由于水凝胶电解质的力学性能差且水在低温下会结冰,限制了水凝胶电解质在储能器件和电子导体方面的应用.加入大豆分离蛋白,以丙烯酰胺和甲基丙稀酰乙基磺基甜菜碱为单体,在二甲基亚砜/H20的混合溶液和氯化锂的存在下,通过自由基聚合制备了高力学性能、高导电性的防冻有机水凝胶.其具有良好的电导率(最高37.5 mS/cm)、良好的力学性能(最大应力69 kPa,最大应变762.5％)、优良的韧性和抗疲劳性能,对应变和温度具有良好的响应性、宽的传感窗口及稳定性,具有应用于传感器领域的潜力.另外,所制备的超级电容器在20℃和-20℃均表现出良好的电化学性能,20℃时,0.2 A/g电流密度下,超级电容器的比电容为62.1 F/g,5 A/g的高电流密度下,比电容仍有30 F/g;同时具有良好的抗冻性能和循环稳定性,-20℃时,0.5 A/g电流密度下,超级电容器循环10 000圈后仍能保持20℃下容量的92％.

Hydrogel electrolytes have high room‐temperature conductivity and can be widely used in energy storage device. However, hydrogels suffer from the inevitable freezing of water at subzero temperatures, resulting in the diminishment of their conductivity and mechanical properties. How to achieve high conductivity without sacrificing hydrogels’ flexibility at subzero temperature is an important challenge. To address this challenge, a new type of zwitterionic polymer hydrogel (polySH) electrolytes is fabricated. The anionic and cationic counterions on the polymer chains facilitate the dissociation of LiCl. The antifreezing electrolyte can be stretched to a strain of 325% and compressed to 75% at −40 °C and possesses an outstanding conductivity of 12.6 mS cm −1 at −40 °C. A direct hopping migration mechanism of hydrated lithium‐ion through the channel of zwitterion groups is proposed. The polySH electrolyte‐based‐supercapacitor (SC) exhibits a high specific capacitance of 178 mF cm −2 at 60 °C and 134 mF cm −2 at −30 °C with a retention of 81% and 71% of the initial capacitance after 10 000 cycles, respectively. The overall merits of the electrolyte will open up a new avenue for advanced ionic conductors and energy storage device in practical applications.

Polymer hydrogel electrolytes with high conductivity can be used in extremely low temperatures such as −40 °C. In article number 2009438, Libin Liu and co-workers report a new type of antifreezing zwitterionic polymer hydrogel (polySH) electrolyte. The zwitterionic groups are favorable for the dissociation of LiCl. A Li+(H2O)n hydration structure can hop and migrate through the channel of the zwitterionic group. The excellent antifreezing property and conductivity make the polySH electrolyte applicable in ion conductors and energy storage devices.

Traditional liquid electrolytes are volatile, flammable, and easy to leak, which makes the energy storage device easy to burn and explode in the case of overcharge and short circuit. Here, by utilizing the active P-H bond of a flame retardant (DOPO) to graft onto the polymer chain, flame-retardant organic gel electrolytes were fabricated to address these issues. The gel electrolyte had good ionic conductivity of 4 mS cm(-1) at 20 degrees C and good flame retardant ability. By changing the molar ratio of the monomers and the salt concentrations, the mechanical strength of the gel electrolyte could be adjusted (maximum stress approximate to 28 KPa, maximum strain approximate to 305 %). The transport mechanism of lithium ions in the gel polymer electrolyte was proposed. The gel electrolyte-assembled supercapacitor (SC) possessed better electrochemical properties than that of SC assembled by liquid electrolyte. Importantly, the gel-based SC remained basically unchanged under multiple bending cycles. Additionally, the gel electrolyte had good low-temperature tolerance (0.1 mS cm(-1) at -40 degrees C). The gel electrolyte-assembled SC could work normally in the temperature range of -20 to 60 degrees C. The multiple advantages of gel electrolyte expand the applications in ionic conductor and energy storage devices.

The design and fabrication of conductive hydrogels with high stretchability, compressibility, self-healing properties and good adhesion remains a significant challenge. We have fabricated composite hydrogels by random polymerization of acrylic acid (AA) and dopamine (DA) in the presence of multi-walled carbon nanotubes (MWCNTs). The π-π interaction between DA and MWCNTs makes MWCNTs stably and homogenously dispersed in water. The fabricated PAA-PDA/CNT composite hydrogels possess relatively high mechanical strength (maximum Young’s modulus: 800 kPa) and can be stretched to 1280% strain and compressed to 80% strain. The multiple hydrogen bonding formed between functional groups of PAA-PDA and MWCNTs can effectively dissipate energy and quickly achieve self-healing. The composite hydrogels also show good adhesion and can easily adhere to various inorganic or organic surfaces. In addition, the hydrogel reveals stable strain sensitivity and can be used as skin sensors.

The P(DAC-co-AM)/CNT hydrogels synthesized by random copolymerization possess multi-functions due to the reversible ionic interaction and hydrogen bond interactions.

A novel polyampholyte gel electrolyte with high ionic conductivity and high mechanical strength was developed and was suitable for supercapacitors.