Process for preparing power type lithium-ion battery anode material by using supercritical/subcritcal water thermal process

Abstract

The invention relates to a process for preparing a power type lithium-ion battery anode material by using a supercritical / subcritcal water thermal process. The process comprises the following steps of: (1) continuously injecting two fluids of a raw material lithium source and a mixed liquid consisting of an iron source / manganese source and a phosphoric acid source into a mixer for mixing; (2) preheating a third fluid formed by deionized water, and adding the third fluid into the mixer to be mixed with the two fluids in the step (1); (3) leading the mixed liquid of the three fluids discharging from the mixer in the step (2) to enter a high temperature and high pressure reaction kettle for carrying out hydrothermal crystallization reaction; (4) cooling a product liquid obtained from the hydrothermal crystallization reaction through a heat exchanger, filtering by a filter to remove large-grain particles and impurities, and leading the filtrate into a solid-liquid separator; (5) continuously collecting particles precipitated in the solid-liquid separator, and drying to obtain dry powder of the battery anode material. The process can be carried out continuously and is beneficial to improving the operation efficiency and reducing the energy consumption.

Description

technical field [0001] The invention relates to a process for preparing positive electrode materials of lithium ion batteries, in particular to a process for preparing positive electrode materials for power lithium ion batteries by super / subcritical hydrothermal process. Background technique [0002] Power lithium-ion batteries with high specific energy, high specific power, high safety, and long cycle life are ideal power sources for future electric vehicles and various electric tools. Among them, lithium iron phosphate (LiFePO 4 ) and lithium manganese phosphate (LiMnPO 4 ), is currently the most concerned and promising cathode material for the preparation of power lithium-ion batteries. However, LiFePO 4 The lithium ion diffusion coefficient of the positive electrode material (1.8*10 -14 cm 2 the s -1 ) and electronic conductivity (10 -9 S cm -1 ) are relatively low, and do not meet the requirements for the positive electrode material of power lithium battery, alt...

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Problems solved by technology

However, LiFePO 4 The lithium ion diffusion coefficient of the positive electrode material (1.8*10 -14 cm 2 the s -1 ) and electronic conductivity (10 -9 S cm -1 ) are relatively low, and do not meet the requirements for the positive electrode material of power lithium battery, although LiFePO 4 The theoretical capacity is as high as 170mA·h·g -1 , but Fe 3+ / Fe 2+ relative to Li + The electrode potential of / Li is only 3.4V, which also limits the LiFePO 4 material development

As for another material LiMnPO 4 , due to Mn 3+ / Mn 2+ relative to Li + The electrode potential of Li / Li is 4.1V, which is just located in the stable electrochemical window of the existing electrolyte system, so the high potential of 4.1V makes this material have the advantage of potential high energy density, while synthesizing LiMnPO 4 Low cost and environmentally friendly; but due to LiMnPO 4 The extremely poor conductivity of the material, which is generally considered an insulator, led to the synthesis of LiMnPO capable of reversible charge and discharge. 4 Very difficult, which limits its development and application

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