Pre-lithiation to build low-temperature lithium batteries -Lithium - Ion Battery Equipment
Recently, iChEM researchers, Professor Wang Yonggang of Fudan University, and their research group used a simple pre-lithiation method to construct a Li2V2(PO4)3//LixC lithium battery system, which exhibited high power, long life and good low temperature. performance. The related research results were published online on November 14, 2017 in German Applied Chemistry (Angewandte Chemie International Edition, 2017, DOI: 10.1002/anie.201710555) under the title "ASimplePre-lithiationStrategytoBuildHigh-RateandLong-lifeLithium-ionBatterywithImprovedLow-temperaturePerformance" .(Lithium - Ion Battery Equipment)
In recent years, electric vehicles powered by lithium batteries are developing rapidly. However, it is well known that the performance of lithium batteries decreases rapidly with decreasing temperature. This will greatly limit the application of electric vehicles in winter or some alpine regions. Previous studies have shown that, in addition to the low ionic conductance of the electrolyte at low temperatures, the low-temperature performance of conventional lithium batteries based on graphite anodes is also limited by the desolvation/solvation of lithium ions into and out of graphite at low temperatures. In response to this problem, the research group replaced the traditional graphite anode with a pre-lithiated hard carbon anode, and combined with the lithium vanadium phosphate (Li2V2(PO4)3) cathode to form a new battery system.
In recent years, prelithiated hard carbon has been applied to hybrid lithium-ion capacitors and exhibits excellent electrochemical performance. However, the pre-lithiation process is complicated and expensive, which involves the use of pure lithium electrodes, and has potential safety hazards. In this study, the researchers cleverly utilized the multi-step delithiation process of Li3V2(PO4)3 cathode material to realize the prelithiation of hard carbon. During the first charging process, lithium ions are extracted from the positive electrode to form Li2V2(PO4)3, and the extracted lithium ions are intercalated into the hard carbon negative electrode to form a prelithiated hard carbon negative electrode (LixC). Subsequently, Li2V2(PO4)3 and LixC constitute a lithium battery system. When charged and discharged at 3.5 to 4.3 V (Fig. 1), the battery exhibited supercapacitor-like high power and long life. In addition, although the conventional electrolyte LB303 was used, the battery exhibited excellent low temperature performance. At minus 40 degrees Celsius, its capacity can maintain 67% of the normal temperature capacity, far superior to conventional lithium batteries. This is mainly due to the good low temperature performance of the nanocarbon-coated Li2V2(PO4)3 cathode material and the relatively fast kinetic process of the prelithiated hard carbon anode at low temperature. However, it is worth noting that only part of the capacity of Li3V2(PO4)3 is used in this battery system, and the energy density is limited, so it is more suitable for use as a start-stop battery. In addition, as the temperature decreases, the ionic conductance of the electrolyte decreases rapidly, which increases the internal resistance of the battery, thus, the battery exhibits obvious polarization at low temperature. In follow-up research, it is necessary to further develop high-performance low-temperature electrolytes to improve the electrochemical performance of such batteries at low temperatures.
The work was jointly completed by Liu Yao, a second-year doctoral student of the Department of Chemistry of Fudan University, and Yang Bingchang, a second-year master student. This research was supported by the National Natural Science Foundation of China and other related projects.
In recent years, electric vehicles powered by lithium batteries are developing rapidly. However, it is well known that the performance of lithium batteries decreases rapidly with decreasing temperature. This will greatly limit the application of electric vehicles in winter or some alpine regions. Previous studies have shown that, in addition to the low ionic conductance of the electrolyte at low temperatures, the low-temperature performance of conventional lithium batteries based on graphite anodes is also limited by the desolvation/solvation of lithium ions into and out of graphite at low temperatures. In response to this problem, the research group replaced the traditional graphite anode with a pre-lithiated hard carbon anode, and combined with the lithium vanadium phosphate (Li2V2(PO4)3) cathode to form a new battery system.
In recent years, prelithiated hard carbon has been applied to hybrid lithium-ion capacitors and exhibits excellent electrochemical performance. However, the pre-lithiation process is complicated and expensive, which involves the use of pure lithium electrodes, and has potential safety hazards. In this study, the researchers cleverly utilized the multi-step delithiation process of Li3V2(PO4)3 cathode material to realize the prelithiation of hard carbon. During the first charging process, lithium ions are extracted from the positive electrode to form Li2V2(PO4)3, and the extracted lithium ions are intercalated into the hard carbon negative electrode to form a prelithiated hard carbon negative electrode (LixC). Subsequently, Li2V2(PO4)3 and LixC constitute a lithium battery system. When charged and discharged at 3.5 to 4.3 V (Fig. 1), the battery exhibited supercapacitor-like high power and long life. In addition, although the conventional electrolyte LB303 was used, the battery exhibited excellent low temperature performance. At minus 40 degrees Celsius, its capacity can maintain 67% of the normal temperature capacity, far superior to conventional lithium batteries. This is mainly due to the good low temperature performance of the nanocarbon-coated Li2V2(PO4)3 cathode material and the relatively fast kinetic process of the prelithiated hard carbon anode at low temperature. However, it is worth noting that only part of the capacity of Li3V2(PO4)3 is used in this battery system, and the energy density is limited, so it is more suitable for use as a start-stop battery. In addition, as the temperature decreases, the ionic conductance of the electrolyte decreases rapidly, which increases the internal resistance of the battery, thus, the battery exhibits obvious polarization at low temperature. In follow-up research, it is necessary to further develop high-performance low-temperature electrolytes to improve the electrochemical performance of such batteries at low temperatures.
The work was jointly completed by Liu Yao, a second-year doctoral student of the Department of Chemistry of Fudan University, and Yang Bingchang, a second-year master student. This research was supported by the National Natural Science Foundation of China and other related projects.
