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Cobalt precursor produced through a loop precipitation process for Li-ion battery application

IP.com Disclosure Number: IPCOM000251554D
Publication Date: 2017-Nov-09

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Cobalt precursor produced through a loop precipitation process for Li-ion battery application

This disclosure relates to cobalt precursors for Lithium Cobalt Oxide (LCO) cathode materials for rechargeable lithium batteries and a special loop process to produce these precursors. More particularly, this disclosure focuses on supplying large particle size cobalt precursors with ultra-low impurity levels, with the aim that the final LCO cathode materials have a high electrode press density, making them particularly suitable for energy demanding applications like batteries for smart phones and tablets.

LCO cathode materials are generally synthesized by solid state reactions, wherein a source of lithium - for example Li2CO3 - is blended with a Co containing precursor, and the mixture is fired in an oxygen containing atmosphere - for example air - to yield the final lithium cobalt oxide powder. Generally, LCO has roughly the stoichiometry LiCoO2 and its crystal structure is an ordered rock salt structure where the cations order into 2-dimensional Li and Co layers. The space group is R-3M.

Despite of some inherent limitations like poor safety and high cost, LiCoO2 still is the most applied cathode material for rechargeable lithium batteries. There is a strong demand driven by customer expectations to increase the energy density of rechargeable lithium ion batteries, especially for portable electrical devices such as smart phones and tablets applications. Although Lithium Nickel Manganese Cobalt ternary oxides (NCM) cathode materials, especially high Ni content NCM or Nickel-Cobalt-Aluminum (NCA) materials have the advantage of a higher specific capacity than LCO, the volumetric energy density of NCM is still not as high as LCO, mainly because of its lower electrode press density. Other drawbacks of high Ni content NCM include bulging issues and safety concerns in a Li-ion battery. So, LCO cathode material still dominates in the market of small Li-ion batteries for consumer electronic devices. 

One way to improve the specific energy density of a Li-ion battery is packaging as much cathode and anode active materials as possible (in weight) into a battery: the more LCO material in the cathode electrode with a specific volume, the more electrical energy can be stored in the Li-ion battery. The desirable way to increase the LCO loading is by using large and dense LCO particles, which can minimize the dead volume of a cathode electrode having the same percentage of active material. The amount of LCO loaded in the cathode electrode can be defined by the electrode press density.

The other way to improve the energy density is to increase the charge voltage, which requires more robust cathode materials which can be charged at higher voltages. Problems appearing or becoming more severe if the charging voltage is increased are (a) low safety, (b) poor storage properties during storage of charged batteries at elevated temperature and (c) poor cycling stability. ...