Lmfp cathode materials with improved electrochemical performance

Abstract

Particulate LMFP cathode materials having high manganese contents and small amounts of dopant metals are disclosed. These cathode materials are made by milling a mixture of precursor materials in a wet or dry milling process. Preferably, off- stoichiometric amounts of starting materials are used to make the cathode materials. Unlike other high manganese LMFP materials, these cathode materials provide high specific capacities, very good cycle life and high energies even at high discharge rates.

Description

technical field [0001] The present invention relates to olivine lithium manganese iron phosphate cathode materials for lithium batteries and methods of making such materials. Background technique [0002] Lithium batteries are widely used as primary and secondary batteries for vehicles and many types of electronic equipment. These batteries typically have high energy and power densities. [0003] LiFePO 4 Known as a low-cost material, it is thermally stable and has low toxicity. It can also exhibit very high rate capacity (high power density) when made with small particle size and good carbon coating. For these reasons, LiFePO 4 Has found use as a cathode material for lithium batteries. However, LiFePO 4 Has a relatively low operating voltage (3.4 V vs. Li+ / Li) and thus has a low energy density relative to oxide cathode materials. In principle, the operating voltage and thus the energy density can be achieved by replacing some or all of the iron with manganese to prod...

AI Technical Summary

Problems solved by technology

However, structural stability and charge transport are adversely affected by the replacement of Fe with Mn, and the resulting specific capacity has dropped significantly below the theoretical level

Energy and power densities are also disappointingly low

In addition, the battery cycle performance of LMFP electrodes is usually lower than desired because of the capacity loss upon cycling.

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