All-solid-state battery with low interface resistance and preparation method of all-solid-state battery

Abstract

The invention discloses an all-solid-state battery with low interface resistance and a preparation method of the all-solid-state battery, the all-solid-state battery comprises an integrated battery cell, and the integrated battery cell comprises a positive electrode current collector layer, a positive electrode layer, a buffer layer, an organic-inorganic composite electrolyte membrane, a negativeelectrode layer and a negative electrode current collector layer which are arranged in sequence; the organic-inorganic composite electrolyte membrane comprises a high-molecular polymer matrix, a lithium salt and an inorganic filler, the high-molecular polymer matrix is selected from polyvinylidene fluoride or a polyvinylidene fluoride-hexafluoropropylene copolymer; the lithium salt is selected from at least one of LiTFSI, LiFSI, LiClO4, LiPF6, LiBF4, LiBOB, LiDFOB and LiPF2O2. According to the invention, a layer of soft contact is formed between hard interfaces of the positive electrode and the negative electrode, multiple layers of films are integrally formed, different component film structures are seamlessly interconnected, and the interface problem of the solid-state battery is effectively improved. The solid-state battery provided by the invention has excellent capacity exertion and cycling stability, and the preparation method is high in efficiency and low in cost.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to an all-solid-state battery with low interface resistance and a preparation method thereof. Background technique [0002] Traditional lithium-ion batteries use organic liquid electrolytes. Under abnormal conditions such as overcharging and internal short circuits, the batteries tend to heat up, causing the electrolyte to swell, spontaneously ignite or even explode, posing serious safety hazards. [0003] The all-solid-state lithium battery based on solid electrolyte, because of the use of solid electrolyte, does not contain flammable and volatile components, completely eliminates safety hazards such as battery smoke and fire caused by battery leakage, and is known as the safest battery system. In addition, solid-state lithium batteries also have the advantages of high energy density, long cycle life, wide operating temperature range, wide electrochemical window, flexible advantages, ...

AI Technical Summary

Problems solved by technology

[0004] Although the all-solid-state lithium battery shows obvious advantages in many aspects, there are also some urgent problems that need to be solved: the ionic conductivity of the solid electrolyte material is low; the interface impedance between the solid electrolyte / electrode is large, and the interface compatibility is poor; at the same time, The volume expansion and contraction of each material during the charging and discharging process lead to easy separation of the interface; electrode materials that match the solid electrolyte need to be designed and constructed, etc.

[0005] (1) Physical contact problem: point contact is maintained between the electrolyte and the electrode, which makes defects such as cracks and pores easy to occur between the electrolyte and the electrode, and the existence of defects limits the transmission of lithium ions at the interface

[0006] (2) Chemical contact problems: side reactions occur between the electrolyte and the electrode, the stability of the solid-solid interface decreases, the interface impedance increases, and the rapid migration of lithium ions cannot be achieved, etc.

[0007] Research in the field of solid-state batteries in recent years has shown that the contact characteristics of the solid-phase interface in solid-state batteries are relatively poor, and its structure is dense, and the matching of mechanical and chemical performance parameters between electrodes and electrolyte materials is relatively complicated.

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