Silicon-carbon anode materials have significantly improved the energy density of mobile phone batteries, and many phones have begun to exceed the 6000mAh mark. However, in the AI era, relying solely on an increase in battery energy density may not meet users' demands for battery life.

Not long ago, Apple showcased its AI layout and capabilities to the outside world, including a series of AI features that transform the mobile phone system level, enabling cross-app collaboration, accessing personal data and contexts, and collaborating with Open AI to introduce ChatGPT into mobile phones.

But at the same time, the power consumption of AI on mobile phones has also raised concerns in the market. Musk once said, "The speed of AI technology development is unprecedented, and by next year, humans will not have enough power to run all the chips." OpenAI CEO Altman also mentioned that AI technology will consume far more electricity than people expect.

In fact, whether it's calling large models from the cloud or running smaller models directly on the phone, both will accelerate power consumption. However, there has not been much growth in mobile phone battery capacity in recent years, making it equally crucial to increase battery capacity as the implementation of AI applications.

From chip performance to large storage, from high-refresh screens to mobile phone cameras, every area closely related to user experience has undergone visible changes in the past few years. Now, the slowest-progressing mobile phone battery will also usher in a new round of competition before the advent of the AI era.

01

The Competition of Mobile Phone Batteries Begins

In 2013, the A7 processor on the iPhone 5s had 1 billion transistors. A decade later, in 2023, the iPhone 15 came with the latest Apple chip, the A17 Pro, which has 19 billion transistors. In ten years, the number of transistors has increased by 19 times, indicating that Moore's Law has not completely failed.

However, the battery capacity has presented a different picture. The iPhone 5S had a battery capacity of 1560mAh, while the iPhone 15 standard edition has a battery capacity of only 3349mAh. Even for Android phones, the battery capacity was generally between 4000-5000mAh a few years ago. Limited by materials, lithium batteries have been developing slowly since their commercialization in 1991, and their energy density has even stalled at times.

But the situation is changing.

On June 20th, OnePlus held another "unpackaged" launch event, focusing on batteries. OnePlus and Ningde New Energy (ATL) jointly announced the "Glacier Battery," adopting the most popular silicon-carbon anode battery technology. With the Glacier Battery, the battery capacity of the OnePlus Ace 3 Pro has reached 6100mAh for the first time. Although the capacity has increased, the volume has been reduced by 3% compared to a 5000mAh ordinary graphite battery.

The day after OnePlus announced its Glacier Battery, Lenovo Mobile also revealed that the upcoming moto razr will adopt the latest battery solution, using a high-voltage silicon-carbon anode. Lenovo specifically named this battery the "Xinghai Battery," which boasts an energy density of up to 822Wh/L.

The internal competition of batteries had already begun before this, and the most notable manifestation was that every mobile phone manufacturer gave their own mobile phone batteries a grand name. In addition to OnePlus's Glacier Battery, there are also Xiaomi's Jinshajiang Battery, Honor Qinghai Lake Battery, Huawei's Whale Battery, and vivo's Blue Ocean Battery. Fortunately, the number of mobile phone brands is limited, otherwise the lakes, seas, mountains, and rivers would probably not be enough.

And these batteries, without exception, all use silicon-based negative electrodes (including silicon carbon and silicon oxygen negative electrodes, etc.).

As early as 2019, Xiaomi's concept model Max Alpha was equipped with nano silicon based batteries. A year and a half later, the Xiaomi 11 Pro became the first mobile phone in China to be equipped with a silicon-based negative electrode material. Xiaomi uses a silicon oxygen negative electrode, with a battery capacity of up to 5000mAh. Soon, Huawei Mate Xs 2 also adopted high silicon negative electrode batteries.

In 2023, the Honor Magic 5 Pro was equipped with the Qinghai Lake battery released by Honor, which is considered the first smartphone product to commercialize silicon carbon negative electrode battery technology. And vivo adopts a new generation of silicon carbon negative electrode material for blue ocean batteries, which has an energy density about 20% higher than ordinary graphite negative electrode batteries. This battery will be equipped on vivo S19 series smartphones, breaking the energy density of 809Wh/L for the first time.

However, behind the silicon carbon negative electrode batteries used by mobile phone manufacturers, almost all come from the same supplier - ATL (Ningde New Energy). People often confuse Ningde Era with Ningde New Energy. Although Ningde New Energy and Ningde Times have a deep connection, they do not have any equity relationship and their business directions are clearly different. Ningde New Energy focuses on the production of lithium batteries in the consumer electronics field, while Ningde Times focuses on power batteries.

