The size of the partition depends mainly on your system disk space and your specific application. If it is only for daily use, it is suggested that 10-20G can meet most requirements.

If your system provides multi-user login, you can enlarge it appropriately. Generally, the configuration of 500- 1024M per user can meet the demand.

It is suggested that /var/ and /usr/local should be partitioned independently, or more space should be allocated appropriately, but generally 10G is enough for each partition.

If there is still room left, the city can be divided into an independent partition or multiple logical partitions according to the needs of different applications.

What's the difference between linux super users and ordinary users?

In Linux system, there are three types of users, namely system users, ordinary users and root users.

1. Ordinary user: a real user of Linux, who can log in by user name and password. Usually, the UID of ordinary users is greater than 500;

2. System users: some special users when the system is running. These users are often unable to log on to the system, but some processes need such users to run. For example, the htpd process in the system is run by the user apache;

3.root user: also called root, with a UID of 0, is also the super user in the system and has the highest authority.

In Linux system, there are user groups besides users, and user groups are also distinguished by numbers, that is, GroupID, or GID for short.

Where can Linux be applied?

Present situation of lithium battery industry

1

lithium battery

Lithium battery refers to the secondary battery with lithium intercalation compound as anode and cathode material. During the charging and discharging process, lithium ions are deintercalated between the two electrodes. Compared with traditional lead-acid batteries and nickel-chromium batteries, lithium batteries have the advantages of high energy density, long cycle life, good charge-discharge performance, high working voltage, no memory effect, less pollution and high safety. Lithium batteries are equivalent to the internal combustion engine of traditional fuel vehicles. For China, which intends to catch up with developed countries such as Europe, America, Japan and South Korea in the new energy industry, developing lithium battery industry has long been a national strategy.

Lithium batteries account for more than 40% of the cost of new energy vehicles, which is the largest cost component. The core of lithium battery is mainly composed of four key materials: cathode material, electrolyte and separator. According to the research report of IIT in Japan, the proportion of anode material, cathode material, electrolyte and separator is about 30%, 10%, 17% and 25% respectively. (Figure 1)

Figure 1 lithium battery material cost ratio

2

Upstream and downstream of the overall industrial chain of lithium batteries

The overall industrial chain of lithium batteries is long and covers a wide range of industries. Raw materials mainly include mineral resources such as lithium, cobalt, nickel, manganese, aluminum, fluorine and graphite, and petroleum and coal chemical resources such as polyethylene, polypropylene, asphalt and nylon. The upstream industry covers the manufacture of cathode materials, cathode materials, electrolytes, separators, aluminum foils, copper foils and lithium batteries. The midstream industries include lithium battery manufacturers, mainly engaged in the production and integration of cylindrical, flexible and metal shell batteries; The downstream industries are lithium battery applications, such as digital electronic products, new energy vehicles, power battery recycling, energy storage equipment and other industries. (Figure 2)

Figure 2 Lithium battery industry chain

Classification of lithium batteries

1

Classification by cathode materials

According to the classification of cathode materials, lithium batteries can be mainly divided into lithium cobaltate, lithium manganate, lithium ferrous phosphate, lithium titanate and ternary materials.

lithium cobaltate

The first successfully commercialized cathode material for lithium ion batteries. Due to the shortcomings of relatively scarce cobalt resources, high price and toxic impact on the environment, coupled with the poor safety performance and relatively low capacity of this material, its application and long-term development are greatly limited. At present, lithium cobalt oxide batteries are mainly used for batteries of digital products.

Lithium manganate

Mainly spinel lithium manganate. Compared with lithium cobaltate, it has the characteristics of rich resources, low price, little environmental pollution and excellent safety performance. However, the structure of spinel is difficult to maintain integrity and its cyclicity is poor. The dissolution of manganese in electrolyte and Jahn-Teller effect (configuration deformation of nonlinear molecular electron cloud in some cases) lead to serious capacity attenuation of materials. The advantage of lithium manganate is low cost, but the disadvantage is that the specific energy has reached the limit, and it can only be used for special vehicles in specific application fields.

