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Why is the mobile phone battery becoming less and less durable?

2025-01-28 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > IT Information >

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Shulou(Shulou.com)11/24 Report--

When the editor is fishing for fish and playing with his mobile phone.

Found that the battery of the editor's cell phone was fleeting.

This makes me have to sigh.

Turn around and look for the charger.

Why are our mobile phones becoming more and more useless?

It starts with our batteries.

01. The early product of mobile phone battery in 1973, the world's first mobile phone was born in Motorola Lab. This phone is very bulky, but thanks to the built-in Ni-CD battery, the phone can break away from complicated electronic circuits and make real-time mobile calls.

As the first battery built into the mobile phone, Ni-CD battery itself is relatively bulky. Most of the popular "mobile phones" in the last century use nickel-cadmium batteries. The capacity of Ni-CD battery is low, and it contains toxic cadmium, which is not conducive to the protection of ecological environment. And the Ni-CD battery also has a very obvious memory effect: if the charge is not completely discharged before charging, the battery capacity will be reduced over time.

Basic structure of Ni-CD battery [2] in 1990, Sony of Japan first developed Ni-MH battery. Compared with its predecessors, Ni-MH batteries can not only be thinner, but also improve their capacity effectively [3]. The advent of Ni-MH batteries makes mobile phones more portable and can support longer calls. Therefore, with the emergence of Ni-MH batteries, bulky Ni-CD batteries have been gradually replaced, and compact mobile phones have become popular. But Ni-MH batteries still have a memory effect, which is why the previous generation of mobile phones needed to be fully discharged and then recharged. Moreover, due to the limited energy density of Ni-CD batteries, mobile phones at that time could only support relatively simple tasks such as making phone calls, which is still a big gap from our smartphone form now.

02. The rise of lithium batteries the metal lithium was discovered in the 19th century. Lithium has a unique advantage as a primary battery because of its relatively low density, high capacity and relatively low potential. However, lithium is a very active alkali metal element, resulting in very high environmental requirements for the preservation, use or processing of lithium metal, and it is much more complex than other metals. Therefore, in the process of studying lithium battery with lithium as electrode material, scientists have overcome many research problems through the continuous development and improvement of lithium battery, and finally let it become what it is today after many stages.

The lithium battery with metal lithium as negative electrode was first commercialized. Lithium fluorocarbon battery was invented by Panasonic in 1970. This kind of battery has large theoretical capacity, stable discharge power and small self-discharge phenomenon. But this kind of battery cannot be recharged and belongs to primary lithium battery [2].

In the 1970s, Stanley Stanley Whittingham, a developer from ExxonMobil (ExxonMobil), proposed the principle of charge and discharge of ion-intercalated batteries, and issued a patent for lithium titanium disulfide batteries in 1975. In 1977, Whitingham's team working for Exxon developed secondary batteries with aluminum-lithium alloy Li-Al as negative electrode and titanium disulfide TiS alloy as positive electrode, in which Al-Li alloy can improve the stability of lithium metal and enhance battery safety [2]. During the discharge process, the electrochemical process of the battery is as follows:

Negative electrode: Li-e-→ Li+

Positive: xLi+ + TiS "+ xe- → LixTiS"

Among them, TiS resin is a layered compound, and the interaction between the layers is weak van der Waals force (Van der Waals Force). Smaller lithium ions can enter the interlayers of TiS tiles and undergo charge transfer, and store lithium ions, similar to squeezing jam into sandwiches. This process is ion intercalation [4] [5]. In the process of discharge, the TiS ions in the electrolyte are inserted between the Li+ layers of the positive electrode to accept the charge and form LixTiS ions.

The structure of TiS cathode and the principle of intercalation reaction during discharge [6] Lithium metal is mainly used as anode material in secondary lithium battery at this stage, and the life and safety of battery are improved by improving cathode material. As the earliest commercialized secondary lithium battery, using metal lithium as negative electrode material has lower negative electrode potential, high energy density and portability, but its safety has also been widely questioned. In the late spring of 1989, the first generation metal lithium battery produced by Canadian company Moli Energy exploded, which brought the commercialization of metal lithium battery to a standstill for a time.

In order to improve the safety of lithium battery, the development of new electrode materials is very important for lithium battery. However, using other lithium compounds as negative electrodes instead of lithium will increase the negative electrode potential, reduce the energy density of lithium batteries, and reduce the battery capacity. Therefore, finding suitable new electrode materials has become a difficult problem in the field of lithium battery research.

