Charging and discharging method for improving energy supplementing speed and energy efficiency of lithium-carbon dioxide battery

Abstract

The invention discloses a charging and discharging method for improving the energy supplementing speed and the energy efficiency of a lithium-carbon dioxide battery. Aiming at the problems of low energy complementing speed, low energy efficiency, short battery life and the like when the existing lithium-carbon dioxide battery is charged by adopting constant current density, the invention provides a charging method adopting constant voltage, namely, under the conditions of fixed cut-off capacity and discharge current density, the lithium-carbon dioxide battery is charged to the cut-off capacity at the constant voltage. Compared with traditional constant-current-density charging, the constant-voltage charging method provided by the invention has the advantages that the charging speed (the charging time is shortened) and the energy efficiency of the lithium-carbon dioxide battery are remarkably improved. The method has excellent universality, is suitable for lithium-carbon dioxide batteries of various different catalyst systems, effectively overcomes the limitation of constant current charging, and is more beneficial to promoting the practical application of the lithium-carbon dioxide batteries.

Description

Technical Field

[0001] The present invention relates to the field of lithium-carbon dioxide batteries, and in particular to a charge and discharge method for improving the energy replenishment speed and energy efficiency of lithium-carbon dioxide batteries. Background Art

[0002] The continued consumption of fossil energy and the resulting massive greenhouse gas emissions (especially carbon dioxide) have become a major challenge hindering the sustainable development of human society. Among numerous carbon management technologies, lithium-carbon dioxide (LiCO) batteries (LiCO) have attracted significant attention due to their unique dual functionality: not only does this technology achieve efficient energy storage and controlled release through the reversible electrochemical conversion of CO, but it also opens up new avenues for the resourceful utilization of CO, making LiCO batteries a highly promising next-generation green energy storage technology. However, the slow kinetics and poor reversibility of the CO reduction and evolution reactions in LiCO batteries directly lead to problems such as slow recharge rates and low energy efficiency. Currently, LiCO batteries are typically recharged using a constant current density. While charging at a lower constant current density can achieve higher energy conversion efficiency and longer cycle life, it suffers from the limitation of slow recharge rates. Increasing the current density, while accelerating recharge rates, inevitably exacerbates electrode polarization, reduces energy efficiency, and shortens battery life, severely hindering the development of LiCO batteries. The traditional constant current density charging mode is difficult to meet the dual needs of rapid energy replenishment and efficient energy storage, becoming a key technical bottleneck restricting the practical application of lithium-carbon dioxide batteries. Summary of the Invention

[0003] In response to the above-mentioned problems in the prior art, the present invention aims to provide a charge and discharge method that improves the energy replenishment speed and energy efficiency of lithium-carbon dioxide batteries, thereby promoting the practical application of lithium-carbon dioxide batteries.

[0004] The solution of the present invention is: using Ketjen black as a conductive agent, polytetrafluoroethylene as a binder, and a positive electrode catalyst to make a positive electrode sheet to assemble a lithium-carbon dioxide battery. Under the conditions of fixed cut-off capacity and discharge current density, charging to the cut-off capacity at a constant voltage can improve the charging and energy efficiency of the lithium-carbon dioxide battery.

[0005] As a preferred technical solution, the electrocatalyst in the positive electrode sheet is a metal-based catalyst such as Pd, Pt, Ir, Ru, Mo, Cu, Ni, Co, Fe, and Mn.

[0006] As a preferred technical solution, the mass fraction of the electrocatalyst is 5-95%, the mass fraction of Ketjen black is 0-95%, and the mass fraction of polytetrafluoroethylene is 5-30%.

[0007] As a preferred technical solution, the cut-off capacity of the charge and discharge test is 100-20000 μAh / cm 2 , discharge current density is 10~10000 μA / cm 2 , the constant charging voltage is 3.5~4.5V.

[0008] Advantages of the present invention: 1. Compared with constant current density charging, charging at a constant voltage has a high charging speed and energy efficiency, which is more in line with actual application requirements.

[0009] 2. Charging at a constant voltage can significantly improve the cycle stability of lithium-carbon dioxide batteries, allowing the batteries to have a longer service life.

