The present invention provides an excellent nonaqueous electrolytic solution capable of improving low-temperature and high-temperature cycle properties and load characteristics after high-temperature charging storage, an electrochemical element using it, and an alkynyl compound used for it. The nonaqueous electrolytic solution of the present invention comprises containing at least one alkynyl compound represented by the following general formula (I) in an amount of from 0.01 to 10% by mass in the nonaqueous electrolytic solution.
R.sup.1(O).sub.nX.sup.1R.sup.2(I)
(In the formula, X.sup.1 represents a group C(O), a group C(O)C(O), a group S(O).sub.2, a group P(O) (R.sup.3), or a group X.sup.3S(O).sub.2O. R.sup.1 represents an alkenyl group, a formyl group, an alkyl group, an acyl group, an arylcarbonyl, an alkanesulfonyl group, an alkynyloxysulfonyl group, an arylsulfonyl group, a dialkylphosphoryl group, an alkyl(alkoxy)phosphoryl group, or a dialkoxyphosphoryl group; R.sup.2 represents an alkynyl group or an alkynyloxy group; R.sup.3 represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an alkoxy group, an alkenyloxy group, an alkynyloxy group, or an aryloxy group; n indicates 0 or 1.

A surface modified lithium titanate and preparation method thereof is provided. In the surface modified lithium titanate, the deactivating groups distributed on the surface of the lithium titanate are OPRRR, OP(OR)RR, OP(OR)(OR)R, and OP(OR)(OR)(OR), where R, R and R are identical or different C1C8 alkyl or alkenyl groups. The deactivating groups are bonded to the lithium titanate via a bond or a bridge. The exemplary surface modified lithium titanate can effectively lower its catalytic activity, reduce the gassing of lithium ion batteries, and therefore improve the high temperature storage and high temperature cycle performance of lithium titanate batteries. The exemplary preparation method is simple, has great repeatability, a low cost, low pollution to the environment, and is suitable for industrial production.