Reversible reduction of Li₂CO₃

Abstract

ARTICLE This journal isLithium carbonate (Li 2 CO 3 ), either as a product of the conversion reaction or as an important component of the solid-electrolyte interphase (SEI) layer on the anode of a lithium ion (Li-ion) battery, is known to be chemically inactive in both reducing and oxidizing atmospheres. No sufficient evidence was shown that Li 2 CO 3 can be reduced, let alone to recognize its reduction products. Here we clarify that Li 2 CO 3 , as a product of conversion reaction of cobalt carbonate (CoCO 3 ) upon Li insertion, can indeed be further reduced/converted to lithium carbide (Li 2 C 2 ) and lithium oxide (Li 2 O), based on spectroscopic and transmission electron microscopic analyses. These findings will have important guidance to designing electrode (materials) with more stable cycling performances, finding ways to convert some inert compounds to useful electrode materials, and search for electrode materials with higher specific capacities, as well as in understanding the excess reversible capacity of some electrode reactions.

Single‐Phase Mixed Transition Metal Carbonate Encapsulated by Graphene: Facile Synthesis and Improved Lithium Storage Properties

“…and transition metal oxides (TMOs), which manifest intrinsically enhanced safety and high electrochemical activity originating from reversible conversion reactions, are promising candidates of LIBs anode materials . Especially, compared with TMOs, TMCs usually show higher theoretical capacities owing to the facilitated multistep redox reactions of C 4+ in CO 3 2− under the catalysis of freshly generated metal nanoparticles together with the polyvalence‐state electrochemical reaction of the transition metal ions (e.g., CoCO 3 + 2Li + + 2e − ↔ Li 2 CO 3 + Co; Li 2 CO 3 + 5Li + + 5e − ↔ 0.5Li 2 C 2 + 3Li 2 O) . Moreover, because TMCs are often employed as precursors of TMOs, developing TMC electrodes can lower the production cost and increase the preparation efficiency to realize straightforward scaling up.…”

Core–Shelled Low‐Oxidation State Oxides@Reduced Graphene Oxides Cubes via Pressurized Reduction for Highly Stable Lithium Ion Storage

“…Figure S16 (Supporting Information) exhibits the discharge capacities of RGO at a current density of 890 mA g −1 ; it is clear that the discharge capacities of either RGOA or RGO reduced by hydrazine are much lower than those of SC‐CoO@RGO and SC‐Fe 3 O 4 @RGO cubes. Therefore, the excess discharge capacity could not be simply attributed to RGO contribution, while it might be resulted from several positive factors: (1) an efficient synergistic effect between RGO and metal oxides, (2) reversible formation/dissolution of polymeric gel‐like films, (3) reversible transformation of solid‐electrolyte interphase layer . In addition, the enhanced cycling stability in present of RGO is investigated by examining their final structures after cycles (Figure S17, Supporting Information).…”

Recent Progress and Challenges of Micro‐/Nanostructured Transition Metal Carbonate Anodes for Lithium Ion Batteries

“…Where did the additional capacity originate from exactly? In recent years, many studies have focused on this abnormal capacity . As schematic in Figure , two‐step reaction mechanism including the redox conversion of MCO 3 (Step I) and the reduction of Li 2 CO 3 to Li 2 O and Li 2 C 2 (Step II), is proposed and identified based on the experimental results.…”