Dual carbon accumulator

The dual carbon accumulator , also known as the dual ion accumulator, is a variant of the accumulator that is related to the lithium accumulator . However, as a special feature, both electrodes , both the cathode and the anode , are made of porous graphite . The first developments on this accumulator go back to work in the early 1970s with the United States Navy , followed by work at the chemical company Dow Chemical in the late 1980s . There have been repeated attempts to commercially exploit this type of battery, including in 2014 by the Japanese company Power Japan Plus for planned applications in electric cars . As of 2020, this type of accumulator has not yet achieved any noteworthy economic importance.

functionality

The electrolyte between the electrodes is made of lithium hexafluorophosphate (LiPF ₆ ), a salt of lithium , and is dissolved in an anhydrous solvent such as dimethyl sulfite or propylene carbonate that is not directly involved in the electrochemical process .

When the battery is uncharged, the positive ions (Li ⁺ ) of the lithium salt are in the solution; when charged, they are stored in the negative graphite electrode (anode) and form LiC _{6 there} . The negative anions of the salt (PF ₆ ^- ) are stored on the positive electrode . When discharging, this process is reversed and the lithium ions and anions are converted into the salt solution.

The following electrochemical process takes place on the positive electrode when it is charged:

${\displaystyle \mathrm {PF_{6}^{-}} +\mathrm {nC} \longrightarrow +\mathrm {C_{n}(PF_{6})} +e^{-}}$

and on the negative electrode when charged:

${\displaystyle \mathrm {Li^{+}} +\mathrm {mC} +e^{-}\longrightarrow \mathrm {LiC_{m}} }$.

The overall reaction of the loading is:

${\displaystyle \mathrm {PF_{6}^{-}} +\mathrm {nC} +\mathrm {Li^{+}} +\mathrm {mC} \longrightarrow \mathrm {C_{n}(PF_{6})} +\mathrm {LiC_{m}} }$.

The directions of the arrows reverse when discharging. As can be seen, the concentration of the salt in the electrolyte is reduced during charging. To avoid the conductivity of the solution becoming too low, an excess of electrolyte salt is used.

Individual evidence

1. ↑ Patent US3844837 : Nonaqueous battery. Applied on August 7, 1972 , published October 29, 1974 , Applicant: US Navy, Inventor: D. Bennion, J. Dunning, L. Hsueh, W. Tiedemann. ‌
2. ↑ ^{a b} Patent US4830938 : Secondary battery. Filed March 17, 1988 , published May 16, 1989 , Applicant: The Dow Chemical Company, Inventor: Frances P. McCullough, Charles A. Levine, Roy V. Snelgrove. ‌
3. ↑ Japanese start-up seeks to commercialize dual-carbon battery technology. 2014, accessed August 3, 2016 . 
4. ↑ Patent EP2939304 : Non-aqueous electrolytic storage element. Filed December 25, 2013 , published November 4, 2015 , Applicants: Ricoh Company, Ltd., Inventors: Anna Hirowatari, Eiko Hibino, Nobuaki Onagi, Okitoshi Kimura, Hisamitsu Kamezaki, Yasunori Sugimoto. ‌