Half cell 354 Lithium Batteries

Figure 3.5.7 Selected cathode and anode materials and electrolytes used in today s lithium batteries (darker colors) and possibly useful future technologies (lighter colors). For electrode materials, the width of the boxes displays demonstrated capacities (note the different scales for positive (cathode) and negative (anode) electrode materials). The height of the boxes corresponds to the half-cell potential and its variation for different states of charge. References [12-20],...

Room-temperature ionic liquids (denoted RTILs) have been studied as novel electrolytes for a half-century since the discovery of the chloroaluminate systems. Recently another system consisting of fluoroanions such as BF4 and PFg , which have good stability in air, has also been extensively investigated. In both systems the nonvolatile, noncombustible, and heat resistance nature of RTILs, which cannot be obtained with conventional solvents, is observed for possible applications in lithium batteries, capacitors, solar cells, and fuel cells. The nonvolatility should contribute to the long-term durability of these devices. The noncombustibility of a safe electrolyte is especially desired for the lithium battery [1]. RTILs have been also studied as an electrodeposition bath [2]. 

LiVMoOe was successfully synthesized using the conventional solid-state reaction method, and its chemical and physical properties were examined by several analytical methods. We have shown that LiVMoOe does not possess good structural characteristics for a lithium half cell (Li/LiVMoOe) as a cathode in non-aqueous electrolyte environment. Furthermore, we suggest that LiVMoOe may instead be considered as an anode material of choice for developing rechargeable lithium-ion battery technology. 

As shown in the schematic in Fig. 4.1, the Li-air battery consists of lithium metal as anode, Li-ion conducting organic/aqueous electrol d e, and a porous cathode composed of carbon, catalyst, and binder. During discharge, lithium metal is oxidized to lithium ions and releases electrons as described by the following half-cell reaction... 

One method is to move away from pseudocapacitance and employ a lithium intercalation system to create a hybrid battery-supercapacitor. In this system, graphite (a common choice in battery systems) is a very low potential intercalation material. By appropriately matching the electrode mass, a stable half cell potential near 0.1 V can be maintained for changing lithium concentration in the electrode (Figure 3.19). The lithium stored acts as a supply for ion pairing at the cathode, which is a high performance carbon double-layer material in the form of active carbon [45] or graphene [46]. 

Figure 11.19 Half-cell reactions in a lithium/polyaniline battery during charge and discharge.

A lithium battery, which is different from a lithium-ion battery, uses lithium metal as one electrode and carbon in contact with Mn02 in a paste of KOH as the other electrode. The electrolyte is lithium perchlorate in a nonaqueous solvent, and the construction is similar to the silver battery. The half-cell reactions involve the oxidation of lithium and the reaction... 

This is a laboratory experiment. Carbon was studied as a half-ceU (section 2.2.3) with a metal lithium electrode as the counter electrode. The difference in voltage between these two electrodes is, naturally, very low. This is one of the reasons why carbon is often used as the negative electrode in hthium-ion secondary batteries instead of metal hthiiun, because it does not decrease the voltage of a cell too greatly. Such a decrease would lower the specific energy (defined in section 2.4.16.). It should be noted that in this half-ceU , carbon is a positive electrode because it is used in conjunction with lithium. 

In a 2001 survey of altemative propulsion vehicles, of 68 vehicle models, about 2/3 are hybrid or all electric. Only 26 of the 68 are currently available the rest are being planned. Of those planned, about 35% are EVs and the rest are either gasoline/hybrid or diesel/ hybrid. Three battery types were identified as being used in these vehicles. About half use lead-acid batteries, about 40% use nickel-metal hydride, and the rest use lithium-ion. Of the vehicles available at this time, over 60% use lead-acid, 30% use nickel-metal hydride, and the rest use lithium-ion batteries. Some of the vehicles in the planning stage may use fuel cells as part of the power system. 

---