynamic characteristics of the graphite negative electrode become worse. During the charging process, the electrochemical polarization of the negative electrode is obviously intensified, and the precipitated lithium metal is easy to form lithium dendrite, which breaks through the membrane and leads to a short circuit between the positive and negative electrodes.

Try to avoid charging lithium-ion batteries at low temperatures. When the battery must be charged at a low temperature, it is necessary to charge the lithium ion battery at a low current (i.e., slow charge) as far as possible, and fully use the lithium ion battery after charging, so as to ensure that the lithium metal precipitated from the negative electrode can react with graphite and re-embed into the graphite negative electrode.

Enterprises and scientific research institutions in the industry explore and tackle the problem of low temperature resistance of batteries, mainly focusing on the process improvement of existing anode and cathode materials, and creating conditions for the battery to work at low temperature by improving the local environmental temperature of the battery. With the further development of lithium battery technology, there will be a further breakthrough in the low temperature environment.

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