After 1980, John Bannister Gudinave (John Bannister Goodenough), who teaches at the University of Oxford in England, discovered the compound lithium LiCoO cobalt (LCO), which can hold lithium ions. LiCoO cathode has higher potential than other kinds of cathode materials at that time. This enables the lithium battery with LiCoO cathode to provide higher voltage and higher battery capacity. [7] [8]

Schematic diagram of crystal structure of lithium cobalt [9] Lithium cobalt crystal has a layered structure and belongs to hexagonal system. Among them, the octahedral lattice composed of O and Co atoms is arranged into CoO layers on the plane, and the CoO layers are separated by lithium ions to form a planar lithium ion transport channel. This enables lithium cobalt oxide to transport lithium ions quickly through planar lithium ion channels. The detachment and intercalation process of lithium ion in lithium cobalt is similar to that of intercalation. In the process of mild charge and discharge, lithium cobalt can keep the crystal structure stable. However, with the gradual removal of lithium ions, lithium cobalt oxide tends to transform to monoclinic system [2]. In the lithium battery with lithium cobalt as positive electrode, the reaction of positive electrode during discharge is as follows:

Positive: Li1-xCoO "+ xLi+ + xe- → LiCoO"

Schematic diagram of lithium ion removal from lithium cobalt oxide during discharge [9] compared with titanium disulfide, lithium cobalt oxide cathode material has higher positive potential, and layered lithium cobalt oxide can transport lithium ion faster. It is an excellent cathode material for lithium-ion battery.

In the same year, Rachid Yazami (Rachid Yazami) discovered the phenomenon of recyclable ion intercalation of lithium ions in graphite and verified the feasibility of graphite as the cathode of lithium battery [10]. Graphite has a lamellar structure, and similar to TiS graphite, the middle layer of graphite is connected by a weak van der Waals force, which enables smaller lithium ions to enter the graphite interlayer and transfer charge.

Graphite has a layered structure, and the layers are connected by van der Waals force [11] in the 1983 paper [12], Yazami used polyethylene oxide-lithium perchlorate solid-state electrolysis, and lithium metal as the negative electrode, graphite as the positive electrode to form the primary battery. During the discharge, the graphite as the positive electrode reacts as follows:

NC + e-+ Li+ → (nC, Li)

Then it happens: (nC, Li) → LiCn

During the discharge of primary battery with graphite as positive electrode, lithium ion intercalation occurs in the graphite layer, resulting in charge transfer and the formation of compound LiCn.

03. The arrival of lithium-ion battery in 1982, (Asahi Kasei Corporation) Akira Yoshino (Yoshino Akira) of Asahi Kasei Company in Japan used lithium cobalt oxide as the positive electrode and polyacetylene (C2H2) n as the negative electrode to construct the sample of lithium-ion battery [13]. In the discharge process of lithium cobalt oxide battery, lithium ion migrates from the positive electrode of the battery to lithium cobalt oxide through the electrolyte to realize battery discharge.

However, there are still many problems in lithium cobalt oxide battery. The negative polyacetylene of the battery has low energy density and low stability. Therefore, Akira Yoshino used a new graphite-like material "soft carbon" instead of polyacetylene as the anode material of the battery, and made the first lithium-ion battery prototype in 1985 and applied for a patent [10]. The prototype of lithium-ion battery designed by Akira Yoshino has become the prototype of many modern batteries.

Schematic diagram of lithium-ion battery discharge and lithium ion migration process compared with lithium battery, the primary battery designed by Akira Yoshino with carbon material as negative electrode and lithium cobalt as positive electrode gets rid of metal lithium, so this kind of battery is also called "lithium-ion battery". Due to the intercalation reaction of lithium ion in both positive and negative electrodes in lithium cobalt ion battery, the rapid charge transfer is realized by the rapid intercalation of lithium ion, so this battery structure is also known as rocking chair battery.

In 2019, the Nobel Prize in Chemistry was awarded to American scientist John B. Goodenough, British scientist M. Stanley Whittingham and Japanese scientist Akira Yoshino for their contributions to lithium-ion battery research.

