Alleviating Voltage Hysteresis by Interconnecting Truncated Octahedral LiNi0.5Mn1.5O4 Cathode Particles Using Exfoliated Graphene

Abstract

High-voltage spinel LiNi_0.5Mn_1.5O₄ (LNMO) has been highlighted as one of the most promising cathode materials for next-generation Li-ion batteries. However, its performance is known to have shortcomings, i. e., voltage hysteresis induced by the increasing impedance of LNMO during electrochemical cycling at high voltage operation. This paper demonstrates an innovative design of LNMO cathode materials to alleviate voltage hysteresis by combining unique characteristics of truncated octahedral LNMO with 2D exfoliated graphene (EG). The exposed (100) plane of truncated LNMO particles is known to have superior Li⁺ ion conduction. Meanwhile, the (111) plane is known to have excellent resistance to metal dissolution. Moreover, it was revealed that the presence of the EG framework as an interconnection aide could significantly improve the charge transfer process, helping to alleviate the voltage polarization. The sample with optimum LNMO-EG composition shows a stable electrochemical performance with a capacity retention of 86.56 % after 300 cycles of charge-discharge measurement at 1 C while exhibiting almost 3 times lower voltage hysteresis (0.233 mV/cycle) compared to the pristine LNMO (0.678 mV/cycle). This result demonstrates that combining the uniqueness of truncated LNMO and 2D EG can be a promising strategy to improve the electrochemical performance of LNMO cathode materials for next-generation batteries.