Recently, John B. Goodenough, the "father of lithium batteries," as the corresponding author, published two articles on JACS in one day talking about all-solid electrolytes.
Goodenough et al. have developed a Li+ glass electrolyte with a large energy gap and a lithium ion conductivity σLi>10^2 S/cm. When used in a Li/glass electrolyte/Li symmetric battery, it can be cycled thousands of times at room temperature under the current density of 3 mA/cm^2, showing low deposition/dissolution resistance.
Recently, in the article "Non-Traditional, Safe, High-Voltage Rechargeable Cells of Long Cycle Life", they designed a room temperature all-solid-state secondary battery. This battery structure includes a lithium metal negative electrode, a glass electrolyte, and a traditional oxide positive electrode coated with a plasticizer. With a current density of 153mA/g and a voltage range of 2.5-5.0V, the battery cycle life exceeds 23,000 times. In addition, the battery also exhibits good rate performance because of the presence of electric dipoles in both the Li+ glass electrolyte and the plasticizer. The electric dipole makes the plasticizer/positive interface and the plasticizer/electrolyte interface both form an electric double layer. The existence of the electric double layer provides a guarantee for the safety of the battery and fast and long-term charging and discharging.
Figure 1. Electrochemical performance of Li/Li + glass electrolyte/LNMO
In the article "Garnet electrolyte with an ultra-low interfacial resistance for Li-metal batteries", Goodenough et al. introduced an optimization method for garnet-structured solid electrolyte (garnet) used in lithium metal batteries. They believe that the Li7La3Zr2O12 solid electrolyte with a garnet structure is very promising because the electrolyte also has a high lithium ion conductivity at room temperature and can be used not only in lithium metal batteries but also in lithium redox flow batteries.
But there are three main problems with garnet structure electrolyte:
The electrochemical window is controversial, and the experimental results are inconsistent with the calculated results;
The interface resistance is large and the lithium dendrites grow rapidly;
During the storage of the material, it is very susceptible to moisture, forming an insulating layer of Li2CO3 on the surface of the material, and the Li+ conductivity is seriously attenuated.
The author found that the cause of these problems is the presence of a thick Li2CO3 layer and Li-Al-O glass phase on the surface of the electrolyte material. Therefore, this problem is effectively solved by a simple high-temperature carbonization treatment method, so that the chemical stability of the electrolyte can reach 4.4V, which significantly reduces Li/garnet, garnet/composite cathode and garnet/organic electrolyte The interface resistance. The assembled Li/garnet/Li symmetric battery, Li/garnet/LiFePO4 battery and Li-S battery all exhibit low overpotential, high Coulomb efficiency and stable cycle performance.
Figure 2. Schematic diagram of garnet LLZT and LLZT-C as electrolytes in lithium metal batteries
Figure 3. Electrochemical performance of all solid-state lithium metal batteries at 65℃
He is still "tossing" when he is over 90 years old, it's a role model for our generation!
References:
[1] Maria Helena Braga, Chandrasekar MSubramaniyam, Andrew J. Murchison, and John B. Goodenough, Non-Traditional, Safe, High-Voltage Rechargeable Cells of Long Cycle Life, J. Am. Chem. Soc.,2018, DOI: 10.1021/jacs.8b02322
[2] Yutao Li, Xi Chen, Andrei Dolocan, Zhiming Cui, Sen Xin, Leigang Xue, Henghui Xu, Kyusung Park, and JohnB. Goodenough, Garnet electrolyte with an ultra-low interfacial resistance for Li-metal batteries, J. Am. Chem. Soc., 2018, DOI: 10.1021/jacs.8b03106
