The development of lithium batteries

The origin of the battery device may start with the discovery of the Leiden bottle. The Leiden bottle was first invented by Dutch scientist Pieter van Musschenbroek in 1745. The Leyden jar is a primitive capacitor device. It is composed of two metal sheets separated by an insulator. The metal rod above is used to store and release charge. When you touch the rod When the metal ball is used, the Leiden bottle can keep or remove the internal electric energy, and its principle and preparation are simple. Anyone interested can make it by themselves at home, but its self-discharge phenomenon is more severe due to its simple guide. Generally, all the electricity will be discharged in a few hours to a few days. However, the emergence of the Leiden bottle marks a new stage in the research of electricity.

In the 1790s, Italian scientist Luigi Galvani discovered the use of zinc and copper wires to connect frog legs and found that frog legs would twitch, so he proposed the concept of "bioelectricity." This discovery caused the Italian scientist Alessandro to twitch. Volta's objection, Volta believes that the twitching of the frog's legs comes from the electric current generated by the metal rather than the electric current on the frog. To refute Galvani's theory, Volta proposed his famous Volta Stack. The voltaic stack comprises zinc and copper sheets with cardboard soaked in saltwater in between. This is the prototype of a chemical battery proposed.
The electrode reaction equation of a voltaic cell:

positive electrode: 2H^++2e^-→H_2

negative electrode: Zn→〖Zn〗^(2+)+2e^-

In 1836, the British scientist John Frederic Daniell invented the Daniel battery to solve the problem of air bubbles in the battery. The Daniel battery has the primary form of a modern chemical battery. It consists of two parts. The positive part is immersed in a copper sulfate solution. The other part of copper is zinc immersed in a zinc sulfate solution. The original Daniel battery was filled with copper sulfate solution in a copper jar and inserted a ceramic porous cylindrical container in the center. In this ceramic container, there is a zinc rod and zinc sulfate as the negative electrode. In the solution, the small holes in the ceramic container allow the two keys to exchange ions. Modern Daniel batteries mostly use salt bridges or semi-permeable membranes to achieve this effect. Daniel batteries were used as a power source for the telegraph network until dry batteries replaced them.

The electrode reaction equation of the Daniel battery:

Positive electrode: 〖Cu〗^(2+)+2e^-→Cu

negative electrode: Zn→〖Zn〗^(2+)+2e^-

So far, the primary form of the battery has been determined, which includes the positive electrode, the negative electrode, and the electrolyte. On such a basis, batteries have undergone rapid development in the next 100 years. Many new battery systems have appeared, including the French scientist Gaston Planté invented lead-acid batteries in 1856. Lead-acid batteries Its large output current and low price have attracted wide attention, so it is used in many mobile devices, such as early electric vehicles. It is often used as a backup power supply for some hospitals and base stations. Lead-acid batteries are mainly composed of lead, lead dioxide, and sulfuric acid solution, and their voltage can reach about 2V. Even in modern times, lead-acid batteries have not been eliminated due to their mature technology, low prices, and safer water-based systems.

The electrode reaction equation of lead-acid battery:

Positive electrode: PbO_2+〖SO〗_4^(2-)+4H^++2e^-→Pb〖SO〗_4+2H_2 O

Negative electrode: Pb+〖SO〗_4^(2-)→Pb〖SO〗_4+2e^-

The nickel-cadmium battery, invented by the Swedish scientist Waldemar Jungner in 1899, is more widely used in small mobile electronic devices, such as early walkmans, due to its higher energy density than lead-acid batteries. Similar to lead-acid batteries. Nickel-cadmium batteries have also been widely used since the 1990s, but their toxicity is relatively high, and the battery itself has a specific memory effect. This is why we often hear some older adults say that the battery must be fully discharged before recharging and that waste batteries will contaminate the land, and so on. (Note that even current batteries are highly toxic and should not be discarded everywhere, but current lithium batteries do not have memory benefits, and over-discharge is harmful to battery life.) Nickel-cadmium batteries are more damaging to the environment, and Their internal resistance will change with temperature, which may cause damage due to excessive current during charging. Nickel-hydrogen batteries gradually eliminated it around 2005. So far, nickel-cadmium batteries are rarely seen in the market.

