SHANGHAI, May 15 (SMM) - Transactions remained thin in nickel sulphate market as ternary precursor plants still restocked only as needed. The production schedules of precursor plants did not improve and some even lowered their output. Price negotiations between sellers and buyers were in a stalemate. Some nickel sulphate producers had to sell at discount as inventory backlogs tightened their cash flows. Although demand did not show signs of strong recovery, lithium price rally left downstream enterprises more willing to make inquiries. As such, the price drop of nickel sulphate may slow down this week.