Thin body and long battery life will become the standard feature of smartphones

I still remember that at the Redmi Turbo 3 launch conference, when introducing the battery life of this phone, Redmi brand general manager Wang Teng smiled helplessly and said that in order to have a thinner body and feel, Turbo 3 can only choose to be equipped with a 5000mAh battery.

In less than 2 months, various manufacturers have come up with a new generation of thin and large "black technology" batteries: the vivo S19 mobile phone equipped with a 6000mAh battery has a body thickness of only 7.19 mm; OnePlus' new "Glacier" "Battery" has a large capacity of 6100mAh, but is thinner than an ordinary 5000mAh battery.

▲ Picture source: Weibo @digital chat station

The thinnest straight smartphone in history was born ten years ago

The new iPad Pro released in May has sparked heated discussions due to its 5.1 mm body that is thinner than the iPod nano.

This ultra-thin iPad is just the beginning. According to Bloomberg, future Apple devices will set off a "slimming" trend. In addition to the iPad, iPhone and Mac products will all become thinner and lighter. iPhone 17 is also expected to launch a new "Slim" model that focuses on thinness and lightness.

It is said that fashion is a circle, and digital products may be the same. As early as ten years ago, the "downsizing" trend had already spread among manufacturers.

In 2014, Apple launched the iPhone 6. The thickness of 6.9 mm has not yet been surpassed by the iPhone, and the two domestic manufacturers, OPPO and vivo, are even thinner.

OPPO R5, with a thickness of 4.85 mm, is too thin to accommodate a 3.5 mm headphone jack. In 2014, it was "ahead of the times" in letting the Micro-USB port share the audio function.

With its "thinness" of 4.75 mm, vivo X5 Max claims the title of the world's thinnest candy bar smartphone, and has yet to be surpassed by anyone.

This ultimate pursuit of mobile phone thickness is actually easy to understand. OPPO and vivo are both offline mobile phone brands. Their ultra-thin bodies can be felt by consumers online just by looking at them. Battery life, the biggest concession, happens to be something that offline purchasers cannot quickly feel. shortcomings.

Ultra-thinness also allows OV to take a different differentiation route from other manufacturers. Compared with the 7.9 mm thick Huawei Mate 7 and even the 8.9 mm thick Xiaomi 4 in the same period, OV mobile phones, which originally did not have an advantage in terms of product strength, It also has a unique selling point that no one else has but I have.

▲ Xiaomi Mi 4 is really just “a steel plate” in terms of thickness

The cost is also obvious. With a small body of less than 5 mm, some components can be made small and thin to save space, but the battery can only be compromised at the time. Therefore, both OPPO R5 and vivo X5 Max are equipped with 2000mAh batteries.

For comparison, the Samsung Galaxy S5 of the same period, with a smaller screen size than these two phones, was equipped with a 2810mAh battery, and of course the thickness was also 8.1 mm.

The small battery also brings a chain reaction. Both vivo X5 Max and OPPO R5 are equipped with a low-frequency revision of Qualcomm Snapdragon 615 to reduce power consumption, resulting in a more conservative performance release of this originally mid-range chip.

▲ vivo X5 Max, photo source: Phone Bluff

Moreover, the reduction in the thickness of the mobile phone obviously has a marginal effect on the user. Although the mobile phone is 4 mm thin, the user experience may not be as good as equipped with a larger battery.

It is worth mentioning that the weight of the two 4 mm phones is almost the same as the 145-gram Galaxy S5. The OPPO R5 is also 10 grams heavier than the S5. Therefore, although the phone is thinner, the weight has not been reduced at the same time. The feel improvement is limited.

▲Samsung Galaxy S5

Therefore, after pursuing the ultimate ultra-thin body, OV began to explore the art of "water-bearing": how to ensure that the body of the mobile phone is as thin and light as possible without excessively sacrificing other performance.

The successors of the two ultra-thin mobile phones, OPPO R7 and vivo X6, both have returned to the 6 mm level, and both accommodate a battery of about 2400mAh. Although the thickness has increased by about 1.5 mm, the two mobile phones are still in the category of thin mobile phones. category.

▲ vivo X6, thickness 6.56 mm

Then the trend of various companies began to build "bucket phones", and began to roll out various configurations such as image quality, performance, and battery life. The thickness of smartphones, which had dropped, began to increase again.

