The Lithium-Ion Battery

Chemical stability Stable in battery for long time 

The desirable properties of separators for lithium-ion batteries include low resistance, low shrinkage, and uniform pore structure. 

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One criterion for the anode material is that the chemical potential of lithium in the anode host should be close to that of lithium metal. Carbonaceous materials are therefore good candidates for replacing metallic lithium because of their low cost, low potential versus lithium, and wonderful cycling performance. Practical cells with LiCoOj and carbon electrodes are now commercially available. Finding the best carbon for the anode material in the lithium-ion battery remains an active research topic. 

It was concluded [93, 94J that, on long cycling of the lithium-ion battery, the passivating layer on the carbon anode becomes thicker and more resistive, and is responsible, in part, for capacity loss. 

The above success of SLC product line indicates that design parameters taken as targets for development meet expectations of the lithium-ion battery application. 

The following chapter contains a collection of six papers specifically dedicated to the topic of metal/graphite composites as candidate active materials for the negative electrodes of the lithium-ion batteries of the near future. Editors believe this chapter to be a very first attempt made in the worldwide electrochemical literature to group metal/graphite composite lithium-ion battery developers into a stand-alone section of a book. 

Figure 1. Typical galvanostatic charge (1) - discharge (2) curves of the lithium-ion battery grade graphite, SL-20 (Superior Graphite Co., USA), as tested at C/20 rate in 2016 coin cells having Li metalfoil as counter electrode and electrolyte EC.DMC + lMLiPFf,.

The contribution by Rouzaud et al. teaches to apply a modified version of high resolution Transmission Electron Microscopy (TEM) as an efficient technique of quantitative investigation of the mechanism of irreversible capacity loss in various carbon candidates for application in lithium-ion batteries. The authors introduce the Corridor model , which is interesting and is likely to stimulate active discussion within the lithium-ion battery community. Besides carbon fibers coated with polycarbon (a candidate anode material for lithium-ion technology), authors study carbon aerogels, a known material for supercapacitor application. Besides the capability to form an efficient double electric layer in these aerogels, authors... 

Cost is always a problem when vehicles are made in limited numbers since the parts will cost more. The lithium ion batteries used in Nissan s Altra EV were reported to cost close to six figures. Since electric cars sell for 30,000 or more, a lease can soften the cost of the vehicle. It also isolates the user from expensive battery replacements. Even these subsidized leases required an extra 100 or more in monthly payments compared to a more conventional vehicle. Leasing allows the manufacturers to keep control of the vehicle for repairs and recalls. As the technology changes, a lease keeps customers from having a 2-3 year vehicle that is out of warranty with needing obsolescent, expensive parts. 

Despite the concerns raised by XRD, FQCM, and thermodynamics, the Besenhard model still received extensive support from various experimental observations as summarized below and soon became the prevalent model used by researchers in the lithium ion battery community. 

The rechargeable battery (NiCd, NiMH, and lithium-ion) market for 2003 for portable electronics was around 5.24 billion, around 20% more then 2002. The lithium-ion battery market was around 3.8 billion ( 73%). They are now used in more than 90% of cellphones, camcorders, and portable computers, worldwide, and have also been adopted in power tools recently. 

Separators in lithium ion batteries must separate positive electrodes and negative electrodes to prevent short circuits, and must allow passage of electrolytes or ions. Porous films and nonwoven fabrics of resins are known separators. The lithium ion battery separators are also required to exhibit stable properties at high temperatures such as in charging, and therefore high heat resistance is desired (21). 

Preferably, the lithium ion battery separators range in average fiber diameter from 1-3 p, and in basis weight from 10-20 g m-2 The average fiber diameter and basis weight are substantially the same before and after the pressing. The lithium ion battery separator desirably has a porosity of 40 to 50%, and a thickness of 20-45 p. A lithium ion battery separator with this porosity value provides a low internal resistance and does not pass electrode substances to prevent short circuits. The thickness in the above range is suitable for the separator to be applied to small sized lithium ion batteries (21). 

FIGURE 10.14 Depiction of the time line for the development of the lithium-ion battery system. 

As shown in Table 9, another class of Li batteries includes inorganic solutions in which the solvent may be S02 or S0C12 and in which the electrolyte is LiAlCl4. In these batteries the solvents are also the cathode active material. Another type of Li battery, which is very important because of properties such as high cycle life, rechargeability, and improved safety, is the lithium ion battery. 

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