[0010] 3. Charging at a constant voltage has excellent universality. Whether the lithium-carbon dioxide battery is assembled using precious metal-based catalysts or inexpensive transition metal-based catalysts, the constant voltage charging mode can significantly improve the overall performance of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 The battery of Example 1 has a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , the charging current density is 100 μA / cm 2 When the constant current density charge and discharge test is carried out, the time-voltage curve is obtained; Figure 2 The battery of Example 1 has a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , the charging current density is 100 μA / cm 2 When the constant current density charge and discharge test is carried out, the energy efficiency evolution curve is obtained; Figure 3 The battery of Example 1 has a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , the charging current density is 100 μA / cm 2 When the constant current density charge and discharge test is carried out, the charging time evolution curve is obtained; Figure 4 The battery of Example 1 has a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , when the charging voltage is constant at 4.0 V, the charge and discharge test is carried out, and the time-voltage evolution curve obtained; Figure 5 The battery of Example 1 has a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , when the charging voltage is constant at 4.0 V, the charge and discharge test is carried out, and the energy efficiency evolution curve obtained; Figure 6 The battery of Example 1 has a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 When the charging voltage is constant at 4.0 V, the charge and discharge test is carried out, and the charging time evolution curve is obtained. DETAILED DESCRIPTION

[0012] The present invention will be further described below with reference to the following examples. The examples and their results are intended only to illustrate the present invention and should not, and do not, limit the present invention as described in detail in the claims.

[0013] Example 1: A charge-discharge method for improving the energy recharge rate and energy efficiency of a lithium-carbon dioxide battery, comprising the following steps: using 45% by mass of Ketjen carbon as a conductive agent, 10% by mass of polytetrafluoroethylene as a binder, and 45% by mass of reduced graphene oxide loaded with ruthenium nanoparticles as an electrocatalyst to prepare a positive electrode sheet, assembling a lithium-carbon dioxide battery, and performing a charge-discharge operation at a cutoff capacity of 200 μAh / cm 2 When 100 μA / cm 2 The battery was discharged at a constant current density of 1.5 V and charged at a constant voltage of 4.0 V.

[0014] (1) If Figure 1 As shown, at a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , the charging current density is 100 μA / cm 2 When the constant current density charge and discharge test was carried out, the battery could only cycle 91 times.

[0015] (2) If Figure 2 As shown, at a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 , the charging current density is 100 μA / cm 2 When constant current density charge and discharge tests were carried out, the battery energy efficiency was less than 69%.

[0016] (3) If Figure 3 As shown, at a cut-off capacity of 200 μAh / cm2 , the discharge current density is 100 μA / cm 2 , the charging current density is 100 μA / cm 2 When the constant current density charge and discharge test is carried out, the battery charging time is 2 hours.

[0017] (4) If Figure 4 As shown, at a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 When the charging voltage is constant at 4.0 V, the charge and discharge test is carried out and the battery can cycle stably for 134 cycles.

[0018] (5) If Figure 5 As shown, at a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 When the charging voltage is constant at 4.0 V, the charge and discharge test is carried out and the battery energy efficiency is higher than 71%.

[0019] (6) If Figure 6 As shown, at a cut-off capacity of 200 μAh / cm 2 , the discharge current density is 100 μA / cm 2 When the charging voltage is constant at 4.0 V, the charge and discharge test is carried out. The first charging time of the battery is 0.23 hours, and the charging time of the battery is no more than 2 hours during the entire 134 cycles.

[0020] This invention provides a charge-discharge method for improving the recharge rate and energy efficiency of lithium-carbon dioxide batteries. Under constant cutoff capacity and discharge current density, the battery is charged at a constant charging voltage. Compared with constant current density charging, lithium-carbon dioxide batteries under a constant voltage charging regime achieve higher energy efficiency and recharge rate, making them more suitable for practical applications.

[0021] The basic principles, main features and advantages of the present invention are shown and described above. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements are intended to fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A charge-discharge method for improving the energy recharge rate and energy efficiency of a lithium-carbon dioxide battery, characterized by: A lithium-carbon dioxide battery is assembled using Ketjen black as a conductive agent, polytetrafluoroethylene as a binder, and a positive electrode catalyst to make a positive electrode sheet. Under the conditions of fixed cutoff capacity and discharge current density, it is charged to the cutoff capacity at a constant voltage to improve the charging speed and energy efficiency of the lithium-carbon dioxide battery.

2. A charge-discharge method for improving the energy replenishment speed and energy efficiency of a lithium-carbon dioxide battery according to claim 1, characterized in that: The electrocatalyst in the positive electrode sheet is a metal-based catalyst such as Pd, Pt, Ir, Ru, Mo, Cu, Ni, Co, Fe, and Mn.

3. The charge-discharge method for improving the energy replenishment speed and energy efficiency of a lithium-carbon dioxide battery according to claim 1, characterized in that: The mass fraction of the electrocatalyst is 5-95%, the mass fraction of Ketjen black is 0-95%, and the mass fraction of polytetrafluoroethylene is 5-30%.

4. A charge-discharge method for improving the energy replenishment speed and energy efficiency of a lithium-carbon dioxide battery according to claim 1, characterized in that: The cut-off capacity of the charge and discharge test is 100~20000 μAh / cm 2 , discharge current density is 10~10000 μA / cm 2 , the constant charging voltage is 3.5~4.5V.

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