Nobel laureates: from left to right are American scientist John B. Goodenough, British scientist M. Stanley Whittingham and Japanese scientist Akira Yoshino [4] the development of lithium-ion battery is promoted by the emergence of lithium-ion battery with carbon material as negative electrode and lithium cobalt as positive electrode. With the deepening of researchers' research on lithium-ion battery, three systems of cathode materials for lithium-ion battery have been developed: lithium cobalt (LCO), lithium iron phosphate (LFP) and ternary nickel-cobalt-manganese (NMC / NCM) system. Among them, lithium cobalt system has relatively higher battery capacity and plays an important role in the field of 3C electronic products such as mobile phones, computers and so on. Lithium iron phosphate system and ternary lithium system have higher stability, so they are widely used in new energy vehicles. [14]

The emergence of lithium-ion batteries has completely changed our way of life. Compared with Ni-CD battery and Ni-MH battery, lithium-ion battery has higher energy density, and lithium-ion battery with the same battery capacity is more portable, which can support the high power consumption of smart phones with rich functions. At the same time, most lithium-ion batteries have no memory effect and do not need to be fully discharged and recharged, so lithium-ion batteries can be recharged on demand. Compared with lithium battery, the charging rate of lithium-ion battery is significantly higher. And the charging rate of lithium-ion battery is fast, which greatly facilitates our life. Therefore, in mobile phones, mobile computers, new energy vehicles and other application scenarios, lithium-ion batteries gradually replace Ni-CD batteries and Ni-MH batteries in some scenarios because of their excellent performance.

Why is the battery life of mobile phones getting shorter and shorter? Pain-memory effect of Ni-CD battery for Ni-CD battery, the grain of cadmium in the negative electrode of Ni-CD battery prepared by sintering is thicker. When Ni-CD battery is not completely charged and discharged for a long time, the grain of cadmium is easy to gather and gather into blocks. At this point, a secondary discharge platform is formed when the battery is discharged. The battery will use this primary discharge platform as the end point of battery discharge, the capacity of the battery becomes lower, and the battery will only remember this low capacity in the future discharge process [15]. This is why the older generation of mobile phones with Ni-CD batteries are often advised to fully discharge before charging. However, with the continuous improvement of the processing technology of Ni-CD battery and Ni-MH battery, the effect of memory effect on battery capacity has been continuously reduced, and the harm of complete charge and discharge to battery life has gradually emerged.

Nickel-cadmium battery has obvious memory effect, while lithium-ion battery has almost no memory effect. And because the energy density of lithium-ion battery is higher than that of nickel-cadmium battery, lithium-ion battery is mainly used in our mobile phones, computers and other products. Therefore, we do not need to worry about the memory effect of lithium-ion batteries when we use smartphones or computers loaded with lithium-ion batteries.

Excessive charge and discharge of Li-ion battery leads to life decline

Lithium cobalt has a high theoretical capacitance, but the actual capacity of lithium cobalt is far less than the theoretical capacity in the process of use. Because after we charge and discharge lithium-ion batteries beyond this capacity, lithium cobalt will have an irreversible charge-discharge process, that is, we often say that the battery is overcharged or overdischarged. This process is accompanied by the structural phase transition of lithium cobalt, which reduces the capacity of the battery.

Schematic diagram of monoclinic phase transition of lithium cobalt in six directions [16] when the battery is overcharged, lithium cobalt from the negative electrode of lithium ion battery removes a large amount of lithium ions, and the remaining lithium ions are not enough to support the original structure of lithium cobalt, resulting in the transformation of Li1-xCoO crystals from hexagonal to monoclinic, and the original hexagonal structure collapses without ion support. In this process, the phase transition of lithium cobalt is not completely reversible, and the change of unit cell parameters, stress change and lithium ion vacancy compression lead to the capacity attenuation of lithium ion battery. [17] [18]

The instability of high-voltage lithium-ion battery in addition to the irreversible change of battery capacity caused by the structural phase transition of lithium cobalt oxide, the increase of output voltage of lithium-ion battery also leads to other side reactions in lithium-ion battery and the life of lithium-ion battery decreases. At present, smart phones on the market usually use a charge-discharge voltage of about 4.4V [14]. High voltage can improve the capacity of lithium-ion battery and accelerate the charge and discharge rate of lithium-ion battery. However, it is followed by a series of side effects, such as the increase of side reactions on the electrode surface of lithium-ion battery, the instability of electrolyte under high voltage and so on.