With the support of new battery technology, battery capacity has reached the level of 5500mAh. In addition to the OnePlus Ace3 Pro achieving 6100mAh, the Honor Magic6 Pro equipped with Qinghai Lake batteries has a battery capacity of 5600mAh, while vivo's X100Ultra has achieved 5500mAh, and the S19 has also surpassed 6000mAh for the first time.

Mobile phone battery life has also begun to enter the "2" era. For example, the soon to be released OnePlus Ace3 Pro has reached 2 days of DOU, and several models under vivo have also reached this number.

In fact, DOU (Daily Office Use) is an internal testing metric for various companies, and there is no unified testing standard. However, its logic is to simulate a user's daily computer usage through big data. Moreover, due to the complexity of the user group, each individual's experience and perception of battery life may vary.

However, currently it seems that the models that can achieve a 2-day battery life are basically not straight flagship models, either mid to low-end models or foldable models. Although the battery capacity of flagship phones is rapidly increasing with the support of silicon carbon negative electrodes, the top-level configuration of flagship phones often means higher power consumption, and various large-sized image sensors occupy a relatively high amount of mobile phone space. Therefore, there is no direct board flagship Dou that can achieve a 2-day time.

Li Jie, President of OnePlus China, said that silicon carbon negative electrodes and high-capacity batteries will soon become popular. In addition to OnePlus Ace3 Pro, which will be equipped with glacier batteries for the first time, OnePlus will also promote large battery solutions in subsequent projects.

02

The efforts behind the large battery

The significant increase in energy density of mobile phone batteries is due to the commercial use of silicon-based negative electrode materials. The current lithium-ion batteries for mobile phones are composed of several parts, including positive and negative electrodes, electrolytes, and separators. The positive electrode material is basically lithium cobalt oxide, and the negative electrode material is graphite.

But the energy density of graphite is approaching its limit, and new negative electrode materials have become the key to improving the capacity of lithium batteries. The specific capacity of silicon negative electrode (4200 mAh/g) is much higher than the theoretical specific capacity of graphite (372 mAh/g).

Silicon carbon negative electrode is not a new term, and the corresponding concept has been proposed as early as the 1970s. But due to issues with first effect and volume expansion, it has not been able to be used on a large scale. For example, the volume expansion of pure silicon can reach more than three times that of graphite.

But a few years ago, Group 14, a silicon carbon composite material company in the United States, prepared new materials through CVD vapor deposition, greatly improving the expansion problem of silicon, and has successfully achieved industrialization. The silicon carbon negative electrode material of Ningde New Energy (ATL) comes from Group 14.

ATL Deputy General Manager Zhao Zhongli told Shuzhi Frontline that silicon carbon negative electrode batteries only started mass production last year, mainly because they have solved problems such as silicon expansion and low initial efficiency in recent years. "At an acceptable cost, its energy density can be increased to reduce its expansion." ATL is currently producing silicon carbon negative electrode batteries at full capacity to meet the supply to mobile phone manufacturers. "The industry is currently in a competitive phase, and the speed has become very fast."

Previously, some institutions predicted that the proportion of silicon-based materials used would increase from the current 25% to 40% by 2025.

Moreover, the silicon content of current silicon carbon negative electrode batteries is mostly around 6%. Mako, the founder of True Lithium Research, told Shuzhi Frontline that with the maturity of porous carbon technology, there is still great potential to increase silicon content in negative electrode materials. This also means that as the silicon content increases, the energy density of the battery will continue to increase.

In fact, the industry has been making different efforts to improve the energy density of lithium batteries. Moko told Shuzhi Frontline that in addition to the breakthrough in silicon carbon negative electrode materials, the energy density of lithium batteries has experienced several significant increases in the past. For example, improving the compaction density of materials and increasing voltage. The positive electrode material of mobile phone batteries, lithium cobalt oxide, originally had a standard voltage of 3.7V, but now it has generally increased to 3.8-3.9V, while OnePlus Glacier batteries have achieved 4.53V.

Vivo's recently launched semi-solid state battery started with electrolytes. Electrolyte is the material between the positive and negative electrodes, which functions to transport lithium ions between the positive and negative electrodes. Previously, they were all liquid electrolytes, but there were issues with liquid leakage and safety, and there was a risk of positive and negative short circuits in lithium dendrites. Moreover, in low-temperature environments, the battery life will also decrease.

Solid electrolytes can avoid these issues. However, there is still a long way to go for solid-state electrolytes, and semi-solid batteries are a transitional solution.

