Negative electrode material, negative electrode slurry, battery cell, low-temperature-resistant battery and preparation method thereof

Abstract

The invention discloses a negative electrode material, negative electrode slurry, a battery cell, a low-temperature-resistant battery and a preparation method thereof. The negative electrode material comprises a negative electrode active material and an inorganic solid electrolyte, the negative electrode active material comprises artificial graphite doped with hard carbon, the weight ratio of the hard carbon in the negative electrode active material is 5-30%, and the content of the inorganic solid electrolyte is 5-20% of the weight of the hard carbon. By adding the solid electrolyte, the solid electrolyte and hard carbon are mixed in the artificial graphite and materials are mixed with different particle sizes, the porous negative electrode dressing area is prepared, and the problems that the porosity of a pole piece is low after a traditional artificial graphite negative electrode is rolled, the migration impedance of a battery cell at low temperature is large, and the ionic conductivity at low temperature is low are solved. The hard carbon material is a porous material, and the porosity is further increased by combining the hard carbon material with the solid electrolyte.

Description

technical field [0001] The invention relates to the technical field of battery materials, in particular to a negative electrode material, a negative electrode slurry, a battery cell, a low temperature resistant battery and a preparation method thereof. Background technique [0002] With the energy crisis brought about by the excessive development and utilization of fossil fuels, various metal-ion secondary batteries, especially lithium-ion secondary batteries, have gradually become the The most promising energy storage technology in the field of new energy. [0003] At present, the low-temperature resistance of lithium-ion batteries can meet the requirements of conventional low-temperature use environments (about -20°C), but in cold regions below -20°C or even -40°C, the application requirements have yet to be improved. This is because in a low-temperature environment, the chemical reaction activity decreases, and the kinetic characteristics of the graphite negative electro...

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Problems solved by technology

This is because in a low-temperature environment, the chemical reaction activity decreases, and the kinetic characteristics of the graphite negative electrode deteriorate. During the charging process, the electrochemical polarization of the negative electrode intensifies, causing the migration of lithium ions to slow down. The lithium ions on the surface of the negative electrode have not yet been embedded in In the negative electrode, it has been reduced to metallic lithium and precipitated on the surface of the negative electrode to form lithium dendrites, which is the so-called "lithium precipitation". The lithium dendrite precipitation will pierce the separator and cause a short circuit in the battery, resulting in battery failure.

[0004] In the prior art, one of the most commonly used ways to solve the poor charging performance at low temperature is to improve the low temperature performance of the single cell, mainly by adding film-forming additives and solvents to the electrolyte to improve the interface impedance and ionic conductivity at low temperature. For example, an electrolyte and a battery disclosed in the application number 201710627925.2, the electrolyte contains electrolytes, additives and an organic solvent containing sec-butyl methyl carbonate, which can improve the discharge capacity of the battery at low temperatures and the storage performance at high temperatures to a certain extent , but the minimum can only be used in a low temperature environment of -20°C to 0°C, and still cannot be used in a low temperature environment of -40°C to -20°C

[0005] Another way is to use the heating system mode to ensure that the battery module can be charged normally and safely and quickly at low temperature. For example, a low-temperature charging and heating system and method for a vehicle power battery disclosed in the application number 201410855832.1 uses an internal circulation fan to make the battery The internal heat is more uniform, which increases the consistency of the battery ambient temperature, but the battery management unit, off-board charger, heater, and fan included in the heating system reduce the energy density of the system, and need to consume its own heating energy. further reduced battery life

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