Electrode reaction equation of nickel-cadmium battery:

Positive electrode: 2NiO(OH)+2H_2 O+2e^-→2OH^-+2Ni〖(OH)〗_2

Negative electrode: Cd+2OH^-→Cd〖(OH)〗_2+2e^-

Lithium metal battery stage

In the 1960s, people finally officially entered the era of lithium batteries.

Lithium metal itself was discovered in 1817, and people soon realized that lithium metal's physical and chemical properties are inherently used as materials for batteries. It has low density (0.534g 〖cm〗^(-3)), large capacity (theoretical up to 3860mAh g^(-1)), and its low potential (-3.04V compared to standard hydrogen electrode). These are almost telling people I am the negative electrode material of the ideal battery. However, lithium metal itself has huge problems. It is too active, reacts violently with water, and has high requirements on the operating environment. Therefore, for a long time, people were helpless with it.

In 1913, Lewis and Keyes measured the potential of the lithium metal electrode. And conducted a battery test with lithium iodide in propylamine solution as the electrolyte, although it failed.

In 1958, William Sidney Harris mentioned in his doctoral thesis that he put lithium metal in different organic ester solutions and observed the formation of a series of passivation layers (including lithium metal in perchloric acid). Lithium LiClO_4

The phenomenon in the PC solution of propylene carbonate, and this solution is a vital electrolyte system in lithium batteries in the future), and a specific ion transmission phenomenon has been observed, so some preliminary electrodeposition experiments have been done based on this. These experiments officially led to the development of lithium batteries.

In 1965, NASA conducted an in-depth study on the charging and discharging phenomena of Li||Cu batteries in lithium perchlorate PC solutions. Other electrolyte systems, including the analysis of LiBF_4, LiI, LiAl〖Cl〗_4, LiCl, This research have aroused great interest in organic electrolyte systems.

In 1969, a patent showed that someone had begun to try to commercialize organic solution batteries using lithium, sodium, and potassium metals.

In 1970, Japan's Panasonic Corporation invented the Li‖CF_x ┤ battery, where the ratio of x is generally 0.5-1. CF_x is a fluorocarbon. Although fluorine gas is highly toxic, the fluorocarbon itself is an off-white non-toxic powder. The emergence of Li‖CF_x ┤ battery can be said to be the first real commercial lithium battery. Li‖CF_x ┤ battery is a primary battery. Still, its capacity is huge, the theoretical capacity is 865mAh 〖Kg〗^(-1), and its discharge voltage is very stable in the long-range. Hence, the power is stable and the self-discharge phenomenon small. But it has abysmal rate performance and cannot be charged. Therefore, it is generally combined with manganese dioxide to make Li‖CF_x ┤-MnO_2 batteries, which are used as internal batteries for some small sensors, clocks, etc., and have not been eliminated.

Positive electrode: CF_x+xe^-+x〖Li〗^+→C+xLiF

Negative electrode: Li→〖Li〗^++e^-

In 1975, Japan's Sanyo Corporation invented the Li‖MnO_2 ┤ battery, first used in rechargeable solar calculators. This can be regarded as the first rechargeable lithium battery. Although this product was a great success in Japan at that time, people did not have a deep understanding of such material and did not know its lithium and manganese dioxide. What kind of reason is behind the reaction?

At almost the same time, the Americans were looking for a reusable battery, which we now call a secondary battery.

In 1972, MBArmand (the names of some scientists were not translated at the beginning) proposed in a conference paper M_(0.5) Fe〖(CN)〗_3 (where M is an alkali metal) and other materials with a Prussian blue structure. , And studied its ion intercalation phenomenon. And in 1973, J. Broadhead and others of Bell Labs studied the intercalation phenomenon of sulfur and iodine atoms in metal dichalcogenides. These preliminary studies on the ion intercalation phenomenon are the most important driving force for the gradual progress of lithium batteries. The original research is precise because of these studies that later lithium-ion batteries become possible.