In addition to putting effort into positive and negative electrode materials, some manufacturers are also beginning to improve the packaging process of batteries. For example, it was previously reported that both Samsung Galaxy S24 Ultra and Apple iPhone 15 will use stacked battery technology to improve energy density and extend service life.

The traditional packaging method uses a winding process, but the advantage of a stacked process is that it can reduce space waste and improve battery capacity under the same volume. At present, stacked battery technology has been widely applied in the field of electric vehicles. However, mobile phone manufacturers have not yet officially released the relevant batteries.

Starting from the iPhone X, Apple has been using a dual layer motherboard and a shaped battery design to fit larger capacity batteries into the iPhone. Many Android phones also adopt a dual cell approach, which involves connecting multiple cells in a single battery through a series of circuits to improve charging efficiency.

03

In the era of AI, simply making larger batteries may not be enough

The Nokia 1100, Nokia's most classic feature phone, has sold a total of 250 million units worldwide, becoming the best-selling phone in the history of mobile phones. And this phone uses a BL-5C lithium battery with a capacity of only 850mAh. Although the capacity is not high, the battery life is very long, and the official standby time reaches 400 hours.

Obviously, the battery life of a mobile phone is not only related to its battery capacity, but also to its power consumption. The basic functions of a functional phone include making phone calls, listening to music, and sending text messages, with very limited power consumption. The high refresh rate screens and chip power consumption of smartphones are constantly increasing, and the user's usage time is also increasing year by year. These factors make it difficult for the battery capacity to keep up with the user's power consumption needs, although it is slowly growing.

A digital blogger once conducted battery life tests on nearly 200 smartphones released from 2019 to 2021. The average battery capacity of the test model increased year by year from 3912.1mAh in 2019 to 4287.93mAh and then to 4498.49mAh. However, during the 5-hour endurance test, the average remaining battery capacity remained almost unchanged at around 50%. This also indicates that although the battery capacity has increased, the power consumption of mobile phones is gradually increasing due to factors such as screen, SOC, and 5G.

So, battery life not only needs to be open source, but also cost saving is equally important.

The battery capacity of iPhone has always been low, but its battery life is not too poor. Its core is to optimize the system and tune the chip. The iOS system has a tombstone mechanism that allows applications to retain their state after entering the background, and then be "frozen" to ensure they enter a low-power state when inactive, while retaining their state for quick recovery, saving system resources and batteries.

Android manufacturers have also made a lot of efforts in system power optimization over the years. For example, vivo has improved computing efficiency through system lightweighting, prioritized system resources to front-end tasks through unfair scheduling, and improved the battery life experience of mobile phones.

OPPO has also developed its own "microarchitecture supercomputing engine", which customizes a dedicated CPU frequency modulation scheduling algorithm based on user touch, vision, and hearing through a CPU scheduling platform, reducing CPU power consumption in high load application scenarios; Support dynamic frame rate refresh, intelligently adjust screen refresh rate in different scenarios, and reduce screen power consumption caused by high refresh rates.

The glorious Dujiangyan Irrigation Project power management system, through the combination of hardware chip and software algorithm, has realized the all-round management and optimization of accurate measurement of electricity, battery safety and charging and discharging strategies.

Everyone's approach is to reduce power consumption and improve battery life through system level resource optimization.

But with the advent of the big model era, the consumption of end-to-end computing power and electricity by AI has also raised many concerns. Although there is no organization or manufacturer yet to estimate how much power consumption a large model will bring to mobile applications, and the AI capabilities on mobile phones are limited, people's perception of power consumption is not strong. However, with the deep application of AI at the mobile system level, it will inevitably increase people's battery life anxiety.

The CEO of Group14 Technologies stated that the increasing number of new smartphone features is driving the demand for next-generation battery technology. He said, "If silicon negative electrode batteries can provide more than 50% increase in energy density, then regardless of whether the efficiency of the equipment can be synchronously improved, the flexibility of equipment manufacturers in system design will be greatly enhanced."

Chip manufacturers are also working hard to reduce power consumption. Qualcomm stated that the Snapdragon X Elite chip consumes only one tenth of the power of traditional chips when running Microsoft's Copilot Plus artificial intelligence assistant, but its performance output is comparable.

The innovation of battery materials and the expansion of mobile phone systems and functions have always been contradictory. In the upcoming era of AI smartphones, besides the advancement of battery materials, how to reduce the power consumption of the phone itself will be a key factor in ensuring the experience.