Synthesis and Electrochemical Performance Enhancement of Li2MnSiO4 Cathode Material for Lithium-Ion Batteries via Mn-Site Ni Doping

Abstract

In exploring the potential of Li₂MnSiO₄ as a cathode material for lithium-ion batteries (LIBs), the key challenges often involve enhancing electronic conductivity and lithium-ion diffusion rates. To address these issues, this paper proposes the combination of solid-state doping and a two-step calcination process to successfully prepare the Li₂Mn_1−xNi_xSiO₄ series of cathode materials, where Ni substitutes Mn at different doping amounts (x = 0, 0.02, 0.04, 0.06, 0.08). The use of chemically equivalent Ni²⁺ ions to replace Mn²⁺ ions is an effective method. Since the ionic radius of Ni²⁺ is smaller than that of Mn²⁺, this substitution can create more voids in the lattice structure. These increased voids provide smoother channels for the transport of electrons and lithium ions, thereby improving the material's electrical conductivity. At a Ni doping amount of 0.06, the material exhibits optimal electrochemical performance, achieving a discharge capacity of 155 mAh g⁻¹ at 0.1 C, significantly superior to undoped lithium manganese silicate. The doping of Mn sites with Ni significantly improves the conductivity and lithium-ion diffusion capabilities of Li₂MnSiO₄, revealing the tremendous potential of doping strategies in optimizing the performance of LIBs cathode materials.