Influence mechanism of life decay of high voltage lithium-ion battery [18] the electrolyte of lithium-ion battery reacts at the solid-liquid interface with positive and negative electrodes to form a passivation layer covering the surface of the electrode. This passivation layer has the characteristics of solid electrolyte, through which Li ions can be embedded and removed freely, so this passivation film is called "solid electrolyte interface film" (solid electrolyte interface), referred to as SEI film [19]. The process of forming SEI film consumes part of lithium ion, which leads to irreversible loss of lithium ion battery capacity. Under the action of high voltage, the side reaction on the surface of this kind of electrode is serious, which makes the capacity of the battery decrease gradually.

When using a mobile phone, you need to pay attention to what high temperature does not charge. In the case of overheating or extremely low temperature of the phone, do not charge the phone. When the mobile phone is overheated, charging the lithium-ion battery at high temperature will also change the positive and negative electrode structure of the lithium-ion battery, resulting in irreversible attenuation of the battery capacity. Therefore, try to avoid charging the mobile phone under the condition of overcooling or overheating, which can also effectively prolong its service life.

Timely battery replacement in the process of using digital products such as mobile phones, notebooks or tablets, when we find that the back cover of the battery is deformed, the battery appears drum bags and other abnormal conditions, we should stop using the battery in time and replace the battery with the manufacturer to avoid the safety risks left by the improper use of the battery as far as possible.

reference

[1] Martin Cooper _ Baidu Encyclopedia

Https://baike.baidu.com/item/%E9%A9%AC%E4%B8%81%C2%B7%E5%BA%93%E5%B8%95/3066905?fr=ge_ala

[2] the development history of https://zhuanlan.zhihu.com/ battery is 146768161.

[3] Ni-MH (MH-Ni) battery-Zhihu https://zhuanlan.zhihu.com/ pram 630028868

[4] The Nobel Prize in Chemistry 2019. NobelPrize.org. Nobel Prize Outreach AB 2023. Sun. 13 Aug 2023.

[5] Binghamton professor recognized for energy research https://www.rfsuny.org/rf-news/binghamton-energy/binghamton---energy.html

[6] Hongwei,Tao,Min,et al.TiS2 as an Advanced Conversion Electrode for Sodium-Ion Batteries with Ultra-High Capacity and Long-Cycle Life.[J] .Advanced Science, 2018.

[7] Lithium-ion battery Wikipedia https://en.wikipedia.org/ wiki / Lithium-ion_battery

[8] John B. Goodenough Facts https://www.nobelprize.org/prizes/chemistry/2019/goodenough/facts/

[9] Lithium Cobalt Oxide-LiCoO2, https://www.chemtube3d.com/lib_lco-2/

[10] Lithium-ion battery Wikipedia https://en.wikipedia.org/ wiki / Lithium-ion_battery#cite_note-31

[11] Graphite Wikipedia https://en.wikipedia.org/ wiki / Graphite

[12] Yazami R, Touzain P. A reversible graphite-lithium negative electrode for electrochemical generators [J]. Journal of Power Sources, 1983, 9 (3): 365371.

[13] Akira Yoshino Wikipedia https://en.wikipedia.org/ wiki / Akira_Yoshino

[14] A brief introduction to contemporary lithium-ion battery system Zhihu https://zhuanlan.zhihu.com/ pplink 374494628

[15] memory effect Baidu encyclopedia https://baike.baidu.com/ item/% E8 AE% B0% E5 BF%86% E6% 95% 88 E5 BA%94/1685065?fr=ge_ala

[16] Reimers J N, Dahn J R. Electrochemical and Insitu X-Ray-Diffraction Studies of Lithium Intercalation in Lixiliary 2 [J] .Journal of the Electrochemical Society, 1992, 139 (8): 2091-2097.

[17] Research Progress of Lithium Cobalt as Lithium Ion cathode material https://www.chemicalbook.com/NewsInfo_21664.htm

[18] Zhang Jienan. Failure Analysis and Modification of High Voltage Lithium Cobalt [D]. University of Chinese Academy of Sciences, 2018.

[18] Schlasza C, Ostertag P, Chrenko D, et al.Review on the aging mechanisms in Li-ion batteries for electric vehicles based on the FMEA method [C] 2014 IEEE Transportation Electrification Conference and Expo (ITEC). IEEE, 2014

[19] Why is SEI film formed in lithium-ion battery? What are the specific steps for the formation of SEI films? What is the structure of SEI film? Zhihu https://www.zhihu.com/ tardis / bd / art / 603133202?source_id=1001

This article comes from the official account of Wechat: Institute of Physics, Chinese Academy of Sciences (ID:cas-iop), author: * 0

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