Lithium ion battery, preparation method thereof and electric vehicle

Abstract

The invention provides a lithium ion battery, a preparation method and an electric vehicle. The lithium ion battery comprises a positive electrode, a negative electrode and a composite solid electrolyte layer positioned between the positive electrode and the negative electrode, wherein the composite solid electrolyte layer comprises a positive electrode side solid electrolyte layer, a negative electrode side solid electrolyte layer and an intermediate layer solid electrolyte layer clamped between the positive electrode side solid electrolyte layer and the negative electrode side solid electrolyte layer; the positive electrode side solid electrolyte layer, the negative electrode side solid electrolyte layer and the intermediate layer solid electrolyte layer all contain first inorganic solidelectrolyte; the intermediate solid electrolyte layer further comprises second inorganic solid electrolyte. The composite solid electrolyte can delay the problem that lithium dendrites penetrate through the electrolyte layer to cause micro short circuit in the battery, and can avoid the problem that the electrolyte layer is reduced by the lithium dendrites to fail, so that the cycle performance and the safety performance of the whole battery are greatly improved.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, in particular to lithium ion batteries and electric vehicles. Background technique [0002] Sulfide solid-state electrolyte materials in all-solid-state lithium batteries have excellent Li + Conductivity and processing performance have attracted much attention. Common sulfide solid electrolyte materials include Li 2 S-SiS 2 , Li 2 S-P 2 S 5 , Li 2 S-GeS 2 -P 2 S 5 Wait. The electrolyte layer in the all-solid-state lithium battery based on the sulfide solid-state electrolyte in the current literature and research is Li 2 S-SiS 2 , Li 2 S-P 2 S 5 , Li 2 S-GeS 2 -P 2 S 5 one or more of. In 2011, the research team of Kamaya, Tokyo Institute of Technology, Toyota Motor Corporation and High Energy Accelerator Research Institute (Nature Materials, 2011, 10:682-686) developed the superionic conductor with the highest ionic conductivity so far—Li 10 GeP 2 S 12 , room temperature ...

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Problems solved by technology

[0003] The existing technology has the following major disadvantages: ① If only Li 10 GeP 2 S 12 As the electrolyte layer, metal lithium cannot be used as the negative electrode, and matching other negative electrode materials will greatly reduce the energy density of the battery system; ②Li 2 S-P 2 S 5 The interface stability between the electrolyte and lithium metal is high, but if only Li 2 S-P 2 S 5 When the electrolyte matches the lithium metal anode, the Li 2 S-P 2 S 5 It is easy to form nano-lithium dendrites inside and cause micro-short circuit of the battery

③The double-layer electrolyte structure can avoid Li 10 GeP 2 S 12 direct contact with lithium metal, but from Li 2 S-P 2 S 5 The nano-lithium dendrites formed in the electrolyte layer will still interact with Li 10 GeP 2 S 12 contact, and due to Li 10 GeP 2 S 12 The reduction products with nano-lithium dendrites have good electronic conductivity, which will lead to Li 10 GeP 2 S 12 Layers are continuously reduced, eventually leading to Li in the double-layer electrolyte structure 10 GeP 2 S 12 layer loses Li + conduction, battery failure

④ Li 10 GeP 2 S 12 The "Ge" in is a rare metal, expensive, and Li 10 GeP 2 S 12 Large-scale application in the battery system will inevitably lead to an increase in battery cost

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