Polyanion-containing cathodes

Although simple oxides such as LiCo02, LiNi02, and LiMn204 with highly oxidized redox couples respectively) were able to offer high ceU 

LiMnP04 is of particular interest because of the environmentally benign manganese and the favorable position of the redox couple at 4.1 V vs,  

However, Li2MnSi04 suffers from poor cycle life, which is most likely caused by Jahn-TeUer distortion and loss of crystallinity during cycling. In addition, these materials also suffer from poor electronic conductivity and the consequent slow reaction kinetics. Therefore, various synthetic routes such as sol-gel and microwave-solvothermal methods have been employed to prepare nanostractured materials, and coating with electronically conductive agents has been carried out to improve their electrochemical performance [127-129]. 

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The third member of orthosilicate family of cathode materials, Li2CoSi04, has not attracted a lot of attention - probably due to several reasons. The first could be due to expected much higher voltages of cobalt-containing polyanions, the second might be due to even worse intrinsic conductivity expected for Li2CoSi04 and, last but not the least, cobalt-based orthosilicates cannot be justified as a cheap or environment-friendly material. 

As the potential of an insertion compound-based lithium battery is determined by the difference between the chemical potentials of electrodes (Eq. 1.6), the crystal chemistry of the cathode governs the cell voltage. As an example. Fig. 4.3 illustrates the role of the polyanions, i.e., (P04) and, in iron-containing... 

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