In 1975, Martin B. Dines of Exxon (the predecessor of Exxon Mobil) conducted preliminary calculations and experiments on the intercalation between a series of transition metal dichalcogenides and alkali metals and in the same year, Exxon was another name Scientist MS Whittingham published a patent on Li‖TiS_2 ┤ pool. And in 1977, Exoon commercialized a battery based on Li-Al‖TiS_2┤, in which lithium aluminum alloy can enhance the safety of the battery (although there is still a more significant risk). After that, such battery systems have been successively used by Eveready in the United States. Commercialization of Battery Company and Grace Company. The Li‖TiS_2 ┤ battery can be the first secondary lithium battery in the true sense, and it was also the hottest battery system at the time. At that time, its energy density was about 2-3 times that of lead-acid batteries.

Positive electrode: TiS_2+xe^-+x〖Li〗^+→〖Li〗_x TiS_2

Negative electrode: Li→〖Li〗^++e^-

At the same time, Canadian scientist M. A. Py invented the Li‖MoS_2┤ battery in 1983, which can have an energy density of 60-65Wh 〖Kg〗^(-1) at 1/3C, which is equivalent to Li‖TiS_2┤ battery. Based on this, in 1987, the Canadian company Moli Energy launched a truly extensively commercialized lithium battery, which was widely sought after worldwide. This should have been a historically significant event, but the irony is that it is also causing the decline of Moli afterward. Then in the spring of 1989, Moli Company launched its second-generation Li‖MoS_2┤ battery products. At the end of the spring of 1989, Moli's first-generation Li‖MoS_2┤ battery product exploded and caused a large-scale panic. In the summer of the same year, all products were recalled, and the victims were compensated. At the end of the same year, Moli Energy declared bankruptcy and was acquired by Japan's NEC in the spring of 1990. It is worth mentioning that it is rumored that Jeff Dahn, a Canadian scientist at the time, was leading the battery project at Moli Energy and resigned because of his opposition to the continued listing of Li‖MoS_2 ┤ batteries.

Positive electrode: MoS_2+xe^-+x〖Li〗^+→〖Li〗_x MoS_2

Negative electrode: Li→〖Li〗^++e^-

So far, lithium metal batteries have gradually left the public's sight. We can see that during the period from 1970 to 1980, scientists' research on lithium batteries was mainly focused on cathode materials. The final goal is invariably focused on transition metal dichalcogenides. Because of their layered structure (transition metal dichalcogenides are now widely studied as a two-dimensional material), their layers and There are enough gaps between the layers to accommodate the insertion of lithium ions. At that time, there was too little research on anode materials during this period. Although some studies have focused on the alloying of lithium metal to enhance its stability, lithium metal itself is too unstable and dangerous. Although Moli's battery explosion was an event that shocked the world, there have been many Cases of the explosion of lithium metal batteries.

Moreover, people did not know the cause of the explosion of lithium batteries very well. In addition, lithium metal was once considered an irreplaceable negative electrode material due to its good properties. After Moli's battery explosion, people's acceptance of lithium metal batteries plummeted, and lithium batteries entered a dark period.

To have a safer battery, people must start with the harmful electrode material. Still, there are a series of problems here: the potential of lithium metal is shallow, and the use of other compound negative electrodes will increase the negative electrode potential, and this way, lithium batteries The overall potential difference will be reduced, which will reduce the energy density of the storm. Therefore, scientists have to find the corresponding high-voltage cathode material. At the same time, the battery's electrolyte must match the positive and negative voltages and cycle stability. At the same time, the conductivity of the electrolyte And heat resistance is better. This series of questions puzzled scientists for a long time to find a more satisfactory answer.

