Exploiting Cation Intercalating Chemistry to Catalyze Conversion-Type Reactions in Batteries.

Effective harvest of electrochemical energy from insulating compounds serves as the key to unlocking the potential capacity from many materials that otherwise could not be exploited for energy storage. Herein, an effective strategy is proposed by employing LiCoO 2 , a widely commercialized positive electrode material in Li-ion batteries, as an efficient redox mediator to catalyze the decomposition of Na 2 CO 3 via an intercalating mechanism. Differing from traditional redox mediation processes where reactions occur on the limited surface sites of catalysts, the electrochemically delithiated Li 1- x CoO 2 forms Na y Li 1- x CoO 2 crystals, which act as a cation intercalating catalyzer that directs Na + insertion-extraction and activates the reaction of Na 2 CO 3 with carbon. Through altering the route of the mass transport process, such redox centers are delocalized throughout the bulk of LiCoO 2 , which ensures maximum active reaction sites. The decomposition of Na 2 CO 3 thus accelerated significantly reduces the charging overpotential in Na-CO 2 batteries; meanwhile, Na compensation can also be achieved for various Na-deficient cathode materials. Such a surface-induced catalyzing mechanism for conversion-type reactions, realized via cation intercalation chemistry, expands the boundary for material discovery and makes those conventionally unfeasible a rich source to explore for efficient utilization of chemical energy.