Lithium-ion battery and its preparation method and electric vehicle

Abstract

The application provides a lithium-ion battery, a preparation method and an electric vehicle, the lithium-ion battery includes a positive electrode, a negative electrode, and a composite solid electrolyte layer between the positive electrode and the negative electrode, and the composite solid electrolyte layer includes a positive electrode side solid electrolyte layer , the negative electrode side solid electrolyte layer and the intermediate layer solid electrolyte layer sandwiched 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 Each layer contains a first inorganic solid electrolyte, and the intermediate solid electrolyte layer also includes a second inorganic solid electrolyte. The composite solid electrolyte can delay the problem of lithium dendrites penetrating through the electrolyte layer and cause micro-short circuits inside the battery, and can avoid electrolyte The layer is reduced and failed by lithium dendrites, which greatly improves the cycle performance and safety performance of the entire battery.

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 ion conductivity so far—Li 10 GeP 2 S 12 , room temperature io...

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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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