The first problem for scientists to solve is to find a safe, harmful electrode material that can replace lithium metal. Lithium metal itself has too much chemical activity, and a series of dendrite growth problems have been too harsh on the use environment and conditions, and it is not safe. Graphite is now the main body of the negative electrode of lithium-ion batteries, and its application in lithium batteries has been studied as early as 1976. In 1976, Besenhard, J.O. has conducted a more detailed study on the electrochemical synthesis of LiC_R. However, although graphite has excellent properties (high conductivity, high capacity, low potential, inertness, etc.), at that time, the electrolyte used in lithium batteries is generally the PC solution of LiClO_4 mentioned above. Graphite has a significant problem. In the absence of protection, the electrolyte PC molecules will also enter the graphite structure with the lithium-ion intercalation, resulting in a decrease in cycle performance. Therefore, graphite was not favored by scientists at that time.

As for the cathode material, after the research of the lithium metal battery stage, the scientists found that the lithiation anode material itself is also a lithium storage material with good reversibility, such as LiTiS_2,〖Li〗_x V〖Se〗_2 (x =1,2) and so on, and on this basis, 〖Li〗_x V_2 O_5 (0.35≤x<3), LiV_2 O_8 and other materials have been developed. And scientists have gradually become familiar with various 1-dimensional ion channels (1D), 2-dimensional layered ion intercalation (2D), and 3-dimensional ion transmission network structures.

Professor John B. Goodenough's most famous research on LiCoO_2 (LCO) also occurred at this time. In 1979, Goodenougd et al. were inspired by an article on the structure of NaCoO_2 in 1973 and discovered LCO and published a patent article. LCO has a layered intercalation structure similar to transition metal disulfides, in which lithium ions can be reversibly inserted and extracted. If the lithium ions are completely extracted, a close-packed structure of CoO_2 will be formed, and it can be re-inserted with lithium ions for lithium (Of course, an actual battery will not allow the lithium ions to be extracted entirely, which will cause the capacity to decay quickly). In 1986, Akira Yoshino, who was still working at Asahi Kasei Corporation in Japan, combined the three of LCO, coke, and LiClO_4 PC solution for the first time, becoming the first modern lithium-ion secondary battery and becoming current lithium The cornerstone of the battery. Sony quickly noticed the "good enough" old man's LCO patent and obtained authorization to use it. In 1991, it commercialized the LCO lithium-ion battery. The concept of lithium-ion battery also appeared at this time, and its idea Also continues to this day. (It is worth noting that Sony's first-generation lithium-ion batteries and Akira Yoshino also use hard carbon as the negative electrode instead of graphite, and the reason is that the PC above has intercalation in graphite)

Positive electrode: 6C+xe^-+x〖Li〗^+→〖Li〗_x C_6

Negative electrode: LiCoO_2→〖Li〗_(1-x) CoO_2+x〖Li〗^++xe^-

On the other hand, in 1978, Armand, M. proposed the use of polyethylene glycol (PEO) as a solid polymer electrolyte to solve the problem above that the graphite anode is easily embedded in solvent PC molecules (the mainstream electrolyte at that time still uses PC, DEC mixed solution), which put graphite into the lithium battery system for the first time, and proposed the concept of rocking-chair battery (rocking-chair) in the following year. Such a concept has continued to the present. The current mainstream electrolyte systems, such as ED/DEC, EC/DMC, etc., only slowly appeared in the 1990s and have been in use ever since.

During the same period, scientists also explored a series of batteries: Li‖Nb〖Se〗_3 ┤ batteries, Li‖V〖SE〗_2 ┤ batteries, Li‖〖Ag〗_2 V_4 ┤ O_11 batteries, Li‖CuO┤ batteries, Li ‖I_2 ┤Batteries, etc., because they are less valuable now, and there are not many types of research so that I won't introduce them in detail.

• Li-ion battery stage

The era of lithium-ion battery development after 1991 is the era we are now in. Here I will not summarize the development process in detail but briefly introduce the chemical system of a few lithium-ion batteries.

An introduction to current lithium-ion battery systems, here is the next part.