Lithium iron phosphate

Rich in raw materials, lower in price than other materials, environmentally friendly, good in cycle performance and high in safety, which makes it widely used in the field of passenger cars. However, lithium iron phosphate material has poor conductivity and low tap density, which leads to low volume energy density and limits its further application.

lithium titanate

Lithium titanate is a material with obvious advantages and disadvantages, which can be used as both positive electrode and negative electrode. When used as a cathode material, the disadvantage of low energy density is prominent, but when used as a cathode material, its advantages of long life cannot be fully utilized by other short-lived cathode materials. The advantages of lithium titanate are fast charging (fully charged in 5min and 5min), long service life, high safety and wide working temperature range. However, its short board with low energy density and easy flatulence is only suitable for buses, buses and other areas with relatively insensitive cruising range, and there is no technical breakthrough.

third

Inspired by the doping modification of lithium cobalt oxide, ternary materials have developed rapidly. Ternary materials combine the advantages of lithium cobaltate, lithium nickelate and lithium manganate (lithium aluminate) to form a ternary body, which can give full play to the functions of the three components. High energy density is the most prominent advantage of ternary battery compared with other cathode batteries, but the relatively low safety is the biggest reason for its limited development. Ternary materials are mainly divided into two categories: nickel cobalt manganese (NCM) and nickel cobalt aluminum (NCA). Among them, nickel (Ni) provides capacity. The higher the content, the greater the energy density of the battery. Cobalt (Co) contributed part of the capacity and stabilized the structure. Manganese (Mn)/ aluminum (Al) is mainly used to stabilize the structure. The synergy of the three materials, * * * gives play to the advantages of high energy density and low cost of ternary materials.

The traditional "3C" lithium battery is mainly made of lithium cobaltate. As the computer and mobile phone market is close to saturation, the future mainly depends on the innovation of smart phones and the expected explosion of smart wearable products, so the demand for lithium batteries in the current "3C" field will maintain a steady low growth rate.

In recent years, with the implementation of China's new energy vehicle policy and the rapid expansion of new energy vehicle output, power lithium batteries have exploded, directly driving the shipment of corresponding lithium ferrous phosphate and ternary cathode material batteries.

Ternary batteries became popular from 20 17. According to statistics, in the first three quarters of 2065438+2007, the output of China's power lithium battery was 3 1GWh, of which 49% was nickel-cobalt-manganese ternary material (NCM), 40% was lithium ferrous phosphate and 8% was lithium manganate. At the same time, according to the national plan, the energy density of power batteries will reach 350Wh/kg in 2020, 400Wh/kg in 2025 and 500Wh/kg in 2030. The inclination to the high energy density of power lithium batteries has made many enterprises and markets turn their attention to ternary material lithium batteries, while lithium iron phosphate batteries seem to be neglected.

According to statistics, there are currently four kinds of Ni-Co-Mn ternary materials (NCM): 333, 523, 622, 8 1 1 (numbers represent the proportion of Ni-Co-Mn elements, for example, NCM523 represents the ratio of Ni: Co: Mn of 5:2:3). The higher the content of Ni as the main active element, the more obvious the capacity advantage of the battery. At present, ternary battery enterprises mainly use NCM333 and NCM523. NCM622 has entered the supply chain system of some enterprises, and NCM8 1 1 is in the research and development stage.

2

Classification by packaging materials

Square hard shell (aluminum shell/steel shell) battery

The outer shell of square hard-shell battery is made of aluminum alloy, stainless steel and other materials, and the inner core is wound or laminated, which has better protection effect than soft-package battery (aluminum-plastic film battery) and the safety of the core is greatly improved than that of cylindrical battery.

Power lithium battery with square aluminum shell is developed on the basis of steel shell. Compared with steel case, aluminum case has become the mainstream of square hard-shell power lithium battery case because of its light weight, safety and performance advantages. Because the square hard-shell power lithium battery can be customized according to the product size, there are thousands of models on the market, and it is difficult to unify the process because there are too many models.

Flexible battery (aluminum-plastic film battery)

Key materials used in soft-packed lithium batteries, such as anode materials, cathode materials, separators, electrolytes, etc. It is not much different from the traditional steel case and aluminum case lithium battery. The biggest difference lies in the soft packaging material (aluminum-plastic composite film), which is the most critical and technically difficult material in soft packaging lithium batteries. Soft-pack lithium battery is the abbreviation of aluminum-plastic film soft-pack lithium battery, which is mainly to distinguish it from the traditional lithium battery with hard shell packaging such as aluminum metal. Flexible battery has better safety, lighter weight and larger capacity. The disadvantages of flexible battery are poor consistency, high cost and easy leakage.

