Preparation of N-doped porous carbon matrix in a solid–liquid coexisted NaCl template and its applications in Li–S batteries

Li–S batteries have beenconsidered as the most desirable candidate for next-generation batteries because of their high energy density and low cost, although the problems of the insulating nature of S and Li2S and the “shuttle effect” of polysulfides in Li–S batteries have to be addressed. In this work, we propose NaCl templates and a solid–liquid coexistence strategy to synthesize an N-doped carbon matrix with interconnected micro-mesoporous structure. Benefiting from the critical state of solid–liquid coexistence at the melting point of NaCl and a pretreatment by pressure, a unique porous structure with an interconnected network of micropores and mesopores is obtained. The micropores can prevent the dissolution of polysulfides, the mesopores can increase the S loading, and the interconnected pore network can significantly improve the usage of active materials. As a result, the cathode with the N-doped carbon matrix shows improved electrochemical performances.