OPPO, which once pursued the ultimate thinness and lightness, returns to its true flagship series with the first OPPO Find X. It comes with a variety of configurations and the body thickness reaches 9.6 mm, which is almost twice as thick as the OPPO R5.

▲ OPPO Find X, which is nearly 1 cm thick, uses a curved screen in appearance to make it appear as thin as possible

A mobile phone that is only half a catty, one centimeter thick and weighs two hundred grams is almost like a "brick". If you are lying on the bed and playing with the mobile phone, if you accidentally catch it, you may also break the bridge of your nose.

▲ Actor Zhou Xun was lying down playing with his mobile phone, and the bridge of his nose was hit by the mobile phone.

With almost all price ranges being able to meet the full range of configurations, the trend of “thinness and lightness” has returned to mobile phone manufacturers. Especially for mid-range models, since they do not require top-notch stacking capabilities, and in recent years various manufacturers have been interested in improving the appearance of mid-range models, many mid-range models have gradually moved towards thinner, lighter and more fashionable models.

For example, OPPO and vivo, which focus on offline mid-range flagship Reno and S series, have always been interested in making a fuss about thinness and lightness.

▲ vivo S19, thickness is 7.19 mm

Different from 10 years ago, various manufacturers that have grown into "adults" said that this time they "want both" thinness and battery life.

Thin body and long battery life are no longer single-choice questions

The contradiction between thinness and battery life seems to be irreconcilable from the beginning. In order to integrate a thin and light body, mobile phone manufacturers have eliminated the removable battery on the mobile phone. When the mobile phone is out of power, replacing the battery has become an "alien technology" that will never come back like the headphone jack.

▲ The last time I used a mobile phone with a removable battery was the Lumia 640. Source: iFixit

But technology is always developing, and there are solutions to conflicts. The new generation of battery technology allows greater capacity to be packed into a smaller body. If you have paid attention to the recent domestic mobile phone batteries, you should find the names "Blue Ocean Battery", "Qinghai Lake Battery", "Glacier Battery" and "Jinshajiang Battery" a bit familiar.

These "watery"-sounding batteries are actually behind a battery technology called "silicon carbon anode."

Here we need to explain the principle of lithium batteries. The inside of the battery is divided into two areas by a separator: the positive electrode and the negative electrode, as well as the electrolyte filled inside the battery. During charging, the lithium ions in the positive electrode will pass through the separator from the electrolyte into the negative electrode, and when discharging, they will enter the positive electrode from the negative electrode, so the negative electrode can be simply understood as the "storage pool" of lithium ions.

At present, the material for the negative electrode of lithium batteries in the industry is generally graphite. In fact, the lithium ion capacity of graphite is not very large. The advantage is that the material is relatively easy to obtain and the technology is more mature.

At this point, the meaning of "silicon-carbon negative electrode" is self-evident – using carbon-silicon composite materials as the negative electrode of the battery.

Compared with graphite, silicon-based materials can absorb more lithium ions, and the theoretical limit of specific capacity can reach 12 times that of graphite materials. Even the current small-scale application of silicon-carbon anode materials has the highest actual specific capacity than the theoretical limit of graphite anodes. About 13-20% higher than capacity.

▲ OnePlus Glacier Battery Technology Communication Meeting

Recently, when various manufacturers introduce new batteries, they always mention a value "battery energy density", which means how much battery capacity can be provided in the same volume.

Theoretically, if other conditions and conditions are consistent, a battery with a higher energy density can provide a larger battery capacity in the same volume, or achieve a smaller battery volume with the same battery capacity.

Now let’s take a look at the battery energy density of several carbon-silicon anode batteries from all over the world:

  • Xiaomi “Jinshajiang Battery”: 779Wh/L
  • Honor "Qinghai Lake Battery" (first generation): 740Wh/L
  • vivo "Blue Ocean Battery": 809Wh/L
  • OnePlus “Glacier Battery”: 763Wh/L
  • Lenovo/moto "Xinghai Battery": 822Wh/L

For comparison, the current upper limit of the energy density of graphite anode batteries is around 700Wh/L.

▲ Left: Honor Qinghai Lake carbon silicon battery Right: iPhone 15 Pro Max graphite battery

A breakthrough and difficulty in silicon-carbon batteries lies in the "silicon content" of carbon-silicon materials: During the charging and discharging process, the expansion and contraction effects of silicon will be very serious, so pure silicon-based negative electrode batteries are very unstable and need to combine carbon and silicon. Compound to enhance battery stability.

