Lithium–sulfur (Li–S) batteries hold great promise in the field of power and energy storage due to their high theoretical capacity and energy density. However, the “shuttle effect” that originates from the dissolution of intermediate lithium polysulfides (LiPSs) during the charging and discharging process is prone to causing continuous irreversible capacity loss, which restricts the practical development. Beyond the traditional Li–S batteries based on the dissolution-diffusion mechanism, novel Li–S batteries based on solid-phase conversion exhibit superior cycling stability owing to the absolute prevention of polysulfides shuttling. Radically eliminating the formation of polysulfides in cathodes or cutting off their diffusion in electrolytes are the two main ways to achieve solid-phase conversion. Generally, direct transformation of sulfur to final Li₂S without polysulfides participation tends to occur in short-chain sulfur polymers or special molecular forms of sulfur substances, while specific regulations of liquid electrolytes with solvating structure or solid-state electrolytes can effectively suppressing the polysulfides dissolution. In this review, we systematically organized and summarized the structures and approaches to achieve solid-phase conversion, introduce their preparation methods, discuss their advantages and disadvantages, and analyze the factors and effects of different structures on battery performances. Finally, the problems demanding a prompt solution for the practical development of solid-phase conversion-based Li–S batteries, as well as their future development direction, are suggested.

Ionic gel electrolyte retains the characteristics of non-volatilization, non-flammability and outstanding electrochemical stability of ionic liquid, and shows good electrochemical performance combined with the excellent characteristics of different matrix materials, which is considered to be the best choice to achieve high energy density and safety at the same time. In this paper, a flexible and self-healing ionic gel electrolyte was prepared using a solvent-assisted method based on a zteric ion (ZI) copolymer. Abundant hydrogen bonds and synergistic interaction of ions in the electrolyte system endowed it with remarkable self-healing ability. An ionic conductivity of 9.06 × 10⁻⁴ S cm⁻¹ at room temperature was achieved. Moreover, the lithium-ion transference number was increased to 0.312. The ionic gel electrolyte has a self-healing function which guarantees long-term tolerance during charging and discharging. The capacity retention rate of the Li//LiFePO₄ battery was 96% after 155 cycles at 0.1 C at 60 °C. This polymer electrolyte is expected to solve the problem of increasing polarization, which is caused by the low lithium ions migration number in ionic liquid electrolyte. And ultimately, it gave rise to a good rate performance.

The water-based binder has the advantages of non-toxic, non-flammable, small odor, and no pollution to the environment. However, there are problems such as low bond strength and poor battery cycle life of commonly used binders on the market. In this paper, the acrylic binder is modified. In addition, acrylic acid/methacrylic acid, acrylonitrile, and octadecyl acrylate/octadecyl methacrylate are copolymerized at high temperature, and a new binder for graphite anode is successfully developed. The binder can significantly improve the affinity between the graphite anode and the electrolyte and the integrity of the graphite particles during the cycle, so that the battery has better electrochemical performance. During the charge and discharge cycle of 1 C, the graphite anode coated with PAANa as a binder was able to cycle 360 cycles and remain stable, which is far better than the 192 cycles of the commercial binder LA133. It is proved that the experimental formula has a certain commercial application prospect.

The water-based binder has the advantages of non-toxic, non-flammable, small odor and no pollution to the environment. However, there are problems such as low bond strength and poor battery cycle life of commonly used binders on the market. In this paper, the acrylic binder is modified. Acrylic acid/methacrylic acid, acrylonitrile, and octadecyl acrylate/octadecyl methacrylate are copolymerized at high temperature, and a new binder for graphite anode is successfully developed. The binder can significantly improve the affinity between the graphite anode and the electrolyte and the integrity of the graphite particles during the cycle, so that the battery has better electrochemical performance. During the charge and discharge cycle of 1 C, the graphite anode coated with PAANa as a binder was able to cycle 360 cycles and remain stable, far better than the 192 cycles of the commercial binder LA133. It is proved that the experimental formula has a certain commercial application prospect.

Ionic gel electrolyte retains the characteristics of non-volatilization, non-flammability and outstanding electrochemical stability of ionic liquid, and shows good electrochemical performance combined with the excellent characteristics of different matrix materials, which is considered to be the best choice to achieve the high energy density and safety at the same time. In this paper, a flexible and self-healing ionic gel electrolyte is prepared by solvent-assisted method based on a zteric ion (ZI) copolymer. Abundant hydrogen bonds and synergistic interaction of ions in the electrolyte system endowed it with wonderful self-healing ability. The ionic conductivity of 9.06×10-4 S cm-1 at room temperature was achieved. Besides, the tLi+ was also increased to 0.312. The self-healing function of the ionic gel electrolyte ensured the long-term tolerance of the SHIGE. The capacity retention rate of the Li//LiFePO4 battery is 96% after 155 cycles at 0.1 C at 60 oC. This polymer electrolyte is expected to solve the problem of increasing polarization，which is caused by the low lithium ions migration number in ionic liquid electrolyte. And ultimately, it gives rise to a good rate performance.