Lithium metal negative electrode, preparation method thereof and lithium-ion battery

A lithium metal negative electrode and lithium ion battery technology, applied in the field of lithium metal negative electrodes, can solve the problems of hindering lithium ion migration, capacity attenuation, and coulombic efficiency reduction, so as to improve cycle stability and safety, inhibit growth, and promote electrodeposition Effect

Inactive Publication Date: 2020-12-29
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the lithium metal negative electrode is prone to uncontrollable lithium dendrite growth due to the uneven deposition of lithium during the charging and discharging process. The lithium dendrites will pierce the separator and contact the positive electrode, causing a short circuit, resulting in a decrease in the safety of lithium ions; Otherwise, lithium dendrites will destroy the SEI film on the surface of the lithium metal negative electrode, and the repeated rupture and repair process of the SEI layer will lead to continuous consumption of active lithium and electrolyte, and a continuous decrease in Coulombic efficiency; in addition, during the dissolution process of lithium dendrites, close to the substrate Due to the higher current density, the needle-shaped lithium at the site is preferentially dissolved, resulting in electrochemically inert and chemically active "dead lithium". The accumulation of "dead lithium" will hinder the migration of lithium ions, resulting in a sharp increase in the polarization of lithium-ion batteries. The capacity decays rapidly, and the cycle stability of lithium-ion batteries decreases

Method used

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  • Lithium metal negative electrode, preparation method thereof and lithium-ion battery
  • Lithium metal negative electrode, preparation method thereof and lithium-ion battery
  • Lithium metal negative electrode, preparation method thereof and lithium-ion battery

Examples

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preparation example Construction

[0027] see figure 1 , a preferred embodiment of the present invention also provides a method for preparing the lithium metal negative electrode, comprising the following steps:

[0028] In step S11, a substrate is provided, and the material of the substrate is lithium metal.

[0029] Step S12 , under a mixed atmosphere of nitrogen and argon, sputtering the substrate with tin metal as a target to form a composite interface layer on the substrate, thereby obtaining the lithium metal negative electrode.

[0030] Wherein, the lithium metal negative electrode includes a substrate and a composite interfacial layer deposited on the substrate. The substrate is lithium foil, and the composite interface layer includes lithium tin alloy and lithium nitride.

[0031] During sputtering, nitrogen gas reacts with the substrate to form the lithium nitride. At the same time, during the sputtering process, argon gas collides with electrons and ionizes into argon ions, and the argon ions bomb...

Embodiment 1

[0042] In the first step, lithium metal sheet and tin metal are provided.

[0043] In the second step, magnetron sputtering is performed on the lithium metal sheet with tin metal as a target under a mixed atmosphere of nitrogen and argon to obtain a lithium metal negative electrode. Among them, the vacuum degree of the chamber before sputtering is set to 10 -4Pa, the volume ratio flow of nitrogen and argon in the sputtering process is set to 1:1, the total gas flow is set to 80sccm, the power of magnetron sputtering is set to 80W, the air pressure is set to 4Pa, and the time of magnetron sputtering is set to 20min.

[0044] Assemble the battery:

[0045] The lithium metal negative electrode prepared in Example 1 was assembled into a Li-Li symmetrical battery in an argon-protected glove box. Among them, the separator is PP, and the electrolyte is 1.0M lithium bistrifluoromethanesulfonylimide (LiTFSI) dissolved in 1,3-dioxolane (DOL) and ethylene glycol at a volume ratio of 1...

Embodiment 2

[0047] The preparation method of the lithium metal negative electrode in this example is the same as the preparation method in Example 1.

[0048] Assemble the battery:

[0049] The lithium metal negative electrode prepared in Example 2 and lithium iron phosphate (LiFePO 4 ) positive electrode assembly full battery, electrolyte and additives are the same as in Example 1.

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Abstract

The invention provides a lithium metal negative electrode which comprises a substrate and a composite interface layer arranged on the substrate, the substrate is made of lithium metal, and the composite interface layer is made of lithium tin alloy and lithium nitride. The lithium metal negative electrode can inhibit the growth of lithium dendrites. The invention also provides a preparation methodof the lithium metal negative electrode and a lithium-ion battery.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a lithium metal negative electrode, a preparation method of the lithium metal negative electrode and a lithium ion battery. Background technique [0002] Lithium metal has a very high theoretical specific capacity (3860mAh / g), low redox potential (-3.040Vvs.H + / H 2 ) and lower density (0.534g / cm 3 ), becoming the most ideal anode material for lithium-ion batteries. However, the lithium metal negative electrode is prone to uncontrollable lithium dendrite growth due to the uneven deposition of lithium during the charging and discharging process. The lithium dendrites will pierce the separator and contact the positive electrode, causing a short circuit, resulting in a decrease in the safety of lithium ions; Otherwise, lithium dendrites will destroy the SEI film on the surface of the lithium metal negative electrode, and the repeated rupture and repair process of the SEI laye...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/134H01M4/1395H01M4/04H01M10/42H01M10/0525
CPCH01M4/0426H01M4/134H01M4/1395H01M10/0525H01M10/4235Y02E60/10
Inventor 贺艳兵俞静石凯王翠翠吕伟李宝华康飞宇
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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