Cylindrical battery

There are many kinds of cylindrical lithium batteries, such as18650,21700. The production process of cylindrical lithium battery is mature, the cost of battery pack is low, and the yield of battery products and the consistency of battery pack are high. Because of the large heat dissipation area of battery pack, its heat dissipation performance is better than that of square battery. Cylindrical batteries are easy to be combined in various forms and are suitable for the full layout of electric vehicle space design. Cylindrical batteries are generally encapsulated in steel or aluminum shells, which are relatively heavy and have relatively low specific energy. With the further expansion of the electric vehicle market and the continuous improvement of the requirements for cruising range, vehicle companies put forward higher requirements for power batteries in terms of energy density, manufacturing cost, cycle life and additional attributes of products. Under the premise of no great breakthrough in the field of raw materials, it has become the direction of exploration to appropriately increase the volume of cylindrical batteries in order to obtain more battery capacity.

Industry and the direction worthy of attention

Although the new energy industry is facing the crisis of 20% subsidy, new energy vehicles are currently in the global development stage. With the establishment of the timetable for banning the sale of fuel vehicles in many countries, people can clearly feel that the development of new energy vehicles is accelerating. 2065438+On September 9, 2007, Vice Minister of the Ministry of Industry and Information Technology pointed out that the timetable for stopping the sale of traditional energy vehicles has been started. 2065438+On September 28th, 2007, the Ministry of Industry and Information Technology issued the Measures for the Parallel Management of Average Fuel Consumption of Passenger Car Enterprises and New Energy Vehicle Points, which set the development goal of new energy vehicles in China. National policies are still promoting the promotion of new energy vehicles. What about lithium batteries as the core components of new energy vehicles?

In the first 65,438+00 months of 2065,438+07, the total installed capacity of lithium batteries was 65,438+08.1gwh (non-production), with a year-on-year increase of 365,438+0.43%. With the further popularization of new energy vehicles in the future, the demand for lithium batteries will continue to grow. The report "20 17-2022 China Power Battery Market Survey and Investment Potential" issued by China Commercial Industry Research Institute shows that the output of power batteries in China will exceed 140GWh by 2020. (Figure 3)

Fig. 32016-China power battery output and growth forecast in 2020

Looking at the data, the whole industry still has a bright future. However, under the dual pressure of the downstream new energy automobile enterprises to reduce costs and the upstream raw material supply price to rise sharply, the profit decline of lithium battery manufacturers is inevitable. With the upgrading of production lines and the expansion of production plants, lithium battery manufacturers will face a serious problem: overcapacity of low-end batteries and insufficient supply of high-quality batteries. Due to the positive and negative materials, separators, electrolytes and other supporting materials have also been actively expanded in the past year or two, the overcapacity of lithium batteries will also lead to different degrees of imbalance between supply and demand in all aspects of the lithium battery industry chain through conduction. So, what other links in the entire lithium battery industry chain can be concerned about?

1

Cobalt and nickel raw material end

cobalt

20 17 can be called "the year of cobalt shortage" without exaggeration, and the rapid rise of cobalt price is mainly caused by the superposition of long, medium and short-term factors. From the long-term factor analysis, with the promotion of ternary lithium battery materials and the support of policies, it is certain that ternary lithium battery will be the main battery type of new energy electric vehicles in the future, and its demand will increase greatly. From the analysis of medium and long-term factors, not only in China, but also in the world, the contradiction between supply and demand of cobalt resources, especially primary cobalt resources, will become more prominent in the future, and the situation of short supply is becoming a global consciousness. In the short term, the gradual recovery of the global economy and the interest rate hike of the US dollar have stimulated the overall recovery of commodities and non-ferrous metals. Speculative funds are optimistic about cobalt metal and do not hesitate to invest heavily. (Figure 4)

Figure 4 Fluctuation Chart of Cobalt Price

nickel

The rise of cobalt market is closely related to ternary batteries seizing the lithium iron phosphate battery market. However, behind the optimism, it should be noted that "water can carry a boat and also overturn it". Driven by cost and performance, ternary materials are developing towards high nickel and low cobalt. (Figure 5)