This creates a new contradiction: the higher the silicon content, the greater the energy density of the battery, but correspondingly, the lower the stability.

At present, the silicon content of each new battery is around single digits, and Honor's third-generation Qinghai Lake battery has exceeded the silicon content to 10%, bringing further improvement in energy density.

This actually shows that carbon-silicon batteries still have considerable potential waiting to be tapped. How to increase the silicon content while ensuring battery stability has become a current technological breakthrough for silicon-carbon batteries.

If you want to balance thinness, lightness and battery life, you not only have to pay attention to the battery. The LTPO screen, which has been very popular in recent years, also gives small-body mobile phones the possibility of longer battery life.

▲ OnePlus 9 is one of the earliest mobile phones in China equipped with an LTPO screen

The biggest advantage of the LTPO screen is that it can achieve a wide range of refresh rate changes, from 10-120Hz on the iPhone 13 Pro, to the lowest 1Hz on the OPPO Find X7, and even to the current 0.5Hz.

This kind of "clear motion" screen refresh rate uses a low refresh rate to save power when the phone presents static content, and returns to a high refresh rate when sliding to present a delicate look and feel.

Also because it can achieve an extremely low refresh rate, the mobile phone’s “Always on Display” always-on display function is also more power-saving.

At this year's Realme GT Neo6 SE launch conference, product manager Toby introduced the benefits of the LTPO screen and said that the power saved by the 8T LTPO screen on the Realme GT Neo6 SE is equivalent to adding a 300mAh battery to the phone. capacity.

Therefore, this mobile phone with an actual 5500mAh battery has a DOU battery life test of nearly 2 days, and the body thickness and weight are controlled below 9 mm and 200 grams.

Thin = future?

As soon as the news that Apple was going to make an "ultra-thin iPhone" came out, public opinion quickly split into two factions:

Supporters believe that today's mobile phones, which often weigh 1 centimeter and half a kilogram, are not user-friendly enough and have calluses on their little fingers.

The opposition believes that there is no point in making digital products thinner, and it also sacrifices battery life that will affect the experience.

But the actual performance of the new iPad Pro may be able to give the opposition a "reassurance".

Although it is extremely thin and light, the battery life of the new iPad Pro is almost the same as that of the previous generation. This is despite the fact that the battery capacity of the new iPad Pro is slightly smaller than that of the previous generation.

Behind this is the magic of the new M4 chip, optimized design and manufacturing process, and higher energy efficiency ratio. Even with the battery becoming smaller, the battery life can be the same as before.

What's more, the iPad Pro itself is Apple's tablet product line that focuses on professionalism and performance. The new iPad Pro equipped with Apple's latest M4 chip is capable of various high-energy tasks. Many reviewers even feel that this chip is a bit weak on the iPad platform. "Qucai".

It can be seen that unlike 10 years ago, today's digital products use processors with lower power consumption, the screens are more power-saving, and the batteries are higher-density. Today's ultra-thin bodies are not "thin" with shortcomings in performance and battery life, but "robust" with high integration of various components and high battery density.

Therefore, thinness and lightness are not just a gimmick created by manufacturers. Behind them are breakthroughs in various technologies. Thin design is therefore regarded as a symbol of engineering and technological innovation. We are in the "sweet spot" of slow technological progress.

The pursuit of thinness and lightness is not only the wishful thinking of manufacturers, but also the long-standing expectations of users for technology products.

Just like the MacBook Pro after 2022, although the new mold represents more advanced and powerful productivity, it also makes people miss the old mold that was more curved and thinner in appearance.

Some people even think that this old mold is not backward, but "too advanced".

Or let’s talk about Microsoft’s Surface Pro X back then. Even though the ARM processor brought many problems such as performance and compatibility, the thin and light body compared to the Surface Pro 7 of the same period made people feel that the former was the real future.

▲ Source: The Verge

Of course, although battery life and performance have given the green light to thin and light bodies, how domestic manufacturers can fit the cooling system that has begun to roll out in the past two years into a small body has become a new challenge.

2024 is the year of "AI", so some people say it is the year of the "future". However, in addition to artificial intelligence, digital products that focus on the "thin and light" road may also depict the form of future devices for us.

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