Hydrothermal synthesis of Li₂MnSiO₄: Mechanism and influence of precursor concentration on electrochemical properties

The effect of the precursor concentration on the electrochemical properties of hydrothermally synthesized Li₂MnSiO₄ is investigated. The synthesis mechanism is investigated by analyzing the chemical reaction as a function of reaction time. Results show that Li₂MnSiO₄ is synthesized by a dissolution-recrystallization mechanism through an intermediate Mn(OH)₂ phase. Smaller particles produced from higher concentration precursor solution. Li₂MnSiO₄ with smaller particle size shows larger initial discharge capacity than that of Li₂MnSiO ₄ with larger particle size which are synthesized from lower concentration precursor solution. A maximum initial charge capacity of 323 mAh g^-1 and discharge capacity of 177 mAh g^-1 are achieved through hydrothermal synthesis using a 2.1 M solution, while it shows serious capacity fading. Li₂MnSiO₄ synthesized from 2.1 M solution shows 32% of capacity retention after 20 cycles. Smaller particle size of Li₂MnSiO₄ can induce more serious side reaction with electrolyte due to its larger specific surface area, which results in structural instability during charge-discharge tests.