Fig. 5 Price fluctuation chart of nickel

It is difficult to guess the price fluctuation of "Demon Nickel" roller coaster. At present, in the nickel market, the demand for nickel for power batteries of new energy vehicles is not high, but the price of cobalt remains high. Ternary materials with high nickel and low cobalt have become a trend, and ternary materials with high nickel also have greater advantages in energy density. At present, the ternary material NCM622 has not been popularized, and it may take some time for many manufacturers of cathode materials for power lithium batteries to develop NCM8 1 1. When high-nickel ternary materials gradually become the mainstream of the market, the price of nickel may continue to rise like the price of cobalt this year.

2

Upstream material end

In 20 15 years, the output of China accounted for 49. 1 1%, 56.76%, 67.89%, 57.44% and 38.96% of the global total output of lithium batteries and their upstream materials, respectively. Anode, cathode and electrolyte can basically meet the domestic demand. After the large-scale expansion of diaphragm materials in 20 16 years, the annual output reached10.84 million square meters, and the production capacity of dry diaphragm has been released. It is expected that 20 18 wet diaphragm will gradually complete the import substitution. In 20 16, the domestic demand for aluminum-plastic film was 95 million _, while the domestic production of aluminum-plastic film was 4.94 million _, and the current localization rate was less than 8%.

Aluminum-plastic film is a unique packaging material for soft-packed lithium batteries, which usually consists of three layers, namely, external resistance layer, barrier layer and heat sealing layer. The cost of plastic film accounts for 15%-20% of the cost of flexible battery, while the price difference between domestic and foreign aluminum-plastic films is about 20%-30%. With the downward pressure of subsidies transmitted to the middle reaches, lithium battery manufacturers are facing enormous cost pressure, and it is urgent to reduce the raw material cost of lithium batteries. Therefore, the demand for import substitution and localization of aluminum-plastic film is increasingly prominent. With the increase of global flexible battery penetration rate, the total demand of aluminum-plastic film will also increase significantly. (Figure 6)

Fig. 6 Cost ratio of soft lithium battery

three

Related production of midstream power lithium battery

Technical transformation company

Major lithium battery manufacturers are expanding their scale and increasing their production capacity, which will inevitably bring about the upgrading and utilization of old equipment. The automation rate of domestic power battery production line is far from that of foreign countries. According to statistics, the automation rates of domestic first-line and second-line manufacturers are 60% and 30% respectively, which still has room for improvement compared with the automation rate of 85% of foreign advanced enterprises. And technological transformation companies can enter the lithium battery industry in due course. Because most processes in the production of power lithium batteries have high technical barriers, such as pulp mixer, coater, roller press, die cutter, winder, etc., technical innovation companies can intervene from auto production line, where the technical barriers are relatively low.

Auto production line is mainly responsible for the integration of mature equipment (such as insulation resistance tester, ultrasonic welder, CCD camera, etc.). ), battery movement, turnover, assembly, testing, etc. For technical transformation companies that serve mature industries such as automobile enterprises and electronic components, the core components required by the assembly line, such as servo motor, sensor, CCD camera, cylinder, gripper design, fixture design, robot integration, transmission belt, etc. Technical transformation companies need to combine the technological requirements of lithium battery manufacturers and the details of assembly accuracy, detection accuracy and production rhythm of each process to design equipment upgrading and transformation schemes that meet their requirements.

robot industry

With the rapid expansion of the application of robots in the intelligent manufacturing industry, as well as the shortage of the four major robot families in the world (ABB in Switzerland, Fanuc in Japan, Yaskawa Electric in Japan and KUKA Robot in Germany) and the rising price, it has become a general trend for domestic robots to replace imports. Due to the frequent change of products and the pressure of increasing production capacity, intelligent, flexible and efficient robots have gradually become the main choice for lithium battery manufacturers. Under the national policy of subsidizing the new energy industry by 20%, the downstream manufacturers of new energy vehicles put forward the demand of reducing the cost of power lithium battery manufacturers. At the same time, the price of raw materials is rising, and the pressure from both ends forces the power lithium battery manufacturers to reduce costs as much as possible. Therefore, the market share of domestic robots in the power lithium battery industry chain will gradually increase.

