Magento 1.9 | Add category navigation on sidebar

open your sidebar .phtml files ( in my case is left.phtml )

Then add the jquery , for control the acordion:



and last but not the list , the CSS

/* Custom Category Navigation */

.cat_navigation ul{max-height:0em; display: block; overflow: hidden; -webkit-transition: all 1.3s ease-in; -moz-transition: all 1.3s ease-in; -o-transition: all 1.3s ease-in; transition: all 1.3s ease-in;
}
.cat_navigation .li_active_main ul.active_main{max-height:100em;}
.cat_navigation li{padding: 5px 3px !important;}

a.active_sub{ color:#206682; }

.arrow_ind{float:left; margin-right:.5em; color:#206682;}

.li_active_main .arrow_ind{ -ms-transform: rotate(90deg); /* IE 9 */ -webkit-transform: rotate(90deg); /* Safari */ transform: rotate(90deg); }

.cat_navigation > li.main_li:hover{ cursor:pointer; }