NMR studies of cathode materials for lithium-ion rechargeable batteries.

Lithium intercalation or insertion materials have been widely investigated in the search for new electrode materials for use in high-voltage rechargeable batteries.1-6 The first commercial Li-ion rechargeable battery contains the layered materials LiCoO2 (Figure 1) and graphite as the cathode (or positive electrode) and anode (or negative electrode), respectively.7 Although this battery is the current standard in many applications including cell phones and laptops, its slow charge and discharge rates and cost have prevented its use in applications that require cheap high power and capacity, such as hybrid electric vehicles and electric vehicles. The toxicity of Co is also an issue. A wide variety of materials have been studied,5,6 which include doped LiCoO2 phases, layered compounds based on the LiCoO2 structure (e.g., LiNiO2 8 and LiNi0.5Mn0.5O2 9,10),