Application of computer vision

Like the robot industry, the computer vision application industry also belongs to a very wide range of industries, and the main application industries are concentrated in military, medical, industrial production, artificial intelligence and other fields. Its main applications in industrial production industry are nondestructive size detection and defect detection. With the standardization of power lithium battery industry, the quality control of each production process has been continuously improved, and the traditional manual detection has been unable to keep up with the improvement of production capacity in accuracy and speed. Size detection and defect detection almost run through the whole process of power lithium battery production.

According to different process requirements, the required details such as algorithm logic, CCD camera selection and light source selection are different, and these requirements are special and unique. However, the support algorithms of cognex, Kearns and other industry giants are mostly based on general testing, and the special testing requirements will definitely cause high expenses to the R&D teams of cognex, Kearns and other industry giants. Therefore, domestic computer vision application algorithm companies have the opportunity to enter the power battery industry.

four

Downstream power lithium battery recovery energy storage equipment

Power battery recovery

65438+February 1, The Specification for Recycling and Disassembly of Vehicle Power Batteries was officially implemented. This is the first national standard on power battery recycling proposed by the Ministry of Industry and Information Technology, which clearly points out that recycling and dismantling enterprises should have relevant qualifications, further ensuring the safety, environmental protection and efficiency of power battery recycling. Dismantling specifications strictly stipulate the safety, operating procedures, storage and management of waste power batteries, and to a certain extent, standardize China's vehicle power battery recycling and dismantling, professional technology and power battery recycling system, which is conducive to the development of the industry.

According to statistics, domestic power batteries will enter the peak period of scrapping around 2020, and the cumulative scrapping amount will reach12-170,000 tons, while the actual dismantling and recycling amount in 20 16 years is less than170,000 tons.

Improper handling of cathode materials and electrolyte of power batteries has caused great environmental pollution, and rare metals such as cobalt in China are heavily dependent on foreign countries. According to the calculation of relevant institutions, the recycling market created by recycling metals such as cobalt, nickel, manganese, lithium, iron and aluminum from waste power lithium batteries will be 201kloc-0/0/billion yuan, and 25 billion yuan in 2020. Therefore, power battery recycling will become the key to the development of new energy vehicles in China. Starting from February next year 1, three new national standards for power batteries, such as "Detection of Residual Energy in Vehicle Power Battery Recycling", will also be formally implemented. With the establishment of a relatively perfect national standard system, the disorderly state of power battery recycling and cascade utilization is expected to be improved.

Cascade utilization refers to the reuse value of retired power batteries in energy storage, distributed photovoltaic power generation, low-speed electric vehicles and other fields. When the battery can't be used step by step, it needs to be disassembled and recycled.

Xu Shengming, a researcher at Tsinghua University Institute of Nuclear Energy and New Energy Technology, believes that there is a huge market space for recycling and step-by-step utilization of waste power batteries. "At present, it is in the stage of technology accumulation and research and development. Future recycling technology and technological innovation of cascade utilization are important manifestations of enterprise competitiveness. "

Therefore, enterprises specializing in recycling power batteries will usher in a development period in the next few years.

Energy storage equipment

With the price reduction of lithium batteries in the future, the cascade utilization of lithium batteries will become more and more standardized, and the economy of the energy storage lithium battery market will gradually become prominent. It is predicted that by 2020, the demand for energy storage lithium batteries in China is expected to reach 16.64GWh, and the market growth rate of 20 17-2020 is expected to remain above 40%. If the energy storage market can achieve rapid growth with the battery price reduction, it is expected to bring incremental equipment demand. (Figure 7)

Fig. 7 Demand forecast of energy storage lithium battery

At present, there are no leading enterprises in the lithium battery energy storage market in China, and all major enterprises are in the layout stage, with an output value of less than 500 million yuan. Due to the unclear domestic energy storage policy and the high price of lithium-ion energy storage batteries, there are still some technical bottlenecks.

