Developing　hard　carbon　with　a　high　initial　Coulombic　efficiency　(ICE)　and　very　good　cycling　stability　is　of　great　importance　for　practical　sodium-ion　batteries　(SIBs).　Defects　and　oxygen-containing　groups　grown　along　either　the　carbon　edges　or　the　layers,　however,　are　inevitable　in　hard　carbon　and　can　cause　a　tremendous　density　of　irreversible　Na+　sites,　decreasing　the　efficiency　and　therefore　causing　failure　of　the　battery.　Thus,　eliminating　these　unexpected　defect　structures　is　significant　for　enhancing　the　battery　performance.　Herein,　we　develop　a　strategy　of　applying　a　soft-carbon　coating　onto　free-standing　hard-carbon　electrodes,　which　greatly　hinders　the　formation　of　defects　and　oxygencontaining　groups　on　hard　carbon.　The　electrochemical　results　show　that　the　soft-carbon-coated,　free-standing　hard-carbon　electrodes　can　achieve　an　ultrahigh　ICE　of　94.1%　and　long　cycling　performance　(99%　capacity　retention　after　100　cycles　at　a　current　density　of　20　mA　g(-1)),　demonstrating　their　great　potential　in　practical　sodium　storage　systems.　The　sodium　storage　mechanism　was　also　investigated　by　operando　Raman　spectroscopy.　Our　sodium　storage　mechanism　extends　the　＂adsorption-intercalation-pore　filling-deposition＂　model.　We　propose　that　the　pore　filling　in　the　plateau　area　might　be　divided　into　two　parts:　(1)　sodium　could　fill　in　the　pores　near　the　inner　wall　of　the　carbon　layer;　(2)　when　the　sodium　in　the　inner　wall　pores　is　close　to　saturation,　the　sodium　could　be　further　deposited　onto　the　existing　sodium.