CN-116190791-B - Low-temperature Prussian white sodium ion battery

Abstract

The invention discloses a low-temperature Prussian sodium ion battery which comprises an anode, electrolyte and a cathode, wherein the anode is made of Prussian Bai Zheng electrode materials, the electrolyte comprises sodium salt, an organic solvent and electrolyte additives, the concentration of the sodium salt in the electrolyte is 0.4-0.7 mol/L, and the electrolyte additives comprise fluorocarbonate and fluoroacetate. The low-temperature Prussian sodium ion battery disclosed by the invention has high specific capacity and long cycle life at the low temperature of-20 ℃.

Inventors

• XIE JIAN
• ZHANG XIAOMEI
• XU ZHENG
• ZHAO XINBING

Assignees

• 浙江大学

Dates

Publication Date

20260505

Application Date

20230303

Claims (9)

1. 1. The low-temperature Prussian white sodium ion battery comprises an anode, electrolyte and a cathode, and is characterized in that: The positive electrode is selected from Prussian Bai Zheng electrode materials; the electrolyte comprises sodium salt, an organic solvent and an electrolyte additive; the concentration of sodium salt in the electrolyte is 0.4-0.7 mol/L; The electrolyte additive includes fluorine substituted carbonates and fluoroacetate; The fluorocarbonate is selected from one or more of fluoroethylene carbonate, bifluoroethylene carbonate and trifluoromethyl ethylene carbonate; The fluoro-acetic ester is selected from one or more of ethyl trifluoroacetate, ethyl difluoroacetate, ethyl monofluoroacetate, methyl trifluoroacetate and propyl trifluoroacetate; The electrolyte additive is used in an amount of 1-8 wt% based on 100% of the total mass of the electrolyte.
2. 2. The low temperature Prussian sodium ion battery of claim 1, wherein: The chemical general formula of the Prussian Bai Zheng pole material is Na 2 M[Fe(CN) 6 , and M is one or more selected from Ni, fe, mn, zn, cu.
3. 3. The low temperature Prussian sodium ion battery of claim 2, wherein: in the chemical general formula of the Prussian Bai Zheng pole material, M is selected from Mn, fe and Ni, and the molar ratio of the Mn, the Fe and the Ni is 2.5-5.0:1.0-1.5:1.
4. 4. The low temperature Prussian sodium ion battery of claim 1, wherein: the sodium salt is selected from one or more of sodium hexafluorophosphate, sodium perchlorate, sodium triflate, sodium bistrifluoromethane sulfonyl imide, sodium bistrifluorosulfonyl imide, sodium tetrafluoroborate and sodium bisoxalato borate; the organic solvent is selected from one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate.
5. 5. The low temperature Prussian sodium ion battery of claim 4, wherein: the organic solvent is selected from a mixed solvent of propylene carbonate and one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate.
6. 6. The low temperature Prussian sodium ion battery of claim 1, wherein: the mass ratio of the fluorocarbonate to the fluoroacetate is 3-9:1.
7. 7. The low temperature Prussian sodium ion battery of claim 6, wherein: The mass ratio of the fluorocarbonate to the fluoroacetate is 3-7:1.
8. 8. The low temperature Prussian sodium ion battery of claim 1, wherein: the electrolyte additive is used in an amount of 5-8wt% based on 100% of the total mass of the electrolyte.
9. 9. The low temperature Prussian sodium ion battery of claim 1, wherein: the negative electrode is selected from a low-voltage negative electrode comprising one or more of metallic sodium, soft carbon, hard carbon/soft carbon composite material and metal/carbon composite material.

Description

Low-temperature Prussian white sodium ion battery Technical Field The invention relates to the field of sodium ion batteries, in particular to a low-temperature Prussian white sodium ion battery. Background With the increasing severity of energy and environmental problems worldwide, development of sustainable clean energy sources such as wind energy, solar energy, tidal energy, etc. has attracted widespread attention, but such clean energy sources have the disadvantage of instability, i.e., variability with weather, climate, environment, and thus long-life, sustainable, inexpensive and environmentally friendly energy storage batteries are required. Currently, among a plurality of candidate batteries, lithium ion batteries have become the mainstream of energy storage batteries due to excellent comprehensive performance, but also face problems of resources, safety and the like. In contrast, the sodium ion battery has the comprehensive advantages of good safety, low cost, rich resources, environmental friendliness and the like, and is very suitable for being applied to large-scale energy storage. As a positive electrode material of the sodium ion battery, the Prussian white material has the advantages of low cost, simple preparation and the like. In addition to the abundant resources, the energy storage battery needs to have all-weather working capability, especially excellent low-temperature performance, so as to meet the use requirements of cold areas. To achieve excellent low temperature performance, innovations in the fields of materials, particularly positive electrode materials, electrolytes, and the like are required. In terms of materials, charge transport can be promoted to some extent by adding a conductive agent with high conductivity, such as carbon nanotubes, or reducing the particle size, thereby improving low temperature properties, but increasing the manufacturing cost of the material. In the aspect of electrolyte, the viscosity of electrolyte is higher at low temperature, which is unfavorable for sodium ion transmission, one of the current solutions is to reduce the viscosity of electrolyte at low temperature by using a special low-temperature organic solvent, but the price of the organic solvent is generally higher, so that the manufacturing cost of a battery is overhigh, and the solvent tends to have unfavorable side reaction with an electrode material, and the other solution is to reduce the viscosity of electrolyte at low temperature by reducing the concentration of sodium salt, but the reduction of the concentration of sodium salt tends to sacrifice the mobility of sodium ion, and the ionic radius and atomic mass of sodium ion per se are larger, so that the mobility of sodium ion per se is lower, especially at low temperature. Disclosure of Invention In view of the above problems in the prior art, the present invention discloses a low temperature Prussian sodium ion battery having a high specific capacity and a long cycle life at a low temperature of-20 ℃. The specific technical scheme is as follows: a low-temperature Prussian sodium ion battery comprises a positive electrode, an organic electrolyte and a negative electrode, The positive electrode is selected from Prussian Bai Zheng electrode materials; the electrolyte comprises sodium salt, an organic solvent and an electrolyte additive; The concentration of sodium salt in the electrolyte is 0.4-0.7 mol/L; The electrolyte additive includes a fluorocarbonate and a fluoroacetate. The invention discloses a sodium ion battery, which uses Prussian white material as a positive electrode, and the low-temperature performance of the sodium ion battery is obviously improved by matching special components (adding special additives comprising fluorocarbonate and fluoroacetate) and electrolyte with special content (controlling the sodium salt content in the electrolyte to be 0.4-0.7 mol/L). The Prussian Bai Zheng pole material adopted in the invention has a stable frame structure, and wide pores and channels are used for diffusing large-size sodium ions, so that the bulk diffusion of sodium ions at low temperature is facilitated, and the low-temperature performance is improved. Preferably, the chemical general formula of the Prussian Bai Zheng electrode material is Na 2M[Fe(CN)6, and M is one or more selected from Ni, fe, mn, zn, cu. Preferably, the Mn element is included in the M, the manganese-based Prussian white has high capacity and high working voltage, and is beneficial to improving the energy density of the battery, and more preferably, the Mn element accounts for 50-70mol% of the total M, and even more preferably, 60mol%. Further preferably, M is selected from Mn, fe and Ni, and the molar ratio of the three is 2.5-5.0:1.0-1.5:1. Experiments show that the sodium ion battery assembled by adopting the positive electrode material with the composition and matching with the organic electrolyte with special composition and special content has more