According to the report of China Commercial Industry Research Institute "Investigation and Forecast of Lithium Battery Market in China in 20 17-2022", the market size of lithium battery for energy storage in China in 20 16 is about 5.2 billion yuan. Among them, BYD has the largest market share in energy storage batteries, accounting for14%; Followed by Fulante and Sanyang shares, both accounting for 7%. (Figure 8)

Fig. 820 16 China energy storage lithium battery market competition pattern.

Five kinds of lithium batteries that may subvert the power.

1

Metal air battery

Theoretically, the capacity density of metal-air battery cathode is infinite. Ultra-high energy density can be obtained by using oxygen in the air as the positive electrode and active metals such as aluminum, magnesium, zinc and lithium as the negative electrode materials. However, the research and development cost of air battery is very high, and its problem has not been solved.

2

Solid state battery

The energy density limit of liquid lithium ion battery is 350Wh/kg. Replacing solid-state battery with electrolyte and separator in lithium-ion battery can adapt to anode and cathode materials with higher energy density, and the energy density can reach 500-600Wh/kg, which is recognized as the next generation lithium-ion battery technology. Companies such as Toyota, BMW, Fiske, Bollore, Panasonic, Samsung, Mitsubishi, Hyundai, Dyson, and Contemporary Ampere Technology Co., Ltd. are all stepping up the research and development of solid-state batteries.

three

Lithium-sulfur batteries

The theoretical specific capacity and specific energy of elemental sulfur can be as high as 1675mAh/g and 2567Wh/kg. Sulfur also has the advantages of low price and environmental friendliness, and is expected to become an ideal cathode material for the next generation. Under the same quality, lithium-sulfur battery can have 6-7 times the power of traditional lithium-ion battery, but its service life is not up to expectations at present. In the future, lithium-sulfur battery will become an ideal substitute product after its service life is equivalent to that of lithium-ion battery.

four

fuel battery

Fuel cell is a kind of power generation device that directly converts the chemical energy of fuel and oxidant into electrical energy through electrochemical reaction. Besides hydrogen, common fuels include methanol, hydrazine, hydrocarbons and carbon monoxide. Hydrogen fuel cell has become the main technical route to compete with lithium battery, which has the characteristics of zero emission, long battery life and short hydrogenation time, but it also faces the problems of hydrogen production, storage and safety, as well as the rare problem of catalyst metal platinum.

five

Graphene battery

Graphene, known as the king of materials, has excellent properties such as high thermal conductivity, electrical conductivity and specific surface area, and is the first choice for energy storage, electronics and optoelectronic devices. It is of great significance to apply it to the field of batteries to improve the characteristics of fast charging and high temperature resistance of batteries.

Although graphene has become the focus of competition, and governments and industries have made arrangements, there are still many problems in the application of graphene due to cost and other issues. At present, additives and auxiliary materials are mainly used in the market, so it is difficult to exert its real strength, so it is also called "industrial monosodium glutamate". For example, a battery in which graphene material is added to a lithium battery or used as a conductive agent to improve the fast charging performance is called a "graphene-based battery" instead of a real "graphene battery".

Investment Suggestions for Lithium Battery Industry

Due to the support of national policies in previous years, the whole lithium battery industry was at the forefront, which led to a large amount of capital intervention, thus disrupting the whole market. Since the second half of 20 16, the integration speed of lithium battery industry has obviously accelerated under the guidance of national policies. Before replacing lithium batteries with new batteries, we can continue to pay attention to the following points:

When high nickel cathode materials gradually seize the market, the price of nickel materials rises;

Domestic aluminum-plastic film manufacturers with technical advantages;

The intelligent manufacturing technology transformation company stepped into the lithium battery industry from the lithium battery assembly line upgrade;

Domestic robot manufacturers are gradually involved in the intelligent, flexible and efficient production line upgrade of lithium battery manufacturers;

When the lithium battery industry becomes more and more standardized and the product quality control becomes more and more strict, a mature computer vision team can take the opportunity to grow and develop;

Around 2020, a large number of power lithium batteries will be scrapped, and the development opportunities of battery recycling enterprises and energy storage equipment enterprises will come.

1 like

step on

comment

share

report

What command does linux use to know all users?

View all users in Linux

(1) in the terminal. In fact, you only need to look at the /etc/passwd file.

(2) Look at the third parameter: more than 500 users are users built later. Others are users of the system.

Or use cat/etc/passwd|cut-f 1-d: