IT168 evaluation In fact, when I write an article, my favorite opening sentence is: With the rapid development of smart phones today, 1, words are omitted here. Undeniably, the development speed of hardware and software of smart phones is really growing in a geometric series curve. But even with the rapid development, we are still dissatisfied with smart phones in one way or another. What is restricting smart phones and what is the short board of the barrel effect of smart phones? Today, let's discuss a cliche about smart phones-batteries. Some people say that the smartphone battery has reached the bottleneck, and it is difficult to make a big breakthrough. Is that right? If you want to make a breakthrough in the battery life of smart phones, what improvements are needed in the battery industry, and what optimization is needed in the software algorithm? What smart phone uses high-end power-saving technology nowadays? This will be the problem that this article will discuss with you.
In fact, the development of smart phones has entered a bottleneck, which is a commonplace topic. But if we think about it carefully, what kind of arguments support our basically achieved argument? It's hard for us to explain at the moment. In front of this article, the author used an experiment to see how fast the smart phone battery has developed in recent years. In fact, the principle of the experiment is very simple. By comparing the specific capacity of mobile phone batteries from 25 to now (specific capacity is also called gram capacity, which refers to the amount of electricity contained in each gram of battery), we can simply and intuitively see the development speed of mobile phone batteries from 25 to now.
before doing this experiment, let's briefly introduce some terms we encounter in daily mobile phone batteries, which will help us to know more accurately the batteries of digital products such as smart phones and charging treasures.
mah: mah mah can be said to be the most common parameter in our smartphone battery. Smartphone manufacturers also said at the press conference that we used a 3mAh ultra-large capacity battery. In fact, mAh is not an energy unit, that is to say, it is not accurate to express how much power a battery can have in mAh. MAh represents the total number of electrons released in the battery for external electrons, which is equivalent to coulomb in physics. 1mAh equals 3.6 coulomb electrons. The reason why mobile phones often use mAh as the battery measurement unit is that it is convenient to measure. For example, a 3mAh battery can maintain a continuous current of 3mA and the mobile phone can work for 1 hours. But remember, mAh is not the energy unit of the battery.
working voltage: on the mobile phone battery, we often see the working voltage besides mAh. We often say that this battery is a 3.7V 1mAh battery, or a 3.8V 3mAh battery. This voltage is actually an average value. It roughly means the average working voltage of the battery, or it can be understood as the voltage with the longest normal working time of the battery. Usually we can see that the cell phone battery has a charging voltage and a working voltage. Theoretically, the bigger these two values, the better. The reason is that the battery needs to be maintained above 3.6V when the smart phone is running. When the battery voltage is below 3.6V, most functions of the mobile phone can't be used, and it is turned off. Only a few functions can work with a voltage below 3.6V when turned off. If the working voltage of the battery is larger, it means that the battery can work for longer. The charging voltage is the voltage that cannot be exceeded after the battery is fully charged. If this voltage is exceeded, danger may occur.
Wh: wh is the most accurate energy unit of a battery. In fact, many large batteries use wh to represent the battery capacity. In fact, even notebook batteries use this capacity unit more. Wh is the product of milliampere hour and working voltage. For example, if the working voltage of a 1mAh battery is 3.7V, the battery capacity is 3.7Wh. The specific capacity (or gram capacity and energy density) we mentioned earlier is the number of Wh contained in each gram of the battery.
The relationship among mAh, working voltage, charging voltage and Wh is briefly introduced, and it is also known that Wh is the core parameter that can best reflect the capacity of a mobile phone battery. Next, we will test the mobile phone battery from 25 to 214 to see if the battery development is a bottleneck in these nine years.
Through the test, we got such a picture which is probably a wave. It doesn't always rise slightly as we thought before, but it is a table that sometimes rises rapidly and sometimes falls. In fact, there are many reasons for this. First of all, the author's insufficient sample size is definitely the main reason for this phenomenon. But this picture also contains several stages of the development of smart phones in the past 1 years. Let's briefly explain this part to you first.
first of all, from 25 to 27, the energy density of mobile phone batteries has made a huge leap, with an increase of about 4%. The main reason is that smart phone batteries changed from ordinary liquid lithium batteries to lithium-ion polymer batteries during this period. After a slight increase in 27, 28, 29 and 21, the battery capacity of smart phone declined in 211 and 212. There are two reasons: 1. After the mobile phone battery became bigger, manufacturers paid more attention to the safety of the mobile phone battery and made great improvements in hard shell protection, which led to the increase in the weight of the mobile phone battery. 2. With the addition of more brands such as Internet brands, the battery quality of smart phones began to appear uneven. Finally, we see that in 13 or 14 years, the specific capacity of smart phone batteries has reached its current peak. There are two reasons: 1. More and more manufacturers begin to make built-in batteries, which saves hard shell packaging while ensuring safety. 2. The battery technology has made great progress from 12 to 14 years, and the battery working voltage of high-end smart phones has generally increased from 3.7V to 3.8V..
