Problem Conversion failed when converting date and/or time from character string

alter PROCEDURE [dbo].[sp_ShowTimetable]   
(
 @date datetime
)
as
begin


DECLARE @cols AS NVARCHAR(MAX), @query  AS NVARCHAR(MAX);


SELECT @cols= ISNULL(@cols + ',','') + QUOTENAME(Period_Name)
  FROM (Select Period_Name from tbl_TimetablePeriod where Active=1) AS x;

 select @cols

SET @query= 'Select Location_Name,'+@cols+'
from
(
 Select  temp2.Course_Name+'', '' + temp2.CLASSNAME+'', ''+temp2.TEACHER as TimeTableClass, temp2.Period_Name,TL.Location_Name  from

  (Select  TT.*,TC.Course_Name,TB.Name AS CLASSNAME,TE.First_Name +'' ''+ ISNULL(TE.Last_Name,'''') AS TEACHER,TP.Period_Name
   from tbl_timetable TT JOIN tbl_Course TC ON TT.CourseId=TC.Course_Id
   JOIN tbl_Batch TB on TT.ClassId=TB.Batch_Id
   JOIN tbl_Employees TE on TT.empid=TE.empid
   JOIN tbl_Timetableperiod TP on TT.periodid=TP.Period_Id Where TT.date= convert(datetime,''+@date+'',121))


 as temp2 Right Outer Join  tbl_timetablelocation TL ON temp2.Loactionid =TL.Location_Id
) src
pivot
(
  max(TimeTableClass)
  for Period_Name in ('+@cols+')
) piv'

Exec(@query)

select @query


End