Li-Ion Battery Short-Circuit Protection by Voltage-Driven Switchable Resistance Polymer Layer

Abstract

Safety issues with lithium-ion batteries prevent their widespread use in critical areas of technology. Various types of protective systems have been proposed to prevent thermal runaway and subsequent battery combustion. Among them, thermoresistive systems, representing polymer composites that sharply increase their resistance when the temperature rises, have been actively investigated. However, they are triggered only when the heating of the battery has already occurred, i.e., the system undergoes irreversible changes. This paper describes a new type of protective polymer layer based on the intrinsically conducting polymer poly[Ni(CH3OSalen)]. The response mechanism of this layer is based on an increase in resistance both when heated and when the cell voltage exceeds the permissible range. This makes it possible to stop undesirable processes at an earlier stage. The properties of the polymer itself and of the lithium-ion batteries modified by the protective layer have been studied. It is shown that the introduction of the polymer protective layer into the battery design leads to a rapid increase of the internal resistance at short circuit, which reduces the discharge current and sharply reduces the heat release. The effectiveness of the protection is confirmed by analysis of the battery components before the short circuit and after it.

Thermodynamic model for voltammetric responses in conducting redox polymers

“…Electroactive polymer materials including conducting polymers and redox polymers have a growing influence on the direction of eco-friendly technology development, as they possess good environmental stability and electrical conductivity and have useful mechanical, optical and electronic properties and more. [1][2][3][4] Astonishing development of such materials leads to their wide application in many areas, such as the development of electrode materials and conductive binders for battery applications, [5][6][7][8][9][10] in chemical sensors, 11,12 supercapacitors, [13][14][15] (bio)microelectronics, [16][17][18] safety switches for Li-ion batteries [19][20][21] and so on. Some electroactive polymers and gels are found to be helpful in biomedical applications, especially in drug delivery, artificial tissue development and microfluidics.…”

Potential-Controlled Switchable-Resistance Polymer Layer for Enhanced Safety of Lithium-Ion Batteries with NMC-Type Cathodes

“…In recent reports from our group, 30,31 Beletskii et al proposed the use of a switchable-resistance layer of polymerized nickel salen complex, poly[Ni(CH 3 Osalen)], to protect LFP-based cathodes against overcharging. 30 The approach has garnered interest, with Li et al using a poly(3butylthiophene) layer that successfully protected an NCM811based electrode from overcharging to 4.9 V. 32 Unfortunately, the high onset potential of the resistance change led to unwanted processes in the electrolyte and to irreversible overoxidation of the polymer with significant loss of conductivity and subsequent device failure.…”

“…As compared to the work of Li et al, the approach of Beletskii et al showed protection against short-circuiting as an additional benefit. 31 Poly[Ni(CH 3 Osalen)], which protected LiFePO 4 electrodes 30 by switching to a nonconducting state, is activated when the electrode potential exceeds 4.4 V vs Li/Li + , 33 making it a suitable candidate for protection of NMC-based materials, as the switching of poly[Ni(CH 3 Osalen)] films to nonconducting state conveniently coincides with the upper boundary of the NMC working potential window.…”

“…In recent reports from our group, , Beletskii et al proposed the use of a switchable-resistance layer of polymerized nickel salen complex, poly­[Ni­(CH 3 Osalen)], to protect LFP-based cathodes against overcharging . The approach has garnered interest, with Li et al using a poly­(3-butylthiophene) layer that successfully protected an NCM811-based electrode from overcharging to 4.9 V .…”

“…Unfortunately, the high onset potential of the resistance change led to unwanted processes in the electrolyte and to irreversible overoxidation of the polymer with significant loss of conductivity and subsequent device failure. As compared to the work of Li et al, the approach of Beletskii et al showed protection against short-circuiting as an additional benefit …”