in fact, we can see that the energy density of smart phone batteries has basically increased by 1% during the ten years from 25 to 14 years, with an average annual growth rate of 7.2%. It is said that if this figure is converted into GDP growth rate, it can really be regarded as the road to take off in 1 years. However, how can the CPU's main frequency increase by 15% and the camera's pixel increase by 5%? In fact, it is not that the battery development has encountered bottlenecks, but that other hardware industries are developing too rapidly. Against the backdrop of the big environment, it seems that the development speed of smart phone batteries is too slow. No wonder everyone complains that the battery is not strong. For example, ten years ago, two people earned 1 yuan a month. Ten years later, one person earns 2 yuan, and one person earns 5 yuan. Obviously, the owner of 2 yuan is the one who is being spit out. So can the smartphone battery still usher in a leap? How can we solve the current situation that the battery life of smart phones is not strong? Let's make a brief analysis through two aspects: open source and throttling.
how to open up smart phone batteries?
the battery resources of smart phones are the same as those of all short-term resources, and they need to be open source and thrifty. In introducing the current "open source" innovation of mobile phone batteries, let's first look at the current status of smart phone batteries. Earlier, we also talked about liquid lithium-ion batteries and lithium-ion polymer batteries. What's the difference between them?
when it comes to smartphone battery failure, the first words that come to mind are often bulging and explosion. In fact, battery bulging and explosion are synonymous with liquid lithium-ion batteries. With the development of mobile phones, most manufacturers have begun to use lithium-ion polymer batteries. The biggest difference between lithium-ion polymer battery and liquid lithium-ion battery lies in the different electrolyte forms. Liquid lithium-ion batteries use liquid objects as electrolyte, the most representative of which is the 1865 battery. Liquid lithium-ion batteries have their own advantages, such as long history, low price and good safety factor. This is also why Shenma is currently as small as Xiaomi power supply and as big as Tesla car, for example, using 1865 battery as energy source. However, since the protection of electrolyte usually requires the use of a metal case, if it is not well sealed, it will leak, and if it is overcharged (the charging voltage is too high), the battery will bulge or explode. Nowadays, more and more smart phones begin to use lithium-ion polymer batteries.
the biggest difference between lithium-ion polymer batteries and liquid lithium-ion batteries is that they use solid or colloidal objects as electrolytes. The safety factor is higher. In the case of overshoot, solid or colloidal objects will gasify, and more seriously, they will burn and basically will not explode. However, our common news of mobile phone explosion is usually due to the internal chip explosion or mobile phone spontaneous combustion caused by the overshoot and spontaneous combustion of lithium-ion polymer battery. It's not the explosion of the cell phone battery in our minds. Compared with liquid lithium ion battery, lithium ion polymer battery also has obvious advantages: high working voltage, high energy density, small natural discharge, long repeated service life, no memory effect, small internal resistance, customizable shape, simple design of protection circuit board and so on. But the same problem is that the cost is higher.
▲ Panasonic 1865 battery used by Tesla
After learning about lithium-ion polymer batteries and liquid lithium-ion batteries, let's take a look at the current mainstream battery composition. At present, the mainstream lithium batteries are basically divided into cobalt lithium ion batteries, manganese lithium ion batteries, iron phosphate lithium ion batteries, ternary batteries and so on. Each type of battery has its own advantages and disadvantages. Among them, lithium-ion cobalt battery has the highest energy density, so all smart phone batteries are lithium-ion cobalt battery at present. Other lithium-ion batteries have their own advantages and disadvantages. For example, the latest Tesla car began to use ternary lithium-ion batteries instead of cobalt lithium-ion batteries.
▲ Micro-morphology of lithium cobaltate
As the most active metal element, lithium is second only to hydrogen, which is obviously the best choice for making batteries. However, because it is too active, unstable and very unsafe, people think of using cobalt acid, manganese acid, iron phosphate and lithium as the positive electrode and graphite as the negative electrode to make batteries. As we mentioned earlier, cobalt lithium-ion battery has the highest energy density. Although it has some disadvantages such as less safety and lower working voltage compared with other lithium-ion batteries, it is still the best choice for smart phones, which are small and need a single battery. We talked about open source earlier. How to open source the existing battery technology?
