Synergistic Effect of TMSPi and FEC in Regulating the Electrode/Electrolyte Interfaces in Nickel-Rich Lithium Metal Batteries
journal contributionposted on 23.02.2022, 15:37 by Xiaoyan Zhang, Yufei Ren, Juyan Zhang, Xiangkun Wu, Chunhai Yi, Lan Zhang, Suitao Qi
Nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) with respect to Li metal can enhance the energy density of lithium batteries effectively. However, the unstable Li deposition, together with the dissolution and migration of transition metal (TM) ions toward the anode deteriorate the cycle performance of NCM811||Li battery, especially when commercial carbonate electrolyte is used. Herein, tris(trimethylsilyl)phosphite (TMSPi) and fluoroethylene carbonate (FEC) are used to construct a dual-additive electrolyte, by which both electrodes can be protected. It is found that TMSPi can be preferentially adsorbed on the cathode surface through its strong coordination with Ni4+, playing the role as a HF scavenger and suppressing TM ions dissolution, as well as mitigating the structural degradation of the cathode effectively. When it comes to the lithium anode, the presence of TMSPi may lead to side reactions with Li metal, accompanied by fast dendrite growth. The introduction of FEC could facilitate the formation of stable electrode/electrolyte interfaces on both sides. Particularly, reduce the direct contact between TMSPi and Li anode, thus ameliorate the incompatibility issue. Consequently, the NCM811||Li cell with dual-additive demonstrates excellent capacity retention of 81.2% after 500 cycles at 1 C rate. As a sharp contrast, it only retains 13.9% in the one with blank electrolyte. The findings of this work provide a new insight into enhancing the cycle performance of NCM811||Li system via the synergistic effect between additives.
Read the peer-reviewed publication
fast dendrite growth1 c rate8 </ sub1 </ subunstable li depositiontmspi may leadlithium batteries effectivelyfec could facilitatecommercial carbonate electrolyte2 </ sublithium anodefluoroethylene carbonatecathode effectivelyli metalli anodeelectrolyte interfacesblank electrolyteadditive electrolytework providetransition metalthus amelioratesynergistic effectstructural degradationstrong coordinationside reactionssharp contrastrich liniretains 13preferentially adsorbednew insightions towardincompatibility issuehf scavengerenergy densitydirect contactcycle performancecathode surfaceanode deteriorate500 cycles