Are double ion batteries the bane of lithium-ion batteries?

Limited by high raw material prices, especially the raw material such as lithium carbonate, Co and Ni in the near future have a significant rise in price, lithium ion batteries at present the cost of reduced space is limited.

In order to reduce the cost of unit Wh, people have developed a variety of high energy density storage battery, such as Li - O2 batteries, theoretical specific energy of up to 3600 wh/kg (Li + + O2 + 2 e - = Li2O2, VvsLi/Li + 2.96), far higher than that of lithium ion battery, and has the characteristics of environmental friendly.In order to further reduce costs, people also with Na, zinc and other alternative metal Li, Na - O2 and zinc - O2 batteries, these technologies are currently in the phase of basic technology research and development, at present the main research mainly focused on the metal - electrolyte interface and discharge product research, etc., in which Li - O2 cell development difficulty is small, the more fully, can be used in the short term.

Besides Li - S battery is also a research hotspot, S theory of specific volume can reach 1672 mah/g, theoretical specific energy of 2600 wh/kg, although less in Li - O2 cell, but also far higher than that of lithium ion batteries.Li - S main problems of the battery is currently, S poor electrical conductivity, close to the insulator, large volume expansion (80%), S positive intercalated-li product dissolve in the electrolyte, shuttling between is negative, lead to rapid failure capacity, cycle and storage performance is poor.Of commonly used esters on the current lithium ion battery electrolyte because there are many side effects to application on Li - S battery, so Li - S ethers commonly used battery electrolyte, lead to the high temperature of battery performance is poor.In order to overcome the above problems, the researchers component adopts S nano, surface coating modification, and new methods such as solid electrolyte overcome, at present the studies in Li - S batteries have a number of important progress has been made, so Li - S battery is the most promising in the short term can replace ratio of lithium ion battery energy storage system.

Energy storage areas are never lack of spoiler, emerging in recent years the double ion battery is one of them.Between across the electrodes of lithium ion battery only Li + in different reaction, double ion battery charging process, the anion in the electric field under the action of migration to the anode, embedded in the anode structure and cation to cathode migration, embedded in the cathode, discharge, by contrast, the process of the anode and cathode ions out, get back in the electrolyte, the restoration of the electrolyte concentration.Double ion battery cathode material at present is mainly graphite material, the anion can actually embedded in the graphite structure as early as 1938 by Ru?Dorff and Hofmann found, but as a result of the anion embedded electric potential is higher, so double ion battery electrolyte with a high concentration of acid solution as the electrolyte, it will bring great safety hidden trouble.Until the 90 s, with the commercial application of lithium ion batteries, it was found that if the lithium ion battery anode replacement for embedded anion of graphite materials, can obtain higher voltage double ion battery.Subsequent decades, people began to double ion battery for in-depth research, especially the mechanism of anion embedded in graphite structure carried on the thorough study of "1".

Below are some of the common application in double ion battery electrolyte and their embedded in different graphite materials are potential "2", we can notice from this table, the common PF6 + esters in double ion battery electrolyte PF6 embedded into the potential of graphite structure reach more than 5 v, it also led to a serious problem - electrolyte instability caused by high voltage, so as to make the battery in a loop coulomb efficiency continues to decline, poor circulation performance.With the continuous development of ionic liquid technology in recent years, the heat stability of the ionic liquid, low viscosity and wide electrochemical window, let us see the hope of double ion battery.


Although the academic circle for a lot of reports double ion battery, but we also know less of anion embedded in graphite structure, KoljaBeltrop studies show that the diameter of the anion embedded behavior has a significant influence to its, anion embedded into the greater the diameter of graphite in the more difficult (and considering the common role of anion and electrolyte solvent) "2".


Japanese scientists TatsumiIshihara against PF6 embedded into the behavior of graphite, the study found as PF6 embedding, the distance between the graphite layers gradually expand, the biggest can reach 0.4 nm (flake graphite layer spacing between initial 0.336 nm), also found that the graphite structure under high potential in the nanometer structure of the bubble, which makes nanometer bubble structure of graphite cathode capacity sharply higher, 147 mah/g, it is close to LiCoO2 specific capacity of the "3".


From shenzhen institute of advanced technology, Chinese academy of sciences and China university of science and technology PanpanQin people such as jointly developed an Al electrode double ion battery, PanpanQin preparation on the Al foil coated with a layer of carbon hollow Al nano ball, not only good inhibiting the intercalated-li stress produces in the process, also reduced the current density, so that the cycle of the battery has good performance, under 2 c loop 1500 times, retention capacity can amount to 99%, under the power density of 1780 w/kg, the battery energy density reached 142 wh/kg, this data is higher than that of most commercial lithium ion battery data (about the results of detailed content we will detail in the next article).


On a 30 years is belong to the age of lithium ion batteries, the next 30 years is to belong to that kind of battery?Li - S battery, Li - O2 cell and double ion battery, who will be the destroyers of lithium ion battery?Let us analysis the double ion battery advantages, the first is cost, double ion battery anode is the graphite materials are used, is this alone than using NCA, sliding and LCO positive electrode material of lithium ion batteries cost is much lower.Followed by environmental properties, double ion batteries contain heavy metal elements, hardly is the cathode material of graphite is also very good, will not have serious heavy metal pollution to the environment.Is the most important technological advantages, the current lithium ion battery production equipment and technology can be used to completely double ion battery production, can say once double ion battery technology mature, and start the promotion, the existing lithium-ion battery manufacturers can be on the premise of not changing equipment, within the period of rapid transformation.

Li - S battery, Li - O2 cell and double ion battery who can take the place of lithium ion batteries, to win the next thirty years, what do you think?

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