▲ Increase the density of lithium cobaltate by using three-dimensional nano-grid technology
Method 1: Increase the density of lithium cobaltate. Increasing the density of lithium cobaltate, increasing the number of discharged electrons and coulomb number /mAh is a way to solve the shortage of battery capacity. Of course, we are talking about increasing density at a certain volume. With the technical innovation, the cathode density of cobalt lithium ion battery is increasing. At present, scientists are considering using nano-reticular layer to redistribute the positive electrode of cobalt lithium ion battery, so as to make more rational use of the safe space of the positive electrode. At present, experiments show that this technology can double the battery capacity. However, it should be noted that this technology is only an experiment at present. Considering that the processor has just stepped into 2nm, it will take some years to apply nanotechnology to the positive electrode of civil mobile phone batteries. And we know that lithium cobaltate has its physical density, and the method to improve the density of lithium cobaltate will eventually come to an end. And it is not cost-effective for manufacturers to improve the density, safety and cost on the technology that is already very perfect at present.
method 2: increase the working voltage. The working voltage is controlled by cathode material, electrolyte material and so on. As we said earlier, Wh=mAh× working voltage. If the working voltage can be improved, it can also increase the capacity of the battery. However, due to the current cell phone battery electrolyte withstand voltage of 4.5V, so the charging voltage can not be higher than 4.5V, so it is difficult to improve the working voltage. In fact, manufacturers have made great efforts in working voltage in recent years, from 4.2V/3.7V 1 years ago to 4.35V/3.8V now. Don't underestimate the improvement of .1V, which means that manufacturers have achieved the ultimate in positive electrode, electrolyte and overshoot protection. I believe that before long, there will be a mobile phone battery with a working voltage of 3.85V, but this is also the limit of the working voltage of the mobile phone battery under the existing circumstances. If I really want to raise the working voltage from 3.8V to 3.85V, then the increase of battery capacity can only reach 1.5%, which is still a drop in the bucket.
Method 3: Heterogeneous battery. Improving the space utilization rate is a good way for manufacturers to achieve it at present. At present, many smart phones adopt arc design, but the internal battery still adopts a relatively square rectangular design, which can not make good use of the arc space on the back. The addition of trapezoidal batteries, flexible batteries, cable batteries and other batteries makes the smart phone space more reasonable. LG Chem is at the forefront in this respect. Previously, LG G2 used a trapezoidal battery, which greatly improved the battery capacity. The LG G3 just released is equipped with a conventional battery of 294mAh. If it can be equipped with a trapezoidal battery, the battery capacity may reach 345mAh, which is still very impressive. But increasing the volume to solve the battery capacity problem is a stupid way after all. The price of LG G2 is 2699 yuan. Click to view the details.
▲Li-Air battery technology
Method 4: adopt a brand-new battery. At present, the only way to improve the battery capacity of smart phones as fast as that of camera pixels is to use new material batteries. At present, the lithium-sulfur battery and lithium-oxygen battery, which have a high voice, claim that the energy density can be improved by dozens or even hundreds times compared with the current lithium cobaltate battery, but they are still in the stage of theoretical verification in the laboratory and the production of very few experimental products due to the reasons of cost, immature technology and low safety performance. It is still far away from being installed in our mobile phones, even farther than we mentioned earlier that nano-grid is used to increase the cathode density. Even if the sons can use it, technology will advance by leaps and bounds.
▲ Samsung tested the mobile phone fuel cell very early
Method 5: Fuel cell. Whenever we talk about the bottleneck of the battery, we will hear the sound of the fuel cell. It is true that lithium is very powerful as a battery, but don't forget that the first hydrogen in the periodic table is the Wang Zhongwang of energy. I remember that on the eve of the release of each generation of iPhone, there were various rumors that the iPhone would use fuel cells. The author can only say that the ideal is full and the reality is very skinny. At present, fuel cells can not be commercialized in small scale, and the fuel cells in the hands of non-professional users can not be guaranteed to be safe enough. The author's idea is that the fuel cell has a lot of energy. If it enters the consumer level, several mobile phone batteries can be assembled into a bomb. Wouldn't that be chaos in the world? There are also friends who fantasize about nuclear energy entering the consumer market every day. Think about the current regional security situation and stop dreaming.
The above are five ways to open the source of smart phones, and we also see that they are either still in the experimental stage or the cost is too high. One of the most reliable methods-the application of heterosexual batteries is still to increase the size of mobile phones in essence. It can't be said that mobile phone batteries will not develop rapidly in recent years, but it is difficult to change in essence, and it is almost impossible for us to multiply in our ideal state. Since open source is hard to see results in the short term, let's take a look at throttling. What technology can reduce the power consumption of mobile phones at present?
existing power-saving technology for smart phones
Some people say that money is not saved, and I agree with this view, but in real life, if you don't want to save money without a raise, you must be drunk. The same is true for mobile phones. Earlier, we talked about the current open source.